analysis of federal, state and regional scale transportation project and program data was used to calibrate this ABM. In
University of Vermont Presentations at the 2013 Transportation Research Board Annual Meeting Abstracts from the Conference Integrating Traffic Router and Microsimulator into Land Use and Travel Demand Model Authors: Troy, Austin Abstract: This paper describes a first-of-its-kind attempt at integrating a dynamic and disaggregated land use model with a traffic microsimulator and compares its predictions of land use to those from an integration of the same land use model with a more traditional four-step travel demand model. For our study area of Chittenden County, Vermont, we used a 40-year simulation beginning in 1990. Predicted differences in residential units between models for 2030 broken down by town correlated significantly with predicted differences in accessibility. The two towns with the greatest predicted differences in land use and accessibility are also the towns that currently have the most severe traffic bottlenecks and poorest route redundancy. Our results suggest that our particular integration of a microsimulator with a disaggregated land use model is technically feasible but that in the context of an isolated, small metropolitan area, the differences in predicted land use are small.
Crash Fault Analysis of Out-of-State Drivers in Vermont Authors: Harootunian, Kristine; Aultman-Hall, Lisa; Lee, Brian H. Y. Abstract: This study examined single- and two-vehicle police-reported crashes in Vermont between 2003 and 2008. It evaluated the likelihood of being at fault for Vermont drivers versus out-of-state drivers. Analysis using odds ratios estimated that out-of-state drivers are 98% more likely to be at-fault for a single-vehicle crash and 9% more likely to be at-fault for a two-vehicle crash.Age, gender, season of year, light conditions, and road type were statistically significant interactions for Vermont and out-of-state drivers for single-vehicle crashes. Male drivers and driving during the winter months had more pronounced effects of increasing single-vehicle crash fault for out-of-state drivers than for Vermont drivers. Vermont drivers, on the other hand, were more apt to cause a crash on gravel roads.The interactions were less pronounced for two-vehicle crashes. Being male or an older driver increased crash odds for both groups. Driving during the summer months increased out-of-state drivers crash odds by 21%, while it was insignificant for Vermont drivers. The other factors tested were insignificant for both groups.The crash evaluation of fault for “foreign” drivers’ crashes has been understudied in the United States. Previous research, conducted mostly in other countries, has been limited but has shown that foreign drivers are more likely to be involved in a crash. This study in Vermont strongly suggests the need for further study of this factor as well as identification of associated interventions.
Agent-Based Modeling of Intergovernmental Decision Making: How Institutional Rules Generate Basins of Attraction in Funding Transportation Projects Authors: Zia, Asim; Koliba, Christopher Abstract: A Pattern-Oriented, Agent Based Model (ABM) of an intergovernmental network is presented to demonstrate an application of complex systems and computational modeling in real world transportation policy implementation processes. This ABM simulates the dynamics of intergovernmental decision making that is deployed for transportation project prioritization processes. The ABM simulates baseline and alternate intergovernmental institutional rule structures and assesses their impacts on financial investment flows from federal to state, regional and local scale governments. The current version of the ABM is limited to simulating roadway projects in the state of Vermont that are primarily funded through US Surface Transportation Program and Interstate Maintenance Program. Multiple focus groups, individual interviews, and analysis of federal, state and regional scale transportation project and program data was used to calibrate this ABM. In particular, this ABM demonstrates how institutional rules set by federal, state and regional government agencies generate “basins of attraction” in funding roadway projects. The results from experimental simulations are presented to test system-wide effects of alternate institutional designs on the differential emergence of roadway project prioritization patterns and funding allocations across regions and local towns. Exploration of Intrahousehold Motorized Vehicle Allocation Using 2009 National Household Travel Survey Authors: Nam, Richard; Lee, Brian H. Y.; Aultman-Hall, Lisa; Sears, Justine Abstract: This study examines intra-household vehicle allocation to drivers and trips using data from the 2009 National Household Travel Survey and is motivated by the fact that reallocating household vehicles is a reasonable short-term action to reduce fuel and associated emissions. Models are developed for households in the national sample and for segmentations by population and Census regions. Binomial logistic regression is used to model whether a household fleet is optimal and whether a household is a high potential saver (HPS). Of households with two or more vehicles, 31% are classified as HPS. Linear regression is used to model the number of gallons of fuel a household can potentially save per year with vehicle reallocation. About 59% of households can reduce fuel consumption by an estimated 5.2%, or approximately five billion gallons of fuel nationally, if they reallocate their fleet. Household size and lifecycle, travel behavior, and fleet composition are related to intra-household vehicle allocation. Similar variables are significant predictors of potential gallons of savings and whether a household is an HPS. Models are consistent across regions with minor exceptions. Rural areas had differences from more urban areas. This study has demonstrated that appreciable savings in fuel consumption and associated emissions is plausible through vehicle reallocation and the ability to pursue this countermeasure in the short-term motivates further research to more fully understand causal mechanisms and target households for intervention.
Data Fusion for Multiple-Sensor Nondestructive Evaluation on Concrete Bridge Deck Authors: Cui, Jianhong; Huston, Dryver Roy; Arndt, Ralf Abstract: Corrosion of buried reinforcing steel in concrete bridge decks is one of the dominant damage types in terms of overall bridge maintenance costs. Early-stage detection, location and assessment of corrosion can significantly reduce the damage progression and maintenance costs. This study aims to assess and improve the ability of various nondestructive evaluation (NDE) methods to detect the early stages of corrosion. This paper presents the techniques to apply data fusion on two NDE methods – ground penetrating radar and half-cell potential. Fusing data from multiple NDE methods may result in better and more accurate evaluation of active corrosion.
Relationship Between Measures of Urban Form and Body Mass Index in Nonurban Diabetic Adults: Case Study from Vermont Authors: Troy, Austin; LIttenberg, Benjamin Abstract: We analyzed the relationship between measures of urban form and body mass index (BMI) using data from the Vermont Diabetes Information System (VDIS) on 610 adult diabetics, while controlling for a number of potential confounders, including diet, exercise, income, gender, age, medications, and others. We found a strong positive correlation between BMI and commercial density measured at a 250 meter scale, a result which remained significant even when spatial autocorrelation was accounted for. This result, which is contrary to much of the previous literature, suggests that the mechanism driving the relationship between BMI and density is different in a predominantly rural and exurban region like Vermont than in a large metropolitan area, which is where most of the previous literature was conducted. We hypothesize that the lack of a significant alternative to automobile transport coupled with a dispersed land use pattern means that marginal increases in density in most areas of Vermont are unlikely to lead to significantly greater walkability or active transport. Further, low commercial density may proxy greater access to outdoor recreation opportunities or greater necessity for outdoor physical labor related to rural occupations (e.g. farming) or property maintenance (e.g. brush clearance). However, another result suggests that density is not the only facet of urban form that matters: one of our two models finds a significant reduction in BMI for subjects living within 1 km of a designated downtown core. While density is higher than average in these cores, it may be other design characteristics associated with walkable neighborhoods—such as mix of uses, pedestrian infrastructure, and difficulty in parking—that make them more walkable, leading to lower BMI for nearby residents.
Informing Congestion Management in National Parks Using Stated-Preference Modeling Authors: Pettengill, Peter R.; Manning, Robert E.; Lee, Brian H. Y.; Valliere, William Abstract: This research assessed the relative importance of indicators and standards of quality for recreational travel at two national parks in the United States. Stated preference analysis was used to compare the utility of crowding, convenience, corridor design, and cost in visitors’ transportation choices among private automobile, shuttle bus, and bicycle. Results offer insight into managing traffic congestion and illustrate which management actions may be most effective in influencing visitors’ travel behavior.
Comparisons of Discretionary Passenger Vehicle Idling Behavior by Season and Trip Stage Using GPS and OBD Devices Authors: Dowds, Jonathan R.; Sullivan, James; Aultman-Hall, Lisa Abstract: This study addresses the topic of discretionary passenger vehicle idling, using field data collected from 20 volunteers in Vermont. Each volunteer participated in two, two-week data collection periods, one in the summer and one in the winter. Overall, 15.6% of vehicle operating time was spent idling, consistent with the limited existing data on this topic. In addition, the paper describes a processing method used with in-vehicle GPS and OBD data that allows discretionary idling at the start and end of trips to be separated from the in-travel idling related to traffic or traffic control. Discretionary idling accounted for more than 6.5% of vehicle operating time. Discretionary winter idling events are found to be longer than summer idling events and, among idling events over 60 seconds, trip-start idling to be longer than trip-end idling. Both of these results re-affirm prior findings suggesting that there are opportunities for behavioral changes to reduce idling. The method used to extract discretionary idling is promising for widespread use and large sample data collection efforts. This method will be critical for the many communities that lack robust idling data when considering the costs and benefits of idling behavior change initiatives.
Transportation Network Resolution: Exploring How Much of Road Network Is Needed for Analysis Authors: Sullivan, James; Novak, David; Aultman-Hall, Lisa Abstract: It is typical for travel models to use only a subset of the transportation system links. Often major links such as arterial roads are included in the network but local streets and minor roads are excluded. This paper evaluates the potential significance of 23 such omitted links in the travel demand model network of Chittenden County, Vermont using the Network Trip Robustness measure. The objective is to determine the relative significance of including each of these omitted links in the network. Approximately, half (12) of the links were found to significantly influence the robustness of the network. The analysis demonstrates that the set of links included in a travel-model network must be assessed before effective analyses can be made. If significant network links are omitted from a model network, erroneous conclusions about the effects of new roadway infrastructure or existing roadway disruptions are possible. Seemingly insignificant roads and streets can provide alternative routes, which will provide gains to the network even during relatively minor disruption events.
Comparative Analysis of U.S. Environmental Protection Agency Operating Mode Distribution Generator with Real-World Operating Mode and Emissions Data Authors: Chamberlin, Robert; Holmen, Britt A.; Talbot, Eric; Sentoff, Karen M. Abstract: In June 2012, the Environmental Protection Agency (EPA) released the “Operating Mode Distribution Generator” (OMDG) a tool for developing an operating mode distribution as an input to the Motor Vehicle Emissions Simulator model (MOVES). The tool converts basic information about traffic operations – idle time, grade, and average speed – into an operating mode distribution. This tool is designed to make project-level analyses for CO and PM hot-spots easier to conduct with basic traffic activity data.This paper compares the operating mode distributions obtained from this tool with those measured on a vehicle instrumented with the Total On-Board Tailpipe Emissions Measurement System (TOTEMS). TOTEMS generates a wealth of data, including a vehicle’s speed, idle time, and link grade – all of the inputs necessary to run the OMDG. The comparison is made for 4 signalized intersections on an urban arterial in Burlington, Vermont. This analysis shows that the OMDG, when compared to 31 test runs of an instrumented vehicle, was more accurate under circumstances of no to low grade and higher congestion (higher stop time). Estimation inaccuracies are most critical for specific operating modes -- for CO under high VSP conditions; for PM10 under braking conditions (i.e. VSP
