Dave, I hope you read this report. I just breezed through it and stopped at Figure 16 because it had red and yellow bars. Interestingly, in a split mu surface braking test, two cars had their shortest braking distance with the ABS disabled. Hmmm...
Then I fast forwarded to Table 5, a lane change manuever near the limit of lateral adhesion. Looks like ABS didn't keep any car from spinning out at least once.
This report is only of Task 4 (braking performance) out of 9. Task 8 is "...attempt to infer why the crash data studies did not find the anticipated increase in safety for ABS-equipped vehicles." Ooops, I guess the real world still isn't safer. This is a January 1999 report, so hopefully the other sections have been published and we can read the entire document.
I believe I am entirely consistent with my discussion:
- Nice summary by Tony: ABS won't fix stupid.
- ABS is not a cure for all braking conditions (see the newly linked report)
- I am personally biased because rear brake swaps on Gen 1 cars reduced distance by at least 20% and data contributed by an ABS Viper owner shows little difference (Gen 1 vs. ABS car.) Mechanics and hydraulics are important.
- I have asked what does a 10%-15% shorter stopping distance translate to for crash severity? We keep assuming 100% pass through efficiency of the nut behind the wheel.
- It still depends on driver reaction and some accidents may be avoided. Some accidents will be less severe and cause less injury. Some accidents will be less severe and still cause major injury. However, a blanket statement of "increasing your chances 20%" because the test data stopping distance improvement was 20% is unsupported by any facts.
- Apparently some accident types increased.
Obviously ABS works. I have only argued that the benefit to society (public road safety) is less significant than the measured (idealized) performance benefit. It is not flipping a switch that avoids most accidents, it is a directional improvement along with hundreds of other things.
Like a lock on your door, a safety on your gun, or warnings on beer labels, we still have thieves, shootings and drunks. I think my twisted logic earlier is looking better and better - ABS only benefits drivers perceptive enough to know their car, capability and surroundings. I guess that includes you, Dave!