Part IV of a series

American researchers are analyzing truck crashes to see if there is a place for smart technologies to help reduce the number of collisions or, at least, to lessen the impact of the crashes that do occur.

The stepped up research is because of the US government’s ambitious goal to reduce the number of truck-related fatalities by 50 percent and the number of persons injured in truck crashes by 20 percent by 2010. Researchers are studying crashes to see if there are any opportunities to use Intelligent Transport Systems (ITS) in the quest to reduce the number or impact of crashes. ITS is a name given to any of a number of devices using computers and sensing equipment to make roads, vehicles or drivers smarter. (See the accompanying article for examples of ITS technologies.)

One problem in trying to prevent crashes is that there are hundreds of factors at work in making roads and vehicles safe or unsafe as the case may be. The vehicle itself plays a key role – think of the new rear impact bumpers on trailers, the integrity of tanks carrying fuel or the way the tires are made. The load is also important – consider all the pending new load-securing regulations. Other factors include the road itself (smooth or rough pavements, turning geometry, etc); the weather (rain, snow and ice); and last, but certainly not least, the driver and everything that goes into making one driver safe and another not so safe. Because so many factors play a role in truck crashes, there is no simple way to prevent them. Hence the need for a detailed analysis of the massive data files collected on truck crashes in the US.

Lawrence Barr and Wassim Najm at the Volpe National Transportation Systems Center in Cambridge, Massachusetts are two people studying crashes. The Volpe Center is a research branch of the US Department of Transportation. Barr and Najm have analyzed four of the most common types of truck crashes to see if there is a need for ITS technologies. The four most common categories of truck crashes (see the accompanying table) accounted for about 70 percent of all truck crashes in the US in 1998.

Their analysis suggests that fatigue may be a big factor in the first of the four categories – run-off-road crashes. These account for 8.6 percent of all commercial vehicle crashes in the US. (Barr and Najm’s data uses “commercial vehicle” which, although including buses, is mainly trucks.) Police reports show that the most common “first critical event,” accounting for 49 percent of these crashes, is a “roadway departure.” In other words, one or more of the truck’s tires simply wandered off the edge of the pavement. As Barr and Najm note, “it is generally believed that a substantial number of run-off-road crashes may be due to drowsiness and fatigue.” The next most common “first critical event” listed in the police reports, accounting for 34 percent of the crashes, is “control loss” – something like a tire blowing out or hitting a patch of ice.

While Barr and Najm don’t go on to suggest ITS technologies that could prevent run-off-road crashes caused by fatigue, other researchers have been experimenting with devices that warn drivers when they appear to be dozing off. They measure such things as the rate at which the driver makes small adjustments to the steering wheel or the driver’s eye movements.

A second category of crashes, rear-enders, accounts for 19.3 percent of all collisions. In 67 percent of these cases it is a truck ploughing into another vehicle and 40 percent of the time it is another vehicle rear-ending the truck. (The two numbers add to more than 100 per cent because in some collisions both things happen.) What’s interesting in Barr and Najm’s numbers is that in 94 percent of these collisions, the leading vehicle is either stopped (23.9 percent), de-accelerating (43.4 percent) or moving at a constant, but slower, rate of speed (26.7 percent). This suggests there is an urgent need for some ITS technology that could either warn a driver that he is approaching another vehicle too quickly or even a technology that would take over from the driver and actually slow the vehicle down. Indeed, such technologies – Adaptive Cruise Control – already exist as explained in the accompanying article (see pg. 14). In May of this year, the US National Transportation Safety Board made a recommendation that the Department of Transportation develop standards for collision-warning systems and, after doing so, make it mandatory for all new trucks to be equipped with them.

The third big category of crashes, accounting for almost one quarter of the total, is labeled “lane change crashes.” Most occur on a road or highway at places other than an intersection. In 1998, 92,085 trucks (actually “commercial vehicles”) were involved in this type of a collision and 60 percent of the time it was the truck that was attempting to change lanes. Again, this seems to indicate that something like a sideways looking radar device could be used to prevent many of these collisions.

Crossing-path collisions at intersections account for 16.7 percent of all truck crashes. And these are the most complex to analyze because there are many possible ways for collisions to occur at intersections. Barr and Najm’s analysis show that, for trucks, most (41.4 percent) crossing-path collisions occur when two vehicles are proceeding through an intersection at right angles to each other. And these are split almost equally between intersections with signals and intersections with no light signals. The next two biggest categories (21.3 percent and 21.2 percent, respectively) occur when one vehicle is turning left across the path of another vehicle and is struck by the vehicle either traveling in the opposite direction or at right angles to the turning vehicle. In about two-thirds of these “left turn across path” type of collisions, it is the truck that is making the left turn. Although it is not clear what type of ITS technology could prevent these crossing path collisions (“smarter” light signals?), the numbers from the analysis by Barr and Najm will be used to see if anything could be used.

Of course, while this search for smart technologies to make roads safer is exciting, we shouldn’t overlook the single biggest thing needed to make roads safer: smarter drivers.