Traffic aware cruise control behavior

[enemji]

It is almost as if the TACC was programmed to emulate the common but poor driver behavior of racing up to a slower vehicle and then slamming on the brakes when getting close enough to be in imminent danger of crashing into the slower vehicle.

But then maybe it is like the roll-through-stop-signs behavior that FSDB apparently had for a while -- could it be that the developers with poor driving skills programmed it to emulate their own poor driving habits rather than emulating safer and smoother driving skills?

The question I have is what is the range of the camera vision? That will be the limiting factor.

For example, using my eyes, on a straight highway I can see an overturned truck laying across the road almost a mile away and instantly start preparing to slow down. Does the Tesla have that range of vision? Or does it wait till it is 150 feet away and than slam on the brakes?

 

[Dewg]

The question I have is what is the range of the camera vision? That will be the limiting factor.

For example, using my eyes, on a straight highway I can see an overturned truck laying across the road almost a mile away and instantly start preparing to slow down. Does the Tesla have that range of vision? Or does it wait till it is 150 feet away and than slam on the brakes?

Telsa has this noted on their website:

Front Cameras = 250m (820ft or 0.16 miles) max distance
Door Pilar Cameras = 80m (262ft or 0.05 miles)
Blindspot Cameras = 100m (328ft or 0.06 miles)
Rear Camera = 50m (162ft or 0.03 miles)

 

[sleepydoc]

The question I have is what is the range of the camera vision? That will be the limiting factor.

For example, using my eyes, on a straight highway I can see an overturned truck laying across the road almost a mile away and instantly start preparing to slow down. Does the Tesla have that range of vision? Or does it wait till it is 150 feet away and than slam on the brakes?

the corollary to this is does it look past then car in front of you? If you're paying attention, you watch the traffic 2-3 cars ahead, not just the first car. If you see everyone braking then you (should) start braking whether the guy in front of you is or not.

In general, my experience with FSD and TACC is it tends to follow too close and brake too late. I'll routinely disengage because I'm approaching a red light and the car wants to accelerate up to it and brake rather than coast at a lower speed and brake less (or ideally, hit the light when it turns green.) Even in cases where I know I'll have to stop, I find that TACC tends to brake late and hard.

 

[Pacernow]

All,
Does TACC have the resume feature that you find on ICE cars? Example: with my ICE cars I would engage the cruise control and tap the brake to slow down and then to increase my speed I would push the resume feature. In MY LR AWD it does not appear to have the resume feature. Therefore I have to press down on the stalk to have TACC back on. Thank you for your replies.

 

[sleepydoc]

All,
Does TACC have the resume feature that you find on ICE cars? Example: with my ICE cars I would engage the cruise control and tap the brake to slow down and then to increase my speed I would push the resume feature. In MY LR AWD it does not appear to have the resume feature. Therefore I have to press down on the stalk to have TACC back on. Thank you for your replies.

No. You can set it so it automatically follows the speed limit, though, which ends up being the same (or better.)

 

[enemji]

Telsa has this noted on their website:

Front Cameras = 250m (820ft or 0.16 miles) max distance
Door Pilar Cameras = 80m (262ft or 0.05 miles)
Blindspot Cameras = 100m (328ft or 0.06 miles)
Rear Camera = 50m (162ft or 0.03 miles)

Which very clearly means that get ready to stop real fast if you are driving down an empty I-40 at 70 mph and you come across a stopped vehicle

 

[sleepydoc]

Which very clearly means that get ready to stop real fast if you are driving down an empty I-40 at 70 mph and you come across a stopped vehicle

True, but that would be the case regardless, even for a human driver. The 60-0 stopping distance for the model 3 is listed as 133 feet which would be about 150 feet from 70 MPH. 70 MPH is just over 100 feet per second so the car would need to start braking within 1 second of the object entering its 'view.' I'm sure this is also why AP is limited to 80 MPH. Any faster and it probably couldn't react in time.

 

[enemji]

True, but that would be the case regardless, even for a human driver. The 60-0 stopping distance for the model 3 is listed as 133 feet which would be about 150 feet from 70 MPH. 70 MPH is just over 100 feet per second so the car would need to start braking within 1 second of the object entering its 'view.' I'm sure this is also why AP is limited to 80 MPH. Any faster and it probably couldn't react in time.

Can you imagine the fear in the eyes of the passengers as the car keeps hurtling towards that stopped vehicle on an empty road till it is 150 ft away?

 

[Yelobird]

Can you imagine the fear in the eyes of the passengers as the car keeps hurtling towards that stopped vehicle on an empty road till it is 150 ft away?

That’s the braking distance Not when it starts braking. I’ve been in rush hour traffic that goes from 70 to 7mph and it drives just like most people would drive without issue.

 

[sleepydoc]

Can you imagine the fear in the eyes of the passengers as the car keeps hurtling towards that stopped vehicle on an empty road till it is 150 ft away?

That reminds me of a joke my dad told me once:
"When I die I'd like to go peacefully in my sleep, like my father. Not screaming in terror like all the passengers in his car!"

 

[sleepydoc]

That’s the braking distance Not when it starts braking. I’ve been in rush hour traffic that goes from 70 to 7mph and it drives just like most people would drive without issue.

The problem is, in the situation @enemji described - traveling 70 -80 MPH approaching a stopped object in the roadway, the car will be at the limits of its capabilities for detecting and stopping. Even if a human can see the object further than 250' away, if the car doesn't detect or react to it, the car will keep driving until it enters the car's field of 'vision' and at that point need to slam on the brakes to stop in time.

Fortunately, such cases are quite rare. Even in the situation you describe, most people aren't waiting until the they're 20' shy of the car's braking limits to start applying them; they start braking as soon as the car in front of them does.

 

[enemji]

That’s the braking distance Not when it starts braking. I’ve been in rush hour traffic that goes from 70 to 7mph and it drives just like most people would drive without issue.

You are missing the situation. Let me describe this again.

It is 10pm on a moonless night. You are the lone driver driving on a 2 lane road which has no street lights.

Your Tesla is on autopilot going the speed limit of 60mph.

Up ahead on the road, just 2 minutes ago, a truck has stopped with no emergency markers.

In this situation, the earliest the tesla will start braking is when the headlights shine on the stationary truck.

Assuming that the headlight shines upto 160 feet on low beam (average), it will start braking at that distance, leaving only about 33 feet of clearance between the car and that stationary vehicle when it does finally stop.

The assumption is that the tesla will start braking when it detects the stationary truck 160 ft away. But that is a false assumption as it will take precious time and distance before it realizes that the truck is stationary. So in all fairness, the tesla will end up with a crumpled front end at best and dead or injured passengers at worst.

 

[enemji]

The problem is, in the situation @enemji described - traveling 70 -80 MPH approaching a stopped object in the roadway, the car will be at the limits of its capabilities for detecting and stopping. Even if a human can see the object further than 250' away, if the car doesn't detect or react to it, the car will keep driving until it enters the car's field of 'vision' and at that point need to slam on the brakes to stop in time.

I bring up this rare situation simply because that is the very situation where I got into my one accident in my driving of 30 years, and that happened almost 26 years ago. By the time my car stopped, the cars front end was crumpled. Fortunately though that crumple zone saved me as my car had no airbags. I literally opened my car doors and walked away.

 

[enemji]

Actually, from your description, it sounds like you’re using it in heavier traffic which makes me wonder if that’s why it does better for you. When I think about it, I haven’t had much/any phantom braking in stop and go traffic or moderate traffic where there’s a car in front of me. It’s usually on emptier roads.

The AP needs reference points. The more the better, I guess. The tragic part of AP will be driving on a lonesome highway such as the I-40 in the middle of a moonless night.

 

[3sr+buyer]

Assuming that the headlight shines upto 160 feet on low beam (average), it will start braking at that distance, leaving only about 33 feet of clearance between the car and that stationary vehicle when it does finally stop.

According to the IIHS, a Tesla Model 3's low beam headlights provide at least 5 lux illumination about 300 feet ahead on the right side of a straight road, and about 210 feet ahead on the left side of a straight road. If the high beams are on, they would give 5 lux out to about 500 feet ahead on a straight road.

2022 Tesla Model 3 4-door sedan

2022 Tesla Model 3 4-door sedan - midsize luxury car

www.iihs.org

 

[enemji]

You are certainly correct for AP/FSD, but not for TACC. Cruise Control has 1 job - maintain a set speed. Traffic Aware Cruise Control has 2 jobs - maintain a set speed unless there is traffic going slower than your set speed. Slowing for a curve it not one of its jobs.

If you need to change speeds for curves, you should disengage cruise control or not be using it in the first place.

Wrong. Cruise control has only 2 jobs - Brake and accelerate. When it includes steering, it is no longer a “cruise control”.

 

[Marty3SR+]

I haven't ever had these problems with my 2021 Model 3, no fsd. And I also won't ever have a problem of being afraid it won't stop for a stalled car far ahead. Why? Because as soon as I see it, I will take over as any responsible driver should. But if I fall asleep or something, I'm not going to complain if it stops too fast.

Also, for those who like to have more following distance for changing lanes... if you're doing that a lot, perhaps cruise control is not something you should be using. When I first used it, I loved the fact that I could relax in stop and go traffic, not worry about trying to save a few minutes off the commute, and just chill. It stops and starts smoothly - as smoothly as any human driver, and doesn't delay either. But if I'm in a hurry, I won't use it.

 

[sleepydoc]

Wrong. Cruise control has only 2 jobs - Brake and accelerate. When it includes steering, it is no longer a “cruise control”.

Well, to be a bit pedantic, plain, dumb cruise only maintains speed; the driver has to brake. Adaptive cruise maintains speed, braking if necessary for the car in front of you. 'TACC' supposedly goes further and takes other things into account. No one has been able to clearly describe what they are other than to say they are (at least part of) the reason for phantom braking.

I bring up this rare situation simply because that is the very situation where I got into my one accident in my driving of 30 years, and that happened almost 26 years ago. By the time my car stopped, the cars front end was crumpled. Fortunately though that crumple zone saved me as my car had no airbags. I literally opened my car doors and walked away.

This is part of the reason some states have lower speed limits at night but I think you were also limited by poorer headlights from 25 years ago.

Here's a link to the IIHS' headlight tests for the model Y. In general I've found them to be quite good but I also nthink headlights in general have improved. I can say for a fact that they're far better than the headlights on our 10 year old odyssey.

 

[3sr+buyer]

This is part of the reason some states have lower speed limits at night but I think you were also limited by poorer headlights from 25 years ago.

Yes, incandescent / halogen headlights might have been barely adequate for high speed night driving on unlit roads if they had decent beam patterns, but many had poor beam patterns and were inadequate for high speed night driving on unlit roads.

HID and LED headlights produce much more light, although some have poor beam patterns that are glare annoyances to other drivers and/or still do not put enough light to help the driver see things at a distance.

 

[enemji]

Well, to be a bit pedantic, plain, dumb cruise only maintains speed; the driver has to brake. Adaptive cruise maintains speed, braking if necessary for the car in front of you. 'TACC' supposedly goes further and takes other things into account. No one has been able to clearly describe what they are other than to say they are (at least part of) the reason for phantom braking.


This is part of the reason some states have lower speed limits at night but I think you were also limited by poorer headlights from 25 years ago.

Here's a link to the IIHS' headlight tests for the model Y. In general I've found them to be quite good but I also nthink headlights in general have improved. I can say for a fact that they're far better than the headlights on our 10 year old odyssey.

Absolutely. Agree on all points.