Speed perception by drivers as dependent on urban street design; a case-study

The strategy of sustainable road safety aims to match the road design characteristics to the target travel speeds, on every road type. This study examined the speed perception by drivers on collector urban roads in Israel, as reflected in their actual travel speeds and in the "appropriate" speeds reported by drivers. First, field surveys were conducted to collect detailed data on the road design characteristics, travel speeds, vehicle traffic and pedestrian activities on 80 urban street sections, in fifteen cities. Second, a drivers' survey was undertaken in proximity to the areas of the field surveys, to collect drivers' opinions about appropriate speeds on various street sections. The survey included 200 drivers, where each participant estimated four pictures with representative layouts of the study streets. Multivariate regression models were developed to examine the relationship between street characteristics, traffic exposure and travel speeds, as well as to explore the relationship between the driver characteristics, street design and "appropriate" speeds as reported by drivers. The results showed that road layout type was the most influential on selecting speeds. Multi-lane dual-carriageway roads are characterized by the highest actual and reported speeds, lower speeds are attributed to single-lane dual-carriageway and single-carriageway roads, and the lowest ones - to one-way streets. Among other characteristics moderating actual travel speeds were: higher pedestrian activity on the street, higher visual narrowing, more pedestrian attractions, presence of non-signalized junctions. The selection of "appropriate" speeds by drivers was affected by the street layout, the road visual narrowing, the socio-economic level of the town and driver's personal characteristics. The drivers believed that for moderate street layouts, the appropriate speeds should be around 40 km/h, i.e. below the existing speed limit. The road design characteristics that were found to affect the speed selection by the drivers may be applicable for attaining targeted travel speeds on collector streets.