Spiral Lane Markings: A Review of Lane Discipline

Abstract

Roundabouts are quite effective as junction control measures; reducing crashes by eliminating certain conflict points and managing capacity by virtue of its self-regulating ability. Amongst other forms of circulatory carriageway markings, spiral markings have been acknowledged as a way of reducing a driver’s decision-making responsibilities and leading drivers to their choice exit lanes hence improved safety. Conversely, signalization becomes imperative as it offers an equitable means of controlling right-of-way at all arms of the roundabout especially where problems of unbalanced flows exist. Considering these issues a question comes to mind; “what proportion of drivers contravene the principles of lane discipline which several authors claim to be the highlight of spiral markings?” It was on this premise that this research was borne with specific objective of observing the lane discipline at a roundabout.  This was achieved by installation of video cameras at strategic locations around the circulatory carriageway of the roundabout, with an observational study (survey); analysis of same, considering class of vehicles, traffic and light conditions being carried out. The transgressions observed were classified as minor and major transgressions and full lane changes; analyzed using simple statistical analysis. Following an hourly average for a three-day period, there were 33%, 23%, 17% car transgressions and 55%, 43%, 42% truck transgressions at unsaturated, partially saturated and saturated periods respectively. It was therefore concluded that there are more transgressions at unsaturated periods and transgressions generally are of the minor form, trucks are more involved in the observed transgressions, and that transgressions increase when roundabouts get busier which was quite a surprising finding as the reverse was expected.

Keywords: Roundabout, Transgression, Traffic, Markings.