Title of Example

Example

How do you persuade about four thousand motorists to change their old trusted route? The municipality of Utrecht chose for a simple, but drastic solution. The traffic lights on the Catharijnesingel, an important connecting road, give very short green times. And that helps. In a few weeks time the number of cars and trucks diminished by twenty percent. Enough to meet the air quality standards.

Adapting the traffic lights was the only way to meet the standard (limit value plus margin of tolerance/ LV+MOT) for nitrogendioxide. The Catharijnesingel forms a narrow connection between four busy, wide roads. And big trees are creating a roof of foliage under which the air pollution is accumulating. Adaptation of the road profile to the traffic is undesirable. One short traffic diversion leads to new problems. Moreover such measures cost a lot of money. The principle of dosing lights is simple. They give very short green times and let pass a limited number of cars.

Because of this motorists are persuaded to take other routes by way of wider roads with a better air quality. Put another way: you disperse the traffic to several, better routes. The implementation of the measure proved to be more difficult. The first question cropping up was which green times are the most appropriate. Do you shorten them gradually, so motorists can get used to the measure? Or do you do what is necessary right away with the risk of a sudden impact. The project team choseto make the change all at once, because it is difficult to turn off the tap when you get many complaints. The team found it difficult to estimate what impact the measure would have on motorists. In advance the team informed them with notice-boards on the Catharijnesingel and Venuslaan. But that did not help very much. On the first day the measure became effective, there were as many cars as before. Motorists had noticed the boards, but they did not attach consequences to it. And then the telephone was red-hot.

notice-board Venuslaan: dosing traffic

dosing light

People did not understand the relation with air quality. Now how can this? We are puffing all together before the traffic light!, was a much-heard response. So the team had to explain that the intention is to remove a part of the traffic to a number of routes with a better air quality. And that stagnation at the dosing lights on the Catharijnesingel and Venuslaan causes no problems for local air quality by the wide profiles combined with open building or by the absence of houses. Of course the total emission increases by the longer waiting time, but that impact is negligible at urban level. This shows that communication is very important. With hindsight more information resources should have been put on. Now, after a few months, motorists have got used to the situation. The municipality of Utrecht is satisfied with the results. The traffic on the Catharijnesingel has already decreased by twenty percent. Now the yearly average concentration is just 1 ug/m³ above the standard (LV+MOT) for nitrogendioxide. By the time the limit value for nitrogendioxide becomes effective, Utrecht will meet the limit value.

20% less traffic on the Catharijnesingel

Last Updated

13th January 2005