Report numberRA-MOW-2011-023
TitleThe influence of traffic management on emissions
SubtitleGuidebook for good practice
AuthorsBart Degraeuwe
Bert De Coensel
Bart Beusen
Madhava Madireddy
A Can
Ina De Vlieger
Published byPolicy Research Centre for Mobility and Public Works, track Traffic Safety 2007-2011
Number of pages60
Document languageEnglish
Partner(s)VITO en Universiteit Gent
Work packageOther: Sustainable transportation

The mission of work package 8.3 was to investigate the influence of traffic management on the reduction of emissions of air pollution and noise from road traffic flows. This was done by implementing an emission model and noise model as two external plug-ins into the traffic simulation software Paramics.


A preceding literature study on emission models and initial tests with microscopic traffic simulation, presented in a separate technical report (see Trachet et al., 2010), demonstrated that suitable emission models are available for studying the effect of traffic management. For CO2 and noise, it was shown that microscopic traffic simulation can be used to study the effect of this traffic management prior to implementing.


The present report focuses on the influence of traffic management on emissions and noise. It consists of both an elaborate literature study and the analysis of specific case studies in separate model simulations. The table below gives an overview of the results of the literature study. For these new simulations the suggestions of the steering committee were taken into account. In this way the Zurenborg neighbourhood in Antwerp and the E313 highway between Geel and Antwerp were selected as study areas.


In the Zurenborg neighbourhood the effect of speed reductions was studied. In the proper neighbourhood the speed was reduced from 50 to 30 km/h, on the major roads (Singel) from 70 to 50 km/h and on the freeway from 100 to 70 km/h. This results in a decrease of emissions and noise. Also the effect of traffic light synchronization was determined. The presence of a green wave results in a decrease of emissions but an increase in traffic noise.
Specific analyses on the E313 freeway between Geel-Oost and Antwerpen indicate that the introduction of variable speed limits (VSL) has only very little direct effect on air pollutant and noise emissions. There may be an indirect effect through the reduction of accidents and the corresponding congestion. Air pollutant emissions are minimal around a speed of 90 km/h. Given that the current average speeds on the E313 during rush hour are around 50 km/h, decreasing average speeds will lead to extra air pollution, but, on the other hand, will lead to lower noise levels along the freeway. Furthermore, measures that enhance traffic flow fluency without attracting more traffic can decrease air pollutant emissions, but will increase noise emissions.


It has to be noted that various literature review studies indicate different results for the same measure. Depending on the specific characteristics of the measure considered (e.g. dimensions of the roundabout, magnitude of the speed reduction,...) or the features of the local situation (e.g. dimensions of the road, applicable speed limits, amount of traffic,...), the impact results might differ largely between locations/studies. Due to the importance of local characteristics when assessing the impact of traffic management schemes we therefore recommend to examine the impacts on traffic flow, emissions,... case by case. Each situation should be examined thoroughly and priorities on the desired outcome (e.g. on traffic flow, safety, air quality,...) need to be established in advance to select the most valuable traffic management measure for each situation. The model chain applied within the case studies of this project, combining information on vehicle intensities, road characteristics and (noise)emission functions on a microscopic level, appeared to be a very useful tool for examining this kind of policy questions.


In addition, on-the-field analyses were performed within a confined additional research (‘vrije onderzoeksruimte’). Hereby we analysed on-the-road speed profiles (recorded by an on-board logging device) to examine the link between speeds, speed limits and fuel consumption (CO2 emission). The lowest average fuel consumption (CO2 emission) is obtained for the 70 and 90 km/h speed limits. At highway speeds, engines are operating very efficiently but the air resistance is increasing sharply, leading to higher fuel consumption, and  CO2 emissions.


For a more detailed summary of the findings we refer to Chapter 5 (Conclusions). More detailed information on the literature study and the specific case studies can be found in the current report.

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The Policy Research Centre for Traffic Safety carries out policy relevant scientific research under the authority of the Flemish Government. The Centre is the result of a

cooperation between Hasselt University, KU Leuven and VITO, the Flemish Institute for Technological Research.


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