Stop Chicken Little: The Truth about Traffic Calming  in Portland, Maine

Stevens Avenue Project : French Auto Club Report

The following is a International Automobile Federation (France) report on a study done 

by the Austrians. It measured actual tailpipe emissions, not just a computer model 

of what might happen.


Alliance Internationale de Tourisme                     (33)

Federation Internationale de l’Automobile           (33)

Place de la Concorde

PARIS, France


Meeting of 6th September 1994 in Munich

Item 4.4.

Power and Speed of Vehicles

Rapporteur: Mr. Jean-Martin Kuntschen (TCS)


An impact study on the environment carried out in Austria and based on normal driver behaviour demonstrated that speed bumps had negative effects on both the environment and fuel consumption. A regular traffic flow would therefore always be more environment-friendly.

A TCS mobile exhaust fume measuring device (MAMA) was used to carry out the tests. The equipment consisted of a high precision measuring device placed in a medium-range vehicle in which the catalytic converter had been tuned in advance. Before the test took place, all the measuring devices were inspected and calibrated by the Combustion Engines Institute of the Technical University of Vienna Test with six speed bumps

The test took place on a 1.5 km stretch of road containing six speed bumps. Speed was limited to 30 km/h.

The test took place in two phases, In the first phase, the vehicle slowed down to 15 km/h before the bumps and accelerated to 30 km/h after the bumps-as is the practice of many drivers.  In the second phase the vehicle came to a halt before each bump.

Staggering results

The results of the tests were as follows: a vehicle which slows down to 15 km/h before the bump and accelerates to 30 km/h immediately after the bump emits 10 times as much nitrogen oxide (NOx) as a vehicle which maintains a constant speed of 30 km/h. NOx emission per kilometre thus increases from 0.03 gm to 0.3 gm.

The vehicle which drew to a halt at each bump showed a NOx emission of 0.24 gm/km, i.e. 8 times more than that of a vehicle maintaining a constant speed of 30 km/h. On the stretch of road containing speed bumps carbon monoxide (CO) emissions were three times as great as those of a vehicle maintaining a constant speed. Fuel consumption increased from 7.9 litres to an additional two litres (9.9) per lOO km on the stretch of road where the vehicle braked six times. Carbon dioxide emission (CO2) increased in the same way. Hydrocarbon (HC) emissions were so low in all cases that they were below the probative level.