Flashed on M25; adaptive cruise

[tylerdurden]

Just looking for a general opinion - not legal advice.

Driving on M25; are in adaptive cruise. Monitors speed limited and adjusts. Works beautifully.

I am doing 70; overhead signage changes speed to 50mph about 200m infront. I am in auto mode, fully expecting car to detect and reduce speed to 50; but this does not happen. Unfortunately as I realise and brake hard passing the overhead gangway had fixed yellow cams that flashed me. Fully expecting to get a ticket.

Now the thing is, the signs changed but my only explanation as to why the car did not immediately respond was that the radar signals were not activated at the same time (or whatever it is that the cars use to detect the speed limit). Normally works beautifully.

Would you not expect the speed signalling systems to be activated at the same time as the signage changes and that the new speed is registers further up the road to allow for speed changes to take effect in time.

Kinda feeling hard done by here.

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[chun]

Taycan cameras have a hard time seeing overhead signs, like those on top of bridges. So the sooner you learn this, and adapt to it, the better.

nothing wrong with the car, just can’t see so high up due to camera position and angle

in normal circumstances, where the car actually sees the sign, it will absolutely slow down before reaching the sign, in accordance with the law. In my case, going down from 120 to a 80 zone, the car sees the new speed limit, shows a 80 in a blue pulsing circle and slows down to 80 before reaching the sign

 

[anonymouse]

Sorry about that, it’s no fun. The smart motorways are particularly tricky, as they do sometimes set a speed limit and have a camera at the exact same point. I got flashed on the M5 under those circumstances, as did almost every vehicle, but I must have braked enough because no ticket came.

Do you have Innodrive? One of its functions is to look well ahead and pre-set the target speed, so you are already decelerated to the correct speed when you pass the limit point. (This is one of the few areas where Porsche’s tech is better than Tesla’s - the latter doesn’t start braking until after the sign - that could get you a fine in these circumstances). Innodrive displays the upcoming target speed in a blue circle - each time I see a speed limit coming, I glance to see what the car plans to do, and intervene if it isn’t correct.

There are sometimes data errors. It’s not anything transmitted locally. I think the source of speed limits is a combination of a database, which needs to be updated and read by the car and hence subject to delays; supplemented by the car’s camera which may or may not read motorway gantry signs.

 

[tylerdurden]

that's exactly what happened. smart motorway with a new speed at exactly the same location as the speed cams.

 

[tylerdurden]

well I have learned something. I thought the rads were transmitting a speed signal but it appears the car cams are working it all out from the signs. Magic

 

[anonymouse]

well I have learned something. I thought the rads were transmitting a speed signal but it appears the car cams are working it all out from the signs. Magic

Maybe.
The satnav data provider might also be getting it from a National Highways dataset: https://www.trafficengland.com/services-info

 

[JasMK]

Just looking for a general opinion - not legal advice.

Driving on M25; are in adaptive cruise. Monitors speed limited and adjusts. Works beautifully.

I am doing 70; overhead signage changes speed to 50mph about 200m infront. I am in auto mode, fully expecting car to detect and reduce speed to 50; but this does not happen. Unfortunately as I realise and brake hard passing the overhead gangway had fixed yellow cams that flashed me. Fully expecting to get a ticket.

Now the thing is, the signs changed but my only explanation as to why the car did not immediately respond was that the radar signals were not activated at the same time (or whatever it is that the cars use to detect the speed limit). Normally works beautifully.

Would you not expect the speed signalling systems to be activated at the same time as the signage changes and that the new speed is registers further up the road to allow for speed changes to take effect in time.

Kinda feeling hard done by here.

There is a 60 second allowance when the speed sign changes apparently, to allow for this kind of situation. If you were only 200m away when the sign changed you should be within the allowance and if a ticket arises you can appeal.

Article confirming this below

https://www.highwaysindustry.com/mo...nges-to-avoid-being-fined-on-smart-motorways/

 

[TonyR]

I find that Porsche often gets it wrong when it misses a sign or misreads one. I have often seen completely different speed limit displays on the Google Car Play map and the Porsche road sign reader, and more usually it’s Google that is right. But overall think of it as an assistant not a driver so be ready to take over at any time it gets it wrong.

While we’re on automated driving, has anyone worked out how to use the ALK? Mine works fine but if I rest my hands on the steering wheel and let it do its job it complains and asks me to take control. The only way I can seem to convince it I do have ultimate control is to continually wrestle with it so it knows I’m there. Which kind of defeats the whole purpose. Would also love to know if anyone has found. away to switch it on and off through the steering wheel programmable button as its a right faff to press the stalk button then scroll and push the right hand steering wheel roller to switch it on or off.

 

[chun]

I find that Porsche often gets it wrong when it misses a sign or misreads one. I have often seen completely different speed limit displays on the Google Car Play map and the Porsche road sign reader, and more usually it’s Google that is right. But overall think of it as an assistant not a driver so be ready to take over at any time it gets it wrong.

While we’re on automated driving, has anyone worked out how to use the ALK? Mine works fine but if I rest my hands on the steering wheel and let it do its job it complains and asks me to take control. The only way I can seem to convince it I do have ultimate control is to continually wrestle with it so it knows I’m there. Which kind of defeats the whole purpose. Would also love to know if anyone has found. away to switch it on and off through the steering wheel programmable button as its a right faff to press the stalk button then scroll and push the right hand steering wheel roller to switch it on or off.

I assist it with 1 finger and try to mimic the curves of the road. Basically pushing it ever slightly with 1 finger in the direction it was already turning, or holding it ever so slightly from the direction it is pulling. I find it quite intuitive

To turn it on, you simply push forward the driver assist stalk, that’s the lower one on the left of the steering wheel. To turn it off, you press the brake slightly

 

[anonymouse]

if I rest my hands on the steering wheel and let it do its job it complains

I have always assumed it does the same thing as a Tesla, ie relies on torque not pressure or presence of hands. However unlike a Tesla, it also interprets torque as an instruction to reposition the line it's driving on. So usually I have just a little gentle torque, and if the road goes the other way instinctively apply a bit of torque in the other direction. If that fails, when it complains I just give a little wiggle of the wheel.

 

[TonyR]

To turn it on, you simply push forward the driver assist stalk, that’s the lower one on the left of the steering wheel. To turn it off, you press the brake slightly

Yes, but that turns both the ACC and ALK on or off together. I‘m talking about switching just the ALK on and off.

 

[ovonrein]

Do you have Innodrive?

He.must have. ACC alone would never reduce the target speed automatically. The look ahead of PID ain't much use under the circumstances. However, I have never heard of anyone being flashed within seconds of the gantry changing the speed limit.

 

[ovonrein]

Yes, but that turns both the ACC and ALK on or off together. I‘m talking about switching just the ALK on and off.

I find it is easiest to select/deselect via PCM/Car/Assistance. You can probably program that screen to the diamond.

 

[TonyR]

He.must have. ACC alone would never reduce the target speed automatically. The look ahead of PID ain't much use under the circumstances. However, I have never heard of anyone being flashed within seconds of the gantry changing the speed limit.

Sometimes the flashes are not real speed flashes but just flashes to encourage drivers to slow down. The innards of a camera with the accuracy needed to record a speed offence are apparently not cheap so they have cheaper ones which flash but don’t take pictures and are not as accurate on what your speed actually is because it doesn’t matter. They rotate them around between proper speed cameras, faux flashing no cameras and empty camera boxes AIUI

 

[ovonrein]

May be I hear what you are saying. You THINK to have seen a flash but you have not actually received a FPN yet. I would not worry too much. The camera may well have been real and may well have targeted you but they will probably suppress the FPN because the infringement registered within seconds of the speed changing.

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