And at a moderate sprint, like most adults do when they try to cross a roadway with vehicular traffic, that is 4-5 m/s, giving the vehicle 0.4 - 0.5 seconds to stop. 40 MPH ~ 18 m/s that gives the vehicle 7-9 meters to stop.
No human could brake that well, and simply jamming the brakes would engage the ABS leading to a longer stopping distance. Not to mention the human reaction time of 0.5 - 0.75 seconds would have prevented most people from even lifting the foot off the accelerator pedal before the collision, even if they were perfectly focused on driving.
> simply jamming the brakes would engage the ABS leading to a longer stopping distance
I was taught that the entire point of ABS is so that you can just jam the brake and have the shortest stopping time instead of modulating it yourself to avoid skidding. Do you have any source to the contrary?
ABS is intended to enable steering by increasing static road friction. It is not intended to decrease stopping distance, and in many cases increases stopping distance by keeping the negative G's away from the hard limit in anticipation of lateral G's due to steering.
Older dumb ABS systems would simply "pump the pedal" for the driver, and would increase stopping distance in almost all conditions, especially single-channel systems. Newer systems determine breaking performance via the conventional ABS sensors and additionally accelerometers. These systems will back off N G's, then increase the G's bisecting the known-locked and known-unlocked condition, trying to find the optimum. These systems _will_ stop the car in the minimum distance possible, but very few cars use it.
I was taught the point of ABS was to keep control over steering while stepping on the brakes instead of skidding out of control into god knows what/who
Wikipedia backs me up but adds that it also decreases stopping distance on dry and slippery surfaces, while significantly increasing stopping distances in snow and gravel. I’m from a country with a lot of snow so that makes sense.
That's correct. The ABS basically takes away the brake pressure as soon as the wheels block. On most surfaces this will shorten your stopping distance versus a human blocking the tires. It is never the optimal stopping distance though.
In terms of split second reactions, it's pretty much optimal still to just jam the brakes if you have ABS. It's much better than braking too little, which is what most non-ABS drivers would have done.
When you block the wheels in loose snow or gravel, it piles up in front of the tire and provides a fair amount of friction. This is usually the fastest way to stop, and one of the reasons that gravel pits along corners in motor racing are so effective.
That said, the point of ABS is in the rare event that you have to brake full power, the system automatically help you do it at a near optimal (slightly skidding) without additional input, and you remain full steering ability.
If you don't have ABS you'd need to train that emergency stop ability on a daily basis to even come close.
> Wikipedia backs me up but adds that it also decreases stopping distance on dry and slippery surfaces,
Many cars, such as my POS Ford Focus, use a single-channel ABS system. These systems will oscillate all four brakes even if only one is locked. Combined with the rear-wheel drum brakes, the ABS considerably increased stopping distances on dry road.
No human could brake that well, and simply jamming the brakes would engage the ABS leading to a longer stopping distance. Not to mention the human reaction time of 0.5 - 0.75 seconds would have prevented most people from even lifting the foot off the accelerator pedal before the collision, even if they were perfectly focused on driving.