Design of Safe Light Rail Transit (LRT) Roundabouts

Abstract

[Abstract]: While travelling at-grade in an urban environ- ment, a Light Rail Transit (LRT) system needs to traverse road intersections of various complexities. These intersec- tions, including roundabouts, are major hotspots (risky points) in LRT networks. There are several documents re- lated to the treatment of conventional LRT intersections for guaranteeing safety, but almost no reference to LRT round- abouts design, except for the French guidelines. This paper addresses safety issues related to LRT roundabout design. The paper contains, firstly, the explanation of the differ- ences between the roundabout management without and with an LRT running through it, and the consequences for road vehicle drivers’ behavior. Secondly, the appropriate- ness of using a roundabout in the insertion of an LRT in a specific intersection is discussed. Finally, the main consid- erations for designing a safe LRT roundabout are present- ed, taking into account general aspects such as visibility, perception and protection, and more specific ones such as the adequate insertion of the LRT in the roundabout, its size and number of lanes, as well as some traffic light im- provements that may enhance safety. Additionally, some re- al case examples are presented at the end of the paper to il- lustrate how the safety of a given LRT roundabout can be improved once it has been built.