Autopilot died in a tunnel, then came back

[mikeash]

I drove through the Baltimore Harbor Tunnel yesterday while using autosteer. About halfway through the (1.4 mile long) tunnel, it suddenly screamed at me to take over. I had both hands on the wheel and was actively engaged anyway (narrow lanes and close walls!) so I did and it was no sweat. A message on the instrument cluster said something to the effect of, forward radar visibility reduced. After exiting the tunnel I tried to reengage autopilot, but it just beeped at me and gave me the same message. This applied to both autosteer and plain TACC. I thought maybe I had hit something that damaged or obstructed the radar. Then a couple of minutes later, it came back on and worked fine for the rest of my drive home.

My speculation is that the radar got confused in the tunnel environment, then took a couple of minutes afterwards to make sure everything was working OK before it was willing to resume. Has anyone seen this happen in similar circumstances, and does anyone know if my speculation is at all correct?

 

[chillaban]

That doesn't sound unusual. I had a previous car with Bosch radar sensors for adaptive cruise control (very similar to or the same model as the Tesla one) and in a very similar circumstance (in a long tunnel) disengaged ACC with an "ACC blinded" message.

In my case I had to reboot the car in order to restore ACC... seems like Tesla built in some way of resetting the system.


Might be worth asking Service to pull the logs though just to make sure it's not a sensor malfunction coincidentally happening in a tunnel.

 

[mikeash]

I've got a few other minor things I need to bring up with the service center, so I'll mention this as well.

 

[Max*]

Has anyone seen this happen in similar circumstances, and does anyone know if my speculation is at all correct?

Yes. I posted about it about a year ago (not that I expect everyone to read every post). Same tunnel, same situation -- except it was TACC only (AP wasn't out yet).

But it doesn't happen everytime, I'd say it was 1/10 times that it died mid-tunnel. Also, once the beeping starts the car starts to use regen on full blast, and when you're going 60mph+, it kicks in hard, so beware of drivers behind you.

 

[NikeWings]

Our TMC headlines are becoming worthy of an award event.....
I nominate this one for 5 Tessies.

 

[mikeash]

I'd like to thank the academy, and my wife for supporting me through these difficult times....

Max, thanks for the corroboration. I did try to search for similar occurrences, but couldn't find anything. There were a bunch of people asking about tunnels, which probably made it hard to pick out people talking about problems.

 

[NikeWings]

Earlier this year, I hitched a ride in my buddy's Tesla from Logan airport thru the Ted Williams tunnel. It was bumper to bumper and kept telling him to take control, although he could re engage pretty quickly only to get the warning again. He eventually just shut it off and chalked it up to below sea level challenges Not knowing any better, I believed him. Does that make any sense to you guys?

 

[Max*]

@NikeWings For me, when it disengaged, it was exactly as the OP stated. I could not re-engage TACC for a while (maybe 1-2 miles) after I left the tunnel.

I've gotten the red-hands-of-death-take-over-immediately message on regular roads, usually when AP gets confused, but I would be able to re-engage AP in those instances immediately.

I can understand that the multi-path from inside the tunnel may be what caused the issues for me, but I don't understand what sea level has to do with it. The radar wont see through the walls, too high of a frequency.

 

[NikeWings]

@NikeWings
I can understand that the multi-path from inside the tunnel may be what caused the issues for me, but I don't understand what sea level has to do with it. The radar wont see through the walls, too high of a frequency.

Yah, I didn't have my car then so I was just riding, looking around and not really watching/listening to him. But now I am curious and will call him. Its a weird explanation in hindsight. Thx Max.

 

[stopcrazypp]

Earlier this year, I hitched a ride in my buddy's Tesla from Logan airport thru the Ted Williams tunnel. It was bumper to bumper and kept telling him to take control, although he could re engage pretty quickly only to get the warning again. He eventually just shut it off and chalked it up to below sea level challenges Not knowing any better, I believed him. Does that make any sense to you guys?

Radar sensors are well known to have trouble with tunnels. I doubt it had anything to do with elevation.

 

[Electroman]

I wouldn't use AP in situations like that with narrow lanes, without a shoulder and next to a wall.

 

[Max*]

I would use AP in situations like that with narrow lanes, without a shoulder and next to a wall.

I assume you meant you wouldn't, but it works surprisingly well.

 

[mikeash]

I obviously would, but only with my hands firmly on the wheel ready to prevent it from "correcting" into something. AP does a better job at keeping the car perfectly centered than I do most of the time. When it fails, it tends to fail obviously. Both of us working together makes for the best experience there, at least for me.

 

[2virgule5]

Had almost the opposite experience in the same tunnel 3 weeks ago - emergency braking activated as it sensed a vehicle stopped in the tunnel without lights on, before I could saw it myself. Glad that the radar only disengage 1/10 times.

 

[andrewket]

This happened to me, same tunnel. Now I turn off AP before going through.

 

[andrewket]

Fwiw, I think it's the angle that trips up the radar, mostly while climbing in the tunnel. It starts seeing a concrete "wall" straight ahead and the distance is constant despite the car moving.

 

[Mknac]

I went through the same tunnel yesterday and the same thing happened. I received an error saying there was reduced radar visibility and auto pilot wasn't available. Took about five minutes before it would work again.

 

[Todd Burch]

This happened to me over a year ago in a different tunnel (TACC only obviously). Posted about it somewhere, but it also reset for me a few minutes later.

 

[Mknac]

Just a side note, I was using the navigation and the map on the left side of the dash turned into a tunnel. That was a surprise.

 

[gerti]

I wonder if radar reflectivity of the walls along with proximity to other cars using radar plays a role.