Speeding

[flecc]

Originally Posted by Haku

Anyone know where these speed cameras on downhills are? I've wanted to trigger one just once, but the ones around where I live are on the flat and I can't get up to let alone over 30mph, even with my derestricted bike (that I still haven't got back, 3.5 weeks without it and I'm still very peed off).

I've got some in my area, but a bike doesn't trigger them. The same goes for the advisory speed indicator boards. I've passed at well over the mark those which measure from 31 mph when I'm in my car, but they don't work for the bike.

Gatsos and the like need some hard surface areas to bounce back a signal, a bike rider doesn't provide that and the rounded tubes on the bike don't either.

Some hand gun types can pick up a cyclist but are hopelessly inaccurate when doing it as I've mentioned above. Again they need stable hard surface areas for accurate measurement, plus sufficient speed to provide readings within a time span of minimal operator movement. Under 20 mph doesn't provide that.
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[rog_london]

Originally Posted by flecc

I've got some in my area, but a bike doesn't trigger them. The same goes for the advisory speed indicator boards. I've passed at well over the mark those which measure from 31 mph when I'm in my car, but they don't work for the bike.

Gatsos and the like need some hard surface areas to bounce back a signal, a bike rider doesn't provide that and the rounded tubes on the bike don't either.

Some hand gun types can pick up a cyclist but are hopelessly inaccurate when doing it as I've mentioned above. Again they need stable hard surface areas for accurate measurement, plus sufficient speed to provide readings within a time span of minimal operator movement. Under 20 mph doesn't provide that.
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They all use Doppler radar, and a cyclist reflects back almost none of the received signal, so the receiver cannot distinguish what little is reflected from the ambient noise. Even the Serco cameras (they're the small yellow ones on tall poles which don't flash in the daytime), which use in-road pickup strips, require a considerable area of metal close to the ground, so would never see a cyclist.

Incidentally, a small but relevant technical point, it's not the radar or the road strips which get you convicted - it's the camera. The radar and strips are there purely to trigger the camera, which takes two photographs at an accurately-known interval, and in conjunction with the road markings your speed is then worked out manually by seeing how far your image has moved in the measured time between the snapshots. It's low-tech and hard to argue with. There can be several vehicles within the frame, and as long as the number plates can be seen in the photos the speed of each vehicle can be independently worked out. There may be a speed included in the pictures, but that's based on the Doppler or strip information, and unless there were only one moving object in the pictures it would not be possible to tell who was doing what.

Coppers' hand-guns usually work by means of a laser beam, and can give some sort of a reading provided they are used with skill. I believe the ones they now use also video the operation, so that correct use can be verified in court, and you can't allege that the speed measured was that of a kamikaze seagull. One of the reasons they're inaccurate at lower speeds is that the image of a cyclist can itself be quite fluid in that he's pedalling, so there is body movement which can confuse things no end.

Rog.

[lectureral]

There was one speed advisory sign which used to display my speed in Newcastle - it was on a stretch of road in an underpass. Maybe the confined space allowed it to capture my speed (I think 26 was the highest I ever managed to record).

[flecc]

Originally Posted by rog_london

Incidentally, a small but relevant technical point, it's not the radar or the road strips which get you convicted - it's the camera. The radar and strips are there purely to trigger the camera, which takes two photographs at an accurately-known interval, and in conjunction with the road markings your speed is then worked out manually by seeing how far your image has moved in the measured time between the snapshots. It's low-tech and hard to argue with. There can be several vehicles within the frame, and as long as the number plates can be seen in the photos the speed of each vehicle can be independently worked out. There may be a speed included in the pictures, but that's based on the Doppler or strip information, and unless there were only one moving object in the pictures it would not be possible to tell who was doing what.

Coppers' hand-guns usually work by means of a laser beam, and can give some sort of a reading provided they are used with skill. I believe the ones they now use also video the operation, so that correct use can be verified in court, and you can't allege that the speed measured was that of a kamikaze seagull. One of the reasons they're inaccurate at lower speeds is that the image of a cyclist can itself be quite fluid in that he's pedalling, so there is body movement which can confuse things no end.

Rog.

Yes, as you say Rog, the road markings can't be argued with. Hand guns are a poor method though, and I don't think that a video can reliably show the very small movement which can corrupt a lower speed reading around 30 mph. At much higher speeds it's not a problem though.

It's not only the body movement that can make cyclists readings unreliable, loose clothing moving in the airflow can cause havoc in radar reflections even when they are possible, which isn't always with soft clothing. Those Bournemouth cyclists should stick to soft clothing and not wear a helmet!
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[Mussels]

Originally Posted by lectureral

There was one speed advisory sign which used to display my speed in Newcastle - it was on a stretch of road in an underpass. Maybe the confined space allowed it to capture my speed (I think 26 was the highest I ever managed to record).

I have trouble getting a reading, I need something reflective to trigger them. I'm usually fine when following a car, they show my speed perfectly after the car has passed but won't come on if I'm on my own.

[oriteroom]

"Do Bournemouth use spike strips to stop any errant cyclist who fails to stop for his/her lecture?"


No - they just rely on all the broken beer bottles/glass on the prom to do it for them!!

Mike

[Haku]

I remember seeing something tv ages ago about measuring the speed of cars with the handheld 'guns', in particular the laser based one which if you pointed it at the bonnet it would get false speed readings because the beam could 'slide' from the front to the back (or vice versa) during the reading.

So basically the police are using inaccurate technology to measure the speed of cyclists who don't have (and aren't required to have) speedometers, on a stretch of land where they can't actually arrest/caution anyone going over a certain speed, all because a single two year old got knocked down (and not killed)?

If they were to apply the same rules to vehicles on the roads then everyone would be forced to go about 5mph because of the number of deaths occuring on the roads from fast drivers. FFS.


Anyone up for a 15mph cycling flash mob in Bournemouth?

Just remembered something, my uncle was Mayor of Bournemouth from 30 May 2008 to 29 May 2009. If he was still mayor I'd have sent him an email asking him what he knows about this absurd situation.


BTW, got my ebike back yesterday after 3.5 weeks without it, very pleased, the one thing I missed most was the speed, getting from A to B on a normal bike seemed to take forever.

[Patrick]

Do they set a 10mph limit for running as well? Someone charging down the prom on foot could easily knock someone over.

[Mark/Cytronex]

I know this beach well, every year we do a 60 mile trip on our Cytronex Powered tandem down through the New Forest and Bournemouth then over the Chain Ferry at Sandbanks to the Isle of Purbeck, where we stay at a tandem friendly hotel. It is probably my favourite trip of the year.

Having travelled around 40 miles by then on a sunny August day there is nothing nicer than cycling along the wide road at the back of this beach. Unfortunately you are not allowed to do so between July and August. It's absolutely potty, a big wide surfaced road well behind a beach with very few pedestrians on it and you can't use it. As long as Cyclists apply a small amount of common sense (we ride slowly with the power off and enjoy the veiw) there is no harm to anyone. I can only assume there are a few council officials in Bournemouth with time on their hands.

People bump into each other walking every day (particularly children) - are you going to start fining people for not observing a 10m exclusion zone from the nearest person, or perhaps cover everyone in bubble wrap at the point of entry? Of course breathing can be a bit risky too, you never know when you might inhale a large wasp or something, so perhaps they should ban breathing too during the wasp season.

A life without risk would be very dull indeed and I wouldn't want to end up cornered at a party by the individuals responsible for these silly rules, let alone those who enforce them. So I guess I might end up with a fine at some point, but it might be worth it just for the view!

Whilst I’m enjoying a good moan, instead of concentrating on the likelihood of someone grazing a knee as a result of cycling, maybe the council could try and see the bigger picture. I am sure encouraging everyone to drive to the beach works wonders for council parking income but there are millions of people being affected already by climate change in low lying parts of the world. When the beach has been washed away maybe they will start to take notice!

[lectureral]

Originally Posted by Mussels

I have trouble getting a reading, I need something reflective to trigger them. I'm usually fine when following a car, they show my speed perfectly after the car has passed but won't come on if I'm on my own.

Maybe hanging a cast iron frying pan around your neck or wrapping your torso in aluminium foil might do the trick?