Three minutes’ wait – off with the engine!

Many people are irritated by drivers who leave their engine running unnecessarily while their vehicle is stationary. Participants in the project “Public Agendas and Citizen Participation”, set up by the Dutch Environment ministry (VROM), wanted to know whether public health would benefit if there was less unnecessary idling of car engines. In collaboration with TNO, CE Delft has looked at two pollution hotspots where idling is known to be frequent. The following conclusions were drawn:

• For the average Dutch car, it makes sense to switch off the engine if it is likely to be running for three minutes or more.
• At ‘idling hotspots’ like taxi ranks, bridges and bus stations, drivers are already being informed about the negative impact of their behaviour, although with no compulsion to change it.
• While temporary cutting of vehicle engines reduces emissions, the overall impact on air quality is only limited.

Based on this study, we recommend not to use air quality as the central motive for any policy on idling vehicle engines. Drawing attention to greenhouse gas emissions, fuel wastage and other negative aspects of road transport would appear to be better motives.