BOOK:
NOISE POLLUTION IN URBAN AND INDUSTRIAL ENVIRONMENTS MEASUREMENTS AND NOISE MAPPING
CHAPTER 8 – Impact of Environmental Noise on the Operation of an Urban Transport System
M. Sc. David Queiroz de Sant’Ana and Prof. Dr.-Ing. Paulo H. T. Zannin
Laboratory of Environmental and Industrial Acoustics and Acoustic Comfort, Federal University of Paraná – UFPR, Curitiba, PR, Brazil *Corresponding author:
[email protected];
[email protected]
ABSTRACT
An investigation was made of noise levels on dedicated bus lanes in the integrated bus rapid transit system (BRTS) of the city of Curitiba. Equivalent noise levels (Leq) along the traffic lanes were measured and also predicted through computer simulations based on noise map calculations, using the guidelines of the German standard RLS-90 for noise simulations on roads and in parking lots. Data were collected at 10 sampling points along two of the city’s five transport hubs. These sampling points were selected for their similarity of land use, since they are all characterized by a high density of residential and commercial buildings. The measured equivalent noise levels were higher than 65 dB(A) at all the evaluation points, exceeding the limits established by Curitiba Municipal Law 10.625 of 2002 for this type of urban setting.
1. Introduction
Curitiba, the capital of the state of Paraná, has a population of about 1,7 million (IBGE, 2010) distributed in 75 neighborhoods covering an area of 435 km2. The city’s integrated metropolitan bus rapid transit system (BRTS) carries 1.9 million passengers per day. This BRTS accounts for the direct employment of 12,700 people, comprising drivers, collectors, inspectors, and professionals involved in its maintenance and administrative services. In addition to their role in transportation, the major bus corridors along exclusive lanes make up the hubs that hierarchize the urban street network and regulate urban growth. In a survey conducted in the city of Curitiba, Zannin et al. (2003) found that among noise sources, vehicle traffic was identified as the most annoying for most of the respondents, accounting for 73% of the responses. The demand for transport tends to increase along with the development and growth of the municipality and the metropolitan area; hence, an increase in noise pollution is to be expected. The purpose of this study was to characterize the acoustic profile of the urban environment along Curitiba’s exclusive bus lanes, using measured equivalent sound pressure levels (Leq) and computational predictions by means of noise mapping calculations based on traffic composition. The results were compared with the values recommended by current municipal legislation (Curitiba Municipal Law 10625 of 19 Dec 2002) and the recommendations of the national standard (NBR 10151, 2000). The surveys were conducted at 10 sampling points along the two main thoroughfares, which showed similar characteristics in terms of land use, according to Curitiba Municipal Law 9800 of 03 Jan 2000.
2
2. Curitiba’s bus rapid transit system (BRTS)
Curitiba’s bus rapid transit system (BRTS) is based on exclusive bus lanes, following the urban traffic guidelines established in the 1960s. The city’s rapid growth has led to increasing concern about the expansion of land occupation. The ordering principle established for the city’s urban space was the creation of two expressways, one linking the North and South sides and the other the extreme East to the Center of Curitiba. Two more hubs were added to this initial expressway structure, the West hub and the Southeast hub, forming a hub-and-spoke expressway structure. The traffic hubs comprise three lanes: two marginal freeways for passenger cars, service vehicles and motorcycles, and a central lane for buses. The central lane is dedicated exclusively to buses (see Figure 1).
Figure 1. Exclusive bus lanes
3
The buses that travel along the exclusive lanes are bi-articulated, which allows them to rotate and travel along curves. Their articulation joints are protected by a ribbed outer closure of rubberized material and they can carry about three times more passengers than conventional vehicles (see Figure 2).
Figure 2. Bi-articulated bus The technical characteristics of Curitiba’s bi-articulated buses are as follows: ● Length: 24.52m ● Width: 2.50m ● Height: 3.415m ● Engine: 340 HP diesel; ● Automatic transmission, 5 gears; ● Air suspension; ● Capacity: 270 passengers; ● Boarding: cylindrical tube bus stations with raised platforms.
4
The tube stations for bi-articulated buses have raised boarding-disembarking platforms. Boarding from a tube station platform differs from a conventional bus stop because the platform is elevated about 60 cm from ground level. Passengers board the bus from the raised platform, where a bus fare collector controls the entrance to the station, thus reducing the boarding time as well as the number of people employed for this service. Curitiba’s tube bus stations provide easy access for disabled people by means of lifts installed at one of their ends (see Figure 3). There are 357 tube stations distributed around the city, with the following characteristics: ● Tubular steel structure ● Clear see-through walls ● Lift for handicapped people ● Capacity: ~45 people
According to statistics published by the agency that manages the system, boarding from the raised platform represents savings of 18% in maintenance costs when compared to the traditional mode of operation.
Figure 3. Passenger boarding-disembarking tube bus station 5
3. Materials and Methods
The measurements were taken in three samples of 10 minutes, with the response of the device set to the fast mode and the A-weighted equivalent continuous sound level (LAeq). The measurements were taken in the afternoon, between 2:00 and 4:00 PM, to avoid rush-hour traffic congestions. A B&K 2238 sound level meter was used, placed at a distance of two meters from the buildings (NBR 10151, 2000). The data were analyzed using B&K 7815 Noise Explorer software. The computer simulation (calculation of noise maps) of the noise levels emitted by vehicle traffic along Sete de Setembro and Padre Anchieta avenues was performed based on the parameters of the German RLS 90 standard for the acoustic prediction of roads and parking lots, using Cadna-A 4.2 software. Sete de Setembro and Padre Anchieta avenues were chosen because they adhere more homogeneously to current land use regulations for areas bordering exclusive bus lanes – Special Structural Sector. The calculation of vehicle traffic immissions considers: 1) flow of vehicles per hour, 2) percentage composition of heavy vehicles in the total vehicle flow, 3) speed of vehicles in the evaluated section, 4) type of road pavement, and 5) road slope. Although the RLS 90 standard estimates highway noise immissions, studies have shown that its application to urban traffic is quite satisfactory (Calixto, 2002; da Paz, 2004). The flow of vehicles in the investigated sections was determined from a visual count of vehicles during three separate 15-min observations, considering a speed of 50 km/h. The counted vehicles were divided into two categories: (a) light, and (b) heavy, and their percent participation in the total flow was calculated. The counts and measurements were performed simultaneously, and the three-dimensional acoustic models were created based on the city’s base map – street maps and orthophotos – with the aid of CAD applications.
6
4. Results and Discussion
The A-weighted equivalent sound levels (LAeq) measured along the line of buildings were higher than 69 dB(A), thus exceeding the limit of Leq < 65dB(A) established by local regulations (see Table 1).
Table 1. A-weighted equivalent sound level (LAeq) along the line of buildings on Padre Anchieta and Sete de Setembro avenues Measurement point
Hub
LAeq, in dB(A)
Presidente Taunay
Pe. Anchieta
72
Praça da Ucrânia
Pe. Anchieta
71.2
Bruno Filgueira
Pe. Anchieta
70.4
Bigorrilho
Pe. Anchieta
71.3
Gastão Câmara
Pe. Anchieta
69.8
Eufrásio Correa
Sete de Setembro
68
Alferes Poli
Sete de Setembro
69.6
Oswaldo Cruz
Sete de Setembro
69.5
Coronel Dulcídio
Sete de Setembro
70.3
Bento Viana
Sete de Setembro
73.3
The acoustic maps of the stretches of Sete de Setembro and Padre Anchieta avenues show noise levels between 72 and 78 dB(A). The results of the simulations were quite accurate (Calixto, 2002; Diniz, 2003; Paz, 2004), since the difference between simulated and measured data was approximately (±) 2 dB(A). A comparison of the simulated results and the noise limits established by Curitiba Municipal Law No. 10625 and by the national standard (NBR10151) for noise immissions in residential areas indicates the acoustic pollution of these environments in the daytime (see Figures 4 and 5). 7
Figure 4. Predicted equivalent sound levels (Leq) of traffic noise on Padre Anchieta Avenue
8
Figure 5. Predicted equivalent sound levels (Leq) of traffic noise on Sete de Setembro Avenue
Conclusions
Curitiba’s Special Structural Sector, which is the area surrounding the city’s exclusive bus lanes, presented noise levels exceeding those established by municipal legislation. The surveys carried out in this study revealed noise levels above 65 dB(A) at all the analyzed points.
9
The computer simulations differed by +/- 2 dB(A) from the measured values. Simulations are important because they save time and money in assessing noise pollution, although they do not replace field data, i.e., measurements of sound levels, since variables such as the conditions of vehicle fleet maintenance and pavement quality cannot be addressed by algorithms. However, computer simulations offer undeniable advantages over field measurements insofar as they can cover of large areas. These noise immissions (sound levels measured at the receiver points) can be decreased through the adoption of more rigorous maintenance of light and heavy vehicles, pavement repair and maintenance, reduction of speed limits, etc.
Aknowledgments
The authors gratefully acknowledge the German Government, through the German Academic Exchange Service – DAAD (Deutscher Akademischer Austauschdienst) and the Brazilian Government, through the National Council for Scientific and Technological Development – CNPq, for their financial support, which enabled the purchase of the sound level meters and software used in this study.
References
Calixto A. O ruído gerado pelo tráfego de veículos em “rodovias-grandes avenidas” situadas dentro do perímetro urbano de Curitiba, analisado sob parâmetros acústicos objetivos e seu impacto ambiental. Universidade Federal do Paraná [Noise generated by vehicle traffic on roads and major avenues in the city of Curitiba, analyzed based on objective acoustic parameters and their environmental impact. Federal University of Paraná], Curitiba, PR., 2002 (in Portuguese) 10
Calixto A, Diniz FB, Zannin PHT. Statistical modeling of road traffic noise in an urban setting. Cities, 2003, 20 (1): 23-29. Der Bundesminister für Verkher – DBV (1990). RLS/90: RICHTLINIEN FÛR DEN LÄRMSCHUTZ AN STRAßEN. DBV, Bonn (in German)
Diniz F. Impacto ambiental das emissões sonoras de subestações de energia elétrica na cidade de Curitiba. Dissertação de mestrado – Universidade Federal do Paraná, Biblioteca do Setor de Tecnologia [Environmental impact of noise emissions from electric power substations in the city of Curitiba. Master’s dissertation – Federal University of Paraná, Library of the Technology Sector], Curitiba, Paraná, 2003 (in Portuguese) IBGE – INSTITUTO BRASILEIRO DE GEOGRAFIA E ESTATÍSTICA (2000). Censo demográfico, relatório 2010 [IBGE – Brazilian Institute of Geography and Statistics (2010). Population Census Report 2010] IBGE, Rio de Janeiro (in Portuguese) LEI MUNICIPAL Nº 10.625 de 19 de dezembro de 2002 “Dispõe sobre os níveis de ruído e bem estar da população” [Curitiba Municipal Law No. 10625 of 19 Dec 2002, Establishes regulations on urban noise, public protection and welfare] (in Portuguese)
Paz EC da. Estudo de um modelo de avaliação e predição acústica para ruído de trafego rodoviário. Dissertação de mestrado – Universidade Federal do Paraná, Biblioteca do Setor de Tecnologia, [Study of a model for acoustic assessment and prediction of road traffic noise. Master’s dissertation – Federal University of Paraná, Library of the Technology Sector], Curitiba, Paraná, 2004 (in Portuguese)
11
Prefeitura Municipal de Curitiba. Dados sobre transporte coletivo [Curitiba Municipal Administration. Data on public transport]. Available at: http://www.curitiba.pr.gov.br/ Accessed on 20 Oct 2003 (in Portuguese)
Zannin PHT, Calixto A, Diniz FB, Ferreira JAC. A survey of urban noise annoyance in a large Brazilian city: the importance of a subjective analysis in conjunction with an objective analysis. Environmental Impact Assessment Review, 2003, 23: 245-255.
12
