Drift-Off Crashes and the RUMBLE STRIPS that prevent them Dave Morena FHWA Michigan Division Sep 20, 2007

What is a drift-off crash?

 Driver ASLEEP, DROWSY  Driver DISTRACTED Drift-off crashes are Run-off-road crashes where:

Drift-off crashes are NOT:  swerve to avoid another vehicle  hydroplane  swerve to avoid debris  tire blowout  trailer sway

What do we know about drift-off crashes?

1887 crashes study Drift-off crashes Michigan freeways

 Driver ASLEEP, DROWSY  Driver DISTRACTED (As specified on 1043 reports) - 82% - 18% Drift-off crashes are:

ASLEEP / DISTRACTED vs. AVOID VEHICLE or OBJECT Severity Quiz: 3 times as severe

ASLEEP / DISTRACTED vs. HYDROPLANE ?? Severity Quiz: 5 times as severe

Michigan Freeway Crashes - Severity ,000 crashes/yr Multiple Vehicle mainline Run-Off-Road On-Road (deer) Single Vehicle 6.1 % KA 2. 9 % KA 0.4 % KA K = fatality A = incapacitating injury B = other injury C = possible injury O = property damage only

Michigan Freeway Crashes - Severity ,000 crashes/yr mainline Run-Off-Road DROWSY & DISTRACTED ice, snow on road 2.9% KA wet road 3.4% KA avoid veh, enter, exit, change lanes, passing 6.1% KA Vehicle defect 5.8% KA 17 % KA Multiple Vehicle 2. 9 % KA

CRASH SEVERITY - % KA

Drift-off crash PROFILE Michigan freeway

ALL DRIFT-OFF 48 % K & A crashes 53 % Vehicles drift off which side of road?

0% 1% 2% 3% 4% 5% 6% 7% Time of Day Percent of Crashes Avg = 4.2% Drift off Crashes by Time of Day Dark - 55% Light - 45% time of day

SunMonTuesWedThurFriSat Day Of Week Percent of Accidents Drift off Crashes by Day of Week Avg = %

Drift-off Vehicles by Gender of Driver Males account for: 59% of all Michigan crashes, 71% of fatalities Female Male 69%

Drift-off Vehicles – Driver Age 23% age 16-21

Drift-off Vehicles – Driver Age 19% age All Michigan crashes 23% age Drift off crashes

Truck Involvement Trucks accounted for 11 % of daily vehicle miles parked vehicles hit 10% drift-off vehicle 4%

Driver had been drinking in 21% of all drift-off crashes Alcohol Involvement

 parked vehicle  trees  signpost, light pole  guardrail, bridge rail  hit opposing vehicle  side slope, ditch What can happen to a drift-off vehicle?  recover (no crash) ??? 5 % 14 % 6 % 20 % 1 % 45 %

Once a wheel drops off paved shoulder, drivers have difficulty controlling vehicle: - 32 %  over-correct steering  rollover In 1794 crashes: - 45 %

Crash FREQUENCY: less than one crash / mile / year

Crash RATE: No rumble strips Drivers less likely to drift off on high-volume road

From crash data, problem areas: early morning hours low volume roads curves young driver

$750 / mile / shoulder A MACHINE TO CUT RUMBLE STRIPS: 7” x 16” x ½”

Effect of milled shoulder rumble strips on freeway DRIFT-OFF crashes: % reduction – total crashes 58 % reduction – KA 17 % KA 12 % KA

Concrete intermittent Rumbles Should we install milled rumbles over concrete intermittent?

Concrete intermittent Rumbles Yes – provide continuous alert

Should we install milled rumbles over rolled? Rolled-in Rumble Strips

Yes – Milled rumbles provide vibration

ROLLED MILLED

How do these rumbles affect large-tired vehicles?

Bus/truck rumble demonstration Feb 17, Lansing, MI

Answer: MILLED - vibrates steering wheel, some noise ROLLED - slight noise, drowned out by cab noise CONCRETE INTERMITTENT - drivers unaware

Dave Morena FHWA Michigan Division Questions & Comments