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Proven Safety Countermeasures

Longitudinal Rumble Strips and Stripes on 2-Lane Roads

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U.S. Department of Transportation
Federal Highway Administration

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Photo of a rural two-lane roadway where shoulder rumble strips (i.e, a line of milled pavement that causes vibration and sound, warning inattentive drivers that their vehicles have left the travel lane) have been installed outside the white pavement edgeline on the shoulder.

Longitudinal rumble strips are milled or raised elements on the pavement intended to alert inattentive drivers through vibration and sound that their vehicles have left the travel lane. There are a number of possible applications that can be used:

 

Background
Roadway departure crashes account for approximately 53% of fatal crashes each year on the Nation's highways.  In 2009, 8,780 single-vehicle roadway departure fatalities occurred on two-lane roads.  Rumble strips are designed primarily to address the subset of driver error crashes caused by distracted, drowsy, or otherwise inattentive drivers who unintentionally drift from their lane.   Since driver error occurs on all roadway systems (including 2 lane roads), rumble strips are most effective when deployed in a systemic application.
Continuous rumble strips can be applied on many miles of roads in a cost-effective manner.  NCHRP 641:  Guidance for Design and Application of Shoulder and Centerline Rumble Strips documented the following crash modification factors:

 

While FHWA also recommends the use of rumble strips on multi-lane facilities, the focus here is on two-lane facilities where their use has been somewhat limited in practice and studies show even higher crash reductions than on other roadways.

 

Guidance
Federal, state, and local agencies and tribal governments administering highway projects should consider rumble strips or rumble stripes on highway projects using Federal funds as follows:

Continuous milled center line rumble strips (including in passing zone areas):

Continuous, milled edge line or shoulder rumble strips:

NOTE: On new and reconstruction projects, four feet of paved shoulder should extend beyond the rumble strip.

Key Resources
NCHRP Report 641, Guidance for the Design and Application of Shoulder and Centerline Rumble Strips, 2009
http://onlinepubs.trb.org/onlinepubs/nchrp/nchrp_rpt_641.pdf
Technical Advisory 5040.39, Shoulder and Edge Line Rumble Strips   http://safety.fhwa.dot.gov/roadway_dept/pavement/rumble_strips/t504039/
Technical Advisory 5040.40, Center Line Rumble Strips   http://safety.fhwa.dot.gov/roadway_dept/pavement/rumble_strips/t504040/ 
FHWA Guidance: Revisions to T 5040.39 Shoulder and Edge Line Rumble Strips and T 5040.40 Center Line Rumble Strips
http://safety.fhwa.dot.gov/roadway_dept/pavement/rumble_strips/t5040_memo/
AASHTO Highway Safety Manual (available for purchase)
http://www.highwaysafetymanual.org/pages/default.aspx
Crash Modification Factor (CMF) Clearinghouse [quick search ‘rumble strips’]
http://www.cmfclearinghouse.org

FHWA Contacts
Office of Safety: Cathy Satterfield, cathy.satterfield@dot.gov, 708-283-3552
FHWA Resource Center: Frank Julian, frank.julian@dot.gov, 404-562-3689

FHWA Website:  http://safety.fhwa.dot.gov/roadway_dept/pavement/rumble_strips/