This depends a huge amount on car, driver and situation. It was the right advice for a learner driver in the 90s with no stability control, no experience and no side airbags, because if you’re going to hit something, hitting it front on is the least risky way. I’m not convinced it’s the right advice for a competent driver in a modern vehicle.

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rootusrootus 9 hours ago | parent | next [-]

It is still standard advice today, as far as I know. Tires are better, stability control is better, but all else being equal you are still much more dynamically stable and have a lot more friction with the road when the car is stopping in a straight line than when swerving.

Also, in the case of someone running a stop sign, it is far from a sure bet they are going to hit their brakes at all, so by swerving you increase the odds that you will still hit them, but now it will be while you have exhausted all your adhesion on lateral control. So now instead of a front end collision with all the benefits of airbags and crumple zones, you are at a significant risk of rolling the car or spinning off the road and hitting something immovable with a part of your car lacking crumple zones.

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madaxe_again 8 hours ago | parent [-]

The common mistake is people swerve and brake, which is a terrible combination - you should accelerate through a sudden manoeuvre, as it maintains control through it, much as you should accelerate through corners in general.

	▲	jeffreygoesto 3 hours ago \| parent \| next [-]
		Wunibald Kamm begs to differ. For his circle, it doesn't matter if the additional force that causes the friction to be insufficient is forward or backwards on top of the side force. In critical situations either use your friction for lateral xor longitudinal action, never both at the same time. Brake hard, but then sail through the curve. You want that vector to move along the circle and never leave it. As that is very difficult for an untrained driver, better switch hard between both modes.
	▲	jjmarr 8 hours ago \| parent \| prev [-]
		Thanks! Now I know why the Waymo didn't slow down.

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jacquesm 8 hours ago | parent | prev | next [-]

What about other drivers in that lane? It would have to be 100% sure that any other drivers near it would have enough time to react as well.

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Mawr an hour ago | parent | prev | next [-]

In theory, it depends. In practice, slamming on your brakes is the correct call 99% of the time. To a large extent that is because of the "competent driver" part. I'd expect 80%+ of drivers to consider themselves just that, whereas the truth is of course the opposite.

So, the correct advice is to say "brake, don't swerve", so that drivers internalize that their first thought and reaction in any emergency should be to brake. Teach them to actually brake—fully press on the pedal—while you're at it.

A slightly more nuanced advice would be "brake first, swerve as needed as a follow-up".

But I would never in good conscience be able to give anyone advice to swerve instead of braking.

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madaxe_again 8 hours ago | parent | prev [-]

Absolutely. I was recently driving on a motorway in Portugal when a boulder (giant chunk of granite, 10+ tonnes) fell off the back of a truck - right in front of us, in a heavily laden (7 pax and luggage) car. Immediate massive cloud of dust, I checked my blind spot, veered across two lanes, and continued our journey, unscathed. I looked in the rear view, to see the car behind us jump on the brakes instead of evading. They caught the boulder.

Nobody killed, according to the news, but several taken to hospital in critical condition.

Oh, I say unscathed but our tyre exploded the next day, as apparently we caught a fragment, and again, that’s not a “slam on the brakes” moment, but rather “trundle to a stop on the shoulder and walk to the conveniently nearby tyre shop”.