NHTSA: ABS Braking Increases "Fatal Run-off-Road Crashes" by 34%

Robert Farago
by Robert Farago

A National Highway Transportation Safety Administration (NHTSA) study on Antilock Braking Systems (ABS) reveals that they’re not all that. In fact, the technology increases fatalities in certain circumstances. (Not that Frank Williams didn’t warn you back in 2006.) “ABS has close to a zero net effect on fatal crash involvements. Fatal run-off-road crashes of passenger cars increased by a statistically significant 9 percent (90% confidence bounds: 3% to 15% increase), offset by a significant 13-percent reduction in fatal collisions with pedestrians (confidence bounds: 5% to 20%) and a significant 12-percent reduction in collisions with other vehicles on wet roads (confidence bounds: 3% to 20%).,” “The Long-Term Effect of ABS in Passenger Cars and LTVs” reports [ download pdf here]. “ABS is quite effective in nonfatal crashes, reducing the overall crash- involvement rate by 6 percent in passenger cars (confidence bounds: 4% to 8%) and by 8 percent in LTVs (confidence bounds: 3% to 11%).” That doesn’t sound . . . confidence inspiring. In fact, that nine percent increase looks even worse close up. A LOT worse.

From page 8:

But previous statistical evaluations of ABS have had ambiguous results. Analyses of data from the early 1990s showed significant increases in fatal run-off-road crashes with ABS, on the order of 28 percent. The increase was baffling, given the success of ABS on the test track. However, at that time, many drivers did not yet know how to use ABS correctly. During the mid-1990s, the safety community worked hard to inform the public about the correct use of ABS (“Don’t let up on the brakes”; “Stomp, stay, and steer”). A second generation of analyses circa 2000 showed much smaller increases in run-off-road crashes that were no longer statistically significant. But they were based on just two or three years of data and left uncertainty about the overall effect of ABS.

A nine percent fatalty increase sounds bad. A twenty-eight percent increase is an epic fail. But we’re not finished here:

On wet, snowy, or icy roads, where ABS is most likely to activate, the increase in fatal run-off-road crashes is a statistically significant 34 percent in passenger cars (confidence bounds: 20% to 50% increase). On these roads, all three types of fatal run-off-road crashes increase significantly for cars and so do fatal rollovers of LTVs.


We are still unable to provide a convincing explanation or empirical evidence (other than the crash statistics themselves) for the increase in run-off-road crashes.

The aforementioned Mr. Williams reckons “I still think people don’t understand ABS, and when it starts pulsing and grinding they think something’s wrong and overreact. Maybe instead of spending so much money hyping hybrids, the auto companies need to do some commercials on how the safety systems in their cars work.”

So, is this a whitewash? The report’s emphasis on ABS’ net impact rather and statistical downplaying of ABS’ negative impact certainly should give NHSTA supporters pause. In fact, shouldn’t the NHTSA call for a moratorium on the technology?

But no, the report is suffused with reassurance that the next big thing in safety—federally mandated ESC (Electronic Stability Control)— will sort out the ABS “anomaly.”

Although the preceding analyses show a significant 9-percent increase for ABS on run-off-road crashes of passenger cars, the increase is small relative to the likely benefits of ESC. NHTSA’s 2007 evaluation of ESC, based on statistical analyses through calendar year 2004, found a 36- percent reduction in fatal run-off-road crashes. Thus, the combined effect of ESC and ABS is an estimated 30-percent reduction of fatal crashes.

So that’s alright then? Tell that to the families of drivers and passengers of vehicles where ABS was the difference between life and death, and not in a good way. Either that or just wait for the lawsuit.

Robert Farago
Robert Farago

More by Robert Farago

Join the conversation
2 of 71 comments
  • Rt Rt on Oct 23, 2009
    jmo : Ever figure the reason you didn’t stop is because there wasn’t enough traction to stop you? If the brakes had locked you would have still slid down the driveway just with locked wheels. jmo, you need to re-read my post more carefully. The car WAS able to stop when I defeated the ABS and locked up the wheels. It stopped almost immediatly. It also slowed down perfectly well in gear, when not using the brakes. (incidentally, I was running 4 brand new Blizzaks, not all season bananna peels ) It's pretty well known that ABS does not do well on deep soft surfaces, such as unplowed snow. In these conditions the ABS detects slippage and releases the brakes, when what is really needed is locking up, and allowing the wheels to dig in deeper. BTW, The video you attached was of an icy hard surface, not a soft deep surface. This is a completely different scenario. rpn453, ... exactly.
  • Roundel Roundel on Oct 23, 2009

    If I am braking hard on the highway at the beginning of a jam, I always use the European custom of switching on the Hazards, I have noticed that trucks do this as well. But I think its helpful, especially if I am in the left lane.

  • Lou_BC Collective bargaining provides workers with the ability to counter a rather one-sided relationship. Let them exercise their democratic right to vote. I found it interesting that Conservative leaders were against unionization. The fear there stems from unions preferring left leaning political parties. Wouldn't a "populist" party favour unionization?
  • Jrhurren I enjoyed this
  • Jeff Corey, Thanks again for this series on the Eldorado.
  • AZFelix If I ever buy a GM product, this will be the one.
  • IBx1 Everyone in the working class (if you’re not in the obscenely wealthy capital class and you perform work for money you’re working class) should unionize.