Have you ever wondered what that terrible noise and vibration are when you slightly veer on a roadway? Those noisy bumps are referred to as rumble strips, and they are formed when a ribbon of asphalt has been milled with a special tool. Rumble strips produce sound and vibration to alert drivers when they cross over the centerline or edge line of the roadway. By alerting the driver, rumble strips reduce head-on and roadway departure crashes.
Where centerline rumble strips have been installed on rural two-lane roadways, head-on and opposite direction sideswipe crashes have been reduced by 38-50 percent. Rumble strips on the shoulder of a rural two-lane roadway can minimize roadway departure crashes by 26-46 percent.
Benefits of rumble strips include:
- Decrease in run-off-road crashes caused by driver inattention, driver error, poor visibility, and fatigue
- Little to no maintenance
- Ability to install on new or existing pavements
- Inconvenience for cyclists
- Excessive noise for nearby residents
- Potential for pavement degradation
State agencies have acknowledged the inconvenience for cyclists. To minimize the inconvenience, “bicycle gaps” in the edge line of the rumble strip are often provided to give riders a periodic smooth surface to move between the travel lane and the shoulder should it become necessary.
Sain Associates has been a part of numerous roadway safety assessment teams across Alabama and Tennessee, where rumble strips are incorporated into our safety improvement recommendations. Rumble strips may be annoying, but they have been proven to save lives.