The Iowa Department of Transportation is slowly adding new safety features to the state’s highways. In most cases, the roads are equipped with a rumble strip – short ridges in the shoulder of the pavement, creating a "rumble" effect with tires to alert a driver they’re veering off the road. In other cases, particularly where roadway widths are especially narrow, the DOT produces rumble stripes.
Tom Welch, the DOT’s safety engineer, says rumble stripes are located on the painted edge of the lane, rather than the shoulder. Welch says, "At nighttime, particularly when it’s raining, where normal pavement markings are not as visible or when they’re worn off in the spring, the rumble stripe is still very effective in giving positive guidance to the motorist during those conditions."
Statistics indicate that, every year in Iowa, nearly 160 traffic fatalities occur from a single vehicle, run-off-the-road crash. Welch says the most cost effective way to correct that driver error is with a rumble strip or stripe. The rumble strips and stripes are becoming more common place across the state.
Welch says the DOT installs rumble strips during resurfacing of two-lane roads that carry at least 3,000 vehicles per day. Rumble stripes are placed on narrower roads that don’t have room for a four foot paved shoulder. Some avid bicycling enthusiasts who travel Iowa’s rural highways are not with the ridges, since they pose such a danger for bicycles.
But, Welch says there’s a misconception – since the newly installed strips actually create another 12 inches of travel lane for bicycles. "Everything we’re doing associated with this is a slight improvement for the bicyclists," Welch explains, "it’s not as much as they would like to see, but we’re not putting them in there for the bicyclists." The latest rumble stripe installation in the state was completed in November along Iowa Highway 210 in Story County.