Rumble strips/stripes are a very effective, relatively low cost safety measure intended to deter cross centerline and run off the road crashes.
The New Hampshire Department of Transportation has developed a multi-year plan funded through the Federal Highway Safety Improvement Program (HSIP) to install centerline and shoulder rumble stripes along high volume, undivided state highways to improve safety. The list was developed by staff from Highway Design, Highway Maintenance, and Construction and approved by the Executive Office.
Initially, shoulder rumble strip installation focused on freeways using rolled-in rumble strips of different designs using a modified roller on a pavement rolling machines. Later, paving contractors modified pavement rolling machines to mill rumble strips into existing hardened asphalt pavement. Specifically designed commercially available machines followed.
Rumble strips, also known as sleeper lines, audible lines, "the corduroy", growlers, and "woo woo" boards, are a road safety feature to alert inattentive drivers of potential danger, by causing a tactile vibration and audible rumbling transmitted through the wheels into the vehicle interior. A rumble strip is applied along the direction of travel following an edge line or centerline, to alert drivers when they drift from their lane.
As rumble strips produce audible rumbling in specific audio frequencies based on the spacing of the grooves and the speed of the automobile, they have been used to create novel musical roads. These are also known as "singing shoulders".
The information below is intended to answer some common questions and provide additional information to communities and the general public as to what rumble strips are and why they are installed.
One document was added on 5/22/2019.
- NHDOT Rumble Strip Guidelines - Draft 5/22/2019
Frequently Asked Questions (FAQ)
Why install rumble stripes?
The main reason is SAFETY!
Center line rumble strips on rural two-lane roads:
- 44% reduction of head on / fatal and injury crashes;
Center line rumble strips on urban two-lane roads:
- 64% reduction of head-on / fatal and injury crashes;
Shoulder rumble strips on rural two-lane roads:
- 36% reduction of run-off -road fatal and injury crashes.
Secondary reasons include:
- Improve lane positioning
- Reduce corner cutting through left curves (CRS) and right curves (SRS)
- Decrease centerline/edge line encroachments
Do rumble stripes cause a disruption to motorcycles?
Center line rumble stripes add no measurable risk to motorcyclists.
Do rumble stripes cause a disruption to bicyclists?
Shoulder rumble stripes are installed on the white line delineating the edge of the travel lane and are being designed to provide adequate width to the right of the shoulder rumble for bicyclists. Gaps are placed in shoulder rumbles for cyclists making turns. Rumble stripes alert bicyclists to vehicles leaving the travel lanes and entering the shoulder area.
Are there any concerns about roadside noise?
Noise from rumble strips occur infrequently (typically when an errant vehicle leaves its lane of travel) and for a short duration. "Jake brakes" or motorcycles make considerably more noise for a longer duration than rumble strips. Rumble stripes save lives and have been dubbed by some states as "the sound of safety." A state of Michigan study indicated an increase in noise levels of 8.1dBA for CRS and 10.1dBA for SRS when contacted during a pass-by of the test vehicle.
Some typical noise levels:
Window Fan on High 60-66
Hair Dryer 80-95
Vacuum Cleaner 84-89
Lawn Mower 88-94