Big rigs have the laws of physics on their side, so protecting occupants of smaller vehicles when they collide with them is challenging. The key is preventing these often-deadly crashes in the first place. A new Institute analysis indicates that a combination of 4 crash avoidance features has the potential to prevent or mitigate more than 1 of every 4 large truck crashes, 1 of every 3 injury crashes, and about 1 of 5 fatal crashes if every rig had them.
"These add up to 107,000 large truck crashes a year, including 12,000 nonfatal crashes and 835 fatal ones," says Anne McCartt, Institute senior vice president for research. The findings are important because per unit of travel large trucks are involved in more fatal crashes than other vehicles — 2 per 100 million miles traveled in 2008 compared with 1.4 for cars and 1.8 for light trucks.
Each year about 384,000 crashes involve large trucks, and about 4,100 of them are fatal. Side view assist, or blind spot detection, appears to be the most promising new feature for reducing such crashes. Stability control and lane departure warning show the most potential to lower fatal crashes.
Trucks have big blind spots. Side view assist uses cameras or radar sensors to monitor areas alongside trucks and alert drivers of vehicles in their blind spots. Among the 97,000 annual large truck crashes involving intentional lane changes, this feature could prevent or mitigate nearly 39,000 crashes, or 10 percent of police-reported crashes, including 2,000 injury and 79 fatal crashes.
A number of safety-conscious carriers, mostly large fleets, have outfitted their rigs with crash avoidance features even though no federal mandates or tax breaks exist to help defray up-front costs or put them on even footing with their competitors. Considering that trucks have a life span of 10 years or more, equipping entire fleets with crash avoidance systems is a pricey investment in gear and training that requires faith the benefits will pan out.
Annual large truck crashes potentially prevented/mitigated, by type of system
|Lane departure warning||10,000||1,000||247|
|Electronic stability control||31,000||7, 000||439|
|Forward collision warning||31,000||3,000||115|
|Side view assist||39,000||2,000||79|
|Total unique crashes||107,000||12,000||835|
Percent of large truck crashes that potentially could be prevented/mitigated
|Total unique crashes||107,000||12,000||835|
|Percent of crashes||28%||34%||20%|
"Some operators, particularly smaller independents, may be holding back," McCartt says, "because there's no mandate to level the playing field. Until more trucks have the technology, we won't know if it works like it's supposed to."
Institute researchers examined 2004-08 crash data for single-unit trucks and tractor-trailers, correlating relevant crashes with features designed to prevent them. Considering the limitations of current systems such as how bad weather affects sensor readings, the researchers estimated how many crashes could be prevented. For example, forward collision warning/mitigation could prevent 37 percent of large truck front-to-rear crashes. This technology uses cameras, radar, or sensors to monitor a truck's path and alert the driver of a potential collision with a vehicle or object. Some systems require drivers to react to warnings, while others may automatically brake or steer a truck to reduce crash severity or avoid a crash altogether.
Fatigue is a persistent problem in the trucking industry. Truckers' long work hours cause sleep deprivation and disrupt normal rest cycles (see "Safety consequences of driving longer," Feb. 14, 2009). Lane departure warning and prevention systems can help drowsy or distracted drivers focus on the road and recognize the need for a rest break. Cameras track a truck's position within the lane and alert the driver if the truck is in danger of straying across lane markings. The technology is relevant to about 10,000 crashes a year.
About half of all truck driver deaths, compared with about 1 of 4 car occupant deaths, occur when trucks roll over. Two kinds of stability control systems intervene when truck motion becomes unstable, risking rollover, jackknife, or other loss of control. The first, which activates when a truck and/or trailer accelerates laterally, could prevent 13,000 single-vehicle large truck crashes a year. Electronic stability control incorporates roll stability with directional stability to prevent understeer or oversteer. It could prevent another 10,000 large truck single-vehicle crashes a year. Both kinds of stability control also address multiple-vehicle crashes. Combining 2-vehicle crashes with relevant single-vehicle ones, about 31,000 large truck crashes a year are relevant to stability control. Of these, 7,000 involve injuries and 439 involve fatalities.