1.1 Background. Olmsted County prepared this Strategic Highway Safety Plan (
SHSP) as part of a ...... 8.1 A4- Support Legislation to change seat belt usage
from a .... Figure 4.8 Confirmation Light in Dakota County .... Dodge County
CSAH 22.
Olmsted County
Highway Safety Plan September 2009
Submitted to:
008MKE
TB072009
Table of Contents 1. Introduction ....................................................................................................................1-1 2. Comprehensive Crash Analysis .....................................................................................2-1 3. Safety Emphasis Areas..................................................................................................3-1 4. Safety Strategies............................................................................................................4-1 5. Detailed Crash Analysis .................................................................................................5-1 6. Safety Projects ...............................................................................................................6-1 7. Safety Policies................................................................................................................7-1
Section 1
Introduction
1. Introduction 1.1 Background Olmsted County prepared this Strategic Highway Safety Plan (SHSP) as part of a comprehensive effort to reduce the number of fatal and life changing injury crashes that occur on the County’s system of highways. Other elements of this comprehensive approach include working with the Southeast Minnesota Towards Zero Death organization, participating in a fatal crash review committee along with members of law enforcement and emergency medical service providers and coordinating with the Sheriff’s Department in order to identify opportunities for targeted enforcement campaigns. The traffic safety priorities identified in this SHSP are the results of a data driven analysis of the approximately 12,000 crashes that occurred in Olmsted County over the five year period between 2003 and 2007. This analytical process was consistent with the guidelines developed by the Federal Highway Administration in response to the safety initiatives contained in SAFETEA-LU (the most recent Federal Highway legislation) and with the process that produced Minnesota’s SHSP. The primary objective of this Plan is to identify a specific set of safety oriented projects (the implementation of specific strategies at specific locations) and to have these projects directly linked to the causation factors associated with the most severe crashes on the County’s system of highways. The basic steps in the process to link crash causation to mitigating strategy to location on the County highway system include (Figure 1.1): •
conducting a comprehensive crash analysis in order to disaggregate all crashes in Olmsted County by system (State vs. local), severity (in order to focus on fatal plus A type injury), location (urban vs. rural), intersection related vs. road departure and crash type (Chapter 2)
•
identifying Olmsted County’s Safety Emphasis Area’s – a subset of twentytwo categories of crash causation dealing with driver behavior, infrastructure and emergency medical services (Chapter 3)
•
identifying a short list of high priority safety strategies that have been identified as being effective at reducing specific types of crashes (Chapter 4)
•
identifying locations (segments, horizontal curves and intersections) on the County’s highway system that are most at-risk based on a variety of system wide factors, including; severe crashes, design features, traffic volume and land use (Chapter 5)
•
identifying safety improvement projects (specific strategies at specific locations) that would be eligible for funding from the State’s Highway Safety Improvement Program – HSIP (Chapter 6)
INTRODUCTION
1-1
Select Critical Emphasis Areas Adopt Mission, Vision & Goal
Develop Comprehensiv e List of
Shortlist of Strategies
Effectiveness & Implementatio
Develop High Priority Safety
Safety Strategies Workshop
Critical Strategie s
Detailed Crash Analysis
Develop Safety Investment
Identify Safety Related Policies Figure 1.1 Olmsted County Safety Plan Process
This process is basically a multi-step prioritization exercise – the causes of the most frequent type of severe crashes in Olmsted County were identified, this resulted in identifying a short list of high priority safety emphasis areas, this generated a short list of safety strategies which were then applied to Olmsted County’s system of highways in order to identify specific safety improvement projects at the locations that were identified as being most at-risk.
1.2 Traffic Safety is an Important National Issue Fatal and life-changing traffic crashes are a public health epidemic in the United States, with 42,642 people killed in traffic crashes in the U.S. in 2006 — an average of nearly 117 people killed every day (see Figure 1.2). In the same year, approximately 2.5 million people were injured. Over the past 15 years, the number of fatalities has slowly but steadily increased while the traffic fatality rate has remained at approximately 1.45 fatalities per hundred million vehicle miles of travel (HMVMT) (see Figure 1.3).
INTRODUCTION
1-2
Persons Killed in Traffic Crashes 60,000 1,060
52,627 1,024
50,000 45,000
875
1,000
47,087
980
42,642 42,013
44,525 42,589
40,000 National
1,100
51,093
800
777
39,250
35,000
615
644
30,000
650
538
558
25,000
900
655
700 600
568 494
20,000
500
Minnesota
55,000
1,200
400 National
15,000
300
Minnesota
10,000
200
5,000
100
0
0 1965
1970
1975
1980
1985
1990
1995
2000
2005
Year
Figure 1.2 Trend in Traffic Fatalities in Minnesota and Across the Nation
All of this has occurred after significant and steady decreases in traffic fatalities and fatality rate through the 1970s and 1980s. It was in reaction to this trend that the Federal Highway Administration (FHWA) and the American Association of State Highway and Transportation Officials (AASHTO) recognized a need for a new approach to traffic safety. The response has been a renewed focus on addressing the most severe crashes, including fatal and life changing crashes, using a data driven process, encouraging the Four Es – Education, Enforcement, Engineering, and Emergency Medical Services (EMS) – to work in coordinated efforts, and setting new goals to measure progress. Currently, the FHWA and the AASHTO set a goal to reduce the number of traffic fatalities by 1,000 each year for the next twenty years. The FHWA has determined that achieving this goal will only be accomplished if they partner with the individual States in order to be more successful at implementing projects and programs that target the factors contributing to the greatest number of fatal and severe crashes. In a similar fashion, the Minnesota Department of Transportation (Mn/DOT) recognized that it must engage the local agencies in strategic safety planning efforts because a review of the crash data reveals that approximately one-half of statewide traffic fatalities occur on the local road system and rural local roads are likely the most at-risk part of the system.
1.3 Minnesota’s Plan to Improve Traffic Safety Similar to what happened at the National level; there were significant reductions in the number of traffic fatalities in Minnesota with corresponding decreases in the fatal crash rate from a peak in the 1970s. Between 1980 and 2000 there was a slightly increasing trend in
INTRODUCTION
1-3
Trends in Traffic Fatality Rate 6.0
National Minnesota
5.5
5.0
5.2
5.0
Fatality Rate (100MVM)
4.74 4.4 4.1
4.0
3.35
3.5
3.0
3.0
3.35 2.76
3.0
2.51 1.91
2.0
1.98
1.64 1.51
1.0
0.0 1960
1.42 0.99 0.87
1.27 1.07
1965
1970
1975
1980
1985
1990
1995
2000
2005
2010
Year
Figure 1.3 Trend in Traffic Fatality Rate in Minnesota and Across the Nation Figure 1.4 Review of Traffic Fatalities by CEA for District 6 and Olmsted County Driver Behavior Emphasis Areas
Unbelted*
AlcoholRelated
SpeedingRelated
Young Driver Involved
Single Vehicle Run-Off Road
Intersection
Headon
3,008
1,271 (52%)
1,068 (36%)
850 (28%)
718 (24%)
965 (32%)
1,004 (33%)
611 (20%)
368
168 (54%)
108 (29%)
124 (34%)
89 (24%)
142 (39%)
99 (27%)
78 (21%)
State Highway
217 (59%)
87 (45%)
38 (18%)
62 (29%)
40 (18%)
68 (31%)
66 (30%)
50 (23%)
Local Roads
151 (41%)
81 (68%)
70 (46%)
62 (41%)
49 (32%)
74 (49%)
33 (22%)
29 (19%)
Total Fatalities
Statewide Total District 6
Infrastructure Emphasis Areas
* Percentage for unbelted fatalities determined using vehicle occupant fatalities instead of all fatalities. Note: Shaded cells indicate the District or Olmsted County was five percentage points above the state average. Source: 2007 Minnesota SHSP using 2001-2005 crash data.
the number of traffic fatalities while the fatal crash rate flattened, primarily due to increasing levels of vehicle miles traveled (the denominator in the crash rate equation). However, since 2000, both the number of traffic fatalities and the fatal crash rate have dropped by approximately 20%. The Minnesota Department of Transportation in cooperation with the Minnesota Department of Public Safety developed the Minnesota Comprehensive Highway Safety Plan (CHSP) in December 2004. This Plan set forth a unified approach to address traffic fatalities in
INTRODUCTION
1-4
Minnesota, created a Statewide goal for reducing traffic fatalities, identified key crash types to target (known as Critical Emphasis Areas) and identified high priority strategies that formed the focus of future programs and projects (known as Critical Strategies). The 2004 CHSP was updated to the 2007 Minnesota Strategic Highway Safety Plan (SHSP) so that the Minnesota Plan complies with requirements in the most recent Federal legislation — SAFETEA-LU. The 2007 Minnesota SHSP updated the statewide traffic safety goal, analyzed crash data in each Mn/DOT District and county, and also included outreach to the Mn/DOT districts and counties to provide education about the key findings in the 2007 Minnesota SHSP. The 2007 Minnesota SHSP established a new traffic safety goal — reduce the number of traffic fatalities to 400 or fewer by 2010. And in setting a new goal, the 2007 Minnesota SHSP recognized the importance of reducing fatalities and life changing injuries in rural areas and on the local system. Without addressing these two important parts of Minnesota’s transportation system, it is unlikely that Minnesota will achieve its new traffic safety goal. However, fatal and life changing crashes on rural and/or local are spread across a large system (more than 50,000 miles of roads), resulting in low density of severe crashes. As a result, the Minnesota SHSP called for adoption of proactive and system-wide deployment of low-cost strategies that can be cost-effectively deployed across many miles of roadways.
1.3.1 Priorities Identified in the 2007 Minnesota SHSP for District 6 and Olmsted County The update of the Minnesota’s safety plan included a review of fatal and life changing crashes in each Critical Emphasis Area (CEA) for each District and on the local roads for each county. For District 6 (see Figure 1.4) — the Mn/DOT District that includes Olmsted County — the SHSP highlighted that unbelted drivers, alcohol-related, speeding and young drivers and single vehicle road departure crashes were over represented. For the entire system of local roads in District 6, the priorities are the same – crashes involving driver behavior and single vehicle run-off-the-road (SVROR) crashes. The analysis in the SHSP of the local roads in each of the counties that makes up District 6 revealed that Olmsted County has the highest number of both total crashes and severe crashes in comparison to the eleven counties in District 6. Olmsted County was listed as a high priority in District 6 for the following CEA’s: Reducing Impaired Driving, Speeding Related and all of the infrastructure related categories – Single Vehicle Road Departure, Intersections and Head-On crashes. This analysis provided the initial insight relative to priorities for Olmsted County’s infrastructure improvements – the focus of this Strategic Highway Safety Plan (SHSP). The Minnesota SHSP review of Olmsted County’s local road crashes in the infrastructure CEA’s shows that SVROR accounted for 38% of the fatalities and 19% of fatalities were intersection-related. In addition, of the severe (fatal plus A type injury) in Olmsted County, lane departure crashes (SVROR plus head-on crashes) accounted for 33% and intersection related crashes accounted for 54%. This supports an initial focus on lane departure and intersection related crashes as priorities in Olmsted County.
INTRODUCTION
1-5
Section 2
Comprehensive Crash Analysis
2.
Comprehensive Crash Analysis
2.1
County Wide Crash Overview
The analysis of crashes in Olmsted County was conducted using the Minnesota Crash Mapping Analysis Tool (MnCMAT). MnCMAT is a map-based computer application that provides a crash data base for every county in Minnesota. In MnCMAT individual crashes are spatially located by reference point along all roadways in each county and over 70 pieces of information are provided for each crash, including; route, reference point, day/date/time, severity, crash causation, road characteristics and driver condition. For Olmsted County, a data set consisting of five years of crash records was assembled; this data set includes a total of 11,151 crashes. In safety analysis, it is recommended to include more than one year of data in order to reduce the possibility of looking at a year that is unusual, to include as many years as necessary to produce a data set that will provide statistically reliable results, but to be careful going too far back in history because of a concern that conditions might have changed (for example, roads could have been reconstructed, STOP signs added, speed limits changed, etc.). For Olmsted County, it was concluded that a data set covering five years with over 11,000 crash records would be sufficient to provide the desired level of statistical reliability. The data set indicates that Olmsted County averages approximately 2,230 crashes per year on all systems of roads. Of these, 13 involve fatalities (0.6%), 54 involve severe injuries (2.4%) and 1,462 are property damage only (65%). Disaggregating these crashes by highway system results in the following (Figure 2.1): •
52% of fatal crashes on the local system (County, municipal and township)
•
70% of severe injury crashes on the local system
•
59% of all crashes on the local system
COMPREHENSIVE CRASH ANALYSIS
2-1
5 Year Crashes Olmsted County 11,151 334
Example All – % Severe – %
State System 4,596 – 41% 111 – 33%
Interstate 259 – 5% 9 – 8%
Expressway 4,207 – 92% 95 – 86%
Local System 6,555 – 59% 223 – 67%
2-Lane 130 – 3% 7 – 6%
Urban 5,416 – 83% 120 – 54%
Unsignalized 1,220 – 23% 34 – 28%
All Way Stop 141 – 12% 1 – 3%
Other 2,625 – 48% 59 – 49%
Rural 1,139 – 17% 103 – 46%
Signalized 1,571 – 29% 27 – 23%
Thru-Stop 1,044 – 83% 33 – 97%
Right Angle – 619 (59%), 19 (58%) Rear End – 116 (11%), 4 (12%) Left Turn – 109 (10%), 2 (6%) Sideswipe (Same) – 42 (4%), 0 (0%)
Road Departure 447 – 39% 47 – 46%
On Curve 171 – 38% 19 – 40% Right Angle – 566 (36%), 11 (41%) Rear End – 516 (33%), 7 (26%) Left Turn – 207 (13%), 5 (19%) Sideswipe (Opp.) – 84 (5%), 0 (0%)
Intersection 425 – 37% 31 – 30%
Other 276 – 62% 28 – 60% Right Angle – 149 (35%), 16 (52%) Left Turn – 42 (10%), 4 (13%) Rear End – 76 (18%), 2 (6%) Ran Off Road – 66 (16%), 2 (6%)
Figure 2.1 Olmsted County Crash Disaggregation
Source: MnCMAT Crash Data, 2002-2006. Severe is fatal plus serious injury crashes
This distribution reinforces the importance of Olmsted County’s efforts to implement a safety improvement program – the majority of crashes in Olmsted County are on the local system, not on the State’s system of highways which have previously been the focus of deployment of safety improvement projects. The next level of analysis focuses solely on the approximately 1,300 crashes per year on the local system (MnDOT does their own analysis of the State’s system and develops their own highway safety projects). Of these 1,300 crashes, approximately 1,083 (83%) occur in urban areas and 228 (17%) occur in rural areas. However, when only severe crashes are considered, there is almost an even split with 24 crashes (54%) in urban areas and 21 crashes (46%) in rural areas. In urban areas, 244 crashes (23%) occur at STOP sign controlled intersections, 314 crashes (29%) occur at traffic signals and the remainder of the urban crashes (48%) is not intersection related. The primary crash type at these urban intersections is a right angle, 59% at the STOP controlled and 36% at the traffic signals. It should be noted that these fractions of angle crashes are more than double the expected values for similar intersections across Minnesota. In rural areas, crashes are almost evenly distributed between the 89 road departure crashes (39%) and the 85 intersection crashes (37%). Key factors associated with these crashes include; 38% of the road departure crashes occurred in horizontal curves and 35% of the intersection crashes were right angle. Both of these statistics are much greater than expected, the fraction of curve related road departure crashes is about four times higher than the fraction of rural mileage that is on a horizontal curve and the fraction of angle crashes is about twice the value at similar rural STOP controlled intersections in Minnesota.
COMPREHENSIVE CRASH ANALYSIS
2-2
Section 3
Safety Emphasis Areas
3.
Safety Emphasis Areas
In the late 1990’s The American Association of State Highway and Transportation Officials (AASHTO) and the Federal Highway Administration (FHWA) conducted an evaluation of national efforts to reduce the number of traffic related fatalities through the on-going Highway Safety Improvement Program. Both AASTO and FHWA concluded that the state’s efforts had not been sufficiently effective to lower the number of fatal crashes and two key factors were identified; the states efforts were not focused on the primary factors causing the fatal crashes so that too many of the safety projects that were being implemented were not the result of a data driven mapping process that directly linked crash causation to effective mitigative strategies. In response, AASHTO and FHWA developed a recommended safety program development process that included disaggregating system wide crash data into twenty-two categories (emphasis areas) dealing with Drivers, Special Users, Vehicles, Highways, Emergency Services and Management. The objective of this first step is to help agencies identify the safety priorities for their system using the specific crash data for their system. In addition, the identification of safety emphasis areas will also assist in subsequent steps in the process by helping reduce the universe of possible safety strategies to the short list associated with specific safety emphasis areas. This process was first conducted in Minnesota during the preparation of the State’s Strategic Highway Safety Plan (SHSP) and resulted in the identification of the following State wide safety emphasis areas: •
Driver Behaviors – Young drivers, Aggressive driving, Impaired driving and Seat belt usage
•
Highways – Road departure and Intersections
An identical process was followed in Olmsted County that resulted in the distribution of severe crashes among AASHTO’s twenty-two emphasis areas illustrated in Figure 3.1. This exercise indicates the categories where crashes are either over represented based on a comparison to State wide averages or where there is large enough number of crashes to represent an opportunity for a substantial crash reduction. As a result of this exercise, Olmsted County has adopted the following emphasis areas as the highest priority for safety on the local system of highways. •
Driver Behavior – Young drivers, Aggressive driving, Impaired driving and Seat belt usage
•
Special Users - Bicyclists
•
Highways – Road Departure (County Highways) and Intersections (County Highways and City Streets)
SAFETY EMPHASIS AREAS
3-1
Emphasis Area
Drivers
Statewide Percentage (2007 SHSP)
Percentage of Severe Crashes
Olmsted County CEAs
Young drivers
24%
34%*
9
Unlicensed drivers
11%
--
Older drivers
18%
22%
Aggressive driving
28%
25%*
9
Impaired driving
36%
15%*
9
Alert drivers
19%
14%
--
--
Seat belt usage
52%
30%*
Pedestrians
8%
3%
Bicyclists
1%
4%
Motorcycles
9%
19%
Heavy vehicles
15%
7%
--
--
Safety awareness
Special Users
Vehicles
Safety enhancements
Highways
Train collisions
1%
0%
Road departure
32%
47%
Varies
Varies
Intersections
33%
48%
Head-On
20%
8%
Consequence of leaving road
Safer work zones
EMS Management
2%
--
Varies
--
Information and decision support systems
--
--
More effective processes
--
--
Enhancing Emergency Capabilities
9 9
9 9
Figure 3.1 Olmsted County Emphasis Areas
Source: MnCMAT Crash Data, 2002-2006. Asterisk- MN SHSP. Olmsted Co. % = Severe crashes on CSAH or CR divided by Severe Crashes
The key conclusion is that a focus on these safety emphasis areas represents the greatest potential to significantly reduce the number of severe crashes in Olmsted County.
SAFETY EMPHASIS AREAS
3-2
Section 4
Safety Strategies
4. Safety Strategies 4.1 Background Following the identification of the Safety Emphasis Areas, a short list of potential safety improvement strategies was assembled and a prioritization exercise was conducted at a Safety Workshop, in order to produce a list of Olmsted County’s highest priority safety strategies. The culmination of the safety planning process occurs with the development of highway safety projects that involve the application of the highest priority strategies at specific locations on Olmsted County’s highway system that were identified as being at-risk based on a combination of crash, traffic volume and roadway characteristics. The source of the initial list of potential safety strategies is the National Cooperative Highway Research Program (NCHRP) 500 Series Reports – Guidance for Implementation of AASHTO’s Strategic Highway Safety Plan. This series of guides was developed to assist state and local highway agencies reduce the number of crashes in targeted safety emphasis areas. The guides basically correspond to the emphasis areas outlined in AASHTO’s Strategic Highway Safety Plan and each guide contains a “best practices” list of strategies with value added information including; relative implementation costs and the expected safety effectiveness – Proven (widely deployed and subject to a rigorous statistical testing), Tried (widely deployed but either lacking the statistical testing or with inconclusive results) and Experimental (too narrowly deployed to provide statistically significant results). The following sections document the development of Olmsted County’s short list of high priority safety strategies that was assembled for each of the County’s identified safety emphasis areas. The strategies are assigned to two basic categories – Infrastructure and Driver Behavior. The development process began with a review of the NCHRP 500 series reports, followed with a an initial screening of the strategies performed by County staff and culminated with a prioritization exercise with the County’s Safety Partners at a Safety Strategies Workshop.
4.2 Infrastructure Based Strategies 4.2.1 Road Departure Crashes From 2002 through 2006, there was an average of 89 road departure crashes per year on Olmsted County’s system of rural highways. These road departure crashes accounted for nearly 44% of all fatal crashes on the County’s system and 21% of severe crashes (fatal + A-injury crashes) in rural areas during the five year period. The majority of these fatal road departure crashes occurred during good weather conditions (93%) and on dry pavements (75%). Other characteristics of these fatal crashes that are worth noting include: •
Crashes on weekends are over represented (43% actual vs. 28% expected).
•
Crashes during periods of darkness are over represented (64% actual vs. 11% expected) and 35% of the crashes occurred between midnight and 3 AM.
SAFETY STRATEGIES
4-1
•
70% of the involved drivers were male and 67% of these were under 30 years of age.
One final characteristic stands out – 38% of all road departure crashes occur in horizontal curves, even though curves only account for around 10% of the mileage of the County’s highway system. The initial list of strategies for reducing road departure crashes was based on information contained in Volume 6 of the NCHRP 500 series reports and contains thirteen items that are focused on achieving three primary objectives: •
Keep vehicles from encroaching on the roadside – 8 strategies involving improvements to the road edge. The guidance suggests that these (generally) low cost signs, markings and design features should be the highest priority for deployment because if you keep vehicles on the road, whatever is beyond the edge becomes a secondary issue.
•
Minimize the likelihood of crashing into an object or overturning if the vehicle travels off the shoulder – 3 strategies that improve the clear zone – that area that extends from the road edge to the edge of the right-of-way. The guidance suggests that these (generally) higher cost efforts to remove obstacles and make slopes and ditches more traversable should be a lower priority because of the greater challenges associated with implementation, including; the much higher construction costs, possible need for acquiring new right-of-way and the potential need for environmental clearances and/or permits.
•
Reduce the severity of crashes – 2 strategies that address upgrading highway hardware. Upgrading guardrails and impact attenuators is considered to be a relatively low priority activity because it involves having to invest a moderate amount of money at a few locations that are only rarely struck during road departure crashes (at the national level striking a guardrail is involved in 3% of the road departure crashes and there were no instances of hitting a guardrail noted in the data set for Olmsted County).
This initial list of strategies was then reviewed by County staff and five were eliminated from further consideration because they were considered to be either too expensive (regrading slopes and ditches could cost several hundred thousand dollars per mile and require the acquisition of additional right-of-way) or involved experimental strategies that had no history of application in Minnesota (mid-lane rumble stripes and delineating roadside objects with reflective tape). This screening effort resulted in the list of eight high priority road departure strategies identified in Figure 4.1.
SAFETY STRATEGIES
4-2
Objectives
15.1 A -- Keep vehicles from encroaching on the roadside
Strategies 15.1 A1 -- Install shoulder rumble strips 15.1 A2 -- Install edgelines "profile marking", edgeline rumble strips or modified shoulder rumble strips on section with narrow or no paved shoulders 15.1 A3 -- Install centerline rumble strips 15.1 A4 -- Provide enhanced shoulder or delineation and marking for sharp curves
Relative Cost Typical to Implement Timeframe for and Operate Effectiveness Implementation Low Tried Short Low
Experimental
Short
Low
Experimental Tried / Proven / Experimental
Short
Low
Short
15.1 A6 -- Provide enhanced pavement markings
Low
Tried
Short
15.1 A8 -- Apply shoulder treatments *Eliminate shoulder drop-offs *Shoulder wedge *Widen and/or pave shoulders
Low
Experimental/ Proven
Medium
15.1 B -- Minimize the likelihood of crashing 15.1 B2 -- Remove/relocate objects in hazardous into an object or locations overturning if the vehicle travels off the shoulder
Moderate to High
Proven
Medium
15.1 C -- Reduce the 15.1 C1 -- Improve design of roadside hardware severity of the crash
Moderate to High
Tried
Medium
Figure 4.1 Road Departure Safety Strategies Source: NCHRP 500 Series
4.2.2
Intersections
Almost 50% of the crashes on Olmsted County’s system are intersection related, approximately 640 crashes per year. These intersection related crashes account for about 30% of fatalities on the County system and 40% of severe crashes. The majority of these crashes occur during good weather (91%) and on dry pavements (85%). Key characteristics associated with severe intersection crashes include: •
67% of the crashes occur in urban areas and these are evenly distributed between signalized and unsignalized intersections.
•
The remaining 33% of the intersection crashes occur at rural, STOP controlled intersections.
•
The predominant crash type at intersections is a right angle crash – 59% at urban unsignalized, 36% at urban signalized and 35% at rural unsignalized locations.
•
Crashes on week days are over represented.
•
Crashes during the afternoon hours are over represented.
•
Approximately 60% of the involved drivers are male and both very young and middle aged drivers are over represented.
The initial list of 28 strategies for reducing crashes at signalized intersections and 49 strategies for unsignalized intersections was based on information contained in Volume 12 and Volume 5, respectively, of the NCHRP 500 series reports. These strategies address
SAFETY STRATEGIES
4-3
signal operations and visibility, intersection geometry, enhancing enforcement, managing access in the vicinity of the intersection, improved signs and markings, street lighting and the application of new technologies. This initial list was reviewed with County staff and approximately one-half of the strategies were eliminated from further consideration. Examples of the strategies that were not carried forward include: •
Strategies that were not associated with reducing the predominant crash type auxiliary turn lanes were not carried forward because they are intended to reduce rear end crashes.
•
Strategies that are intended to address conditions that are not common in Olmsted County - 85% of intersection crashes occur on dry pavements, so strategies intended to improve pavement skid resistance were not carried forward.
•
Strategies that have not proven to reduce crashes in Minnesota – installing transverse rumble strips on the minor approaches to STOP controlled intersections was not carried forward because research has never been able to demonstrate a crash reduction and because research has shown that the primary factor contributing to angle crashes at STOP controlled intersections is gap recognition as opposed to intersection recognition.
This screening effort resulted in the identification of 10 priority strategies for signalized intersections (Figure 4.2) and 28 strategies for unsignalized intersections (Figure 4.3). Objectives
17.2 A -- Reduce frequency and severity of intersection conflicts through traffic control and operational improvements
17.2 B -- Reduce frequency and severity of intersection conflicts through geometric improvements 17.2 D -- Improve driver awareness of intersections and signal control 17.2 E -- Improve driver compliance with traffic control devices 17.2 F -- Improve access management near signalized intersections 17.2 G -- Improve safety through other infrastructure treatments
Relative Cost to Implement and Operate
Effectiveness
Typical Timeframe for Implementation
Low
Tried / Proven
Short
Low
Proven
Short
Moderate
Proven
Medium
Low
Tried / Proven
Short
Low
Proven
Short
17.2 B3 -- Improve geometry of pedestrian and bicycle facilities
Low
Tried / Proven
Short
17.2 D2 -- Improve visibility of signals and signs at intersections
Low
Tried
Short
17.2 E2 -- Supplement conventional enforcement of red-light running with confirmation lights
Low
Tried
Short
17.2 F1 -- Restrict access to properties using driveway closures or turn restrictions
Low
Tried
Medium
17.2 G3 -- Coordinate closely spaced signals near at-grade railroad crossings
Moderate
Tried
Long
Strategies 17.2 A1 -- Employ multiphase signal operation 17.2 A2 -- Optimize clearance intervals 17.2 A4 -- Employ signal coordination along a corridor or route 17.2 A6 -- Improve operation of pedestrian and bicycle facilities at signalized intersections 17.2 A7 -- Remove unwarranted signal
Figure 4.2 Signalized Intersections Safety Strategies Source: NCHRP 500 Series
SAFETY STRATEGIES
4-4
Objectives
Relative Cost to Implement and Operate
Effectiveness
Typical Timeframe for Implementation
Moderate
Tried
Medium
Low
Tried
Short
17.1 B4 -- Provide bypass lanes on shoulders at Tintersections
Low
Tried
Short
17.1 B11 -- Restrict or eliminate turning maneuvers by signing
Low
Tried
Short
17.1 B12 -- Restrict or eliminate turning maneuvers by providing channelization or closing median openings
Low
Tried
Short
High
Tried
Long
High
Tried
Medium
Strategies
17.1 A -- Improve management of 17.1 A1 -- Implement driveway closure/relocations access near unsignalized 17.1 A2 -- Implement driveway turn restrictions intersections
17.1 B -- Reduce the frequency 17.1 B13 -- Close or relocate "high-risk" intersections and severity of intersection conflicts through geometric design 17.1 B14 -- Convert four-legged intersections to two Timprovements intersections 17.1 B16 -- Realign intersection approaches to reduce or eliminate intersection skew
17.1 C -- Improve sight distance at unsignalized intersections
High
Proven
Medium
17.1 B17 -- Use indirect left-turn treatments to minimize conflicts at divided highway intersections
Moderate
Tried
Medium
171. B18 -- Improve pedestrian and bicycle facilities to reduce conflicts between motorists and nonmotorists
Moderate
Varies
Medium
17.1 C1 -- Clear sight triangle on stop- or yield-controlled approaches to intersections 17.1 C4 -- Eliminate parking that restricts sight distance
17.1 D -- Improve availability of 17.1 D1 -- Provide an automated real-time system to inform gaps in traffic and assist drivers in drivers of suitability of available gaps for making turning and judging gap sizes at unsignalized crossing maneuvers intersections 17.1 E1 -- Improve visibility of intersections by providing enhanced signing and delineation 17.1 E2 -- Improve visibility of intersections by providing lighting 17.1 E -- Improve driver awareness of intersections as 17.1 E4 -- Provide a stop bar (or provide a wider stop bar) on viewed from the intersection minor-road approaches approach 17.1 E5 -- Install larger regulatory and warning signs at intersections 17.1 E9 -- Provide pavement markings with supplementary messages, such as STOP AHEAD 17.1 F2 -- Provide all-way stop control at appropriate 17.1 F -- Choose appropriate intersections intersection traffic control to minimize crash frequency and 17.1 F3 -- Provide roundabouts at appropriate locations severity 17.1 G -- Improve driver compliance with traffic control devices and traffic laws at intersections 17.1 H -- Reduce operating speeds on specific intersection approaches
17.1 I -- Guide motorists more effectively through complex intersections
Low
Tried
Short
Low
Tried
Short
Moderate
Experimental
Medium
Low
Tried
Short
Moderate to High
Proven
Medium
Low
Tried
Short
Low
Tried
Short
Low
Tried
Short
Low
Proven
Short
High
Proven
Long
Moderate
Tried
Short
Low
Tried
Short
Moderate
Proven
Short
Moderate
Proven
Medium
17.1 G1 -- Provide targeted enforcement to reduce stop sign violations 17.1 G2 -- Provide targeted public information and education on safety problems at specific intersections 17.1 H1 -- Provide dynamic speed feedback signs 17.1 H2 -- Provide traffic calming on intersection approaches through a combination of geometrics and traffic control devices 17.1 H3 -- Post appropriate speed limit on intersection approaches 17.1 I1 -- Provide turn path markings 17.1 I2 -- Provide a double yellow centerline on the median opening of a divided highway at intersections 17.1 I3 -- Provide lane assignment signing or marking at complex intersections
Low
Tried
Short
Low
Tried
Short
Low
Tried
Short
Low
Tried
Short
Figure 4.3 Unsignalized Safety Strategies Source: NCHRP 500 Series
4.3
Driver Behavior Based Strategies
4.3.1
Seat Belt Usage
Not using a seat belt is one of the key factors contributing to fatal crashes in Olmsted County. Crash data for the years 2002 – 2006 shows that 30% of the fatal crashes involved unbelted occupants and information provided by the County Sherriff indicates that in 2008, 78% of fatal crashes involved an unbelted occupant. In response to these statistics, a list of
SAFETY STRATEGIES
4-5
seven strategies was assembled that is based on both the NCHRP 500 series reports and from a safe communities program in Wright County. These strategies focus on two areas – increasing the use of occupant restraints and educating parents about the proper use of child and infant restraints. The priority seat belt usage strategies are documented in Figure 4.4. Objectives
Strategies 8.1 A1- Conduct highly publicized enforcement campaigns to maximize restraint use. 8.1 A- Maximize use 8.1 A2- Provide enhanced public education to population groups of occupant restraints with lower than average restraint use rates. by all vehicle 8.1 A3- Encourage the enactment of local laws that will permit occupants standard enforcement of restraint laws. 8.1 A4- Support Legislation to change seat belt usage from a secondary to a primary offense. 8.1 B- Insure that restraints, especially child and infant restraints, are properly used
8.1 B1- Provide community locations for instruction in proper child restraint use, including both public safety agencies and health care providers, that are almost always available. 8.1 B2- Conduct high-profile “child restraint inspection” events at multiple community locations. 8.1 B3- Train law enforcement personnel to check for proper child restraint use in all motorist encounters.
Relative Cost to Implement and Operate
Effectiveness
Typical Timeframe for Implementation
Moderate-High
Proven
Medium
Low
Proven
Short
Low
Tried
Medium
Low
Proven
Medium
Low
Tried
Short
Low
Proven
Short
Moderate
Tried
Short
Figure 4.4 Seat Belt Usage Safety Strategies
Source: NCHRP 500 Series and Safe Communities of Wright County
It should be noted that while Olmsted County was going through the safety planning process, Minnesota was a secondary state relative to the enforcement of seat belt usage – a driver could only be issued a citation for not wearing a seat belt if they were stopped for another violation. This status as a secondary state lead to the inclusion of a strategy to support legislation to change enforcement of seat belt usage from a secondary to a primary offense. In May, 2009 the Legislature passed into law a statute that makes Minnesota a primary state and that law went into effect in August, 2009.
4.3.2
Impaired/Aggressive/Young Drivers
Drivers under the age of 21 years were involved in more that one-third of fatal crashes in Olmsted County and aggressive and impaired driving were factors that contributed to 25% and 15% of fatal crashes, respectively. The priority list of fourteen strategies was developed that focus on two areas – enforcement and education. The enforcement related strategies include support for more effective techniques and for legislation that would allow the use of two proven effective strategies that are currently prohibited in Minnesota – the use of sobriety checkpoints (that are allowed in 38 states) and the use of ignition interlocks as a condition for license reinstatement following a DWI. The education related strategies are primarily focused on helping young drivers and a public information campaign to deter aggressive driving. The priority Impaired, Aggressive and Young Driver strategies are documented in Figure 4.5.
SAFETY STRATEGIES
4-6
Objectives
More Effective Traffic Enforcement Laws
Ensuring Safer Bicycle Travel
Deter aggressive driving
Strategies Support legislation to allow sobriety checkpoints (38 states allow) Enhance DWI detection through special DWI patrols and related traffic enforcement Publicize and Enforce Zero Tolerance Laws for Drivers Under Age 21
Proven
Medium
Low
Tried
Short
Moderate
Proven
Short
Targeted enforcement to deter aggressive driving in specific population, including those with a history of such behavior and at specific locations
Low
Tried
Short
Seek increased County adoption of policies to better accommodate bicyclists on public roads, and encourage legislatures to fund bicycle facilities
Low
Tried
Short
Low Moderate
Proven Tried
Short Medium
Moderate
Tried
Medium
Increase bicycle helmet usage Provide separate trails for bicycling Provide wide paved shoulders along designated bicycle routes Reduce nonrecurring delays and provide better information about these delays Establish stronger penalties for BAC test refusal than for test failure Eliminate diversion programs and plea bargains to non-alcohol offenses Incarcerate offenders
Public Outreach and Awareness Campaigns
Typical Timeframe for Implementation
Low
Suspend driver's license administratively upon arrest Prosecute, Impose Sanctions on, and Treat DWI Offenders
Relative Cost to Implement and Operate Effectiveness
Support legislation to require ignition interlocks as a condition for license reinstatement Engage parents through outreach programs designed to educate parents about driving tips for their teens Develop parent-teen driver's education presentations and handbook aimed at educating individuals on the risk of teen driving Create a seat belt challenge among high schools to encourage teens to buckle up Develop and implement a public education/information program on bicycle safety targeting all age groups of bicyclists and drivers Conduct educational and public information campaigns against aggressive driving
Moderate-High Experimental Low
Proven
Medium
Low
Tried
Long
Moderate
Tried
Long
Moderate-High
Proven
Long
Low
Proven
Medium
Low
Tried
Medium
Moderate
Tried
Medium
Low
Tried
Short
Moderate
Tried
Short
Moderate
Tried
Short
Figure 4.5 Impaired/Aggressive/Young Driver/Bicycle Safety Strategies Source: NCHRP 500 Series and Safe Communities of Wright County
4.3.3
Bicycles
The analysis of Olmsted County’s crash records data base found that bicycle related crashes are relatively infrequent, they account for approximately 4% of severe crashes (about 2/year). However, this frequency exceeds the statewide average (1%) and recent information indicates that bicycle related crashes are one of only two safety emphasis areas to see an increase over the past several years (the other emphasis area with an increase in crashes is motorcycles). As a result, a priority list of four bicycle safety strategies was assembled (Figure 4.5).
SAFETY STRATEGIES
4-7
Figure 4.6 Workshop Voting Results
SAFETY STRATEGIES
4-8
4.4
Safety Strategies Workshop
A key element in Olmsted County’s safety planning process included conducting a Safety Strategies Workshop. The Workshop was held on January 7th, 2009 at the 4H Building on the County Fair grounds and was attended by 50 Safety Partners representing: •
•
Olmsted County Public Works Law Enforcement Planning Public Health Board of Commissioners Cities Rochester Public Works, Law Enforcement and Elected Officials Elected officials from Byron, Chatfield, Oronoco and Stewartville
•
Mn/DOT District 6 staff Central Office staff representing State Aid to Local Government and Traffic Engineering
•
Townships
•
Mayo Clinic
•
Bicycle Advocates
•
Driving Educators Figure 4.7 Edge Line Rumble StripE’s
The two primary objectives of the Workshop included sharing the results of the data driven analytical process and to provide a forum to review and discuss the short list of safety strategies with the County’s Safety Partners. During the Workshop, the Safety Partners also participated in an exercise that resulted in a further screening of the safety priorities – the highest ranked infrastructure and driver behavior based strategies are identified in Figure 4.6 and can be summarized as follows: •
•
Infrastructure Strategies -
Edge Line Rumble StripE’s (a series of grooves at the road edge that includes the white edge line – Figure 4.7)
-
Red Light Confirmation Lights (Figure 4.8)
-
Improved Traffic Signs, Delineation (Figure 4.9)
-
Traffic Signal Coordination
-
Center Line Rumble Strips (Figure 4.10)
Markings
and
Driver Behavior Strategies -
Developing
parent/teen
Figure 4.8 Confirmation Light in Dakota County
driver
education
SAFETY STRATEGIES
4-9
campaign -
Support legislation changing seat belt enforcement to a primary offense (note – this legislation was passed and went into effect in August, 2009)
.
Figure 4.9 Improved Traffic Signs, Markings and Delineation
Figure 4.10 Centerline Rumble Strips
SAFETY STRATEGIES
4-10
Section 5
Detailed Crash Analysis
5.
Detailed Crash Analysis
The initial County wide analysis of crashes found that of the almost 1,300 crashes that occur on Olmsted County highways annually, approximately 83% occur in urban areas. However, when severe crashes were considered (fatal + A-injury) there was an almost even distribution with 24 severe crashes per year in urban areas and 21 severe crashes per year in rural areas. A more detailed review of the crash data found that four elements of the County system account for the majority (60%) of these severe crashes: 1) Rural highway segments (20%) 2) Urban STOP controlled intersections (16%) 3) Rural STOP controlled intersections (13%) 4) Urban signalized intersections (11%) The following sections document the results of detailed crash analysis of these four elements of Olmsted County’s highway system and describe the characteristics and factors that contribute to the crashes that occur at these locations. This information was then used in a series of prioritization exercises that identified specific locations that are considered to be at-risk and therefore, candidates for safety investments.
5.1
Rural Highway Segments
There are 324 miles of rural highway in Olmsted County’s system and the predominant type of crash is a single vehicle running off the road. These single vehicle crashes account for almost 40% of all rural crashes and 46% of the severe rural crashes. Given that the desired end product is a list of safety projects – the deployment of specific mitigation strategies at specific locations, a series of questions need to be answered. First, are all rural segments equally at risk? If so, any approach to implementation would be equally effective. However, if some segments are more at-risk than others, the most cost-effective approach to implementation would involve a screening exercise to identify the subset of the most at-risk segments. The first step of the detailed analysis of crashes along rural road segments consisted of disaggregating the 324 miles of rural highways into volume categories and then determining the distribution for each category of miles, vehicle miles of travel (VMT) and road departure crashes. The results of this analysis are illustrated in Figure 5.1 and suggest that the approximately one-half of the system mileage with daily traffic volumes between 500 and 2,000 vehicles per day (VPD) is most at-risk based on the fact that the fraction of road departure crashes on these segments exceeds the fraction of VMT, these segments have the highest rate of road departure crashes (0.5 road departure crashes per million vehicle miles of travel) and this rate is 60% to 100% higher than for any of the other volume categories.
DETAILED CRASH ANALYSIS
5-1
35%
CSAH Mileage (~324 miles)
33%
VMT Road Departure Crashes (275 total)
30% 26% 25% 23%
23%
21% 20%
20%
19% 18%
17% 15%
15%
14% 13% 10%
10% 8%
8% 8%
7%
7%
5% 5%
4% 2% 0% 0% 0%
0% 0-500
500-1000
1000-2000
2000-2500
2500-3000
3000-3500
3500-4000
4000+
Figure 5.1 CSAH Mileage and Road Departure Crashes By ADT Source: MnCMAT Crash Data, 2002-2006.
The second step in the detailed analysis consisted of ranking the 38 segments in the 500 to 2,000 VPD volume category based on the number of road departure crashes, total crashes and severe crashes. The results of this analysis are illustrated in Figure 5.2 and indicate a suggested priority that has the 3.4 mile segment of CSAH 36 (between US 52 and CR 143) ranked highest as a result of 12 road departure crashes, 3 severe crashes and 25 total crashes and the 1.9 mile segment of CSAH 18 (between CSAH 12 and the Wabasha County line) ranked 38th with no crashes during the study period. The data also indicate that these 38 segments contain almost one-half of the road departure crashes that occur on Olmsted County’s rural highways and almost 70% of all severe crashes.
DETAILED CRASH ANALYSIS
5-2
Route CSAH 36 CSAH 3 CSAH 3 CSAH 14 CSAH 13 CR 112 CR 104 CSAH 10 CSAH 15 CSAH 5 CSAH 24 CSAH 6 CSAH 10 CR 142 CR 117 CSAH 8 CSAH 5 CR 133 CR 114 CSAH 11 CSAH 3 CSAH 12 CR 111 CSAH 20 CSAH 7 CSAH 16 CSAH 16 CSAH 9 CSAH 14 CSAH 20 CR 143 CSAH 14 CSAH 8 CSAH 25 CSAH 27 CSAH 19 CSAH 10 CSAH 18
From US 52 CSAH 6 CSAH 14 Dodge County Dodge County CSAH 14 CR 117 US 14 TH 30 CSAH 25 CSAH 2 CSAH 3 Chatfield city limit CSAH 7 CSAH 15 CSAH 6 Dodge County CSAH 22 55th Street NW CSAH 12 CSAH 2 CSAH 4 CSAH 3 CSAH 1 TH 30 US 52 CSAH 8 CSAH 20 CSAH 10 US 63 CSAH 16 (west) CSAH 36 CSAH 3 Mower County CSAH 3 CSAH 12 CSAH 23 I-90 CSAH 12
To CR 143 CSAH 4 CSAH 13 CSAH 3 (west) Goodhue County US 52 CSAH 4 Wabasha County CSAH 25 US 14 Wabasha County US 63 I-90 Sheek Street N CSAH 8 CSAH 35 CSAH 3 CSAH 14 Wabasha County TH 247 CSAH 14 US 52 US 52 CSAH 16 I-90 CSAH 20 CSAH 1 Winona County CSAH 11 US 63 CSAH 11 US 52 CSAH 6 CSAH 22 Wabasha County US 14 US 14 Wabasha County
ADT 1050 884 1072 600 760 1070 1100 1070 552 680 820 875 569 770 980 1150 1450 1600 600 668 800 810 820 500 790 793 800 820 850 940 1104 1450 1500 1720 900 940 1200 1200 Total Countywide Rural Corridor Total
Length 3.4 17.5 8.2 5.3 1.7 4.4 6.6 10.2 6.6 5 4.7 7.6 8.2 5 3.4 1.8 5 2.4 2.1 7.5 0.25 3.5 2.6 4.6 2.3 3.8 1.4 3 3.2 4.4 2.4 2.9 0.5 5.5 1.7 1.9 1.7 1.9 164.2 323.5
RoR Crashes 12 10 10 6 6 6 6 5 4 4 4 4 3 3 3 3 3 3 2 2 2 2 2 1 1 1 1 1 1 1 1 1 1 1 0 0 0 0 116 275
Crashes K A Total 2 1 25 1 4 21 3 15 1 8 2 7 1 17 8 1 12 6 8 5 8 1 3 1 3 1 4 1 1 4 5 7 4 1 1 8 2 3 1 3 1 4 4 1 5 1 6 1 2 2 3 1 11 2 1 1 10 2 1 1 0 0 8 23 239 15 40 539
Figure 5.2 Prioritizing Rural Segments with ADT between 500 and 2,000
The detailed crash analysis also identified a subset of the rural highway system that appears to be a factor that contributes to the overall frequency of road departure crashes – horizontal curves (Figure 5.3). The 324 miles of rural County highways contains 239 horizontal curves and the total length of these curves is approximately 31 miles, or slightly less than 10% of the system mileage. However, 40% of both total road and severe road departure crashes occur in horizontal curves. As a result, it was concluded that horizontal curves are an at-risk element of the County’s rural highway system and as was the case with the rural highway segments, an analysis was completed to prioritize the curves based on the relative degree of risk. The results of this analysis documented the following crash characteristics: •
Almost 75% of the curves had no crashes during the five year study period. DETAILED CRASH ANALYSIS
5-3
•
Four of the curves had 1 fatal crash – none had 2 fatal crashes.
•
One curve had 2 A injury crashes and nine more curves had 1 A injury crash.
•
One curve averaged 1 crash per year and the average annual number of crashes per curve was 0.08.
35%
33%
CSAH Mileage (~324 miles) VMT
30%
Total Curve Related RD (112 total)
28% 26%
Total Curve Related (159 total)
26%
25% 21%
21% 20%
20%
20%
18%18%
18% 17% 15%
15%
14% 13% 11% 10%10%
10% 7% 5% 5%
9%
8% 8%
7%
4%
9%
4% 2% 0% 0% 0% 0%
0% 0-500
500-1000
1000-2000
2000-2500
2500-3000
3000-3500
3500-4000
4000+
Figure 5.3 CSAH Mileage and Curve Related Crashes By ADT Source: MnCMAT Crash Data, 2002-2006.
All of this information supports the notion that traditional methods of assigning safety risk based on the number of crashes could not be effective if applied to horizontal curves – there are simply too few crashes in curves to be a reliable indicator of the relative degree of risk. As a result, a new technique was developed for Olmsted County that was based on combining an understanding of the characteristics of the curves in Olmsted County where crashes did occur with the results of similar efforts in other counties in Minnesota and with the results of recently published research by the Minnesota Department of Transportation (Cost-Benefit-Analysis of In-Vehicle Technologies and Infrastructure Changes to Avoid Crashes Along Curves and Shoulders, University of Minnesota and CH2M HILL, June 2009). This detailed crash analysis of curve related crashes suggest that in addition to crashes, four features increase the level of risk at individual curves: •
Curve radius – shorter curve radii result in higher crash rates (Figure 5.4). In Olmsted County, curves with radii less than 1,500 feet have crash rates two to three times greater than curves with longer radii. This relationship is similar to that found in the Minnesota and national research, but in these documents the radii/safety relationship is even more pronounced.
•
Traffic volumes – there is a range of volumes in each system that is over represented relative to the frequency of curve related crashes. In Olmsted County the curves in the volume range between 1,000 and 2,500 VPD accounted for 32% of the mileage, 39% of the VMT and 43% of the curve related crashes
DETAILED CRASH ANALYSIS
5-4
(Figure 5.3). The fraction of the curve related crashes in each of the other volume categories was less than or equal to the fraction of VMT. •
Intersection in the curve – the presence of an intersection in the curve increased the level of risk.
•
Visual trap – the presence of a visual trap (a situation that occurs when a crest vertical curve is ahead of the beginning of the horizontal curve of when there is a minor road continuing on the tangent – Figure 5.5) increased the level of risk.
60%
3 53% Length (~167,100 feet) VMT Severe Curve Crashes (15 total) Curves (240 total) Crash Rate
50%
Percentage (%)
40%
38%
30%
39% 37%
2.5
2
1.8 34% 34%
27%
1.5
27% 1.2
20%
20%
18% 14%
0.8
Crash Rate (crashes/MVM)
2.7
1
0.7
0.7 10%
8%
10%
6%7% 5%
4% 3% 0%
0% 0-500
500-1000
1000-1500
0%
1500-2000
2000-2500
0.5 4%4% 4% 0% 0.0 2500-3000
1%1%0%1%
0
3000-3500
Radius
Figure 5.4 Curve Crashes Disaggregated by Radius Source: MnCMAT Crash Data, 2002-2006.
DETAILED CRASH ANALYSIS
5-5
Figure 5.5 CSAH Visual Trap
This information resulted in the development of a prioritization process that documented these five factors at each of the 239 curves. An example of the application of these factors to a sample of the horizontal curves is illustrated in Figure 5.6 and the results of applying the process, a ranking of the twenty-two most at-risk curves, is documented in Figure 5.7. These twenty-three curves represent under 10% of all curves in Olmsted County’s system, but 50% of the curve related fatal crashes and 64% of the severe curve related crashes. In addition, these curves include one where all five factors were present, six curves where four factors were present and sixteen curves where three factors were present. Corridor 7
Segment CSAH 3
Description Mower Co - CSAH 6
8
CSAH 8
Mower Co - CSAH 6
9
CSAH 4
CSAH 5 - CSAH 22
10
CR 154
US 52 - CR 112
11
CSAH 8
CSAH 6 - CSAH 35
CSAH 8
CSAH 35 - Meadow Crossing Rd
12
Corridor Curve Weighted ADT 1 295 1 1,500 2 1,500 1 1,950 2 1,950 3 2,650 4 2,650 5 2,650 6 3,075 1 2 3 4 1 2 3 4 5 6
1,150 1,150 1,150 1,150 2,100 2,100 3,500 3,500 3,500 3,500
K A 1 0 0 0
Severe RoR Crashes B C PDO K A
0 0 0 0 1 0
0 0 0 0 None None 1 0 None 0 0 0 0 1 1
0 0 0 0 0 0
None None None None 0 0 0 0 0 1 1 0 0 0 1 1
0 0
0 1 0 0 0 0
0 1
1 3 1
1 0 0 0 0 0 0 0 1
0 0 0 0 0 0 0 0 0
1 2 0 0 1 2
0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 1 0 0 0 0
0
Length Radius Curve 800 1,250 1,300 425 150 125 1,250 700 1,150 650 3,000 600 3,000 725 1,150 1,225 1,150 1,875 No Curves 2,500 650 2,200 600 1,150 1,050 1,600 775 600 875 600 875 1,100 325 1,150 850 850 1,000 1,450 825
Intersection on Curve
Chevrons Visual Trap Yes
Yes Yes Yes
x xx xxx
Yes Yes Yes Yes Yes
Rank xxx x x xx xx
Yes Yes Yes
Yes
xx x xxxx xx xxx xxx x x x
Figure 5.6 Curve Prioritization
Source: MnCMAT Crash Data, 2002-2006.
DETAILED CRASH ANALYSIS
5-6
Corridor 7 9 11 18 20 21 22 24
Segment CSAH 3 CSAH 4 CSAH 8 CSAH 11 CSAH 2 CR 133 CSAH 3 CSAH 12
26
CSAH 5
41
CSAH 34
42
CSAH 3
44
CSAH 6
52
CSAH 10
63
CSAH 25
64
CSAH 23
65 71 75
CR 143 CSAH 16 CSAH 18
Corridor Description Curve Weighted ADT Mower Co - CSAH 6 1 295 CSAH 5 - CSAH 22 6 3,075 CSAH 6 - CSAH 35 3 1,150 CSAH 36 - CSAH 2 2 1,500 36th Ave NE - TH 42 4 3,200 55th St NW - CSAH 14 6 1,600 CSAH 14 - CSAH 13 9 1,200 US 52 - US 63 2 3,650 Byron City Limits - Dodge 5 2,150 Co (CSAH 17) 6 2,150 US 14 - CSAH 3 3 2,100 5 1,000 CSAH 6 - CSAH 4 6 1,150 1 1,250 CSAH 3 - US 63 2 1,250 Chatfield City Limits - I-90 4 480 1 1,900 CSAH 3 - CSAH 22 3 1,900 4 295 CSAH 19 - TH 42 5 295 CSAH 11 - CSAH 19 3 350 CSAH 1 - US 52 3 400 CSAH 12 - Wabasha Co 4 1,200
K A 1 0 1 0
0 0 0 0 0
0 1 1 0 0
0 1 0 0
0 0 0 0
0 2 0 0
Crashes Severe RoR B C PDO K A 0 0 0 1 0 1 1 1 1 0 None 0 0 None 0 0 None 0 0 1 0 0 0 0 0 0 0 0 0 0 2 0 0 1 1 0 0 0 0 0 0 1 0 0 None 0 0 0 0 2 0 1 None 0 0 1 0 0 0 0 None 0 0 None 0 0 2 0 0 0 0 1 0 0 0 0 None 0 0 None 0 0 0 0 0 0 1 None 0 0 0 1 0 0 0
Radius 800 1,150 1,150 900 1,050 800 800 1,000 1,100 1,150 1,850 850 850 850 800 800 1,050 1,150 800 800 1,000 850 1,300
Length Curve 1,250 1,875 1,050 725 1,500 1,100 500 725 1,025 325 800 1,350 1,250 1,225 1,250 1,250 975 1,075 1,250 1,200 375 1,275 600
Intersection on Curve Yes Yes Yes Yes Yes
Chevrons Visual Trap Yes Yes Yes Yes
Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
Rank xxx xxx xxxx xxxx xxx xxx xxx xxx xxx xxx xxx xxxxx xxxx xxxx xxxx xxx xxx xxxx xxx xxx xxx xxx xxx
Figure 5.7 High Priority Curves
5.2
Urban STOP Controlled Intersections
Approximately 30% of the severe crashes that occur along Olmsted County’s urban system of highways occur at STOP controlled intersections and the most common type of crash at these intersections is a right angle collision (60%). The detailed analysis found that over 80% of these severe crashes occurred in Rochester and the remainder occurred in Oronoco and Stewartville. The analysis also found: •
The intersections with severe crashes in Oronoco have already been improved as a result of the various upgrading projects along TH 52.
•
The intersections in Stewartville are along a segment of TH 63 that is 30 miles per hour and the officers that investigated the crashes could not identify any contributing factors.
As a result, the detailed analysis focused in on the 80% of the crashes that occurred at STOP controlled intersections in Rochester. The next step in the analytical process involved identifying locations with multiple crashes and in this case all crashes (not just severe) were considered in order to increase the size of the data set. This helps in the identification of factors contributing to the types of crashes which are of most interest – right angle collisions. A total of five intersections in Rochester were identified as having more than five crashes (Figure 5.8) and two items stand out – right angle collisions (48%) are the type most over represented in the sample and two of the multiple crash intersections are located along Circle Drive (NE , NW and SW). Circle Drive is in fact the only road with more than one intersection with multiple crashes. Crash Severity Intersection US 14 & CSAH 7 US 63 & CSAH 6 CSAH 25 & CR 125 CSAH 9 & CR 155 CSAH 22 & CSAH 25 (west) CSAH 22 & 9th St NW
K
A 1
1
B 3 2 4 2 2
C 3 2 4 1 3
PDO 10 13 11 4 4 11
DETAILED CRASH ANALYSIS
5-7
Figure 5.8 Urban STOP Controlled Intersections with more than five crashes Source: MnCMAT Crash Data, 2002-2006.
5.3
Rural STOP Controlled Intersections
Approximately 30% of the severe crashes along Olmsted County’s rural system of highways occur at STOP controlled intersections and the most common type of crash at these intersections is a right angle collision (52%). Given that there are approximately 350 of these intersections across the County, it was determined that the analysis would focus on the subset of intersections where the probability of conflicts was greatest – at the highest volume intersections. A further review of the County’s system found that these high volume intersections can be identified by the jurisdiction of the entering legs – as a result, the subset of STOP controlled intersections included in the detailed analysis were defined by having at least one leg on the County State Aid Highway system and the remaining legs on either the County State Aid or the State Trunk Highway system. This subset was found to include a total of 71 intersections and this group of intersections was found to account for almost onethird of both total and the severe intersection related crashes in the County. In order to further prioritize the Stop controlled rural intersections, additional analysis found that a particular group of intersections had on average the highest crash rates – intersections with a ratio of Minor Leg Average Daily Traffic/Major Leg Average Daily Traffic between 0.3 and 0.5 (Figure 5.9). The twenty-five intersections in this range of ADT’s have crash rates that average more than 0.6 crashes per million entering vehicles and this rate is 50% greater than the Countywide average and more than twice the average in any other volume category.
DETAILED CRASH ANALYSIS
5-8
0.80 Crash Rate
0.70
0.60
Crash Rate
0.50
0.40
0.30
0.20
0.10
0.00 0-0.1
0.1-0.2
0.2-0.3
0.3-0.5
0.5-0.8
0.8+
ADT Range (Minor/Major)
Figure 5.9 Rural STOP Intersections Crash Rate by ADT Range Source: MnCMAT Crash Data, 2002-2006.
Finally, these intersections were prioritized by their crash rate, with the resulting ranking identified in Figure 5.10. It should be noted that these twenty-five intersections account for around 5% of all rural STOP controlled intersections but they account for 19% of total rural intersection crashes and 13% of severe intersection related crashes.
DETAILED CRASH ANALYSIS
5-9
Figure 5.10 Prioritization of Rural STOP Controlled Intersections Source: MnCMAT Crash Data, 2002-2006.
5.4
Urban Signalized Intersections
Approximately 20% of the severe crashes in urban areas in Olmsted County occur at signalized intersections. The most common type of severe crash at the signals along the County’s system in and around Rochester is a right angle collision (41%). The detailed analysis of the crash data found three corridors – CSAH 22 East, CSAH 22 West and TH 14 (the South Beltway where many of the cross streets are County highways) - with the greatest concentration of both total crashes and angle crashes. The twenty-eight signalized intersections along these corridors account for approximately 20% of the signalized intersections in Olmsted County, but they account for 28% of all crashes and 37% of all right angle crashes. In addition, right angle crashes at these twenty-eight signals accounted for 64% of the severe crashes – clearly, crashes, angle crashes and severe angle crashes are over represented at these intersections. The twenty-eight signalized intersections along these high priority corridors are identified in Figure 5.11.
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US 14 from US 52 to CSAH 11 • US 14 and Memorial Pkwy SW (+) • US 14 and 12th St SW (T) • US 14 and TH 63 (+) • US 14 and CR 146 (3rd Ave SE) (+) • US 14 and 8th Ave SE (+) • US 14 and CSAH 1 (11th Ave SE) (+) • US 14 and CSAH 36 (15th Ave SE) (+) • US 14 and CSAH 22 (T) • US 14 and CSAH 11 (+) CSAH 22 (West) from US 52 to US 52/14 • CSAH 22 and West Frontage Rd (+) • CSAH 22 and Chateau Rd NW (+) • CSAH 22 and 55th St NW (+) • CSAH 22 and 41st St. NW (T) • CSAH 22 and CSAH 4 (Valley High Dr NW) (+) • CSAH 22 and 19th St NW (+) • CSAH 22 and 7th St NW (North) (+) • CSAH 22 and 7th St NW (South) (+) • CSAH 22 and CSAH 34 (Country Club Rd SW) (+) • CSAH 22 and CSAH 8 (Bamber Valley Rd SW) (T) • CSAH 22 and CSAH 25 (16th St SW) (T) • CSAH 22 and Fox Valley Dr SW (+) CSAH 22 (East) from US 14 to US 52 • CSAH 22 and CSAH 9 (Collegeview Rd E) (+) • CSAH 22 and CSAH 2 (Viola Rd NE) (+) • CSAH 22 and TH 63 (+) • CSAH 22 and East River Rd NE (+) • CSAH 22 and West River Pkwy NW (+) • CSAH 22 and 18th Ave NW (+) • CSAH 22 and 22nd Ave NW (+) Figure 5.11 Signalized Intersections along High Priority Corridors Note: Italics indicate signals under County Jurisdiction. (+)-Four-leg intersection, (T)-Three-leg intersection
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Section 6
Safety Projects
6.
Safety Projects
One of the key objectives of Olmsted County’s safety planning effort involved identifying low cost safety related projects that are focused on the County’s documented safety emphasis areas. These safety emphasis areas contain the greatest number of severe crashes occurring along the County’s system of highways and deploying mitigations for the factors contributing to these crashes represent the best opportunity to move Olmsted County Towards Zero Deaths. The need for low cost projects that can be widely deployed across the County’s system of highways is based on the fact that Olmsted County averages 45 severe crashes (Fatal + A Injury) per year and these are spread across more than 300 miles of County highways and hundreds of intersections. As a result, the density of these severe crashes is very low and Minnesota’s Strategic Highway Safety Plan has demonstrated that the most effective programmatic approach involves a wide application of relatively low cost safety projects. The effort to develop low cost safety projects is based on the application of high priority strategies at the most at-risk locations that were identified as part of the detailed analysis of the County’s system of highways. The high priority safety strategies were identified in Chapter 4, and basically consist of the following types of improvements: •
Improvements to the edges of rural highways and enhanced delineation of horizontal curves in rural areas.
•
Upgrading the signs and pavement markings, installing street lights and providing dynamic warning signs at rural STOP controlled intersections.
•
Adding technology at signalized intersections to support increased enforcement levels for red light running.
•
Adding channelization and median islands to restrict/control turning maneuvers at urban STOP controlled intersections.
The at-risk locations were documented in Chapter 5, and include rural County highway segments, STOP controlled intersections in both rural and urban areas and signalized intersections. The low cost safety projects that are suggested for implementation are described in the following sections. It should be noted that the list of potential projects is greater than what can reasonably be undertaken in a single year based on funding limitations and that the actual schedule for implementation of individual projects will be a function of securing funding from the State’s Highway Safety Improvement Program (HSIP). It should also be noted that the safety planning process that Olmsted County followed is consistent with the Minnesota’s Strategic Highway Safety Plan and that the high priority safety strategies are among those recommended for local systems in the State’s Strategic Plan. Both of these items put Olmsted County in a position to be successful at securing HSIP funding.
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6.1
Infrastructure Based
6.1.1
Rural Highway Segments
The high priority strategies identified using edge line rumble stripEs and 6 inch wide edge lines (Figure 6.1) to better delineate the road edges and increased use of Chevron warning signs to define horizontal curves in order to help keep drivers on the roads. Three projects involving the deployment of these strategies are suggested.
Figure 6.1 Rumble StripEs and 6 Inch Wide Edge Line
The 324 miles of rural County Highway were divided into 52 distinct segments and these segments were then ranked based on a combination of crash and traffic volume characteristics. The first low cost safety project consists of adding edge line rumble stripEs to the thirty-eight highest priority segments (approximately 164 miles) described in Figure 6.2. This group of highway segments was designated as the highest priority for edge treatments because they fall in a range of daily traffic volumes (500 to 2,000 vehicles per day) that has the highest fraction and rate of road departure crashes. The estimated cost of deploying edge line rumble stripE’s is $2,400/mile and the estimated cost of the project is almost $400,000.
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Route CSAH 36 CSAH 3 CSAH 3 CSAH 14 CSAH 13 CR 112 CR 104 CSAH 10 CSAH 15 CSAH 5 CSAH 24 CSAH 6 CSAH 10 CR 142 CR 117 CSAH 8 CSAH 5 CR 133 CR 114 CSAH 11 CSAH 3 CSAH 12 CR 111 CSAH 20 CSAH 7 CSAH 16 CSAH 16 CSAH 9 CSAH 14 CSAH 20 CR 143 CSAH 14 CSAH 8 CSAH 25 CSAH 27 CSAH 19 CSAH 10 CSAH 18
From US 52 CSAH 6 CSAH 14 Dodge County Dodge County CSAH 14 CR 117 US 14 TH 30 CSAH 25 CSAH 2 CSAH 3 Chatfield city limit CSAH 7 CSAH 15 CSAH 6 Dodge County CSAH 22 55th Street NW CSAH 12 CSAH 2 CSAH 4 CSAH 3 CSAH 1 TH 30 US 52 CSAH 8 CSAH 20 CSAH 10 US 63 CSAH 16 (west) CSAH 36 CSAH 3 Mower County CSAH 3 CSAH 12 CSAH 23 I-90 CSAH 12
To CR 143 CSAH 4 CSAH 13 CSAH 3 (west) Goodhue County US 52 CSAH 4 Wabasha County CSAH 25 US 14 Wabasha County US 63 I-90 Sheek Street N CSAH 8 CSAH 35 CSAH 3 CSAH 14 Wabasha County TH 247 CSAH 14 US 52 US 52 CSAH 16 I-90 CSAH 20 CSAH 1 Winona County CSAH 11 US 63 CSAH 11 US 52 CSAH 6 CSAH 22 Wabasha County US 14 US 14 Wabasha County
ADT 1050 884 1072 600 760 1070 1100 1070 552 680 820 875 569 770 980 1150 1450 1600 600 668 800 810 820 500 790 793 800 820 850 940 1104 1450 1500 1720 900 940 1200 1200 Total Countywide Rural Corridor Total
Length 3.4 17.5 8.2 5.3 1.7 4.4 6.6 10.2 6.6 5 4.7 7.6 8.2 5 3.4 1.8 5 2.4 2.1 7.5 0.25 3.5 2.6 4.6 2.3 3.8 1.4 3 3.2 4.4 2.4 2.9 0.5 5.5 1.7 1.9 1.7 1.9 164.2 323.5
RoR Crashes 12 10 10 6 6 6 6 5 4 4 4 4 3 3 3 3 3 3 2 2 2 2 2 1 1 1 1 1 1 1 1 1 1 1 0 0 0 0 116 275
Crashes K A Total 2 1 25 1 4 21 3 15 1 8 2 7 1 17 8 1 12 6 8 5 8 1 3 1 3 1 4 1 1 4 5 7 4 1 1 8 2 3 1 3 1 4 4 1 5 1 6 1 2 2 3 1 11 2 1 1 10 2 1 1 0 0 8 23 239 15 40 539
Figure 6.2 Rumble StripEs and 6 Inch Wide Edge Line Projects
A second safety project involves adding a 6” wide edge line to an additional fourteen segments (approximately 84 miles) as described in Figure 6.3. These segments were designated as a second priority for edge treatments based on having the next highest fraction and rate of road departure crashes. The estimated cost of installing a 6” edge line is $300/mile and the estimated cost of the project is $25,000.
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Route CSAH 1 CSAH 8 CSAH 4 CR 147 CSAH 2 CSAH 9 CSAH 11 CSAH 21 CSAH 34 CSAH 12 CSAH 5 CR 154 CSAH 35 CSAH 34
From Fillmore County CSAH 35 CSAH 5 48th Street SW 36th Avenue NE CSAH 22 CSAH 36 US 63 CSAH 3 US 52 Bryon city limits US 52 CSAH 8 US 14
To US 52 Meadow Crossing Road CSAH 22 CR 125 TH 42 CSAH 10 CSAH 2 Wabasha County CSAH 22 US 63 Dodge County CSAH 17 CR 112 US 63 CSAH 3
ADT 3395 2190 2695 2210 2557 2146 2195 2600 2100 2330 2125 2800 3150 2100 Total Countywide Rural Corridor Total
Length 10.3 8.7 6.8 3.3 8.5 13.9 6.6 5 4.6 6.6 4 1.6 2 1.7 83.6 323.5
RoR Crashes 16 14 13 11 11 9 9 8 7 7 4 3 3 1 116 275
Crashes A Total 1 25 1 2 21 1 28 16 3 17 19 1 1 16 1 10 17 3 13 1 9 1 10 1 6 2 5 12 209 15 40 539 K
Figure 6.3 6 Inch Wide Edge Line Projects
A third safety project addressing road departure crashes involves adding Chevron warning signs (Figure 6.4) at the group of twenty-two high risk horizontal curves identified in Figure 6.5. The estimated cost of adding chevrons is $1,000/curve and the estimated cost of the project is $22,000.
Figure 6.4 Typical Chevron on Curves
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Corridor 7 9 11 18 20 21 22 24
Segment CSAH 3 CSAH 4 CSAH 8 CSAH 11 CSAH 2 CR 133 CSAH 3 CSAH 12
26
CSAH 5
41
CSAH 34
42
CSAH 3
44
CSAH 6
52
CSAH 10
63
CSAH 25
64
CSAH 23
65 71 75
CR 143 CSAH 16 CSAH 18
Description Curve Mower Co - CSAH 6 1 CSAH 5 - CSAH 22 6 CSAH 6 - CSAH 35 3 CSAH 36 - CSAH 2 2 36th Ave NE - TH 42 4 55th St NW - CSAH 14 6 CSAH 14 - CSAH 13 9 US 52 - US 63 2 Byron City Limits - Dodge 5 Co (CSAH 17) 6 US 14 - CSAH 3 3 5 CSAH 6 - CSAH 4 6 1 CSAH 3 - US 63 2 Chatfield City Limits - I-90 4 1 CSAH 3 - CSAH 22 3 4 CSAH 19 - TH 42 5 CSAH 11 - CSAH 19 3 CSAH 1 - US 52 3 CSAH 12 - Wabasha Co 4
Figure 6.5 High Priority Curves
6.1.2
Urban STOP Controlled Intersections
The detailed crash analysis found that 82% of the severe crashes at urban STOP controlled intersections were in Rochester, that 63% of these involved right angle collisions and that the only highway with multiple intersections with severe crashes was CSAH 22 (Circle Drive). This information combined with the high priority safety strategy that involves restricting crossing/turning maneuvers by providing channelization or closing median openings points to a safety project at the STOP controlled intersections along CSAH 22. The suggested safety project would involve either building median islands or channelizing islands on the minor leg approaches at selected intersections along CSAH 22 (Figure 6.6) that would prevent the most hazardous movements at the intersections – the minor road crossing maneuvers. The estimated cost of these intersection modifications is $75,000/intersection and the estimated cost for addressing the five intersections (Figure 6.7) identified as black spots (those with 5 or more crashes during the study period) is $450,000.
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Figure 6.6 Examples of Median Restrictions Source: Google Maps
Intersection CSAH 22 and 6th Ave CSAH 22 and Century Valley Road NE CSAH 22 and 1st Street NW CSAH 22 and 26th Street/Technology Drive CSAH 22 and 9th Street Figure 6.7 Intersections for Minor Leg Channelization
6.1.3
Ring NE NE NW NW NW
Rural STOP Controlled Intersections
The detailed crash analysis of rural STOP controlled intersections found that the most common crash type at the twenty-five high priority intersections was a right angle collision (57%) and that almost 65% of the severe crashes occurred during dark conditions. Combining this data with the high priority strategies results in three safety projects at rural STOP controlled intersections. The six top ranked intersections (Figure 6.8) on the high priority list have the highest crash rates (five above the critical crash rate), account for 67% of total crashes and 75% of the severe crashes occurring at the twenty-five high priority intersections. The suggested project at these six intersections involves installing a mainline dynamic warning sign (Figure 6.9), street lighting (Figure 6.10) and upgraded signs and pavement markings (Figure 6.11). The estimated cost of adding these safety features is $45,000/intersection and the estimated cost of the project is $270,000. Actual Critical Number Intersection Crash Rate Crash Rate 1 CSAH 23 & CSAH 19 (East) 2.52 2.20 2 CSAH 3 & CSAH 34 1.57 0.92 3 CSAH 3 & CSAH 12 1.22 1.27 4 US 63 & CSAH 14 1.11 0.67 5 US 63 & CSAH 12/TH 247 1.02 0.73 6 TH 42 & CSAH 9 0.85 0.82 Figure 6.8 Top Six High Priority Rural STOP Controlled Intersections
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Figure 6.9 Mainline Dynamic Warning Sign
Figure 6.10 Street Lighting
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Figure 6.11 Upgraded Signs and Markings
The second project involves addressing the next six intersections on the list of high priority intersections (Figure 6.12). These intersections have crash rates above the countywide average and account for over 20% of total crashes occurring at the high priority intersections. The suggested project involves installing street lights and upgraded signs and pavement markings at an estimated cost of $15,000/intersection and an estimated project cost of $90,000. Number 7 8 9 10 11 12
Intersection CSAH 3 & CSAH 5 TH 30 & CSAH 1 TH 30 & CSAH 8 CSAH 11 & CSAH 14 CSAH 20 & CSAH 16 CSAH 11 & CSAH 9
Actual Critical Crash Rate Crash Rate 0.70 1.02 0.56 0.94 0.54 0.85 0.50 1.38 0.49 1.37 0.47 0.81
Figure 6.12 High Priority Intersections 7 thru 12
The third project involves upgrading the signs and pavement markings at the remaining 13 locations (Figure 6.13) on the list of high priority intersections. The estimated cost of SAFETY PROJECTS
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upgrading the signs and pavement markings is $7,000/intersection and the estimated project cost is $91,000. Number 13 14 15 16 17 18 19 20 21 22 23 24 25
Intersection CSAH 16 & CSAH 20 CSAH 14 & CSAH 3 (west) CSAH 6 & CSAH 8 (west) CSAH 14 & CR 112 CSAH 34 & CR 104 CSAH 5 & CSAH 4 CSAH 4 & CSAH 3 (west) CSAH 36 & CSAH 11 US 14 & CSAH 11 CSAH 8 & CSAH 35 CSAH 6 & CSAH 8 (east) CSAH 25 & CSAH 5 CSAH 3 & CSAH 17
Actual Critical Crash Rate Crash Rate 0.40 1.26 0.38 1.24 0.37 1.22 0.19 0.69 0.19 0.94 0.18 0.93 0.18 0.93 0.09 0.75 0.05 0.65 0.00 0.97 0.00 1.08 0.00 1.47 0.00 1.43
Figure 6.13 High Priority Intersections 13 thru 25
6.1.4
Urban Signalized Intersections
The detailed crash analysis of the signalized intersections documented that the most common type of crash is a right angle collision (41%). In order to have two vehicles in the intersection at the same time, it is clear that (at least) one of the vehicles had made an error and was in the intersection when the light was red. A review of the design guides for traffic signals suggests that implementation of a number of mitigation strategies to improve driver’s compliance with signal change intervals, which includes, the use of overhead indications, 12-inch lenses and background shields. A review of the signalized intersections in Olmsted County found that the County, Mn/DOT and the City of Rochester all routinely provide these features. This suggests that signal design features are likely not a factor contributing to the red light running that is associated with the right angle collisions and points towards an enhanced enforcement effort. Conversations with law enforcement officials in Rochester found a recognition that red light running was an important issue, but they were not able to assign enough officers to this detail due to staff limitations and the fact that it requires a minimum of two officers to safely carry out the operation (one on the approach to witness the violation and a second on the far side to chase the violator). In order to enhance the enforcement of red light running, a new technology has been developed involving the addition of a confirmation light (Figure 6.14) on the back of the signal mast arms. This light is wired into the red light circuit of the signal so that one officer on the far side of the intersection can observe the confirmation light (which comes on when the red light is illuminated) and be in a safe position to chase violators. The use of the red light confirmation light was one of the highest ranked safety strategies at the County’s Safety Workshop.
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Figure 6.14 Confirmation Lights in Dakota County
The suggested safety project involves installing the confirmation light at twenty-eight signalized intersections (Figure 6.15) along the three corridors with the greatest concentration of both total crashes and angle crashes – CSAH 22 East, CSAH 22 West and TH 14 (the South Beltway). The estimated cost of adding the confirmation lights is $1,000/approach and the estimated cost of the project is $100,000.
6.2
Driver Behavior Based
In order to address the driver behavior related factors that contribute to severe crashes, the Olmsted County Public Works Department will continue to provide professional staff to participate with their safety partners in a variety of activities, including: • • • • •
Countywide Fatal Crash Review Committee Southeast Minnesota TZD Safe Community coalitions Coordination with the county health department in efforts to educate drivers about seat belt usage, impaired driving and speeding Coordination with the county sheriff’s department and other law enforcement officials regarding snow and ice issues and enhanced efforts to reduce red light running.
6.3
Support Bicycle Safety
In support of addressing bicyclist safety concerns, Olmsted County Public Works Department will increase the level of coordination with ROCOG relative to their Long Range Thoroughfare Plan regarding future bike routes. When county highway projects are being developed on segments that are designated bike routes, consideration will be given to providing full width paved shoulders or an off-road trail, based on the availability of funding and where right-of-way widths are sufficient. In addition, in order to strike a balance between motorist and bicyclist safety, Olmsted County has chosen to employ a bicycle friendly rumble strip design for use along rural highways. The bicycle friendly design has been adopted by a number of state departments
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of transportation (including Minnesota). The design consists of providing a twelve-foot gap in the grooved pattern every sixty feed in order to provide bicyclists an opportunity to move between the traveled land and the shoulder without having to traverse the grooves.
US 14 from US 52 to CSAH 11 • US 14 and Memorial Pkwy SW (+) • US 14 and 12th St SW (T) • US 14 and TH 63 (+) • US 14 and CR 146 (3rd Ave SE) (+) • US 14 and 8th Ave SE (+) • US 14 and CSAH 1 (11th Ave SE) (+) • US 14 and CSAH 36 (15th Ave SE) (+) • US 14 and CSAH 22 (T) • US 14 and CSAH 11 (+) CSAH 22 (West) from US 52 to US 52/14 • CSAH 22 and West Frontage Rd (+) • CSAH 22 and Chateau Rd NW (+) • CSAH 22 and 55th St NW (+) • CSAH 22 and 41st St. NW (T) • CSAH 22 and CSAH 4 (Valley High Dr NW) (+) • CSAH 22 and 19th St NW (+) • CSAH 22 and 7th St NW (North) (+) • CSAH 22 and 7th St NW (South) (+) • CSAH 22 and CSAH 34 (Country Club Rd SW) (+) • CSAH 22 and CSAH 8 (Bamber Valley Rd SW) (T) • CSAH 22 and CSAH 25 (16th St SW) (T) • CSAH 22 and Fox Valley Dr SW (+) CSAH 22 (East) from US 14 to US 52 • CSAH 22 and CSAH 9 (Collegeview Rd E) (+) • CSAH 22 and CSAH 2 (Viola Rd NE) (+) • CSAH 22 and TH 63 (+) • CSAH 22 and East River Rd NE (+) • CSAH 22 and West River Pkwy NW (+) • CSAH 22 and 18th Ave NW (+) • CSAH 22 and 22nd Ave NW (+) Figure 6.15 Signalized Intersections in Rochester
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6.4
Safety Project Summary
6.4.1
Infrastructure Based Projects
Applying the high priority safety strategies at the most at-risk locations along Olmsted County’s system of highways results in the identification of eight types of safety projects with an implementation cost approaching $1.5 million. These projects include: •
Edge line rumble stripE’s
164 Miles
$400,000
•
Enhanced (6”) edge lines
84 Miles
$ 25,000
•
Enhanced curve delineation
22 Curves
$ 22,000
•
Median/channelization
6 Intersections
$450,000
•
Signs, St. Lights & Dynamic Warning
6 Intersections
$270,000
•
Signs & Street Lights
6 Intersections
$ 90,000
•
Signs
13 Intersections
$ 91,000
•
Enhanced Red Light Enforcement
28 Intersections
$100,000
Total
6.4.2
$1,447,000
Driver Behavior Based Activities
•
Continued participation safety partners in Fatal Crash Review Committee, Southeast MNTZD and Safe Community coalitions.
•
Continued coordination with the county public health and sheriff’s department in efforts to educate drivers and enhance enforcement efforts.
6.4.3 •
Support Bicyclist Safety Increased level of coordination with ROCOG relative to incorporating paved shoulders or off-road trails in reconstruction projects along designated bike routes.
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Section 7
Safety Policies
7.
Safety Policies
7.1
Policy Statement for Edge Line Rumble Strips/StripEs
7.1.1
Background
Olmsted County’s Strategic Highway Safety Plan identified road departure crashes along rural highways as one of the County’s key Safety Emphasis Areas. This determination is based on an analysis of the County’s crash records that found while over 80% of all crashes on the local County system occurred in urban areas, almost half of the severe crashes (fatal + A Injury crashes) occurred on rural roads. Of these severe crashes almost half of them involved a single vehicle running off of a rural County Highway. In response to this overrepresentation of road departure crashes along segments of the rural County Highways, Olmsted County identified and evaluated a variety of potential mitigation strategies (as documented in the NCHRP 500 Series Reports on implementation of AASHTO’s Strategic Highway Safety Plan and in the Federal Highway Administration’s Technical Memorandum on Consideration and Implementation of Proven Safety Countermeasures). Current safety related guidance suggests that the first step in addressing road departure crashes involves considering the deployment of techniques and features along road edges that help keep vehicles on the road. These techniques include; enhanced edge line pavement markings, enhanced delineation of highway curves, constructing wider/paved shoulders, providing a safety wedge as part of bituminous paving projects and installing edge line rumble strips/stripEs. Following an evaluation process that considered implementation costs, estimated effectiveness and the outcome of a prioritization exercise with the County’s safety partners; the use of edge line rumble strips/stripEs was selected as a targeted strategy for reducing the incidence of road departure crashes along segments of rural County Highways. Bicycle advocates have expressed concern on the use of edge line rumble strips/stripEs, citing a potential impact to their safety when bicycle tires cross over the grooves of the rumble strips/stripEs. A review of the highway traffic safety literature found several references to concerns about the interaction of bicyclists and edge line rumble strips/stripEs, but no documentation of any injuries or fatalities as a result of them. However, in response to bicyclist’s concerns, a number of States (Alaska, Arizona, Colorado, Florida, Iowa and Minnesota) developed and evaluated alternative rumble strip/stripE designs. These designs included a narrower groove (between 4” and 12” instead of the typical 16”), a shallower profile (3/8” instead of the typical 5/8”) and an intermittent pattern (48’ with grooves followed by 12’ without grooves). The literature goes on to indicate that most of the States, including Minnesota, have dismissed the idea of using narrower grooves because there is not enough tactile sensation to adequately warn drivers. The shallower profile design was also dismissed due to constructability issues using currently available equipment. Minnesota, as well as other states, has adopted the intermittent pattern as their recommended approach to balancing the need of addressing road departure crashes while still providing bicyclists a reasonable opportunity to move between travel lanes and shoulders without having to cross the grooves of the edge line rumble strip/stripE.
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7.1.2
Definitions
Edge Line Rumble Strip = a 12” to 16” wide grooved pattern, approximately ½” deep, constructed on the outside edge of the traveled lane or in the shoulder. Edge Line Rumble StripE = an 8” to 12” wide grooved pattern, approximately ½” deep, constructed on the outside edge of the traveled lane that contains the edge line pavement marking. Experience has demonstrated that installing the edge line pavement marking over the grooves of the rumble strip provides improved visibility of the marking at night and during wet pavement conditions, as well as, extends the life of the pavement marking material. Rural County Highways = those segments that are generally categorized as having a rural drainage system (ditches and culverts), a 55 mph speed limit, daily traffic volumes under 3,500 vehicles per day, and low levels of development (i.e., farmsteads and low density residential).
7.1.3
Policy
It is Olmsted County’s long term goal to reduce road departure crashes along all of the rural County Highway system. A proven effective strategy to achieve this goal is the use of edge line rumble strips/stripEs. Given that the rural system includes approximately 325 miles of County Highways, the total implementation costs could exceed $1 million. This level of funding will require using a phased approach to construct/install the edge line rumble strips/stripEs over several years, as funding permits. Olmsted County will annually evaluate the rural County Highway System, based on traffic volumes, road departure crashes, and shoulder characteristics, and establish a priority for implementation of edge line rumble strips/stripEs consistent with the following guidelines: •
Low Volume Segments (< 500 vehicles per day) = no immediate use of edge line rumble strips/stripEs, unless crash data indicates that they would be a benefit.
•
Moderate Volume Segments (500 – 3,500 vpd) = use of edge line rumble strips/stripEs (intermittent pattern)
•
High Volume Segments (> 3,500 vpd) = no immediate use of edge line rumble strips/stripEs, unless crash data indicates that they would be a benefit.
Olmsted County’s approach to implementing edge line rumble strips/stripEs will include two basic components: 1. Including safety strategies in traditional maintenance and regular construction projects. 2. Adding safety strategies by undertaking stand alone projects that capitalize on securing State and Federal Highway Safety Improvement Funds.
7.2
Policy Statement on Pavement Markings
7.2.1
Background
The Commissioner of Transportation has adopted the Minnesota Manual on Uniform Traffic Control Devices (MMUTCD) for use on all streets and highways of the State of Minnesota. The MMUTCD contains guidelines relating to the design and application of traffic control
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devices – signs, markings and signals, and is in substantial conformance with the national Manual prepared by the Federal Highway Administration (FHWA). The FHWA is in the process of developing minimum retroreflectivity criteria for pavement markings, similar to the recently adopted requirements for maintaining minimum levels of retroreflectivity for traffic signs. When these criteria are formally added to the MUTCD, Olmsted County will be responsible for maintaining pavement markings on the County’s system of highways such that the markings meet or exceed the minimum level criteria.
7.2.2
Definitions
Center line – A 4” wide solid or skip line (10 feet of painted line followed by a 40 foot gap) that denotes the center of road and that the adjacent lane to the left carries traffic in the opposite direction. The solid line is the regulatory device that designates where passing is not allowed and the skip line designates where passing is allowed. Edge line – A 4” or 6” wide line that denotes the edge of rural roads and separates lanes of traffic moving in the same direction on multi-lane highways. Latex paint – A water based paint that typically costs $0.05/foot for a 4” line and has a life expectancy of 2 years on low volume roads (under 1,500 vehicles per day) and 1 year on higher volume roads (greater than 1,500 vehicles per day). Epoxy – A multiple component liquid that is generally more durable than latex, costs $0.20/foot for a 4” line and has a life expectancy of 6 years on low volume roads and 4 years on high volume roads. Edge line rumble strip – A 12” to 16” wide grooved pattern, approximately ½” deep, constructed on the outside edge of the traveled lane or in the shoulder. Edge Line rumble StripE – An 8” to 12” wide grooved pattern, approximately ½” deep, constructed on the outside edge of the traveled lane that contains the edge line pavement marking.
7.2.3
Policy
Olmsted County will have a pavement marking program consisting of both construction and maintenance elements in order to provide reasonable levels of markings (presence and retroreflectivity) on all County highways, consistent with adopted statewide performance measures, 365 days per year. However, it must be recognized that it is not possible to maintain pavement marking minimum retroreflectivity levels for all markings at all times. Winter operations and maintenance activities can damage and even obliterate markings such that pavement markings in the winter and spring may have little or no measurable retroreflectivity. In addition, during wet conditions the performance of conventional pavement markings is typically much less than during dry conditions. In these cases, presence of the marking (regardless of retroreflectivity) after the winter season will be considered a successful marking application. Also, pavement marking replacement periods are limited to seasonal cycles (dry pavements and pavement temperatures above 50 degrees) making it impractical to perform pavement marking maintenance activities during winter months. The construction element of the County’s pavement marking program consists of using the epoxy material for all center and edge lines on new surfaces that are associated with construction and maintenance projects supported by State and Federal funds. The SAFETY POLICIES
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additional State and Federal funds on these projects allows the County to deploy the more durable and longer lasting epoxy markings at a reduced first cost and will also result in a long term reduction in annual maintenance costs (because of the documented longer service life). The maintenance element of the pavement marking program consists of two parts – a visual assessment of in place markings combined with a management approach to identify the segments of the County’s system that will be refurbished in any given year. The visual assessment will consist of County staff conducting a night time inspection of all County highways and recording their determinations relative to whether or not the markings meet the adopted performance measures. The visual observations will supplement the management approach which will track the service life of the markings on every County highway. The annual program for refurbishing the pavement markings will then be developed based on addressing those facilities where the markings have been determined to no longer meet the adopted performance measures. Refurbishing edge and center lines will be done with latex paint and with the schedule based on the following expected service lives: •
•
Low volume highways ¾
Center lines – every year
¾
Edge lines – every other year
¾
This yields a refurbishing project that includes the center line and one edge line (i.e., WB) being done in one year and the same center line and the other edge line (i.e., EB) being done the next year.
High volume highways ¾
Center lines – every year
¾
Edge lines – every year
To address the issue of the performance of the pavement markings during wet conditions, Olmsted County will deploy edge line rumble stripE’s along rural County highways. Experience has demonstrated that installing the edge line pavement marking over the grooves of the rumble strip provides improved visibility of the marking at night and during wet pavement conditions – the paint on the nearly vertical sides of the grooves in the pavement remains above the film of water during most rain events. In addition, the paint in the grooves is protected from damage by snow plows; as a result the service life of the pavement marking is extended.
7.3
Policy Statement on Pedestrian Cross-walks
7.3.1
Background
One of the common strategies requested by the public as a mitigation measure for pedestrian crashes is the installation of a marked cross-walk. However, a research study involving thousands of intersections in dozens of cities across the nation found that marked cross-walks at unsignalized intersections are NOT safety devices.
SAFETY POLICIES
7-4
A separate study found that pedestrian crash rates were actually higher at marked crosswalks and this effect is greatest for multi-lane arterials with volumes greater than 15,000 vehicles per day. This study also identified three strategies that were proven to improve pedestrian safety – sidewalks, median islands and curb extensions. Sidewalks provide pedestrians with opportunities to separate themselves from vehicular traffic. The median islands and curb extensions provide pedestrians with safe places to wait for gaps in traffic, improve lines of sight for both pedestrians and drivers and reduce walking distances and therefore the amount of time pedestrians are exposed to traffic.
7.3.2
Policy
Olmsted County will continue to provide painted cross-walks at signalized intersections because they are an integral part of the intersection design and provide important guidance for both pedestrians and drivers. At existing locations with marked cross-walks, an evaluation will be conducted at each location prior to refurbishing any of the markings. At specific locations, the evaluation process will determine if there is a need for pedestrian amenities based on identifying safety deficiencies. If a need is established, consideration will be given to refurbishing the crosswalk markings in conjunction with adding a center median, curb extensions or both. If it is determined that a center median and curb extensions are not feasible, consideration will be given to not refurbishing the cross-walk. In response to new requests to provide marked cross-walks, an evaluation of the specific location will be conducted. If a need to provide additional pedestrian safety measures is established, a marked cross-walk will only be considered if it is part of a response that also includes a center median, curb extensions or both.
SAFETY POLICIES
7-5
For further information, please contact:
Howard Preston, P.E.
Senior Transportation Engineer 1295 Northland Drive, Suite 200 Mendota Heights, MN 55120 (651)365-8514
[email protected]
008MKE
TB072009
