[ProblemFactory]

> The biggest thing is that people drive when they shouldn't.

It is extremely common to drive beyond your actual "in complete control" speed.

You are supposed to drive slowly enough in snow so that you can correct for unexpected patches of black ice or rocks in the snow slush. You are supposed to leave a long enough gap to be able to react and stop if the car in front of you unexpectedly fully slams on their brakes. You are supposed to drive slowly enough to stop if a kid runs out between parked cars.

Humans almost never do, because unexpected things almost never happen. Traffic flows faster and perhaps smoother, because we willingly accept driving at speeds where we can avoid most, but not all hazards.

But if we expect self-driving cars to always put safety first, then we will find them to be "tediously" slow, even if they have better sensors and faster reaction speed than us.

[curiousGambler]

I don't think we'll care quite so much that a 20 minute drive is now 25 minutes when we have wifi and sitting in the car is basically like sitting in our living room. Driving slow is only tedious when you're doing it, not when you're able to get work done or be entertained throughout.

[jessaustin]

Yeah the norms will be completely different. If an adult kept asking a bus driver or airline stewardess "are we going to be there soon?" while fidgeting and straining to look out the front windows, most people would consider that adult to be poorly adjusted to modern living. It will be the same for robocars.

[majani]

I don't mind stringent enforcement of life saving measures on a place as dangerous as the road, even if it means everybody moving at 10kph in bad conditions. Roads are the biggest killer of youth globally[1], minor emotional factors such as 'tediousness' should not be allowed to get in the way of solving such a big problem

[1] http://www.theguardian.com/global-development/2012/may/02/tr...

[msellout]

I drive at a "correct" following distance. Way back when I took my driving test I was told to allow 1 car length for every 10 MPH speed. So on the highway I leave at least 6 car lengths.

I constantly need to tap the brake and back away as a car cuts into the lane. Almost no one on the highway leaves adequate space for human reaction times.

[sib]

I would say that 1 car length / 10 mph is actually a very short following distance. If an average car is 15 feet in length, at 60 mph, that is only 90 feet. At 60 mph, 90 feet of following distance is only 1.02 seconds. (1 mph == 1.4667 fps)

When I was taught to drive, we were told that 2 seconds of following distance was appropriate.

This just reinforces your point that the typical human driver leaves insufficient following distance.

[david-given]

Some of the roads in the UK have chevrons painted on them at intervals. The idea is that at a normal speed for that road, if you can see two chevrons between you and the car in front, you're leaving the right distance.

It's a good idea; the distance is always bigger than you think.

[ptaipale]

Not bad, but you need an element from the square of velocity (for kinetic energy/braking distance) there to be safe. 1 second is fairly okay at low speeds, but at 60 mph (~100 km/h, 27 m/s) two seconds is shortish and if you are doing 200 km/h (as on a German Autobahn) then 2 seconds (100 m) is not safe in my opinion.

(Although the penalty line in Germany is just this, half the speed in km/h to get meters, i.e. driving closer than 100 meters if going 200 km/h gives you a ticket for tailgating)

[sib]

Completely agree with you. Should have stated that i was taught in the US, where it would be ... slightly atypical to be going 200km/h ;) At the time that I took drivers education classes, the US national speed limit was still 55mph, about 88km/h. At that speed, 2 seconds is probably a good rule of thumb for something that's pretty easier for a driver to observe.

[ptaipale]

True of course. At low speeds, the braking distance is negligible, and the margin is needed for driver reaction. When exceeding 60-80 km/h, the amount of kinetic energy and correspondingly the braking distance will start to dominate what is necessary for safety margin.

[msellout]

When I'm not in heavy traffic I give even more space. But unfortunately at a certain density of traffic the aggression caused by a safe distance actually makes it unsafe as people cut you off and try to "retaliate" for the imagined insult.