Cyclists have a fair rumble grumble

The S.C. Department of Transportation says it is “committed to ... providing better and safer accommodations for people who choose to walk or cycle.” Sometimes, it’s hard to tell.

Even after enjoying unmitigated success with the Arthur Ravenel Jr. Bridge’s bike and pedestrian lane, the DOT continues to miss opportunities to make the state’s streets and roads more bike-friendly. In fact, one local project actually makes bicyclists more unsafe.

The DOT is grinding rumble strips into the edges of some roads to alert motorists when they are too close and avert accidents that occur when vehicles leave the road. To date, about 350 miles of road in Charleston, Berkeley and Dorchester counties have been rumble-stripped. Of the state’s 40,000 miles of roads, almost 4,000 have been rumbled.

Generally it’s a good idea. But not always. Consider the 12 miles on Wadmalaw Island’s portion of Maybank Highway between Church Creek and Rockville. That scenic stretch has been popular with bicyclists, in part because it was repaved to include a 1.5- or 2-foot apron on both sides, giving cyclists some separation from motorists. But rumble strips have changed the outlook for cyclists.

DOT began its rumble strip program in 2008-2009 after the Federal Highway Administration identified South Carolina as one of the states to get its support for decreasing the number of road departure collisions.

About 60 percent of fatal crashes are due to road departures. Statistically, South Carolina was among the worst in the country.

Rumble strips are considered a cost-effective way to combat road departure accidents. When a driver falls asleep or is distracted and drifts to the outside of the lane, he runs over the ridges scraped into the road, making noise and causing the vehicle to vibrate. It can be enough to startle him so he can correct his path.

But rumble strips can be a danger to bicyclists if accommodations aren’t made. They can cause cyclists to lose control of their bikes and fall. They also can damage bicycle wheels, cause flat tires and shake loose parts off the bicycle.

Rumble strips can do their jobs effectively, and safely, if at least four feet of unobstructed roadway shoulder remains after they have been installed. That gives bicycles a place to ride away from motor traffic.

Unfortunately, on Maybank Highway the available space after rumble stripping is more like 10 or 12 inches. That’s not enough, so bicyclists have to ride in the lane of traffic, thereby encouraging drivers who come up behind to drive in the lane meant for opposing traffic. That’s a hazard to bikers and motorists alike.

The DOT consulted with the Palmetto Cycling Coalition, a statewide non-profit, before establishing the department’s policy regarding rumble strips. That group recommended narrower strips, shallower cuts and a pattern of intermittent rather than continuous rumble strips. DOT accommodated those requests.

But instead of choosing which roads to rumble strip based on their history of road-departure accidents, the DOT established criteria based on features of roads where such accidents occur.

For example, roads must be rural. Average daily travel must be 500 vehicles or more. The speed limit must be 45 miles per hour or greater (although part of the stretch of Maybank Highway that was rumble-stripped has a speed limit of 40 mph). And the roadway cannot be part of the list of statewide designated bicycle touring routes.

But cycling advocates say the list is grossly inadequate. Certainly it doesn’t include Maybank Highway, which is — or was — a favorite with bicyclists.

The DOT wants to make roads safer for vehicles. Of course. It should. But it should be ever sensitive to making them safer for a different kind of transportation as well: bicycles.

The DOT is the Department of Transportation — not the Department of Cars.