Rumble Strip Gaps for High-Speed Bicycles

Shoulder rumble strips (SRSs) are a proven safety countermeasure that reduces motor vehicle lane departures; however, they may be seen as an impediment to bicycle travel because they decrease comfort for bicyclists and can affect riders' control while bicycling. Existing literature provides recommendations for the placement of regular gaps in SRSs, but the supporting research is limited to low and moderate bicycle speeds. Roads with SRSs along long, steep grades present a unique set of risks for cyclists because of the possibility of higher bicycle speeds. This study evaluated how variations in SRS gap lengths and shoulder widths affected bicyclists' ability to maneuver through these gaps when riding at higher than average speeds. The findings suggest that as gap length increases, bicyclists may increase downhill speed while reporting fewer instances of discomfort when attempting to cross larger gaps. The likelihood of a bicyclist hitting a simulated rumble strip while crossing a gap decreases modestly as the gap size increases. Shoulder widths in excess of 4 ft do not appear to significantly influence bicyclists' capability of maneuvering across different gap lengths and had only a minor effect on bicyclists' speeds.