The Palmetto Cycling Coalition recently recommended changes to the Rumble Strip Policy at South Carolina’s DOT. A rumble strip is a repeated gouge in the left or right side of the road, in order to warn drivers who veer off the road, by making a loud rumble noise under their tires. South Carolina has a lot of run off the road crashes and deaths compared to other states, and SCDOT decided rumble strips were the most cost effective way to lower the number of these deaths. Unfortunately, a rumble strip on a road means it’s less safe for a bicyclist to ride. If you have ever run into a rumble strip on a bike, you know how unsafe they are.
There’s one thing we can all agree on: we all use our streets, and we want Safe Streets.
- A rumble strip should be a last resort. Before a rumble strip is applied, consider other methods to enhance driver safety: increase pavement skid resistance, add signage and markings, and improve roadway geometry.
- Reduce the rumble strip depth and width, and add a skip pattern, if you must put in a rumble strip.
- Formerly, rumble strips could only be applied to “rural” roads, with speed limits 45 or greater. Raise the speed threshold to 50mph or greater, because every shade of cyclist uses 45mph roadways.
- Within 100 feet of points of interference, such as curbs, gutters, or guardrails, don’t install a rumble strip. It’s highly dangerous there.
- Keep rumble strips off bike corridors, in locally and regionally adopted Bike Master Plans. Locals know best. A 5 foot shoulder or bike lane provides safe space for bicycle use.
- Keep rumble strips off preferred cycling routes in rural areas, and keep them off the State Bicycle Touring routes. If there’s a high crash rate for motorists on that road, only place a rumble strip there if you have at least 2 feet of clear shoulder width for cyclists. If we must balance bike-ability with a dangerous driver zone, do it this way. It’s imperfect, but this is our compromise. Anything less is highly dangerous.
Policy Note: Most of these recommendations stem from other federal and state policy precedents. Advocacy Note: We work with local advocates, who in turn work with city officials and planners, to adopt more Bike Master Plans and more fully recognize preferred cycling routes, urban and rural. We want fewer rumble strips, but if they must go in, we’d like to protect those areas we bike most.