15-Passenger Vans

Risks Associated with Driving 15-Passenger Vans:

Fifteen-passenger vans are popular modes of transport for various people including: community groups, schools, universities and tour operators. Since these vans became available in the 1970's, there have been a number of collisions involving rollovers and fatalities. In a three-month period in 2000, there were four rollovers involving university sport teams and this probably stimulated the analysis by the US National Highway Traffic Safety Administration (NHTSA).

While driving 15-passenger vans is not always inherently dangerous, there are some situations that can result in erratic vehicle response that an inexperienced driver might not be able to control and which could result in a collision or rollover. Because of this, the University of Alberta requires drivers of these vehicles to have more driving experience and have demonstrated the medical fitness and the higher degree of driving knowledge and ability associated with having a Class 4 operator's permit. In addition, drivers will attend a training session that discusses the conditions that can result in loss of vehicle control and also, demonstrate some competency in driving a 15-passenger van.

Concerns for passenger safety arose from an analysis of the accident history of these vehicles over the period from 1994-1997 and which was presented by the NHTSA in April 2001 in a report called The Rollover Propensity of Fifteen-Passenger Vans (PDF, 75.3kb) . A consumer advisory accompanied this document and described the increased chance of rollover with a fully loaded van. A second consumer advisory was issued on April 15, 2002. Such advisories have been characterized as being "unprecedented" for the NHTSA and likely reflect their perception of the urgent nature of the rollover problem.

Some factors that contribute to rollovers include: heavy loads, road and weather conditions, tire failure, excessive speed, consumption of alcohol, driver inattention and driver over-steering during an emergency manoeuvre. Many of the factors reside with the driver including: a lack of knowledge about effects of load on van driving response and inexperience in controlling this type of vehicle in different situations. This is why the University of Alberta requires drivers to have specific training to handle these vehicles. Common sense is not enough.

The Problem:
Basically because of their design, and relative to passenger automobiles, these vehicles are:

• more prone to loss of control when the vehicles are heavily loaded,
• more difficult to recover after they go out of control, and
• more prone to rollover after a driver has lost control.

Table 1 in the NHTSA report shows the incidents of single vehicle accidents and the number of rollovers for vans containing different numbers of passengers. The data showed that when the vans contained fewer than 9 persons, rollovers occurred in 12.7% of the crashes but for vans with over 10 people, rollovers occurred in 35.4% of the crashes. Only single vehicle collisions were considered because of the complexities involved in deciding why a rollover occurred in collisions involving more than one vehicle.

Number of Crashes, Rollovers and Rollover Ratios by Occupancy level of
Fifteen-Passenger Vans in Single Vehicle crashes

Occupancy Level	All Single Vehicle Crashes (n)	All Rollovers (n)	Rollover Ratio (%)	Combined Ratios (%)
< 5	1815	224	12.3	12.7
5 to 9	77	16	20.8
10 to 15	55	16	29.1	35.4
> 15	10	7	70.0

adapted from Table 1 in: "The Rollover Propensity of Fifteen-Passenger Vans". W.R. Garrott, B. Rhea, R. Subramanian and G. Heydinger. National Highway Traffic Safety Administration, April 2001.

The reason for the increases frequency of rollovers when the vans are heavily loaded is because the centre of gravity for the vehicle is raised as more weight is added and the higher the centre of gravity, the less force is required to cause the van to rollover (the effect of base width and raising the center of gravity on tipping can be appreciated if you consider how hard it is to topple a brick that is laid on its side versus one that is stood on end). In addition, as load is increased, the proportion of weight on the rear axle increases and this makes the vehicle more difficult to control. Computer simulations during turns in lightly loaded versus fully-loaded vans at different speeds show that the steering characteristics change depending on van load and this was rated as " a topic for concern". The problem associated with a high center of gravity and rollovers has also been experienced among users of light trucks and sport utility vehicles and since 2001, there have been stability rankings posted for various vehicles. A Static Stability Factor (SSF) below 1.20 is associated with increased risk of rollover and the vehicles with values around 1.0 are of particular concern. Note: these are the values before passenger loads are added to the vehicle.

Other tidbits of information:
- most fatal rollover crashes are single vehicle crashes
- rollover crashes are more likely to result in fatalities than other types of crashes
- just below half of single vehicle rollovers were reported to be preceded by an attempt to avoid the crash by a steering manoeuver. This is compared to one third for rollovers in multiple vehicle crashes.
- US Federal laws prohibit the sale of 15 passenger vans for school-related transport of students aged high school or younger. This does not apply to college students.
- most other provinces in Canada require a Class 4 licence to drive a 15-passenger van.
- on September 02, 2002, Ford Motor Company issued a warning that drivers of full-sized 15-passenger vans should be experienced and have special training to reduce the risk of rollovers.