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TACC now locks to stopped cars?

Matias

Active Member
Apr 2, 2014
3,338
3,674
Finland
^At least in Finland traffic rules dictate, that you should use turn signal in that left turn. Of course all don't use it and that would cause problems with TACC, if it would react to stopped cars in scenario that you described.
 
Last edited:

Cyberax

Member
Jul 28, 2015
395
220
Seattle, WA
What happens in that video is very different than just recognizing a stationary car in front of you. In the video the Tesla is following the blue car and assumes the driver will turn the steering wheel and follow the blue car. To create the same situation again, it is not enough for just the white car to be there.

You don't need anything fancy for this situation. It often fails to lock onto a stationary car in front of you (standing at a red light, for example). I've tried it many times and it often starts braking only when the car in front is dangerously close.
 

green1

Active Member
Mar 25, 2014
4,548
1,123
Calgary, Alberta, Canada
@Troy
I'm sorry, I'm still not seeing the problem, if you are continuing straight in that situation, the car in front of you turns off and crosses the line, your car should lock on to the stopped traffic ahead and stop you safely.
If you ARE turning left across the dotted line you should first of all be decelerating, you should be signalling, and you will be turning the wheel to cause the car to turn. All of which will tell the car you intend to follow the exiting vehicle.
If you are not decelerating, not signalling, using TACC, and exiting, you are doing so many things wrong and unsafe that you are really a very dangerous driver, TACC is not at fault for any consequences. And in fact, even if it thinks you are going straight and slows, it will be doing so at a safe rate rather than a last minute emergency brake like we see when it makes the opposite mistake. It will actually be making you a safer driver while you're trying to do something dangerous.

I just can't come up with a situation where this would be a problem.
 

Troy

Active Member
Aug 24, 2015
1,957
5,869
You want TACC to ignore the car you are locked to and apply brakes because there is a parked car in front of you before the turn. Your idea is, TACC should know you are not taking the turn and therefore it should apply brakes. The problem with this argument is, the distance it would take to stop is always far greater than how close you can be to parked cars in front of you before you start turning. In this video at 1:54 Consumer Reports says "it takes 118 feet at 60 mph to stop on dry pavement". That's 36 meters = 7 car lengths. If your rule was implemented, the rule would be like this: "Apply brakes if there is a parked car within 7 car lengths while taking a turn at 60 mph".

On highways sometimes one lane stops and others continue. That's one problem area. There are also parked cars on the side of the road like in the photo I added. That's second problem area. Basically, in your version, any time the front of your car points to a parked car within 118 feet, emergency brakes should apply at full force completely unexpectedly. I don't think that would be safe.
 
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garygid

Member
Aug 11, 2014
620
114
Laguna Hills, Orange County, CA
I believe that TACC is not following a car, but following a perceived lane.

Then, in your lane, possibly slowing behind an object in the lane,
carefully ignoring out-of-lane objects, like traffic in other lanes,
or parked vehicles that are out of "your lane".

The problen seems to be when there is a stopped object (vehicle)
ahead, and the TACC does not recognize it and lock on at the
normal "far" distance that it would lock onto a moving vehicle.

Then, the TACC keeps going or even accelerating, thinking that
your lane is empty. Finally, recognizing the stopped car, almost
too late, it attempts to stop, but I have not had the courage (or
insanity) to not apply the brakes myself, which deactivates the
TACC.

In fact, the recognition of the stopped traffic is (or was) not done
sufficiently safely, and one needs to be aware of this simple possibility.
 

LetsGoFast

Active Member
Oct 13, 2014
1,329
101
Virginia
I used to think that TACC never locked onto stopped cars, but I was convinced by someone that it did so just not terribly well. If your set speed is low enough, you can cruise up on a stopped car and stop relatively comfortably. At higher speeds, you will end up in an emergency braking situation doing that. TACC has improved with each tweak, but I still think it tends to stop far too abruptly.
 

green1

Active Member
Mar 25, 2014
4,548
1,123
Calgary, Alberta, Canada
You want TACC to ignore the car you are locked to and apply brakes because there is a parked car in front of you before the turn. Your idea is, TACC should know you are not taking the turn and therefore it should apply brakes. The problem with this argument is, the distance it would take to stop is always far greater than how close you can be to parked cars in front of you before you start turning. In this video at 1:54 Consumer Reports says "it takes 118 feet at 60 mph to stop on dry pavement". That's 36 meters = 7 car lengths. If your rule was implemented, the rule would be like this: "Apply brakes if there is a parked car within 7 car lengths while taking a turn at 60 mph".

On highways sometimes one lane stops and others continue. That's one problem area. There are also parked cars on the side of the road like in the photo I added. That's second problem area. Basically, in your version, any time the front of your car points to a parked car within 118 feet, emergency brakes should apply at full force completely unexpectedly. I don't think that would be safe.
I'm sorry, it appears I haven't managed to communicate what I meant very well. Because in my scenario it would never need emergency braking unless you try to crash. Your scenario also counts on making extremely dangerous manoeuvres without signalling, at high speed, and against the explicit instructions that come with TACC. I feel that if you do that, the best course of action for TACC is to slow you safely.
 

RAW84

Member
Oct 6, 2014
614
314
Boston
You don't need anything fancy for this situation. It often fails to lock onto a stationary car in front of you (standing at a red light, for example). I've tried it many times and it often starts braking only when the car in front is dangerously close.

This is the opposite of my experience. I often engage TACC at stoplights because I'm too lazy to hold down the brake. It works almost every time.
 

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