Motorcycle Helmet Impact Zones

This 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.

Helmet crash zones. Source: Dietmar Otte, Medizinische Hochschule Hannover, Abteilung Verkehrsunfallforschung, Germany

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:

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 slide-out and fall due to over-braking 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 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.

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.