T his is my favourite helmet impact diagram. Yes, it’s old but there’s nothing more recent, and nothing to indicate that conditions have changed to invalidate the results. The source is Dietmar Otte, Medizinische Hochschule Hannover, Abteilung Verkehrsunfallforschung, Germany. Note that 35% of impacts occur in the chin area. Because I like my chin I ride with a full face helmet. This diagram was cited in the Hurt Report, as well as Proficient Motorcycling by David L Hough.

Motorcycle Accident Cause Factors and Identification of Countermeasures

The "Hurt" Study

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 MSF rider safety

courses.

A complete non-summarized version of this document is available

from the National Technical Information Service (NTIS) by ordering document

number PB81-206443/LL. The cost is $84.00 each per document plus $5.00 handling

per order. For more information, call the NTIS Sales Desk at 1-800-553-NTIS or

1-703-605-6000.

Summary of 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:

Approximately three-fourths of these motorcycle accidents involved

collision with another vehicle, which was most usually a passenger

automobile.

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.

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.

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 slide-out and fall due to over-braking or running wide

on a curve due to excess speed or under-cornering.

Roadway defects (pavement ridges, potholes, etc.) were the accident cause

in 2% of the accidents; animal involvement was 1% of the accidents.

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.

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.

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.

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.

Weather is not a factor in 98% of motorcycle accidents.

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.

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.

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.

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.

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.

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.

Conspicuity of the motorcycle is most critical for the frontal surfaces of

the motorcycle and rider.

Vehicle defects related to accident causation are rare and likely to be

due to deficient or defective maintenance.

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.

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.

Motorcycle riders with previous recent traffic citations and accidents are

overrepresented in the accident data.

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.

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.

Lack of attention to the driving task is a common factor for the

motorcyclist in an accident.

Almost half of the fatal accidents show alcohol involvement.

Motorcycle riders in these accidents showed significant collision

avoidance problems. Most riders would over-brake and skid the rear wheel, and

under-brake the front wheel greatly reducing collision avoidance

deceleration. The ability to countersteer and swerve was essentially absent.

The typical motorcycle accident allows the motorcyclist just less than 2

seconds to complete all collision avoidance action.

Passenger-carrying motorcycles are not overrepresented in the accident

area.

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.

The large displacement motorcycles are underrepresented in accidents but

they are associated with higher injury severity when involved in accidents.

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.

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.

Motorcycle riders in these accidents were significantly without motorcycle

license, without any license, or with license revoked.

Motorcycle modifications such as those associated with the semi-chopper or

cafe racer are definitely overrepresented in accidents.

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.

Half of the injuries to the somatic regions were to the ankle-foot, lower

leg, knee, and thigh-upper leg.

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.

The use of heavy boots, jacket, gloves, etc., is effective in preventing

or reducing abrasions and lacerations, which are frequent but rarely severe

injuries.

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.

Injury severity increases with speed, alcohol involvement and motorcycle

size.

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.

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.

Voluntary safety helmet use by those accident-involved motorcycle riders

was lowest for untrained, uneducated, young motorcycle riders on hot days

and short trips.

The most deadly injuries to the accident victims were injuries to the

chest and head.

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.

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.

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.

Helmeted riders and passengers showed significantly lower head and neck

injury for all types of injury, at all levels of injury severity.

The increased coverage of the full facial coverage helmet increases

protection, and significantly reduces face injuries.

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.

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.

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.