Use and design of safe roundabouts in light rail transit (LRT) networks

While travelling at-grade in an urban environment, a Light Rail Transit (LRT) system needs to traverse road intersections of various complexities. These intersections, including roundabouts, are major hazardous locations in LRT networks. There are several documents related to the treatment of conventional LRT intersections for guaranteeing safety, but almost no reference to LRT roundabouts design, except for the French guidelines. This paper addresses safety issues related to LRT roundabout design. The paper contains, firstly, the explanation of the differences between the roundabout management with and without an LRT running through it, and the consequences for road vehicle drivers’ behavior. Secondly, the appropriateness of using a roundabout in the insertion of an LRT in a specific intersection is discussed. Finally, the main considerations for designing a safe LRT roundabout are presented: provide adequate visibility; improve perception by pavement, markings and signs; improve protection by separators, finishing of the tracks and traffic lights; and finally, design a good insertion of the LRT in the roundabout, as well as an adequate roundabout size.