Adaptive Cruise Nearly Causes Accident

[nmiller314]

I was driving 72mph in a 70mph zone with adaptive cruise engaged on a divided highway. Things were going well until I started to pass a semi in a clear lane for more than a mile with the semi going 70mph. When the car reached the area of the tractor just forward of the rear wheels, the adaptive cruise suddenly slowed the car to 60mph or less throwing my wife and I against locked shoulder straps. The accident would have occurred as a car approaching from behind going likely 80mph had it not been for the other drive being able to brake in time to avoid a collision. I hit the brake on the Mach E so I did not know how the car would have acted after the sudden slowdown.

I wondered if it was a fluke or something that happens frequently. I kept adaptive cruise engaged most of my 240 mile trip. I noticed small speed adjustments that had I not known to watch for it likely would have gone unnoticed to events similar to the first slowdown. Though my analysis is not scientific I did seem to note the more sudden changes in speed occur when passing a semi with exposed fuel tanks. When passing semis with fiberglass running from the front wheel all the way passed the fuel tanks, the slowdown did not occur.

This problem is beyond annoyance. It is dangerous as any following vehicle has to react to the Mach E's sudden and significant reduction in speed.

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[generaltso]

Turn off speed sign recognition.

 

[Mari76]

I've had that happen to me too while driving on the 5 here in SoCal. I blame the intelligent cruise control where it picks up the diesel speed limit signs, which is much slower. I usually turn it off when I go on road trips.

 

[DevSecOps]

I've had this happen with ACC on multiple Audi's for years and much less occasionally on the MME. It's normally caused by shadows from the Semi truck trailer.

I think the tech is getting much better because many years ago it even happened from overpass shadows.

I know people are attributing this to speed sign recognition, but that doesn't apply hard braking. The hard braking is the emergency brake assist/ACC system thinking you will collide with the semi trucks shadow. This can also happen to people who think they are speed racers and try to approach a vehicle quickly to change lanes at the last minute. In those cases the car doesn't realize that you will change lanes and applies brake to avoid what it thinks will be a collision.

 

[nmiller314]

I've had this happen with ACC on multiple Audi's for years and much less occasionally on the MME. It's normally caused by shadows from the Semi truck trailer.

I think the tech is getting much better because many years ago it even happened from overpass shadows.

I know people are attributing this to speed sign recognition, but that doesn't apply hard braking. The hard braking is the emergency brake assist thinking you will collide with the semi trucks shadow. This can also happen to people who think they are speed racers and try to approach a vehicle quickly to change lanes at the last minute. In those cases the car doesn't realize that you will change lanes and applies brake to avoid what it thinks will be a collision.

Thank you @DevSecOps. I agree this has nothing to do with speed limit signs as there were none anywhere nearby when I observed the occurrence. I also agree the car is sensing what it thinks is some impending crash. I was in my lane for more than a mile before reaching the truck so it was not me changing lanes. I will be driving back from VA to Illinois next week and I'll do some testing on your theory of it being a shadow; I'll pay attention to the position of the sun.

 

[Ford Motor Company]

I was driving 72mph in a 70mph zone with adaptive cruise engaged on a divided highway. Things were going well until I started to pass a semi in a clear lane for more than a mile with the semi going 70mph. When the car reached the area of the tractor just forward of the rear wheels, the adaptive cruise suddenly slowed the car to 60mph or less throwing my wife and I against locked shoulder straps. The accident would have occurred as a car approaching from behind going likely 80mph had it not been for the other drive being able to brake in time to avoid a collision. I hit the brake on the Mach E so I did not know how the car would have acted after the sudden slowdown.

I wondered if it was a fluke or something that happens frequently. I kept adaptive cruise engaged most of my 240 mile trip. I noticed small speed adjustments that had I not known to watch for it likely would have gone unnoticed to events similar to the first slowdown. Though my analysis is not scientific I did seem to note the more sudden changes in speed occur when passing a semi with exposed fuel tanks. When passing semis with fiberglass running from the front wheel all the way passed the fuel tanks, the slowdown did not occur.

This problem is beyond annoyance. It is dangerous as any following vehicle has to react to the Mach E's sudden and significant reduction in speed.

Good afternoon! I would like to take a look into your Mach-E adaptive cruise concern. Can you please send us a DM with your VIN and Ford Dealer info?

 

[nmiller314]

Good afternoon! I would like to take a look into your Mach-E adaptive cruise concern. Can you please send us a DM with your VIN and Ford Dealer info?

Do you have access to the Ford Twitter account? I can send you information there or you will need to provide me more information so I can be ascertained of who you are.

 

[awp0]

I've had this happen with ACC on multiple Audi's for years and much less occasionally on the MME. It's normally caused by shadows from the Semi truck trailer.

I think the tech is getting much better because many years ago it even happened from overpass shadows.

I know people are attributing this to speed sign recognition, but that doesn't apply hard braking. The hard braking is the emergency brake assist thinking you will collide with the semi trucks shadow. This can also happen to people who think they are speed racers and try to approach a vehicle quickly to change lanes at the last minute. In those cases the car doesn't realize that you will change lanes and applies brake to avoid what it thinks will be a collision.

Doesn't emergency brake assist flash a big red message on the cluster? That's what it does in my car in more common lower-speed instances where a car in front slows to turn into a parking lot and I gently (and safely) steer around then without engaging the brakes.

 

[hybrid2bev]

Do you have access to the Ford Twitter account? I can send you information there or you will need to provide me more information so I can be ascertained of who you are.

That is the official Ford Motor Company account, validated by the site admins. It's legit.

 

[DevSecOps]

Doesn't emergency brake assist flash a big red message on the cluster? That's what it does in my car in more common lower-speed instances where a car in front slows to turn into a parking lot and I gently (and safely) steer around then without engaging the brakes.

Yes however if you have ACC engaged it won't do that unless it thinks that it can't stop on its own. So you'll still get hard braking from the ACC system but it won't alert unless you are overriding, by depressing the pedal, or like I said, it thinks it needs manual intervention.

When driving without ACC/BC engaged then its sensitivity to alerting is higher because it assumes you aren't paying attention vs the system paying attention.

 

[newmme]

This is just phantom braking. Report it to NHTSA so it can get fixed. Here is Tesla with same issue: Phantom Braking

 

[awp0]

Yes however if you have ACC engaged it won't do that unless it thinks that it can't stop on its own. So you'll still get hard braking from the ACC system but it won't alert unless you are overriding, by depressing the pedal, or like I said, it thinks it needs manual intervention.

When driving without ACC/BC engaged then its sensitivity to alerting is higher because it assumes you aren't paying attention vs the system paying attention.

Very good to know. Thank you!

 

[Kabish]

I used the "intelligent" cruise control (think they change the name of it now though) for the first month or two that I owned my car. I QUICKLY discovered that the system is awful. I was on the 94 the other day and noticed the car was detecting speed all wonky. I drive this freeway every single day, no reason for it to be doing it. As you can see the "posted" speed changed many times in a matter of a few miles. It would also black out the speed for a while and would go back to 5mph or 20mph. I don't think the system stopped messing up for about another 20ish miles.

For giggles I turned on intelligent cruise just to see if it would slow me down, sure enough was doing 78 and it changed to 35... While it did brake, it was not aggressive seat belt lock braking, but it was enough where if someone was behind me they would not be too happy.

Would not recommend using the system...

 

[ripperAZ]

Jes sayin. The artificial intelligence is merely acting like it should. Artificially, rather than actually intelligent. You get what you pay for
I actually prefer to drive my car. As others have said it does act smarter when you turn off the ridiculous speed sign recognition. Who has ever needed them anyway?

 

[MachEMaster]

I've had this happen with ACC on multiple Audi's for years and much less occasionally on the MME. It's normally caused by shadows from the Semi truck trailer.

I think the tech is getting much better because many years ago it even happened from overpass shadows.

I know people are attributing this to speed sign recognition, but that doesn't apply hard braking. The hard braking is the emergency brake assist/ACC system thinking you will collide with the semi trucks shadow. This can also happen to people who think they are speed racers and try to approach a vehicle quickly to change lanes at the last minute. In those cases the car doesn't realize that you will change lanes and applies brake to avoid what it thinks will be a collision.

Emergency braking assist would have a “Pre Collision” Alert with flashing red on the display and an aural tone, before any brakes are applied.

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