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Dangerous situation with new TACC in snowy conditions

Discussion in 'Model S: User Interface' started by Andyw2100, Jan 26, 2015.

  1. Andyw2100

    Andyw2100 Well-Known Member

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    #1 Andyw2100, Jan 26, 2015
    Last edited: Jan 27, 2015
    I just experienced a pretty dangerous situation with the new TACC in snowy conditions. I wrote the e-mail message below to the [email protected] address, in hopes that they will pass the information along to engineering. I thought I'd share the experience here too, so others may be aware of it, and be appropriately careful.

    --
    I had a very dangerous experience tonight driving in some snow with the new TACC. Everything was working fine, even though visibility was not the best. The TACC was recognizing cars and correctly identifying when they pulled away or changed lanes, until the incident I am about to describe took place. I believe I had the maximum speed set to 50 or 55 MPH. The TACC was engaged, but did not have a target car, as the indicator was gray. I was approaching a car in my lane, and was expecting the indicator to turn blue, and for my car to slow down, and to maintain my maximum distance setting of seven. Instead the TACC never seemed to pick up the car moving more slowly in my lane, so of course I braked well before I would have rear-ended the other car.

    I wanted to bring this to your attention, and also see if you wanted to pull the logs from my car, in case it will help the engineers fine tune the TACC system. I have not engaged TACC again, so the incident is my last use of TACC, and TACC was disengaged when I braked to avoid hitting the car that should have become the target car.

    I am very happy with the TACC system. I just want to help make it better. If this was a situation in which visibility had become an issue, the TACC should have somehow warned me, and said it was not available, or something along those lines. But by continuing to operate, I had every reason to believe that the TACC would slow my car and not allow me to come up directly behind a car in my lane.

    Please let me know what additional information, if any, you need from me.

    Thanks.
     
  2. NigelM

    NigelM Recovering Member

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    I wouldn't trust any sensors (on any car) in snowy conditions. The risk of TACC breaking hard because of snow is probably even greater than the risk of it not detecting other cars at all.
     
  3. yobigd20

    yobigd20 Well-Known Member

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    don't use TACC in bad weather. says so right in the directions. doing so is dangerous and at your own risk. Plus, right above the highlighted note in the following picture it says it has limited deceleration abilities anyway so the car itself isn't going to stop fast if there is an object in front of you. YOU need to be in complete control of the car, always. I wouldn't use it in anything other than clear dry weather conditions, especially it being so new and everyone basically being the world's first beta testers....

    tacc.jpg
     
  4. Todd Burch

    Todd Burch Electron Pilot

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    Agree. Today was my first full day using TACC. It's great as a highway ACC system. It's pretty good in stop and go traffic, although it needs to drive more efficiently with less use of the hydraulic brakes.

    Having said that, this system is definitely not for city driving yet. Too many situations are encountered outside its current intended use when not in a highway environment.

    This is just a first step toward autopilot. We've still got a ways to go.
     
  5. yobigd20

    yobigd20 Well-Known Member

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    TACC Not for use for city driving was also in the directions I think.
     
  6. Andyw2100

    Andyw2100 Well-Known Member

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    I missed that. Now I know.

    There was so much new and exciting in this update, I guess that was easy to miss or forget. But I assure you if I missed it many, MANY other people will too, because I read through the notes and made an effort to understand them all, and I expect there are plenty of people who don't even make the effort. If TACC comes on, and acts like it is working, it should work. There have been plenty of reports here of people getting "Cruise Control Unavailable" notifications. I imagine those are meant for these kinds of situations.

    Also this is a pretty big difference from your traditional cruise control. The fact that now we don't have the ability to just set and maintain a speed in any sort of inclement weather is a bit of a negative. With traditional cruise control there's really no downside to using it, at an appropriately low speed, in bad weather. I see why, if visibility is an issue, we wouldn't want to use TACC in inclement weather, but somehow there should still be a way to set and hold a desired speed.

    - - - Updated - - -

    I responded to the other message first, as apparently I shouldn't have been using TACC at all, and failed to realize that. But it my own defense, I also wasn't using it as if it was 75 degrees and sunny. I was kind of using it more as an experiment, to see what it would do, and was ready to brake if need be pretty much at all times. I would not have allowed the TACC to get me into a situation where it would be braking harder than I would have braked if I had braked earlier. For all I know, it is possible that if I had waited longer, TACC may have recognized the other car and then braked quite hard, but since I was already closer than I wanted to be, and closer than I should have been for the TACC to acquire the other car as a target, I decided to play it safe and just brake.

    This wasn't close to an accident or anything. I just wanted to point out to Tesla the fact that the TACC never acquired the target, and never gave any indication that it wasn't functioning.
     
  7. yobigd20

    yobigd20 Well-Known Member

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    Actually asking questions and bringing this out into its own topic is a good thing because more people need to know what to expect. I figure many people don't actually read the directions or car manuals. The more people understand how to use the system right the better and safer for everyone. Always good to give Tesla Motors feedback about the system too. So thanks!
     
  8. BerTX

    BerTX Member

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    I don't drive in snow or ice. I can't imagine trying to do it with cruise control on -- especially one that could slam on the brakes at any time.

    I assume it was just a test, but testing it in situations it was not designed for seems a bit premature given the current state of the system and software.
     
  9. Andyw2100

    Andyw2100 Well-Known Member

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    Maybe you missed the part of my post where I acknowledged that I had missed the part of the 6.1 notes that said not to use the TACC in the snow. I wasn't willing to rely on this brand new technology in inclement weather completely, so I had it on, but was basically prepared to do whatever I needed to do at all times. I wasn't expecting it to randomly brake hard. If I had remembered reading the warning about not using the TACC in the snow, I wouldn't have been using it at all.
     
  10. EarlyAdopter

    EarlyAdopter Active Member

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    You shouldn't use traditional cruise control in snow, either. If a wheel slips the car will interpret this as it slowing down and it will increase the throttle. Exactly the opposite thing you want to do in those situations.
     
  11. loco

    loco Member

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    I don't have ACC on my Tesla but I know from other cars like BMW and Audi that they occasionally don't lock on a car in front. Especially when going fast (110mph) and closing in on a truck that is going slow (55 mph). Another case is when someone switches to your lane while being just a few meters ahead. It takes some time for the ACC to lock on it.

    It's not a bug. It's normal behavior on all cars with ACC regardless of weather conditions. ACC has to be monitored constantly.
     
  12. ArtInCT

    ArtInCT Always Learning

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    TACC or any other implementation of Adaptive Cruise Control should NOT be used in rain or snow IMHO. I have been using the Volvo XC60 version of TACC for four years, along with the Blind Spot Information System and City Safe System.

    Accumulation of snow, ice, road salt and spray or rain droplets on or in front of any of the sensors can cause the sensors to react inappropriately giving the traffic situation.

    PLEASE OP and others, let us err on the side of caution when using these new driving aids.
     
  13. Matias

    Matias Active Member

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    Unless all four wheels are slipping at exactly the same speed and slipping starts at exatly same time, cruise notices that wheel is slipping and disables itself. This has happened many times for me. Not in Tesla, but in other cars.
     
  14. Andyw2100

    Andyw2100 Well-Known Member

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    I was pretty clear about the conditions in my email, and they were nothing like the ones you describe which result in what you state are not a bug, but rather normal behavior. I was driving 50 or 55 MPH, not anything close to 110 MPH, I came up on another car, not a truck, the other car was not going significantly more slowly than I was, and it did not move into my lane, but rather had been there the entire time my car was approaching, from long before I thought it should have been acquired as a target until well after, at which time I braked, to disengage the cruise control.

    Basically the conditions I describe are the exact, most basic conditions the TACC has to work under, and usually does work under. I'm sure it was the snowy conditions that caused the failure. I now understand that the TACC is not designed to be used in these conditions. I also know that I read through the update release notes and missed that, and that I'm a reasonably smart guy who tries to take things like the instructions in release notes seriously. So if I could make the mistake of engaging TACC in snowy conditions, I absolutely guarantee you there will be thousands of other Model S drivers out there who don't bother to read the release notes at all or who don't understand them or who just don't care who also use the TACC in snowy conditions. This is why I think it made sense for me to write to Tesla about the incident, and why I'm continuing to discuss it now.


    Thanks.

    I acknowledged receipt of the information you just offered me in my second post in this thread. I also wrote that I was driving quite cautiously and really just trying to see how the TACC would behave, rather than relying on it.

    I'm sure your post was well-intended, but in light of what I've already written in this thread, I can't help but take it as somewhat patronizing. You've posted a lot here since you began investigating the P85D you're planning on buying next year, and I know this is not the norm for you. I definitely have respect for your usually clearly written and thoughtful posts. I just had to say that the tone of this one bothered me.
     
  15. BerTX

    BerTX Member

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    Yes, I did, as I didn't refresh the screen before typing my reply, sorry.

    All cruise controls that I have used warn against using them in inclement weather or traffic situations. Obviously the TACC is designed to deal with light highway traffic situations, but again, the system isn't ready for complete dependability. It may be v6.1 of the Tesla software, but it is v1.0 of the TACC.
     
  16. ArtInCT

    ArtInCT Always Learning

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    Did not intend to offend or bother you.... Just stating my 4 years of experience with ACC, BLIS and CITY SAFE.... did not mean to have a tone... gong or other sound...:love:
     
  17. Andyw2100

    Andyw2100 Well-Known Member

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    Right.

    Which is why my post was in no way meant as an indictment or criticism of the system. I wrote to Tesla to try to help them improve TACC 1.0, and posted here to try to help others until Tesla does.
     
  18. ArtInCT

    ArtInCT Always Learning

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    On the this things TM could do is the following....

    if windshield wipers are on or the rain sensor for the windshield wipers "senses wet conditions" then the TACC could disable with an appropriate warning message. A few times my Volvo's BLIS (Blind Spot Information System) has warned me when a sensor has become confused "Cannot Safely Operate"... such as in torrential rain or one other time when snow was packed in around the sensor. It think this is a good thing that the systems can somewhat be aware of environmental situations that hamper their safe utilization. They are tools and in TM's case V1.0 as aptly noted by BerTX.
     
  19. Haggy

    Haggy Member

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    As someone with nine years of experience with ACC, I can tell you that it can work very well with rain. I wouldn't ever use it in snow, nor would I use it with a setting of less than 5 on a Tesla, and if the rain were heavy enough I stall can't say.

    With some other cars, having the wipers on past intermittent will turn off ACC. I had no problems with the fastest intermittent setting and with RainX on other cars, but Tesla recommends against applying it and intermittent wipers don't give a continuous range of speeds, so I'd prefer that they leave it up to the driver's common sense.

    Other differences are that the MS is more aggressive. The car it replaced did 0-60 in 5.9 seconds, and was powerful enough that it could have had ACC as aggressive as the 85. But it didn't. I also have an 2006 Acura RL with ACC and it's less aggressive plus it has a much less powerful engine. ACC is typically designed so that speed changes are more gradual, and if a car is detected ahead, the car with ACC doesn't do everything possible to close the gap ASAP and then slow down to the speed of that vehicle. If you want to get up to speed faster, you leave ACC alone and use the accelerator until you are up to speed and then let ACC do the rest.

    That means that even in clear dry weather, it's more apparent in other cars that something is wrong if ACC isn't slowing you down way ahead of detecting a stopped car ahead. With the MS, if you are seeing gray, you should be ready to use the brakes at a point where you'd be slowing down had you not had TACC rather than waiting for it to kick in. Or at least have your foot hovering over the pedal. That's been my experience in clear weather.

    Everything everybody says about snow holds true, and I can't speak for all roads so it may be dangerous in rain especially at speeds that could cause you to lose control. But you shouldn't be driving at that speed anyway. If you use TACC as a backup, assuming you plan to brake if somebody cuts you off, then I can't see a problem.

    Also for those who wish they could have standard CC in some circumstances, just remember that TACC is CC, and you can set it to any speed you want. It will drive at that speed constantly and the only exception will be that it will slow down if something is in the way, at which point you would have turned off CC. You can turn off TACC at the same point if you want. Likewise, you wouldn't turn on CC until you were up to speed and unimpeded, so if you do the same with TACC, you get CC. Another minor difference is that if you are zooming toward a car with standard CC, don't want to slow down, but want to make a sudden lane change at the last moment, you'd have to put your foot on the accelerator to do the same with TACC. But it also means that you'd end up illegally close if you are at the point that TACC would have slowed you down.

    I've already had ACC save me from a major accident or possibly worse, and I really missed having it in the MS before 6.1.
     
  20. NoMoGas

    NoMoGas Member

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    People, it says right in the release notes that this should not be used during inclement weather. We can't use things against the way we are instructed and then be surprise when dangerous situations occur.
     

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