TRANSPORTATIONTHE INJURY SEVERITY RATE DIFFERENCES INPASSENGER CARS AND PICK UP TRUCKS RELATEDTWO VEHICLE INVOLVED MOTOR VEHICLE CRASHESIN BRITISH COLUMBIA, CANADADESAPRIYA, E.B.R.

BRUSSONI, M.

BC Injury Research and Prevention Unit
Centre for Community Child Health Research, andDepartment of Pediatrics, University of British Columbia
Vancouver, Canada

BC Injury Research and Prevention Unit
Centre for Community Child Health Research, andDepartment of Pediatrics, University of British Columbia
Vancouver, Canada

PIKE, I.

HAN, G.

BC Injury Research and Prevention Unit
Centre for Community Child Health Research, andDepartment of Pediatrics, University of British Columbia
Vancouver, Canada

BC Injury Research and Prevention Unit
Centre for Community Child Health Research
Vancouver, Canada(Received February 24, 2004)
The effect of large vehicle involvement on motor vehicle crash (MVC) rates and severity has long been a concern in MVC analysis literature.
Injuries in drivers and occupants are related to several key factors: the mass of the case vehicle and mass of its collision partner and speed of casevehicle and collision partner at the time of the crash. Objective: To evaluate the relative risk of injury occurrence in collisions between picks up trucks(PU) and passenger sedan cars (PS). Methods: Data from the Insurance Corporation of British Columbia (ICBC) crash data base was used to determine MVC rates and injury occurrence. Descriptive characteristics of the injury location and injury type were analyzed comparing the Odds Ratios
and chi-squares. Results: PS occupants received more injuries; Odds Ratio was 2.49 (95% confidence interval: 2.15-2.88). Conclusion: Occupants in
PS which collide with PU were at twice the risk of injuries. Concussion, whiplash, lacerations and abrasion were more frequent in PS drivers andoccupants than in PU drivers and occupants. Overall, PS drivers/occupants experienced greater injuries than PU drivers/occupants in PU-PS collisions. In this paper, results are shown as odds ratios comparing occupants injuries in PS (case group) with occupant injuries in PU (control group).
Key Words: Passenger sedan cars, Pick up trucks, Vehicle fleet, Vehicle mismatch crashes, Injury severity

1. INTRODUCTION
Worldwide, 3,000 people are killed and 30,000 areseriously injured on roads every day1. Road-traffic injuries are predicted to rise by 2020 to third place in the global burden of disease2. Evidence needs to be developed
to direct policy to eliminate unnecessary injuries related
to motor vehicle crashes in the world. The identificationof effective strategies for the prevention of traffic related
injuries is of global health importance.
The main injury risks for car occupants arise fromthe way vehicles interact with each other and with theroadside in frontal and side-impact crashes. Chief determinants for the degree of severity of injuries in motor vehicle collisions are vehicle size and weight. The European
commission has stated that if all cars were designed tobe equal in standard to the best car currently available in

42 • IATSS RESEARCH Vol.28 No.2, 2004

each class, then an estimated 50% of all fatal and disabling injuries could be avoided3. A recent North American research has shown that replacing light trucks withcars of the same mass would save more than 1,000 lives
a year4.
Transport Canada unveiled a national road safety
strategy entitled “Road Safety Vision 2010,”5 which aims
to achieve the safest roads in the world by 2010. The national targets calls for a 30% decrease in the average numbers of road users killed or seriously injured during the
2008-2010 period (compared to 1996-2001 data). To meetthis new target, continued efforts must be made to identify the new problem areas of traffic safety at the national,
provincial and municipal levels.
As occupant protection offered by new passenger
vehicles has improved, there has been growing concern
about the harm that some vehicle designs may inflict on
occupant of other vehicles with which they collide. Stud-

THE INJURY SEVERITY RATE DIFFERENCES IN PASSENGER CARS AND PICK UP TRUCKS RELATED TWO VEHICLE INVOLVED MOTOR VEHICLE CRASHES IN BRITISH COLUMBIA, CANADA

ies have shown that proliferation of large sport utility vehicles (SUVs) and pickup trucks which are more dangerous to occupants of other vehicles in crashes. It ishighlighted as a chief obstacle in further reduction of
motor vehicle crash related morbidity and mortality inNorth America6. In two vehicle collisions, the protection of all occupants in the subject and the other vehicle
should be considered. Compatibility means that passenger vehicles of disparate size provide an equal level ofoccupant protection in two vehicle collisions7,8. Vehicle
mismatch is defined as design differences between vehicle types which result in disproportionate damage patterns to the vehicles involved in a collision; these design
differences include weight, frame height, and stiffness.
This is also known as crash incompatibility. The damage patterns can result in a violation of the structural integrity of the passenger compartment resulting in increased
risk of serious injury or death to the occupants8,9.
The Canadian as well as British Columbia vehicle
fleet differs in mass, geometry stiffness and many otherparameters. These differences are consequences of different design objectives for these vehicles and result fromconsumer demand, environmental and safety considerations. The following statistics on vehicle ownershipshows us new emerging trends in vehicle fleet in both
Canada and the British Columbia.
Registration of Light Trucks (LT) in Canadian vehicle fleet has been increased from 2,650,799 in 1990 to
4,012,370 in 2001. Significantly the LT (Pickup trucks
and SUVs) ownership has been increased by 51.3% since1990.By comparison; small car ownership has been moderately increased by 7.9% from 5,795,765 in 1990 to
6,254,224 in 2001. Registration of LT in British Columbia vehicle fleet has been increased from 340,549 in 1990
to 636,631 in 2001. Significantly the LT ownership has
been increased by 86.9% since 1990. By comparison,
small car ownership has been increased by 17.9% from
550,495 in 1990 to 747,654 in 2001. It is estimated thatutility vehicles accounted for approximately 40% present
British Columbia vehicle fleet. Increasing utility vehicle
ownership is in Canada and British Columbia which produce crash incompatibilities when they impact cars, represent a substantial threat to the ability of the present setof safety devises to continue maintain a low injury, lowcomplication and reduced injury profile after MVC7.
In addition proportion of LT sales, compared withpassenger cars has approximately doubled during the last
decade to nearly 90%. Furthermore, of all new Canadianvehicle sales in 1997, three of the top four selling models belong to the LT class7,10,11. Not only have LT cap-

DESAPRIYA, E.B.R., BRUSSONI, M., PIKE, I., HAN, G.

tured an increasing share of the market, but also their usage characteristics have changed significantly since theirinitial introduction into the vehicle fleet. They are being
used increasingly more as passenger vehicles since thedemographics of their owners have changed. PU are being used more for the combined conveyance of passengers(through the inclusion of small passenger compartments
behind primary setting) in addition to cargo7. To environmental and safety advocates, the extension of the auto
ownership from sedan cars to pickup trucks is a worrisome development6-8.
Disparity in size of the two vehicles, especially when
the struck vehicle is smaller and lighter, is almost a consistent risk factor for occupant injury7,12. Impact and injury analysis document a negative correlation between
vehicle mass and injury severity in car-to-car crashes13, 14.
The fatality rate for 900-kg passenger cars is 50%
greater than the fatality rate for 1,800-kg passenger cars.
Occupants of smaller cars appear to be at greater risk thanlarger car occupants in many types of collision scenarios15, 16. It is reasonable to assume that small car occupants will be more at risk in collisions that display
certain kinds of mass-related properties7,13.
Kahane17 estimates that a 100 pound reduction in
the average weight of light trucks, defined as PU, vans
and SUVs, results in a reduction of 40 fatalities per year
in US. Importantly, Kahane17 shows that decline of 100
pounds in the average weight of the typical passenger car
results in an estimated increase of 302 more fatalities per
year. The results also indicate that 80% of the injuries/
fatalities associated with car-light truck collisions are occupants of passenger cars. The Insurance Institute forHighway Safety estimates that the relative risk of deathamong occupants of passenger cars that are involved incrashes with light trucks is approximately 47:1 comparedto crashes involving similar size vehicles8. There is evidence that car size does play a role in two vehicle crashes.
The strongest is that when cars of same mass crash into
each other fatality and injury risk is lower for two heaviercars crashing into each other than for two lighter cars
crashing in to each other13,18-20.
Vehicle mismatch crashes should be recognized asa risk factor for injuries. As a PU and SUVs continue
to proliferate the national and provincial vehicle flees,
there should be a high priority in conducting MVC studies on the impact of this trend on injury rates and crashincidence rates. In this study we have attempted to examine the injury severity rate difference in two vehicle
crashes that involved PU-PS in British Columbia during 2002.
IATSS RESEARCH Vol.28 No.2, 2004 •43

TRANSPORTATION

2. DATA AND METHODSWe obtained BC MVC data from Insurance Corporation of British Columbia21. This database provides
information on driver and occupant/rider characteristics
and vehicle characteristics. MVC data for 2002 used inthis study to investigate vehicle incompatibility and estimate the injury rate comparisons between PU-PS involved collisions in BC. For the purpose of this review,mismatch collisions between PS (defined as vehicles on
car frames) and PU (defined as vehicles on truck frames)
has been selected. After applying the exclusion criteria
to the initial data set, 953 of two vehicle PU-PS related
crashes (1,906 vehicles) were identified. In addition 2,719
drivers and occupants involved 1,321 injuries were analyzed to estimate the injury rate difference.
Analyses were performed on crashes involving PSPU vehicles. Odds Ratio (OR) with 95% Confidence Intervals (CI) were calculated to determine the magnitudeof injury severity in vehicle mismatch crashes. In this paper, results are shown as odds ratios comparing occupants
injuries in PS (case group) with occupant injuries in PU(control group).

3. RESULTS
Drivers and crash characteristics-age of the driver
PU drivers differed greatly in their gender distribution, 80% of the total being males. In gender variation in
PS drivers were 1:1 (51 % male and 49% females). The
mean age was 40.8 (SD=16.8) years for PU drivers and43.3 (SD=20.1) years for PS drivers. In comparison, average PU drivers were younger than the PS drivers.
Crash characteristics
75% of PU-PS crashes occurred between 8 a.m. and6 p.m. Accordingly majority of crashes were distributedwith peaks between 8 a.m. and 5 p.m., and (15%), occurred between 6 p.m. and 10 p.m.
PU-PS crash related environmental factors
Environmental factors and, in particular unsafe conditions also are known to result in MVCs and related injury. 72% of PU-PS involved MVCs reported in daylight,
12% in dark with some illumination and 7% with full illumination. It is common knowledge that rain, sleet orsnow not only reduces visibility but also contributes tounsafe road conditions. Most of the MVCs occur in dry

44 • IATSS RESEARCH Vol.28 No.2, 2004

weather conditions (53%) while 17% in wet weather conditions and few (4%) reported when it was snowing.
PU-PS crashes and driver errors
Many PU-PS crashes accounted to driving errors
such as failing to yield the right-of-way (27%), driving
without due care (17%) disobeying traffic signs (13%)
unsafe speed (7%) and alcohol involvement (4%). Overall driver errors was concern PU drivers contributed more
PU-PS crashes (54%) while small vehicle drivers’ drivererrors were contributed to 46% of PU-PS crashes in 2002.
PU-PS crashes and restraint use
Overall seat belt use: A seatbelt was worn by 84%
of PU occupants and drivers compared with 87% of car
drivers and occupants. Moreover, 4% of PU drivers andoccupants did not wear seat belts compared with 1.3%
of PS drivers and occupants. For the other cases, the information on seatbelt wearing was unknown. Many studies have indicated that crash related injury rates can bediffering by rate of seat belt use by vehicle occupants.
Accordingly we have compared seat belt wearing rates
in PU-PS injury group with non injury group as follows:
Table 1 Comparison of restraint use in injury groupversus non injury group in PU-PS crashes
RESTRAINTUSE

INJURYGROUPNON INJURY
GROUP

PU

PS

PU

PS

LAP AND HARNESS

82%

86%

77%

84%

LAP BELT ONLY

6%

5%

4%

4%

NO RESTRAINT USED

7%

4%

2%

1%

UNKNOWN

5%

5%

17%

11%

100%

100%

100%

100%

Total

X2 test-17.54, P < 0.05
As shown in the Table 1 seat belt wearing rates forboth PS and PU drivers and occupants were higher.
Seatbelt use is a protective factor. However 88% belted
PU drivers and occupants and 91% belted PS drivers andoccupants were injured, whereas among injured only 7%of PU drivers and occupants and 4% of PS drivers andoccupants were not using the seat belts at the time ofcrash. 82% of the PU, 88% of the car occupants in non
injury group has wearing the seat belts. The percentageof missing values for this variable was low-5%, 5%, 17%
and 11% respectively. For this reason it was not possible
to conclude that there was an association between injury

THE INJURY SEVERITY RATE DIFFERENCES IN PASSENGER CARS AND PICK UP TRUCKS RELATED TWO VEHICLE INVOLVED MOTOR VEHICLE CRASHES IN BRITISH COLUMBIA, CANADA

differences in rates and seat belt wearing, but equally ahigh rate of seat belt use among PU occupants and PS
occupants might have explained that the particular injury
types in small vehicles cannot be reduced wearing seatbelts alone in PU-PS crashes. In other words protective
nature of the seat belts can be reduced to a greater extent in small vehicles in vehicle incompatible crashes.
This further supports findings in three earlier studies13,18,22 that safety belt effectiveness depends systematically on different vehicle size.
The use of safety belts is the single most effectivemeans of reducing fatal and nonfatal injuries in motor
vehicle crashes. In all types of crashes, manual lap-shoulder belts are approximately 45% effective in reducing fatalities in passenger cars and 60% effective in lighttrucks22, 23. They are estimated to reduce the risk of serious injury to the head, chest, and extremities by 50% to83%23. Lap belts alone, used most often by rear seat occupants, are estimated to be 17% to 58% effective in preventing death compared with no restraints17, 18, 22.
Table 2 Types of injury that occupant sustained in
PU-PS crashes
TYPE OF INJURY

PSPU

CRUDE OR*

95% CI*ABRASION

62

27

2.6

1.65,4.11

BRUISES

163

107

1.72

1.34,2.22

WHIPLASH

316

128

2.80

2.25,3.47

CONCUSSION

18

5

4.08

1.79,6.99

LACERATIONS

40

23

1.97

1.17,3.30

FRACTURE

26

7

4.21

1.82,9.73

OTHER

43

14

4.02

2.44,6.64

TOTAL INJURIES

696

317

2.49

2.15,2.88

No Injuries

1799 2041* OR, odds ratio; CI, confidence interval.

DESAPRIYA, E.B.R., BRUSSONI, M., PIKE, I., HAN, G.

Types of injuries
As shown in the Tables 2 and 3 above, PS drivers
and occupants were received more injuries than PU drivers and occupants (OR, 2.49; 95% CI, 2.15-2.88). Car occupants received more abrasion injuries; odds ratio was
2.6 (95% CI: 1.65, 4.11) Fractures; OR was 4.21 (95%
CI: 1.82, 9.73) lacerations; OR was 1.97 (95% CI: 1.17,
3.30) whiplash; (OR 2.80; 95% CI 2.25, 3.47) and concussions; OR was 4.08 (95% CI: 1.51, 11.02). Concussion, whiplash, lacerations and abrasion were more
frequent in PS drivers and occupants than in PU drivers
and occupants.
Injury location
Upper torso (OR, 3.20, CI 2.07, 4.94); head facenose eye (OR 2.21, CI 1.64, 2.98) neck (OR, 2.68, CI
2.12, 3.40) entire body (OR 4.53, CI 1.85, 11.12) upper
extremity (OR 2.29, CI 1.55,3.39) injuries were more frequent and significant in PS drivers and occupants thanPU drivers and occupants.
Data using crash dummies suggest that MVCs involving passenger cars (PSs) , Light Trucks (LTs) produce
more severe injuries than those involving two Passenger
Cars (PSvPS) or two Light Trucks (LTvLT). Researchdone in this area have shown that how a bullet vehicle, witha high front bumper region and a raised bonnet with very
stiff facial, intrudes significantly into the soft section of asedan shape car resulting in severe head and chest trauma8.
Further analysis of BC vehicle mismatch crash data
revealed that the number of injured drivers and passengers per 1,000 crashes differed substantially by vehicle
type. When a PU collides with a PS, occupants in the PS
injured at a rate of 351 per 1,000 crashes. By comparison, PU vehicles occupants injured at a rate of 160 per
1,000 crashes. When a PU collides with a PS, occupants

Table 3 Comparison of injury locations that occupants sustained in PU-PS crashes
INJURY LOCATIONPS

PU

CRUDE OR*

95% CI*UPPER EXTREMITY (elbow, lower arm, hand, shoulder/upper arm

79

39

2.29

1.55, 3.39

LOWER EXTREMITY (hip/upper leg, knee, lower leg foot)

42

28

1.70

1.05,2.75

UPPER TORSO

79

28

3.20

2.07,4.94

LOWER TORSO (abdomen, pelvis, back)

86

41

2.37

1.63,3.47

ENTIRE BODY

24

6

4.53

1.85,11.12

HEAD, FACE, NOSE, EYE

135

69

2.21

1.64,2.98

NECK

251

106

2.68

2.12,3.40

TOTAL INJURIES

696

317

2.49

2.15,2.88

No Injuries

1799

2041

* OR, odds ratio; CI, confidence interval.

IATSS RESEARCH Vol.28 No.2, 2004 •45

TRANSPORTATION

in the PS injured at a rate of 393 per 1,000 vehicles. By
comparison, PU vehicles occupants injured at a rate of
234 per 1,000 vehicles. Injuries per 1,000 motor vehicle
drivers and occupants are higher in PC occupants (270per 1,000 occupants) when compared to PU drivers andoccupants injury rates (184 per 1,000 occupants) in PUPS related crashes.

4. DISCUSSION
The impact that LT have on crash severity has long
been a concern in the MVC analysis literature. Previous
studies on PU-PS related crashes have confirmed thatthese two categories of vehicles are incompatible from adesign point-of-view23-26. Furthermore a recent studies9,17, 20, 22-27 have shown that a disproportionate number of the injuries in PU-PS crashes are incurred by thePS’s drivers and occupants. A comparison of PU and PS
collisions in the previous literature reveals that the PU ismore aggressive than PS for a number of reasons including their greater weight, stiffer structure, and higher rideheight4. Many PU models have an inherently higher centre of gravity, larger masses, and stiffer chassis. Thesefeatures place occupants of passenger cars at a disadvantage in vehicle mismatch crashes. PU and SUVs have thehighest ride height with an average rocker panel heightof 390 mm. In contrast, subcompact cars have the lowest-riding height with an average rocker panel height of
175 mm. PU and SUVs ride almost 200 mm higher than
mid-sized cars – a geometric incompatibility that would
readily permit the SUV to override any side structure ina car and directly strike the car occupant7.
Our results not only corroborate the previous re7,8,11,23-29
but also support the proposition that occuports
pants in PS are more than two times as likely to be injured
as drivers or passengers in PU. New large size vehicles
are designed to promote increased safety to their own occupants while, with little attention to the safety of small
vehicle users, pedestrian and bikers. This sense of personal security may possibly lead to greater risk-taking by
PU drivers30-32.

5. CONCLUSIONSIn Canada, passenger vehicles are shifting rapidly
from a fleet populated primarily by cars to a fleet dominated by light trucks and vans (LTs). Because LTs are

46 • IATSS RESEARCH Vol.28 No.2, 2004

heavier, stiffer, and geometrically more blunt than passenger cars, they pose a dramatically different type of
threat to car occupants. In conclusion, vehicle mismatchis associated with serious injury in automotive crashes.
The injury risk for PS occupant is greater than the risk
for PU occupant in two-vehicle crashes. The injuries identified in this study support the need for re-designing both
PU and PS to improve vehicle compatibility. Several automobile manufacturers are voluntarily re-designing their
PU to make them more compatible with PS4. However,industry wide design improvements of both PU and PS
will be needed to reduce the effect of mismatch.

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ACKNOWLEDGEMENTS
The vehicle mismatch crash investigation in BC is partly
supported by funding from the Networks of Centers of Excellence(NCE) funded Auto 21 project. We acknowledge and thank the Insurance Cooperation in British Columbia (ICBC) for access to thesedata.

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