Rollover Stability Tops ESC, ATRI Says of Safety Systems

This story appears in the Aug. 20 print edition of Transport Topics.

An analysis of crash data by the American Transportation Research Institute found that trucks equipped with roll stability control systems had fewer rollovers and less crash-related costs than trucks with more expensive electronic stability control systems.

The findings challenge results of tests conducted by the National Highway Traffic Safety Administration, which has proposed a rule to require installation of electronic stability control systems on all new heavy-duty trucks.

“This study definitely finds that . . . RSC [roll stability control] technology is more effective than ESC technology at preventing rollover, jackknife and crashes involving a towed or stuck vehicle, thus providing greater benefit to society and carriers with markedly lower installation costs,” said Daniel Murray, vice president of research for ATRI.

In May, NHTSA proposed a requirement that all trucks with gross vehicle weights of more than 26,000 pounds be equipped with ESC systems, which the agency said could prevent more fatalities and injuries.

However, ATRI said trucks equipped with RSC had lower average crash rates than trucks with ESC — 4.22 per 100 million miles traveled versus 5.60 per 100 million miles.

For trucks equipped with no stability control system, the crash rate was 10.62 per 100 million miles.

ATRI examined three years of data supplied by 14 truckload, less-than-truckload and specialized carriers with 135,712 trucks.

The average cost of RSC technology was $467.18 per unit, compared with $1,180.88 per ESC systems, the study found.

Besides the cheaper price tag, ATRI said the average cost of rollover crashes in trucks with RSC was lower — $3.77 per 1,000 miles — compared with $4.81 per 1,000 miles for ESC-equipped tractors.

Both systems use sensors to detect vehicle instability and automatically apply brakes to prevent a rollover. ESC systems use additional sensors and can apply braking power to steer, drive and trailer axles to prevent jackknife incidents, or loss of control, in addition to rollovers.

NHTSA officials did not respond to a request from Transport Topics to comment on the ATRI study, but a spokesman said the agency “will evaluate all the submitted comments to see if additional testing is necessary to develop the final rule.”

Public comments on the proposal are due Aug. 21.

Ted Scott, director of engineering for American Trucking Associations, said the trade group supports “a rule that would put a minimum standard in place . . . and allow carriers and original equipment manufacturers to go beyond that minimum.”

“The ATRI analysis indicates that RSC is in some cases more effective than ESC,” Scott said.

RSC technology has been available since 2002 and is estimated to be installed on 16% of all new trucks in 2012. ESC systems were introduced in 2005 and are projected to be installed on 26.2% of new trucks this year, ATRI said, based on estimates by the U.S. Department of Transportation.

Manufacturers of stability control systems reiterated their support for the ESC mandate.

“ESC is a higher-performing product,” said Jon Morrison, president of Meritor Wabco, Troy, Mich., a supplier of both RSC and ESC systems.

In any case, Morrison said, the ATRI study provides further evidence that fleets using stability control systems are experiencing a 50% to 60% reduction in rollover crashes.

Fred Andersky, director of government and industry affairs for Bendix Commercial Vehicle Systems, Elyria, Ohio, expressed support for ESC at a public hearing last month at DOT headquarters in Washington, D.C.

“As a business, our preference is to let the market decide technology choices,” Andersky said. “It is our position, however, that if a stability control regulation is forthcoming, ESC is the best technology choice.”

In a report by the Office of Regulatory Analysis and Evaluation released in May, NHTSA officials said implementation of ESC technology on trucks and buses would prevent between 1,807 and 2,329 crashes annually, saving between 49 and 60 lives and preventing between 649 and 858 injuries.

The total cost of equipping 150,000 trucks and 2,200 large buses each year was put at $113.6 million. The net benefit, based on a $6.4 million value for each fatality prevented, was estimated to range from $155 million to $310 million.

The agency said retrofitting existing tractors or trailers with ESC or RSC systems was “not practical” and would cost more than the value of lives saved.

Rollover incidents are rare, accounting for only 2.8% of all large truck crashes, but they are the cause of more than half of all truck driver fatalities.