Autopilot braking hard at bridges

Autopilot braking hard at bridges

We are 5200 miles into a 7500mile road trip around the US, and just twice we have encountered sever braking from autopilot. On each occasion it was on a straight piece of interstate, I10 westbound, and I40 eastbound, and in both cases, the sun was ahead of us casting a very dark shadow of the bridge onto the road. The braking was so severe - i.e dropping 25 to 30mph as fast as it possibly could, that I am fairly sure that if the motorcyclist who was following me had not turned off at the previous exit, he would have run right up my trunk on I40. Is this a common problem? For the rest of the trip I will be leaving AP whenever I see a bridge, then turning it back on afterwards.

On a less important note, on both of the Interstates mentioned, there are very long stretches that are dead straight, and although I hold the steering wheel with both hands at 10 to 2, quarter to 3, or 20 to 4, I get the flashing white reminders at regular intervals. It would be good to see an upgrade that extends the interval between warnings for dead straight roads... just a thought!

alanduxbury | May 5, 2018

Severe not sever...

Dan_CH | May 6, 2018

Same here. Driving at approx. 9pm (i.e. no sun) on freeway yesterday evening with TACC, car suddenly brakes under bridge. Not the first time it happened, and not only when using AP.

johnse | May 6, 2018

For the straight sections, holding wheel with one hand, letting the weight of your arm provide a continuous pressure on the wheel keeps autopilot happy while at the same time giving you a feel for what it is doing, keeping you more connected to the road.

Cuttin | May 6, 2018

Never had this happen, and I have specifically worried about this when I see very dark shadows like bridges or barriers. Mine is fine.

mathwhiz | May 6, 2018

When commenting on exhibited Autopilot behavior(s), it's essential to provide the car's firmware version...


Dan_CH | May 6, 2018

@ mathwhiz: correct, forgot to mention that. It's 2018.14.2

Redmiata98 | May 6, 2018

...and the AP version. My X has AP1 and this has never happened BUT my loaner the other day had it happen numerous times in the same day. The loaner was on AP2. The common 5hread was the sunny day and dark shadows. can thank the nanny nag on the dummies who were bragging about the stupid things they were doing while on AP1 when it first came out. Not likely they will change it or lessen the nag times in the near future.

paul | May 6, 2018

@alanduxbury. I used to get this often last year - going under a bridge caused both the hard braking and sometimes a swerve (just to keep my on my toes).

When I got 2018.10 earlier this year, it stopped happening under bridges, although it still happens periodically at other places - like on the motorway or highways with no traffic in front. It's a great way to scare me, my passengers and the cars behind!

I still reflexively grab the wheel just a little bit harder and raise my foot to the accelerator whenever I go under a bridge.

alanduxbury | May 6, 2018

Sorry I forgot the version number, 2018.12.

rcg1004 | July 28, 2018

Just got my M3 this month and went on a 1,900 mile road trip.

Awesome car, HOWEVER, experienced three hard braking incidents approaching overpasses on interstate. Scared me as well as I think, several other motorists in close by vehicles. Hope Tesla fixes that pretty quick before an accident results from this. Version 2018.24.8

jbbrozm | July 28, 2018

I think it has to do with the shade under the bridge. I have noticed the same affect when driving down my road and passing under a certain set of trees in the afternoon. Doesn't always happen but when it does, its at the same spot.

Teslapalooza | July 31, 2018

I experienced a scary extreme braking event on Sunday when I was driving in the highway. Other occupants in the car literally screamed in terror. Of course I had to counter the breaking by flooring the accelerator so I don't get rear ended.

markcohen | July 31, 2018

I reported on a different thread and continue to have similar events. They are scary and I also hit the accelerator to counter it and avoid getting rear ended.

If you haven't been doing so, I recommend doing a bug report via voice reco AND using the contact function in your manage your car web page to report the incident. I not only received a reply via email, I also had someone call me to follow up and discuss the incidents. To be ready for this, I suggest that you make a note of where and when it happened so that if necessary, you can identify the time and place to Tesla. From the discussion, they were clearly aware of the overpass related incidents. Some of my incidents did NOT happen around an overpass and Tesla was particularly interested in learning about the circumstances around these other incidents.

davidahn | August 2, 2018

Has never happened to me in my 2015 MS AP1 85D, but has happened multiple times to my buddy 2017 MS 75D EAP. SC was able to replicate but couldn't fix it. For them it happened with TACC only, AP off. His wife was quite traumatized and refused to ride in their MS d/t past severe accidents. They are having their MS 75D bought back.

This is obviously a software bug that mistakes overpass shadows for walls. This MUST be fixed, as there are how many hundreds of thousands of such overpasses in the US alone. I have a 2018 MX 100D on order, can't imagine my wife will take it well AT ALL.

As a stopgap measure, what have you all tried that stops this for you? My buddy says turning off automatic emergency braking did NOT avoid this. Does turning off AP/TACC prevent the braking? I could preemptively disable AP/TACC coming up to an overpass.

tommyaros | August 2, 2018

Yes to me also twice on i15 in san diego going thur a car pool lane , going 68mph and brakes hit hard down to 25 .

bp | August 3, 2018

The AP2 software has been getting better - and while it still gets some false positive readings on obstructions ahead, causing unnecessary braking, it's not happening as often as it did last year.

It appears the software is being too conservative when it sees a dark area on the road ahead - which could be from shadows (overhead signs, overpasses, …) or an abrupt change from light to dark roadbed.

The other cause for the rapid braking is errors in the speed limit database. When this happens, you'll see AP/TACC has slowed down to adjust to a lower speed limit displayed on the dashboard - which is likely to happen in areas with recent construction, that haven't been updated in the database.

lilbean | August 3, 2018

I need to get this bumper sticker: I brake for no apparent reason.

Teslapalooza | August 3, 2018

:-) Another good sticker would be, "This vehicle slows for all Apparitions"

lilbean | August 3, 2018

Haha! Good one! I need that one too.

lilbean | August 3, 2018

Such a safe car for ghosts!

teethdood | August 3, 2018

I too have experienced phantom breakings and they were scary and dangerous.

I don't understand how phantom breaking can happen. Teslas with AP1+ all have cameras and radars. Shadows visualized in vision cameras can cause the computer to think there's an obstacle, I get that. But what about the radar? The radar should provide redundancy. According to Tesla, the AP2+ computer is able to analyze 200 frames a second combining all cameras and radar information. It should be able to ignore anomalies between its redundant
camera and radar sensors coupled with fast image processing. Of course I'm not a computer expert so please fill me in.

lilbean | August 3, 2018

They want us protected from all the goblins and ghouls.

lilbean | August 3, 2018

Actually, I think the cars are afraid of ghosts.

bdambrosio | August 3, 2018

@teethdood - 200 frames per second. Maybe, but are you assuming that's each camera? Probably across all cameras. That's pbly one reason current EAP uses only 4 cameras. So current EAP can do 50 frames/sec for each of 4 cameras. And, what does that mean? 'Process' can mean anything from 'crude guess of major objects' to 'build detailed, multi-level representation of every single object in image'. My guess is AP2.5 hardware is closer to the former than the latter.

Tesla | August 3, 2018

Teethdood, it seems obvious to me that if either sensor detects something, camera or radar, the brakes would trigger. That’s what redundancy means - not that if only one senses something it’ll stop.

Clearly it needs to be fixed, but implying that the car shouldn’t stop if the radar doesn’t also trigger is a bit over the top.

Teslapalooza | August 3, 2018

We need to have Bill Murray drive around in a Tesla car on the highways with his ghost catching gear. The car will spot all ghosts for him and he can go about zapping them, and save the rest of us from these annoying ghouls.

lilbean | August 3, 2018

Great ideas @Teslamania.

Teslapalooza | August 3, 2018

@lilbean, I couldn't stop myself from those plugins. It is Friday...after a hard weeks work, everything goes I guess as long as they are in good humor :-)

lilbean | August 3, 2018

@Teslamania Rough week for me here. Son was sent to hospital for ruptured appendix and needed emergency surgery. I’m sleep deprived, hungry, stressed and with my hospital bills, I could have had another Model 3. Ugh!

Triggerplz | August 3, 2018

Lilbean sorry to hear about your son, I hope he gets well soon

lilbean | August 3, 2018

Thanks buddy! He escaped death. :)

Teslapalooza | August 3, 2018

Sorry to hear about that, @lilbean. Hang in there. It is the lighter side of life that helps us all tide over the occasional rough times we all encounter. You certainly know that as good as anyone else.

Triggerplz | August 3, 2018

@Lilbean glad he's ok looking forward to his next YouTube post :)

lilbean | August 4, 2018

Thanks, @Teslamania and Triggerplz. :)

davidahn | August 10, 2018

Re: speed limit database, that was the reason the service center gave my buddy, which would make sense except you don’t brake hard (scaring passengers and risking getting rear ended) just for a speed limit change, you coast down to the new speed limit. If that’s the case, that would be poor coding. But so is mistaking a shadow for an obstacle.

jjgunn | August 11, 2018

Poor coding - aka laziness.

Braking for shadows is easily fixable in the python script. So is DB speed limit changes.

Common sense....sometimes not very common in devs.

Sidk83 | March 10, 2019

Is this still an issue? Is autopilot still making the car brake due to shadows? Please advise as i’m about to go on a road trip after recently ordering AP. Thanks!

jimglas | March 11, 2019

I haven't experienced this recently. 2018.49.20

jjgunn | March 11, 2019

Nope - haven't seen/experienced this since last August 2018 - checked where it happened at my usual routes & everything is fine with 2019.5.15

ScooterJim | March 11, 2019

I am on 2018.50.6. I occasionally experience braking when approaching a bridge, but it is not as abrupt as it use to be. It feels more like a tap on the brake vs stepping hard on the brake. It is still a nuisance.

Zac B | July 9, 2019

I have experienced this issue multiple times per week since getting my model 3 in October of 2018, and my current version (2019.20.4.2) seems to be the worst version yet. While I believe the issue is worse during the day while shadows are present, I drive the same route every day, and it has happened at night, so the issue could simply be repeating at the same location. In addition to, or instead of, shadows, I'm wondering if the issue may be due to the angle or turn in the road before the bridge or the height of the bridge relative to the road at the point the vehicle 'sees' the bridge. The highway I travel does wind left and right and there are small hills.

jjgunn | July 9, 2019

Phantom braking Issue has definitely returned with 2019.20.4.2

Hopefully resolved with next release

tom.dragasoien | February 3, 2020

If there is a road under the bridge and that road has a lower speed restriction, you will experience breaking. This is becuse AP 2.0 and above use speedlimits based on google map while AP 1.0 uses speedlimits taken by front camera (mobileye).

newsgearinfo | May 10, 2020

I have experienced this issue multiple times per week since getting my model 3 in October of 2018, and my current version (2019.20.4.2) seems to be the worst version yet. While I believe the issue is worse during the day while shadows are present, I drive the same route every day, and it has happened at night, so the issue could simply be repeating at the same location. In addition to, or instead of, shadows, I'm wondering if the issue may be due to the angle or turn in the road before the bridge or the height of the bridge relative to the road at the point the vehicle 'sees' the bridge. The highway I travel does wind left and right and there are small hills.

Triggerplz | May 11, 2020


dinhphuong569 | May 14, 2020

Was on autopilot on the interstate, when suddenly M3 applies brakes going under an ... Sometimes they'll brake hard enough to jostle the passengers around.

storifytimes | May 18, 2020

Well, yeah there are some issues with breaks when you shift from high to low very quickly, severe damage can be reached to engine and breaks may burn due to heat.

Check out this topic to know more:

storifytimes | May 18, 2020

Dude, just cool it off, you are over burning the breaks. Does not make more sense if you have to ride long. You can run smoothly with some music or you can buzz off if you run on high speed through the way.