Motorcycle
Accident Cause Factors and
Identification of Countermeasures
The
"Hurt" Study
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Motorcycle
Accident Cause Factors and Identification of Countermeasures, Volume 1:
Technical Report, Hurt, H.H., Ouellet, J.V. and Thom, D.R., Traffic Safety
Center, University of Southern California, Los Angeles, California 90007,
Contract No. DOT HS-5-01160,
January 1981 (Final Report)
The Hurt study,
published in 1981, was a ground-breaking report on the causes and effects of
motorcycle accidents. Although more than 15 years old at this time, the study
still offers riders insight into the statistics regarding motorcycle accidents
and tips on safer riding. With funds from the National Highway Traffic Safety
Administration, researcher Harry Hurt (from which the study gets its common
name) of the University of Southern California, investigated almost every aspect
of 900 motorcycle accidents in the Los Angeles area. Additionally, Hurt and his
staff analyzed 3,600 motorcycle traffic accident reports in the same geographic
area.
This is the same
study that is frequently quoted in the Motorcycle Safety Foundation rider safety
courses.
A complete
non-summarized version of this document is available through: The National
Technical Information Service, Springfield, Virginia 22161
Findings:
Throughout the
accident and exposure data there are special observations which relate to
accident and injury causation and characteristics of the motorcycle accidents
studied. These findings are summarized as follows:
1.Approximately
three-fourths of these motorcycle accidents involved collision with another
vehicle, which was most usually a passenger automobile.
2.Approximately
one-fourth of these motorcycle accidents were single vehicle accidents involving
the motorcycle colliding with the roadway or some fixed object in the
environment.
3.Vehicle
failure accounted for less than 3% of these motorcycle accidents, and most of
those were single vehicle accidents where control was lost due to a puncture
flat.
4.In the single
vehicle accidents, motorcycle rider error was present as the accident
precipitating factor in about two-thirds of the cases, with the typical error
being a slideout and fall due to overbraking or running wide on a curve due to
excess speed or under-cornering.
5.Roadway
defects (pavement ridges, potholes, etc.) were the accident cause in 2% of the
accidents; animal involvement was 1% of the accidents.
6.In the
multiple vehicle accidents, the driver of the other vehicle violated the
motorcycle right-of-way and caused the accident in two-thirds of those
accidents.
7.The failure of
motorists to detect and recognize motorcycles in traffic is the predominating
cause of motorcycle accidents. The driver of the other vehicle involved in
collision with the motorcycle did not see the motorcycle before the collision,
or did not see the motorcycle until too late to avoid the collision.
8.Deliberate
hostile action by a motorist against a motorcycle rider is a rare accident
cause. The most frequent accident configuration is the motorcycle proceeding
straight then the automobile makes a left turn in front of the oncoming
motorcycle.
9.Intersections
are the most likely place for the motorcycle accident, with the other vehicle
violating the motorcycle right-of-way, and often violating traffic controls.
10.Weather is
not a factor in 98% of motorcycle accidents.
11.Most
motorcycle accidents involve a short trip associated with shopping, errands,
friends, entertainment or recreation, and the accident is likely to happen in a
very short time close to the trip origin.
12.The view of
the motorcycle or the other vehicle involved in the accident is limited by glare
or obstructed by other vehicles in almost half of the multiple vehicle
accidents.
13.Conspicuity
of the motorcycle is a critical factor in the multiple vehicle accidents, and
accident involvement is significantly reduced by the use of motorcycle headlamps
(on in daylight) and the wearing of high visibility yellow, orange or bright red
jackets.
14.Fuel system
leaks and spills were present in 62% of the motorcycle accidents in the
post-crash phase. This represents an undue hazard for fire.
15.The median
pre-crash speed was 29.8 mph, and the median crash speed was 21.5 mph, and the
one-in-a-thousand crash speed is approximately 86 mph.
16.The typical
motorcycle pre-crash lines-of-sight to the traffic hazard portray no
contribution of the limits of peripheral vision; more than three-fourths of all
accident hazards are within 45deg of either side of straight ahead.
17.Conspicuity
of the motorcycle is most critical for the frontal surfaces of the motorcycle
and rider.
18.Vehicle
defects related to accident causation are rare and likely to be due to deficient
or defective maintenance.
19.Motorcycle
riders between the ages of 16 and 24 are significantly overrepresented in
accidents; motorcycle riders between the ages of 30 and 50 are significantly
underrepresented. Although the majority of the accident-involved motorcycle
riders are male (96%), the female motorcycles riders are significantly
overrepresented in the accident data.
20.Craftsmen,
laborers, and students comprise most of the accident-involved motorcycle riders.
Professionals, sales workers, and craftsmen are underrepresented and laborers,
students and unemployed are overrepresented in the accidents.
21.Motorcycle
riders with previous recent traffic citations and accidents are overrepresented
in the accident data.
22.The
motorcycle riders involved in accidents are essentially without training; 92%
were self-taught or learned from family or friends. Motorcycle rider training
experience reduces accident involvement and is related to reduced injuries in
the event of accidents.
23.More than
half of the accident-involved motorcycle riders had less than 5 months
experience on the accident motorcycle, although the total street riding
experience was almost 3 years. Motorcycle riders with dirt bike experience are
significantly underrepresented in the accident data.
24.Lack of
attention to the driving task is a common factor for the motorcyclist in an
accident.
25.Almost half
of the fatal accidents show alcohol involvement.
26.Motorcycle
riders in these accidents showed significant collision avoidance problems. Most
riders would overbrake and skid the rear wheel, and underbrake the front wheel
greatly reducing collision avoidance deceleration. The ability to countersteer
and swerve was essentially absent.
27.The typical
motorcycle accident allows the motorcyclist just less than 2 seconds to complete
all collision avoidance action.
28.Passenger-carrying
motorcycles are not overrepresented in the accident area.
29.The driver of
the other vehicles involved in collision with the motorcycle are not
distinguished from other accident populations except that the ages of 20 to 29,
and beyond 65 are overrepresented. Also, these drivers are generally unfamiliar
with motorcycles.
30.The large
displacement motorcycles are underrepresented in accidents but they are
associated with higher injury severity when involved in accidents.
31.Any effect of
motorcycle color on accident involvement is not determinable from these data,
but is expected to be insignificant because the frontal surfaces are most often
presented to the other vehicle involved in the collision.
32.Motorcycles
equipped with fairings and windshields are underrepresented in accidents, most
likely because of the contribution to conspicuity and the association with more
experienced and trained riders.
33.Motorcycle
riders in these accidents were significantly without motorcycle license, without
any license, or with license revoked.
34.Motorcycle
modifications such as those associated with the semi-chopper or cafe racer are
definitely overrepresented in accidents.
35.The
likelihood of injury is extremely high in these motorcycle accidents-98% of the
multiple vehicle collisions and 96% of the single vehicle accidents resulted in
some kind of injury to the motorcycle rider; 45% resulted in more than a minor
injury.
36.Half of the
injuries to the somatic regions were to the ankle-foot, lower leg, knee, and
thigh-upper leg.
37.Crash bars
are not an effective injury countermeasure; the reduction of injury to the
ankle-foot is balanced by increase of injury to the thigh-upper leg, knee, and
lower leg.
38.The use of
heavy boots, jacket, gloves, etc., is effective in preventing or reducing
abrasions and lacerations, which are frequent but rarely severe injuries.
39.Groin
injuries were sustained by the motorcyclist in at least 13% of the accidents,
which typified by multiple vehicle collision in frontal impact at higher than
average speed.
40.Injury
severity increases with speed, alcohol involvement and motorcycle size.
41.Seventy-three
percent of the accident-involved motorcycle riders used no eye protection, and
it is likely that the wind on the unprotected eyes contributed in impairment of
vision which delayed hazard detection.
42.Approximately
50% of the motorcycle riders in traffic were using safety helmets but only 40%
of the accident-involved motorcycle riders were wearing helmets at the time of
the accident.
43.Voluntary
safety helmet use by those accident-involved motorcycle riders was lowest for
untrained, uneducated, young motorcycle riders on hot days and short trips.
44.The most
deadly injuries to the accident victims were injuries to the chest and head.
45.The use of
the safety helmet is the single critical factor in the prevention of reduction
of head injury; the safety helmet which complies with FMVSS 218 is a
significantly effective injury countermeasure.
46.Safety helmet
use caused no attenuation of critical traffic sounds, no limitation of precrash
visual field, and no fatigue or loss of attention; no element of accident
causation was related to helmet use.
47.FMVSS 218
provides a high level of protection in traffic accidents, and needs modification
only to increase coverage at the back of the head and demonstrate impact
protection of the front of full facial coverage helmets, and insure all adult
sizes for traffic use are covered by the standard.
48.Helmeted
riders and passengers showed significantly lower head and neck injury for all
types of injury, at all levels of injury severity.
49.The increased
coverage of the full facial coverage helmet increases protection, and
significantly reduces face injuries. 50.There is not liability for neck
injury by wearing a safety helmet; helmeted riders had less neck injuries than
unhelmeted riders. Only four minor injuries were attributable to helmet use, and
in each case the helmet prevented possible critical or fatal head injury.
51.Sixty percent
of the motorcyclists were not wearing safety helmets at the time of the
accident. Of this group, 26% said they did not wear helmets because they were
uncomfortable and inconvenient, and 53% simply had no expectation of accident
involvement.
52.Valid
motorcycle exposure data can be obtained only from collection at the traffic
site. Motor vehicle or driver license data presents information which is
completely unrelated to actual use.
53.Less than 10%
of the motorcycle riders involved in these accidents had insurance of any kind
to provide medical care or replace property.