Drift-Off Crashesand 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 Drift-off crashes are Run-off-road crashes where:where:

Drift-off crashes are NOT: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 crashes1996 - 2001

2002 study

Drift-off crashes

Michigan freeways

Driver ASLEEP, DROWSY

Driver DISTRACTED

(As specified on 1043 reports)

- 82%

- 18%

Drift-off crashes are:Drift-off crashes are:

ASLEEP / DISTRACTED

vs.

AVOID VEHICLE or OBJECT

SeveritySeverity Quiz:Quiz:

3 times as se

vere

ASLEEP / DISTRACTED

vs.

HYDROPLANE ??

SeveritySeverity Quiz:Quiz:

5 times as se

vere

Michigan Freeway Crashes - SeverityMichigan Freeway Crashes - Severity1996 - 2001

34,000 crashes/yr

Multiple Vehicle

mainline

Run-O

ff-Road

On-Road(deer)

SingleVehicle

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 - SeverityMichigan Freeway Crashes - Severity1996 - 2001

34,000 crashes/yrmainline

Run-O

ff-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 - % KACRASH SEVERITY - % KA

0 5 10 15 20

drift-off road(frwy)

alcohol

speeding

red lightrunning

Drift-off crashPROFILE

Michigan freeway

RL48%

ALL DRIFT-OFF

48 %

K & A crashes

L54%

R53 %

Vehicles drift off which side of road?

0%

1%

2%

3%

4%

5%

6%

7%

1 3 5 7 9 11 13 15 17 19 21 23

Time of Day

Pe

rce

nt

of

Cra

sh

es

Avg = 4.2%

Drift off Crashes by Time of Day

Dark - 55%

Light - 45%

time of day

17.8

20.3

11.412.211.5

13.513.2

0

5

10

15

20

25

Sun Mon Tues Wed Thur Fri Sat

Day Of Week

Pe

rce

nt

of

Ac

cid

ents

Drift off Crashes by Day of WeekDrift off Crashes by Day of Week

Avg = 14. 3 %

Drift-off Vehicles by Gender of DriverDrift-off Vehicles by Gender of Driver

Males account for: 59% of all Michigan crashes, 71% of fatalities

Female Male

69%

Drift-off Vehicles – Driver AgeDrift-off Vehicles – Driver Age

0%

1%

2%

3%

4%

5%

6%

15 20 25 30 35 40 45 50 55 60 65 70 75 80

23% age 16-21

Drift-off Vehicles – Driver AgeDrift-off Vehicles – Driver Age

19% age 16-21

All Michigan crashes

0%

1%

2%

3%

4%

5%

6%

15 20 25 30 35 40 45 50 55 60 65 70 75 80

23% age 16-21

Drift off crashes

Truck Involvement 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?What can happen to a drift-off vehicle?

recover (no crash) ???

5 %

14 %

6 %

20 %

1 %

45 %

Once a wheel drops off paved shoulder, Once a wheel drops off paved shoulder, drivers have difficulty controlling vehicle:drivers have difficulty controlling vehicle:

- 32 % over-correct steering

rollover

In 1794 crashes:

- 45 %

Crash RATE:Crash RATE:

0

5

10

15

20

25

30

35

0 10000 20000 30000 40000 50000 60000

Average Daily Traffic

Cra

sh

es

pe

r 1

00

MV

M

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:A MACHINE TO CUT RUMBLE STRIPS:

7” x 16” x ½”

Effect of milled shoulder rumble strips on freeway DRIFT-OFF crashes:

no rumble strips milled rumbles

Num

ber

of C

rash

es

100

60

7.2

17

40 % reduction

– total crashes

58 % reduction – KA

17 % KA12 % KA

Concrete intermittent RumblesConcrete intermittent Rumbles

Should we install milled rumbles

overconcrete

intermittent?

Concrete intermittent RumblesConcrete intermittent Rumbles

Yes – providecontinuous alert

Should we install milled rumbles

overrolled?

Rolled-in Rumble Strips

Yes – Milled rumbles

provide vibration

ROLLED

MILLED

How do these rumbles affect How do these rumbles affect large-tired vehicles?large-tired vehicles?

Bus/truck rumble demonstrationBus/truck rumble demonstrationFeb 17, 2000 - Lansing, MIFeb 17, 2000 - Lansing, MI

Answer:Answer:

MILLED - vibrates steering wheel, some noise

ROLLED - slight noise, drowned out by cab noise

CONCRETE INTERMITTENT - drivers unaware

Dave Morena

FHWA Michigan Division

517-702-1836

David.Morena@fhwa.dot.gov

Questions & CommentsQuestions & Comments