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On-the-road emission measurements on vehicles at roundabouts (part 3) (ASTRA1992/009)

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Complete with results
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Transport mode
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Transport policies
Environmental/Emissions aspects


Background & Policy context

In (almost) all of the action plans for air pollution, which had to be worked out by the cantons for the attention of the federal government must be decrease of  speed limits in urban areas. Research in this area show serious shortcomings, because it was based solely on test experiments.

The TCS has a mobile gas-measuring system (MAMA), consisting of a VW Golf as a carrier vehicle, a built in analyser and also built-in computer, which processes the signals. Thus measurements of consumption and emissions are possible directly in the traffic. This system has proven its accuracy and suitability for comparative measurements with a stationary CVS (Constant Volume Sampling).


The main project objective is to develop a professionally correct basis for assessing the rate reductions included in the action plans in terms of fuel consumption, pollutant emissions (CO, C02, HC, NOx) and drivability. In four stages, the following speed pairs are examined: 30/50 km / h, 100/120 km / h, 80/100 km / h 60/80 km / h.


Parent Programmes
Institution Type
Public institution
Institution Name
Swiss Government: State Secretariat for Education and Research
Type of funding
Public (national/regional/local)


Final report with evaluation of two possibilities (roundabouts and traffic lights intersections) as a traffic crossing and their influence on emissions, fuel consumptions and journey times. 

Main conclusions of the project are as follows:

Evaluation results show that there is no apparent propensity to change a roundabout intersection. The impact of the transformation of a roundabout intersection on crossing hours, fuel consumption, pollutant emissions, etc. is strongly dependent on  individual factors such as traffic volume, frequency of interruption of the flow of traffic by pedestrians, the report frequency of traffic on the roads between them, etc. Since the frequency of traffic during the day varies considerably for most roundabouts, it follows that a roundabout can have a positive impact at some times, but by also negative impacts in other daily times.

If a crossroads with traffic lights is replaced by a roundabout, the impact will be positive. However, if the roundabout is replacing an intersection without traffic lights consequences for  consumption and pollutant emissions are most often negative because the roundabout disrupt a previously homogeneous mode of conduct. Slowdowns and accelerations forced (and wanted to road safety) by the roundabout generate greater consumption and higher emissions of pollutants.


Lead Organisation
EU Contribution
Partner Organisations
EU Contribution


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