OT Mandatory speed limiters on UK cars from 2022

[Paul]

There are two kinds of CMOS setups on webcams.

Rolling shutter (most common, strobes) and global shutter (doesn't have strobe effect). It's just how the sensor works, not some mechanical contrivance.

There are some still pictures here, of particular distortion effects that happen.

A video from 2013, comparing the two types of CMOS sensors.

CCD sensors tend to be global, because of the readout mechanism. Samples are read out, as if the pixels were arranged in shift registers. The pixel values are "frozen", until the readout operation (shifting) completes. Judging by a quick Google, CCDs haven't entirely disappeared. They run a bit warm perhaps. (They shift "buckets of charge", an analog quantity, and an ADC converter is needed at the end of the shift, to make digital values.)

Paul

[nightjar]

So, probably not likely to affect the ability of a modern vehicle computer to look for repeaters.

There is a way to identify that. If there are three or more street lights together and they *don't* have a repeater sign for any limit (including 30mph), then they are a system of street lights spaced not more than 183m (200 yards) apart.

[Roland Perry]

In message <sha8n9$ofg$ [e-mail]>, at 08:01:46 on Wed, 8 Sep

2021, Paul snipped-for-privacy@needed.>> In message [e-mail]>, at 16:16:21 on Wed, 8

The question is - which sort are in these speed-sign reading cameras (and where are they mounted - inside the windscreen is no use if it's raining/snowing heavily).

[Roland Perry]

Nevertheless, 30mph repeaters outside of heavily traffic calmed urban centres are still rare.

What if the second and third are round a bend you (and/or your limiter's camera) haven't got to yet?

ps. This isn't quibble I just invented, it's been a matter of concern to me for at least 20yrs.

[Robin]

I'm surprised there are any /inside/ heavily traffic calmed urban centres given AFAIK they are still forbidden where there is a system of carriageway lighting by Sch 10 TSRGD 2016.

[Roland Perry]

In message [e-mail], at

15:03:00 >> In message <qeqdndDD [e-mail], at

Where *are* they allowed?

[nightjar]

There are plenty of unlit villages around here that have them.

I would expect the software to assume that any street lighting meant a

30mph limit, until it found something that told it otherwise. It would be programmed to fail safe.

[nightjar]

Where there is no street lighting or the street lights do not comply with the requirements for imposing a 30mph limit; either because there are not at least three lights or because the lights are more than 200 yards apart.

[Roland Perry]

If the village is unlit, what are they "repeating"? If it's a full size signon the edge of the village, then that's what eyeballs and cameras should be looking for.

Assuming it's daylight, how do they tell? Some rural street lighting is an inconspicuous lamp mounted halfway up an overhead-240v-distribution pole, or even a telegraph pole.

[nightjar]

As you pointed out, those signs may be obscured or missing. I can think of two start of limit signs locally that have not been replaced, although they were both knocked over several weeks ago. In one of those cases, the surviving sign is obscured by a tall hedge until the very last minute. Drivers are likely to miss it, but I would hope a camera would not.

I would expect the software to look for the lighting heads, which are quite distinctive even during the day. The lighting head won't be on a telegraph pole. They are thinner than electricity poles and don't meet the required standard to carry mains electricity. (I used to work for an Electricity Board). They may not even be on a pole of any sort. In many High Streets they are mounted on buildings, to keep pavements clear of unnecessary obstructions.

[Steve Walker]

And if you have seen it, you can override the limiter just by accelerating hard for a moment.

[Steve Walker]

I know of at least one village that has a 30 limit and has only a single lamp-post - so who can tell if it is close enough together?!

[Bob Eager]

I don't know what Roland's agenda is, but he seems determined to pick holes in this kind of technology. No one is saying it's perfect, and indeed its users are advised of such. But it's useful all the same.

[Tim+]

Yes, he seems to be talking about the tech as if it?s full autopilot technology rather than a driver aid.

At the end of the day, it?s still the driver in control of it all.

Tim

[Andy Burns]

I've heard of cars using GPS and a database to lookup speed limit, also heard of cars reading signs with a camera, but that's the first time I've heard anyone suggest it can interpret lamp posts, do other countries even have similar rules?

[Andy Burns]

What if the council has permanently turned off the streetlamps (and the rust hasn't quite got to them yet)?

[nightjar]

The rules vary by country, so I would expect the software would have to allow for the differences, for example, knowing that a white French town sign means a 50kph limit, while a blue village one does not.

[nightjar]

As I read the regulations, the lights do not need to be working for the limit to apply. Otherwise, a single failed lamp could be a defence against prosecution.

[Bob Eager]

Mine certainly interprets dual carriageways - as you might expect. In the absence of signs or repeater signs, it assumes duals are 70 and others are 60.

[Roland Perry]

I thought the whole point of an automatic limiter was one didn't need to be checking all the signs all the time, let alone to accelerate (against the advice of the limiter) to avoid being rear-ended by the car behind who is now speeding up.