Speed camera myths

HAL9000

A conversation I overheard yesterday came up with these...

Speed cameras won't get you if you're changing lanes whilst being snapped.

All motorway speed cameras are set for at least 80mph.

On motorways with variable speed limits, the camera's trigger point doesn't vary with the speed limit i.e. it remains at 80mph.

The 10% + 2mph thing is not a guideline, it's the law.

I suspect that the only one of these that might be true is the second one.

DefaultM

I generally don't speed on the motorway because I don't want a fine or to die in a fireball, but I did accidentally go through a camera at about 75 once and nothing happened.

I certainly wouldn't like to test it again though, and I don't understand why people would have this conversation. As though the only reason not to speed is because you might get caught.

Guitar_Slinger

HAL9000 said:

On motorways with variable speed limits, the camera's trigger point doesn't vary with the speed limit i.e. it remains at 80mph.

I'd say this one isn't true. Sometimes I have the pleasure of riding part of the M25 between the M4 and M1, where the variable speed limit goes up and down like a whore's knickers. There's normally somebody coming the opposite way getting their picture taken.

Majorscale

Got done for doing 73 in a variable speed zone when it was dropped to 60mph on the M1 near Nottingham last month!

ICBM

None of them are true.

Nor is the idea that "reflective" number plates will stop the number being recognised. They're just illegal as well.

roundthebend

The "10% + 2mph" one always riles me. It does not mean that you can go 79mph according to your speedo in a 70mph zone. It means, that if the equipment used to record your speed registers you at 79mph then you may well be given the benefit of the doubt to account for inaccuracies in, both, your speedo and the recording equipment.

As such, the only sensible advice is to not exceed the speed limit on your own speedo, and hope that it's not wildly inaccurate. You can't know how accurate the recording equipment is. So forget playing games.

Majorscale

That said, I don't know of anyone who has been done by a motorway average speed camera so I suspect those may be just a scare tactic

Legionreturns

Majorscale said:

That said, I don't know of anyone who has been done by a motorway average speed camera so I suspect those may be just a scare tactic

I'm just about to do a speed awareness course for an average speed camera zap. 57 in a 50 over a little less than half a mile. Very annoyed about it as I had to accelerate to avoid being squished by double stacked lorries swerving into my lane. 

strtdv

roundthebend said:

The "10% + 2mph" one always riles me. It does not mean that you can go 79mph according to your speedo in a 70mph zone. It means, that if the equipment used to record your speed registers you at 79mph then you may well be given the benefit of the doubt to account for inaccuracies in, both, your speedo and the recording equipment.

As such, the only sensible advice is to not exceed the speed limit on your own speedo, and hope that it's not wildly inaccurate. You can't know how accurate the recording equipment is. So forget playing games.

Although I believe under EU legislation your car must not exceed the speed displayed on the speedometer, and therefore it's reasonable to assume that if your speedo says 76mph, you were doing 76 or less.

randella

Majorscale said:

That said, I don't know of anyone who has been done by a motorway average speed camera so I suspect those may be just a scare tactic

Just to save you the bother of finding out yourself, not to be snarky - I do and they're not.

HAL9000

roundthebend said:

The "10% + 2mph" one always riles me. It does not mean that you can go 79mph according to your speedo in a 70mph zone. It means, that if the equipment used to record your speed registers you at 79mph then you may well be given the benefit of the doubt to account for inaccuracies in, both, your speedo and the recording equipment.

As such, the only sensible advice is to not exceed the speed limit on your own speedo, and hope that it's not wildly inaccurate. You can't know how accurate the recording equipment is. So forget playing games.

I believe that, legally, your speedometer is allowed to read over but not under. Therefore an inaccurate speedo shouldn't be an excuse.

darthed1981

I actually read in full the ACPO guidelines for speed enforcement back in the day, and guidelines they were.  If a police officer wants to do you for 71mph on a motorway, it is an absolute offense, so they can.  They are supposed to enforce proportionately, but a lot rests in the hands of individual officers.

The guidelines apparently don't really apply any more, but it is likely they are the source of a lot of these things.  They show a usual guideline of enforcement being appropriate once a speed of +10% + 2mph is reached, but it is just a guideline.  Also the equipment used is typically calibrated to +/- 2mph, but again this is generally, some of the kit is far more accurate.

The cameras are almost all set to this guideline, but if you drive past a school and leaving time at 34mph and get a ticket, don't bitch and moan, that is the definition of proportional enforcement.

Best way to avoid a ticket, don't speed   If you stick to a maximum of speed limit + 10% indicated, then a combination of the guidelines and your speedo's inherent tendency to over-read a bit make it extremely unlikely you will get a ticket.

Also use your heads.  You will probably not get pulled for doing 80mph on an empty motorway, but if you weave in and out of traffic at 75mph on a busy one, you probably will.

Saddlepunk

darthed1981 said:

I actually read in full the ACPO guidelines for speed enforcement back in the day, and guidelines they were.  If a police officer wants to do you for 71mph on a motorway, it is an absolute offense, so they can.  They are supposed to enforce proportionately, but a lot rests in the hands of individual officers.

The guidelines apparently don't really apply any more, but it is likely they are the source of a lot of these things.  They show a usual guideline of enforcement being appropriate once a speed of +10% + 2mph is reached, but it is just a guideline.  Also the equipment used is typically calibrated to +/- 2mph, but again this is generally, some of the kit is far more accurate.

The cameras are almost all set to this guideline, but if you drive past a school and leaving time at 34mph and get a ticket, don't bitch and moan, that is the definition of proportional enforcement.

Best way to avoid a ticket, don't speed   If you stick to a maximum of speed limit + 10% indicated, then a combination of the guidelines and your speedo's inherent tendency to over-read a bit make it extremely unlikely you will get a ticket.

Also use your heads.  You will probably not get pulled for doing 80mph on an empty motorway, but if you weave in and out of traffic at 75mph on a busy one, you probably will.

I used to be a criminal defence barrister back in the 90's and, assuming the law hasn't changed that much since then, I'd say darthed181 knows what he's talking about.

crunchman

As already said, most speedos read faster than you are actually travelling.  Compared with two difference sat navs, mine says 75 or 76 mph when I'm actually doing 70mph.  Got new front tyres now though so wheel diameter might 3 or 4 mm bigger.  Need to work out if that will make a difference.

Gassage

Saddlepunk said:

I used to be a criminal defence barrister back in the 90's

And which model of PRS Private Stock do you own?

ESBlonde

Your cars speedo is inaccurate and not calibrated. Some simple science suggests that when the car is tested new on the manufacturers chosen tyre brand correctly inflated and not worn the tyre circumferance will be X. Over inflation, a different brand of tyre, under inflation, normal wear etc. will all change the value of X. Since X is used to calculate speed from the wheel revolutions, it seems logical that it is a constantly variable answer on the clock. Manufacturers go to great lengths to ensure they don't under declare the speed reading in the car to avoid future legal problems from drivers caught speeding in thier cars and claiming the speedo said they were withing the law.

So if you stick to the cars reading you are always (?) likely to be within the law. I was told by two police officers (both former traffic cops) that the rules they applied were 5%+2 (not 10%). because that was reasonable but they had discretion both ways. Fixed cameras are not always loaded with film, but why take the risk.
You can get some calibration of your cars speed when driving through a village with one of those boards that tells you your speed via radar. Holding speed and letting you sat nav compare is interesting too.

Finally I'll pass on some wise words my son reitterated last year when learning to drive. The speed limit is a maximum limit not a target!

Drive safely everyone and leave enough time for your journey, there are enough cockends on the road, don't be one too.

Snap

I know people who manage motorways, and the installation of speed cameras etc.

SPECS, the average speed cameras, usually aren't on at night. Not always, but usually.

The bridge cameras on the M1 round Nottingham don't work, and that's why they have installed the yellow roadside ones on the bridge risers.

the 10% plus 2 mph is a definite myth.

If you are doing over 86 mph on the M40 in Thames Valley police area, you will get no option to do speed awareness, straight fine and points.

When will cameras be able to nobble people for texting and driving? Some berk was doing that the other day, in the middle lane doing about 80. Ludicrous.

Whitecat

ESBlonde said:

Fixed cameras are not always loaded with film, but why take the risk.

I was told by someone who works with the coppers that they are phasing out the wet-film cameras completely nationwide soon, so I would consider all cameras to be live at all times (which you should do anyway - the whole thing is, just don't speed and none of this is an issue!) As of about five years ago only one in six cameras was loaded, but that number has likely gone up anyway as a revenue measure.

HAL9000

Snap said:

When will cameras be able to nobble people for texting and driving? Some berk was doing that the other day, in the middle lane doing about 80. Ludicrous.

^This. Speed doesn't kill. Bad driving does. People who speed are easy (and legitimate) targets. People who text, use their mobiles, tailgate, etc are generally more dangerous and should be targeted at least as vigourously.

57Deluxe

DefaultM said:

I generally don't speed on the motorway because I don't want a fine or to die in a fireball, but I did accidentally go through a camera at about 75 once and nothing happened.

Sometimes you get forced into a corner and to get out of trouble you have to double it up! Two lanes of lorries fighting it out on cruise control and a steady stream of 90mph Audis in the outer lane and a looming exit makes you do this...

aord43

ESBlonde said:

Finally I'll pass on some wise words my son reitterated last year when learning to drive. The speed limit is a maximum limit not a target!

I've always said this. However when my daughter learned to drive a couple of years ago they do seem to be told that they need to drive "up to the limit" to prove they are confident enough. She was too keen to put her foot down because of this, in my view.