Drift-Off Crashesand the
RUMBLE STRIPS that prevent them
Dave Morena
FHWA Michigan Division
Sep 20, 2007
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
Driver ASLEEP, DROWSY
Driver DISTRACTED
(As specified on 1043 reports)
- 82%
- 18%
Drift-off crashes are:Drift-off crashes are:
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
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%
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
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?
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
Questions & CommentsQuestions & Comments
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