Dangerous situation with new TACC in snowy conditions

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.

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....

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.

Todd Burch said:

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.

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

Andyw2100 said:

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.

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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!

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.

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.

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.

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.

EarlyAdopter said:

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.

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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.

Andyw2100 said:

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.

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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.

Andyw2100 said:

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.

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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:

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.

ArtInCT said:

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..

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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.

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.