Assessing the Environmental Capacity of Local Residential Streets
The inherent conflict between the residential amenity and traffic access functions of local streets causes debate on what constitutes a true “local” road. The concept of 'environmental capacity' was developed to identify a suitable maximum traffic volume on such local streets. It was first introduced by Buchanan and Appleyard in separate research in the 1960?s. Both authors settled on broad-brush traffic thresholds of 2,000-3,000 vehicles per day. Since then, other research has relied heavily on the original Buchanan and Appleyard findings; this paper investigates that presumption in the present day. A residents? survey was applied to four “local” streets with varying traffic volumes in Christchurch, New Zealand. Residents living on those streets with higher volumes felt that their streets were busier, noisier and less safe. There was also an increasing trend for residents along higher volume streets to have their houses turned away from the street and they tended to have less personal involvement and/or knowledge of their neighbours. In the Christchurch context, a more appropriate environmental capacity would appear to be around 1,500-2,000 vehicles per day. This has implications for local town planning and street network design guidance if true local roads are to be achieved.