January-February 2011

Spotlight on Vehicle Safety

Nearly 200,000 crashes involving tractor-trailers occurred in the US this past year—an average of one crash every three minutes—and I got to watch one a recently while driving back to Santa Barbara, CA from an event in Las Vegas. It occurred on the transition ramp from the Westbound Highway 14 to the Northbound Interstate 5, a fairly sharp-climbing, right-hand bend leading out of an equally steep downhill plunge.

I began watching a truck-trailer rig toting a large backhoe-loader about a half-mile before the ramp, thinking he would probably knock of 20-or-so miles per hour before settling into the turn, but as we neared the corner it became apparent that the driver had misjudged the situation, so what happened next seemed preordained—a classic example of last-ditch overreaction. First, the driver dove hard onto the brakes as he entered the turn, causing the trailer to load up against the truck and producing an initial understeer condition. When the driver responded by increasing the steering input, the situation switched instantaneously to oversteer, leading sequentially to loss of control, jackknife, and an uncontrolled slide into the guardrail, where, thankfully, he stuck without toppling 200 feet onto the roadway below.

As I reflect on the accident with 20/20 hindsight, I can’t say with certainty that situation was salvageable, but it wasn’t the extra 20 miles per hour that put the rig into the wall, rather the driver’s flawed reactions. It’s tempting to say, “Yeah, driver error,” and let it go at that. But is that all there is to it? Maybe not. Perhaps some of the new technologies we’re seeing make their way into the transportation field—in this instance an electronic stability control (ESC) system—could have led to a different outcome.

ESC uses sensors to detect when a driver is about to lose control, intervening automatically to provide stability and to help the driver maintain the intended course, especially in oversteering and understeering situations.

A number of studies have been conducted testing the effectiveness of ESC, verifying that it does, in fact, work. Five different studies projected a 30%–35% reduction in single-vehicle crashes, thanks to ESC.

ESC incorporates antilock brake and traction control systems that prevent wheel lock when braking and wheel spin when accelerating, incorporating the actions of both systems, acting to counter lateral forces to further reduce the risk of skidding in all driving situations. Simply put, ESC constantly compares the driver’s intention with the vehicle’s actual behavior.

ICBSS: More Alphabet Soup for Truckers
The Integrated Vehicle-Based Safety System (IVBSS) is a five-year, $32 million cooperative agreement between the US Department of Transportation and a group of partners under the auspices of University of Michigan Transportation Research Institute (UMTRI) at Ann Arbor, MI, testing an integrated system of crash-warning technologies for different types and classes of vehicles. The program focuses on the prevention of rear-end, lane-change, and run-off-road crashes. The prototype vehicles were equipped to provide forward-collision, lane-departure, lane-change, and curve-speed warning functions:

Systems were installed on 10 trucks using visual displays and auditory tones to warn drivers of potential threats. Eighteen drivers from Con-way Freight’s Detroit terminal participated in the heavy-truck field tests. Each participant drove one of the specially equipped, class 8 tractors for 10 months. As the program progressed, data-acquisition systems recorded driver actions and responses to the ICBSS.

In the realm of driver acceptance, UMTRI found that the majority of drivers believed that integrated crash-warning systems would increase driver safety, stating that the ICBSS made them more aware of the traffic environment as well as their lane position. Seven drivers reported that the integrated system potentially prevented them from having a crash, while 15 out of the 18 said they preferred a truck equipped with the integrated safety system and would recommend that their employers purchase such a system.

In terms of driver behavior, the study found that in situations where there were multiple threats, the initial warning was generally enough to get the attention of drivers, resulting in appropriate actions when necessary. Moreover, not only did drivers do a better job of maintaining lane position, but they also responded more quickly to rear-end collision threats.

Based on test findings, UMTRI concluded that integrated crash-warning systems not only offered benefits relative to improved driver performance, but that a clear majority of commercial drivers involved in the study accepted the system and reported subjective benefits from the integrated system they used.

How quickly electronic stability control and integrated crash warning systems might become staples within transport and vocational vehicle operations remains to be seen, but given the results of studies to date, their adoption would seem to warrant your close attention. Have you any thoughts on this?

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Note from Beth Tompkins, Director of Education & Training: The content that appears in our "Comments" section is supplied to us by outside, third-party readers and organizations and  does not necessarily reflect the view of our staff or Forester Media—in fact, we may not agree with it—and we do not endorse, warrant, or otherwise take responsibility for any content supplied by third parties that appear on our website. “All comments are subject to approval”

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