Abstract
This paper reports a project in which two types of streets were monitored, namely streets near playing-grounds and streets with low traffic volume, so called quiet streets. Near the playing-areas the speeds of the cars are restricted to 15 km/h and in quiet streets to 30 km/h. Within this part of the project 44 experimental streets, i.e. 5 near playing areas and 39 quiet streets, and 52 control streets have been observed. The experimental group contains 30 km of streets and the control group contains 35 km of streets. The research design is a before-after study with a control group. The before and after periods were three years each, individually chosen for each experimental street.