NHTSA Proposes Rubber Stamp Brake Throttle Override Rule

For the second time in 40 years, the National Highway Traffic Safety Administration is attempting to upgrade the accelerator control standard by proposing that manufacturers be required to equip all vehicles with a brake override.  A brake override system cuts throttle voltage in electronic throttle control (ETC) vehicles when the brakes and throttle are in conflict. Variations of this type of fail-safe have been incorporated in a number of ETC equipped vehicles since the 1990s.

“We considered establishing a design requirement as the sole requirement for BTO, but the differences among BTO systems currently available from different vehicle manufacturers are significant enough that a design requirement by itself cannot effectively accommodate them all without being overly complex and/or design restrictive. By combining a relatively simple performance test with the basic equipment requirement described above, we can achieve a robust standard which is largely performance-based and minimally costly or burdensome.”

The Notice of Proposed Rulemaking is in direct reaction to the Toyota Unintended Acceleration (UA) crisis, noting the August 2009 deaths of California Highway Patrol Officer Mark Saylor, his wife, daughter and brother-in-law in Lexus ES350 loaner that experienced a UA event at highway speed. But, the proposal appears to be more of a political response than a technological one. It ignores past recalls for UA events that are electronically caused; and it fails to base this upgrade on any statistical analysis. It merely codifies manufacturers’ current equipment without teasing out the differences between more effective and less effective brake override systems, such as the Toyota system, which doesn’t activate in some of the most frequently reported UA scenarios – when the driver’s foot is on the brake – or on no pedal. According to Toyota’s “Smart Stop Technology,” “the feature doesn’t engage if the brake pedal is depressed before the accelerator pedal. The driver must press the accelerator first and then depress the brake.”

Antony Anderson, a U.K.-based electrical engineering consultant who has studied unintended acceleration, says that the rule fundamentally misses the essential ingredient in any failsafe system – independence from the malfunctioning component. This is why many machines, from motorcycles to escalators, have separate kill switches that can independently remove power from the throttle, he says.

“For some reason, the automobile industry seems to think they don’t need to bother,” Anderson says. [The agency] “has a well-developed NHTSA-speak, where they are all the time trying to minimize the possibility of an electronic malfunction.”

“This just captures the state of the industry, not the state of the art,” says Neil Hanneman, an automotive engineer who have overseen automotive electronic designs and has consulted with Congress on Toyota unintended acceleration. “For it to really be a robust standard it would have to address things that have not been addressed yet – which will be with the electronics.”