The Cost of Risk: What causes your crashes?

Is your crash experience typical? How do you know?

Even if you know how your operation’s accident rate compares with national averages, you probably don’t know whether the kinds of crashes you are experiencing are unusual or on a par with other motor carriers.

Determining the cause of truck crashes was the goal of a major study recently completed by the Federal Motor Carrier Safety Administration and the National Highway Traffic Safety Administration. The Large Truck Crash Causation Study (LTCCS) is based on a nationally representative sample of large-truck fatal and injury crashes that were investigated during 2001 to 2003 at 24 sites in 17 states.

The LTCCS generally confirms a key finding of most other studies of truck-automobile crashes: Most are caused by the automobile. In two-vehicle crashes involving a truck and a passenger vehicle, trucks were assigned the “critical reason” in 44 percent of the crashes and passenger vehicles in 56 percent. A critical reason is the immediate reason for the “critical event” – the action that made the collision unavoidable. LTCCS researchers recognized that there might be several contributing factors in a crash, but they coded each crash with only one critical reason.

Of the three principal types of critical reasons – driver, vehicle and environment – driver reasons represent the overwhelming majority of crashes. In crashes where the truck was coded with the critical reason, the critical reason was driver-related 87 percent of the time. And the vast majority of those crashes resulted from two types of errors – decision and recognition. Decision errors include things like driving too fast for conditions, misjudging the speed of other vehicles, following other vehicles too closely or making false assumptions about another driver’s actions. Recognition errors result from inattention or distractions.

Although the results of the LTCCS study aren’t particularly surprising, they suggest that carriers could improve safety by adopting technologies and techniques that aid drivers’ awareness and decision making. That’s certainly the approach that Little Rock, Ark.-based Maverick Transportation has taken in recent years. For example, the large flatbed carrier has installed the Eaton Vorad collision warning system on its tractors for several years and now is spec’ing Roll Stability Control.

More recently, Maverick has installed a Lane Departure Warning (LDW) system from Iteris to address unintentional lane changes. In the LTCCS, lane departures are a big problem in crashes where the truck was coded with the critical reason. The No. 1 critical event in these situations – which include both single- and multiple-vehicle crashes – was the truck being over the lane line or off the road.

The Iteris LDW uses imaging technology to recognize lane markings and judge the vehicle’s position relative to those markings. When the system detects a vehicle drifting toward an unintended lane change – turn signals indicate intended lane changes and disable the warning – the unit emits a “rumble strip” sound from the left or right speaker.

Following a brief test of five units, Maverick already has installed the Iteris LDW on 750 of its 1,100 power units over the past 18 months, says Dean Newell, the carrier’s vice president of safety and training. In 2004, Maverick had 23 crashes attributed to unintentional lane changes or running off the road in 110 million miles traveled, Newell says. That’s a rate of 0.21 per million miles.

Trucks equipped with the LDW system have experienced three crashes in 40.7 million miles – a rate of 0.073 per million miles and a 65 percent improvement, Newell says, adding that there are no other changes in the carrier’s operation that would account for the improvement.

Newell says he has had little resistance to the LDW system, even among veteran drivers. “I had a million-mile driver tell me that it made him a better driver.”

As the results of the LTCCS suggest, the risks of driver inattention and misjudgments don’t disappear with experience.

For FMCSA’s report to Congress and access to databases used in writing the report, go to this site.