Quantifying the effect of street design on driving speed on urban roads

Abstract

Reducing driving speed is a key factor in improving road safety and combatting noise emissions. Over the last decades, many European cities and countries have reduced the speed limits of residential and neighborhood roads from 50 km/h (30 mph) to 30 km/h (20 mph) or even 20 km/h (12 mph). At the same time, there is a discussion to reduce speed limits on main roads in urban areas in several countries. Main roads in urban areas are different from residential roads in several ways, including, but not limited to the type of trips, vehicular mix and the presence of public transport, and are therefore limited in design options to reduce speeds. The study at hand reports on a virtual reality study conducted in Switzerland using a driving simulator. To assess whether road design influences driving speed, participants were asked to drive through a series of streets in VR with varying speed limits and street designs. Speed and lateral position were recorded; in a follow-up survey, participants stated their preferred speed along the same segments and were asked about risk aversion. Results indicate that only certain designs result in slightly lower driving speeds, while controlling for self-reported risk aversion and driving style. Given the characteristics of main roads, measures reducing the (perceived) lane width are promising, but require further investigation.