Have you ever drifted off the road while driving down a highway and been jolted to attention by quick bumps and a loud humming sound? Those were rumble strips, and they may have saved someone’s life.
According to the Virginia Department of Transportation, rumble strips cost between $7,000-$12,000 per mile. The estimated crash reduction varies between 36-64 percent. The Federal Highway Administration considers it to be a proven safety countermeasure.
For automobiles, but not cyclists. On a bike, rumble strips are extremely dangerous and uninviting. The League of American Bicyclists explains what they are:
What are rumble strips?: Rumble strips are raised or grooved patterns in a road’s shoulder designed to alert drivers with noise and vibrations that they are drifting off the roadway. They can be an effective safety measure to prevent run‐off‐the‐road (ROR) crashes, especially on limited‐access highways and rural two‐lane highways with long straight sections.(Rumble strips placed on the centerline can help prevent head‐on crashes.)
People ride bikes all over the place on the Outer Banks in North Carolina. I was recently biking on NC 345 between Manteo and Wanchese. For about 3.5 miles, the two-lane roadway is narrow and passes through a low-lying tidal marsh. It is quite beautiful, especially when you can catch views of the Roanoke and Croatan sounds on each side of the road.
The surface on NC 345 looked to be fairly recent and the rumble strips were a disappointing site. In an area so dedicated to tourism – including cyclists – it was odd that rumble strips were even considered, much less permitted. Though Wanchese is largely a working town, I’m sure that some people would welcome riding a bike to work now and then.
NCDOT has best practices for accommodating all users, but it appears NC 345 violated this policy. In Virginia, VDOT has standards:
POLICY FOR EVALUATING EXISTING SHOULDERS FOR RUMBLE STRIP APPLICATIONS
Minimum of 4 feet outside of the milled rumble strip groove when providing for bicycles. If large bicycle volumes are present or expected, a minimum of 5 foot paved shoulder outside of the groove is desirable, particularly if there are obstructions such as guardrail. Additional shoulder width may be necessary if horse and buggy traffic is present or expected.
(I’d love to see how a horse-drawn buggy would perform on rumble strips.)
There was maybe 2 feet of shoulder on the side of NC 345, which was covered in rumble strips. No where for a cyclist to go but ride in the roadway, which is perfectly legal, but it is hard to keep up with vehicular traffic with a posted 45 mph speed limit.
The League of American Bicyclists has been addressing rumble strip issues for years:
How do rumble strips impact cyclists?: Rumble strips are virtually impossible to ride a bicycle on or over – they are at best uncomfortable, even for a very short distance, and at worst can cause a cyclist to lose control of their bike and fall. They can damage a bicycle wheel, can cause a flat tire, and/or shake lose parts off a bicycle. Consequently, cyclists will avoid riding over them – and when rumble strips leave no room on a shoulder, the cyclist will have no other option than to ride in the travel lane. While rumble strips do not deter car, truck or bus travel, they have a severe impact on bicycling travel, and have ruined popular cycling routes.
If you have rumble strip concerns in your area, consider this advice on how to address it with local authorities.