Motorway roadworks: effects on traffic operations

This paper examines traffic operations at the approaches to motorway roadwork sites in the North West of England and focuses on some of the parameters affecting both safety and capacity. The trade–off between capacity and safety at motorway roadworks represents a dilemma for the traffic engineer. Capacity is reduced with the closure of one or more lanes to traffic. Lower operating speeds may be observed due to the substandard layout and to the lower speed limits imposed on site. Speed cameras are sometimes introduced to enforce the posted speed limits. Observations suggest that traffic behaviour at the approach to a roadwork section differs in terms of drivers’ operating speeds and their choice of lanes. Speed differentials close to the merge section could be a contributory cause of flow breakdowns and are a danger to road–users and workers alike. In addition, some drivers force themselves into the path of others on adjacent lanes by accepting smaller gaps to merge into especially when they are getting closer to the taper section. Previous work suggests that higher accident rates are usually associated with roadwork sections compared with normal motorway ones