Lighting the Way: the Use of Intelligent Road Studs at Spiral-marked Roundabouts
Richard Llewellyn, Transport Research Institute, Edinburgh Napier University
Spiral markings at roundabouts improve traffic flow but can reduce safety due to poor lane discipline. This paper investigates an innovative method of improving lane adherence at spiral-marked roundabouts through the use of intelligent road studs.
The roundabout is an extremely versatile circular form of road junction. Over the past half century, their use has been widespread in the UK and mainland Europe, with other countries such as the United States witnessing increasing adoption. This is for good reason; modern roundabouts are acknowledged as a very safe form of road junction for vehicular traffic, and can be highly flexible in their application.
Research carried out in the 1960s and subsequent years substantially increased understanding of the geometric design of roundabouts and helped reduce accident rates at entries. The introduction of traffic signal control at certain sites has facilitated improved safety and capacity. More recently, the use of spiral markings has further increased capacity by optimally directing traffic flow around the junction through the efficient use of road space.
Whilst the benefits spiral markings bring are welcomed by traffic engineers and road users, there are issues with their use. Most notably, they rely on drivers adhering to lanes as they pass through the junction. Unfortunately, this is not always the case, resulting in an increased risk of accidents and a reduction in capacity due to sub-optimal flow.
This paper investigates an innovative method of improving lane adherence at spiral-marked roundabouts through the use of intelligent road studs. To achieve this, a before-and-after case study of a major spiral-marked, traffic signal controlled roundabout on the Edinburgh City Bypass was undertaken.
Through the use of video analysis, the work investigates the changes in lane adherence by drivers as a result of the installation of the road studs. It compares recorded accident statistics in the two scenarios and through a conflict study, identifies the changes in driver behaviour in various traffic, weather and lighting conditions.
An analysis of the potential for the use of intelligent road studs at spiral-marked roundabouts is presented and recommendations made on potential criteria for their future application.
Association for European Transport