# Rear crossing traffic alert



## HCD3 (Mar 3, 2019)

There’s a bunch of sensors on the rear bumper of the model 3. Is there any reason they can’t be used for the RCTA? This feature was available in all my previous ice cars.


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## iChris93 (Feb 3, 2017)

No rear radar.


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## garsh (Apr 4, 2016)

HCD3 said:


> There's a bunch of sensors on the rear bumper of the model 3.


Those ultrasonic sensors on the bumper only have a range of a few feet (Max distance 8m according to Tesla's website).

Tesla could probably try to use the rear camera to implement such a feature.


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## Frully (Aug 30, 2018)

Wasn't it speculated (patent documents?) that hw3 would support rear radar?


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## MelindaV (Apr 2, 2016)

Frully said:


> Wasn't it speculated (patent documents?) that hw3 would support rear radar?


here's a (speculation) video from about a year ago on that


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## HCD3 (Mar 3, 2019)

I very nearly had a rear collision shortly after posting this. I don’t understand why Tesla can’t do this.


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## HCD3 (Mar 3, 2019)

MelindaV said:


> here's a (speculation) video from about a year ago on that


Thanks very much Mel.


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## HCD3 (Mar 3, 2019)

garsh said:


> Those ultrasonic sensors on the bumper only have a range of a few feet (Max distance 8m according to Tesla's website).
> 
> Tesla could probably try to use the rear camera to implement such a feature.


Thanks Garsh. 8 meters would be plenty no? I think RCTA would be easy to implement.


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## eXntrc (Jan 14, 2019)

Yeah, but if you watch that video the speculation is about secondary forward facing radar for redundancy purposes. As cool as RCTA sounds (using rear radar), personally I think redundancy makes more sense. If you're truly shooting for level 5 autonomy, where the driver isn't expected or required to take over, a radar failure would be unacceptable. The vehicle would likely need to abruptly come to a stop, which would certainly be unacceptable on the highway and not much more acceptable on city streets.


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## iChris93 (Feb 3, 2017)

eXntrc said:


> Yeah, but if you watch that video the speculation is about secondary forward facing radar for redundancy purposes. As cool as RCTA sounds (using rear radar), personally I think redundancy makes more sense. If you're truly shooting for level 5 autonomy, where the driver isn't expected or required to take over, a radar failure would be unacceptable. The vehicle would likely need to abruptly come to a stop, which would certainly be unacceptable on the highway and not much more acceptable on city streets.


About a year ago, Elon tweeted about working on vision only driving so radar redundancy may not be necessary.


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## eXntrc (Jan 14, 2019)

iChris93 said:


> About a year ago, Elon tweeted about working on vision only driving so radar redundancy may not be necessary.


Yeah. And I would love for that to become a reality. Maybe with HW3 + full res camera frames + color frames that could become possible. But every day when I'm looking at visualizations on the screen I'm surprised at how far (or really how close) the car can see other vehicles. I'd love to see the dependency on radar eliminated, but my gut feel is that's still quite a ways away.


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## GDN (Oct 30, 2017)

We had a '13 Fusion that had the rear cross traffic alert and I'm fairly certain it did not have a radar in back. It had the small sonar sensors and a backup camera however. Not sure how they implemented. Cross traffic doesn't have to reach too far, 8 M / rough 25 ft is a long ways to help avoid an incident while backing out of a parking place or driveway, etc.


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## JWardell (May 9, 2016)

My 2017 Mazda has rear cross traffic alert and it only uses the rear camera, and it works impressively well. It's especially great for people walking across my driveway as I'm backing out. Tesla could absolutely do it with the camera alone.
My only guess is it may be patented, in the same way Tesla is prevented from reading speed limit signs because mobileye has a patent.


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## PaulT (Aug 22, 2018)

Our 2017 Subaru Outback only uses camera for rear cross traffic detection and emergency braking. Works great and applies brakes if needed. Tesla should easily be able to do this.


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## Drhalo (Jul 12, 2018)

I have been shaking my head that a car such as the 3 doesn't have this. I have been tweeting Elon about this since 2018.


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## TomT (Apr 1, 2019)

You don't need radar. Our 2013 Ford Escape Hybrid has it using just the rear ultrasonic sensors. And it works spectacularly well. Tesla could surely do it what with their ultrasonic sensors AND cameras...


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