Especially on Texas highways where speed limits exceed 80mph, you'd have to be very alert and likely have to swerve over into the next lane (like the other driver did).

At 80mph, the stopping distance of an average car is around 300 feet once the brake is fully engaged. That exceeds most car radar systems. And with no warning lights the camera won't do much good either.

This seems insane, are you telling me that these cars will travel at a speed whose distance is longer than the radar can detect? That is _guaranteeing_ crashes.

> are you telling me that these cars will travel at a speed whose distance is longer than the radar can detect?

"Low beams or dipped lights should shine about 150 to 200 feet ahead, while high beams or brights should shine about 350 to 400 feet ahead" [1].

Would it be customary for someone on that highway to have their high beams engaged?

[1] https://autoily.com/how-far-should-headlights-shine/

High beams are really for rural roads with very little traffic. If there are at least three lanes of traffic in one direction[1] and enough traffic that a car in front was able to see the collision in their rear view mirror, high beams are not advised.

Using them in this situation will cause major glare from mirrors of the drivers in front, and possibly for the drivers in the opposing direction.

[1] as indicated by the stopped vehicle being reported in the center lane

Which makes the radar range being less than the stopping distance less salacious.

Plus the radar is for gauging relative speed so the car can speed up to the set point if safe or slow down if the car ahead is.

It is not for finding stopped stuff in the middle of the road at high speed. I hear there are too many false positives for that to be done.

I mean yeah if you're on a pitch black highway and you can't see anything outside your headlight beams, you probably shouldn't be going 80 even if that's the speed limit.

No idea where you live but this is probably 99% of highways in the US. Where do you live that the highways are illuminated?

You can't go 80 on most highways.

No street lights doesn't imply pitch black. It may imply poorly illuminated. I can't find a date, only a time, so I can't guess at lunar illumination or cloud cover.

But we don't know how many other vehicles were on the road and what light they were casting. The bystander who reported witnessing the crash was within visual distance, so couldn't have been too far ahead of the MachE. It wasn't reported if there were any other vehicles. If you have enough vehicles on the road (with their lights on) lack of overhead illumination isn't too significant.

Canada

So be it. Going 80+ at night might not be a good idea on most roads.

Some vehicles (like my Subaru) offer automatic emergency steering that can save you when there's not enough distance to brake. The Mach-e doesn't have that per my quick Google (they have some assisted thing but it requires manual steering)

It does not. It has some kind of assist that is supposed to help you swerve fast enough and correct back to normal instead of overcorrecting.

It’s designed to fix driver inputs during a panic. You’re right it doesn’t do anything on its own.

> At 80mph, the stopping distance of an average car is around 300 feet once the brake is fully engaged. That exceeds most car radar systems. And with no warning lights the camera won't do much good either.

I think this is a pretty important point for any well-built self-driving software. Does anyone know if radar advancements could help increase this?

My understanding is no.

The big problem is that a stopped vehicle looks exactly the same to the radar as any other stationary object.

So if it sees something stationary it could be a stopped vehicle or it could be a reflection from a road sign. Or a lip in the pavement. Or something else like that.

Basically from what I’ve heard if it were to try and stop whenever it saw something stopped ahead it would constantly slam on the brakes unnecessarily. So stationary things have to be ignored, and it can’t save you from them.

They all suffer from this. The only solution I’ve heard of is LIDAR but obviously that’s a huge step up.

This probably needs to be added to a safety test suite. Either for the cars or for drivers.

Most adapative cruise control systems explicitly ignore stationary objects while at highway speeds. A vehicle immediately ahead that stops will be detected and responded to. A vehicle that did not move while in sensor range will be ignored.

Also seems like the stopped car could emit a signal that self-driving cars could pick up.

That could be abused really easily if anyone ever figured out how.

It’s have no idea if the risk is worse than the reward or not.

Look into Kia Boys and you will know that this idea would never work in modern USA culture

This is why cars are required to have red retroreflectors on the back, so even if their lights are off you can still see red lights as long as your own headlights are on. I wonder why this failed.

Exactly. It's easy to avoid a stationary object on the road in normal visibility out if your headlights work a damn. Maybe I am just too accustomed to driving on rural third world roads where cows wander at night.

From experience, coming up to traffic jams on highways in the past, you can get deceived by cars ahead either stopped or slowing down - you dont expect that, especially after long monotonous driving, hence need for warning lights.

Indeed. I have never driven more than 4-5 hours at a time. I find driving very taxing for me. I tend to be very focused on the road and drive like everyone and everything is trying to kill me. For this reason I don't use driving aids either not even standard cruise control.

I find they help physically. After a few hours of driving I feel less tired and need to rest arms/legs physically.

The mental toll is nearly unchanged.

So when you stop I feel it’s easier to walk around and shop or whatever since I haven’t been applying as much force constantly.

But you still need that mental brake.

I find adaptive cruise control definitely helps with the mental fatigue as well, because I can concentrate on looking for hazards far ahead instead of having to pay attention to keeping distance to the car ahead. But yeah, I never drive more than a few hours without taking a break anyway.

Especially if they don’t slow down/swerve until the last second. If they had done it earlier you would’ve had more time to start noticing something was going on.

Retroreflectors are good but at a long distance you need a significantly brighter light source/reflection to be visible (intensity falling off with distance squared). At highway speeds that distance for safe stopping is probably in the hundred+ feet range.

It seems like in this case the retroreflectors may have worked. The problem is the car that saw and avoided them blocked the BlueCruise car from seeing them until it was too late.

I came across this a few weeks ago on a snowy highway.

Car way in front of me had its hazards on in the right lane. The center lane was clear, so I decided to make a lane change. I assumed this car was just moving slow in bad conditions, but it was actually completely stopped in the right most lane.

I didn’t realize that until I passed it. Given the conditions, it would have been extremely hard to avoid this car if I had not proactively changed lanes.

There was just absolutely no reason this car should have been stopped in a lane when it could have gotten to th shoulder.

Radar struggles to identify stationary vehicles. Their reflected signals hide in noise from road signs, roadside vegetation, and the road surface itself.

It's worse than that, I think. The typical radar beam is so wide that it can't discriminate between in the road and near the road, so the Doppler selection is the only reason it even works at all. This is very noticeable on our car when you observe how far away laterally a car you've been following has to turn, e.g. when it takes an offramp, before the ACC ignores it.

What brand and model year is that? The first (15 years ago) system from BMW did that too, but the newer ones (2019 model, don't know about the years in between) know which lane the other car is in. There is a setting on European models on whether to overtake on the right or not, so it knows the traffic ahead is in your lane or in the next lane over.

> A car stopped on the highway with no warning lights or anything in center lane, at night

Basically every uber driver does this, double parking wherever they want. So L2 systems need uber detection.

I have literally never seen a highway with parking.

I have literally never seen an uber use a parking spot.