Average speed cameras - the way forward?

[Jaded]

I find it outrageously laughable that if there's a threat of a speeding ticket you have to stare at your speedometer.

Part of the basic skill of driving is managing how fast you drive.

Since SafeSpod and the ABD can't do that without behaving dangerously, maybe they should take the bus. Or cycle.

[αdαmsκι]

Those average speed zones are even easier when the car one is driving has adaptive cruise control - ie the system that maintains a certain distance to the vehicle in front based on radar. Simply set the cruise control to the required speed and just steer without having to even worry about slowing catching up with the vehicle in front.

[The Family Cyclist]

Reckon is should try 50mph rather then 50kph. According to sat Nav my Speedo is 1 to 2 miles slow so indicated 60 is 58 on sat Nav. It's whether I can trust the sat Nav to be accurate.

[orienteer]

Speedos are not allowed to read slower than true speed, but can be up to 10% fast. Satnav generally gives a more accurate reading, but can fluctuate at times.

[Jaded]

Sat Nav is also always historic - the speed you were traveling between two past points.

[Kim]

Sat Nav is also always historic - the speed you were traveling between two past points.

GPS receivers usually measure speed by doppler shift, not distance/time, so the speed reading is instantaneous (and impressively accurate).  But yes, the high-level processor only usually gets a sample from the GPS chipset every second or more, and it can go wibbly in poor reception conditions.

Not that wheel rotation sensors are any more responsive, given the low-pass filtering (mechanical or electronic) involved.  And their calibration is deliberately sloppy (because of the legal requirement not to under-read) and prone to drift with things like tyre wear/pressure.

In general, I'd trust a GPS to give a more accurate measure of crusiing speed, but it's the speedo I'd keep an eye on to avoid speeding.

[Gattopardo]

How do these cameras catch drivers that are inattentive?

Used to drive down the A13 quite alot and the times you could excide the speed limit were usually were during non rush hour times.  Also the speed limit has been reduced over time.  I get the feeling, from using the north circ that speed isnt an issue.

[Wowbagger]

I was very pleased when the A127, which is the dual carriageway serving Southend, was reduced to 50mph and average speed cameras installed. I used to use it several times a week as my route out of Southend and it was quite often jammed up after some crash or other. that became very infrequent after the speed cameras were introduced.

Shortly after this introduction, I recall a discussion at my brother's dining table. Both my brother and sister were up in arms about their "ability" to drive at 70mph along a dual carriageway that was scarcely any different from its state when it was opened in the 1930s. (Even Clement Attlee complained about it when he was PM.) The discussion became quite heated when I said how much better I thought it was that the 50 limit had been introduced. For much of the day the sheer volume of traffic made it impossible to drive safely at a higher speed, and I remain convinced it was drivers trying to exercise their inalienable right to drive at just over the 70mph speed limit that caused all the problems.

[orienteer]

The capacity of a road is greatest at speeds of between 35 and 50mph, as faster traffic has longer gaps between vehicles.

[Mr Larrington]

Speedos are not allowed to read slower than true speed, but can be up to 10% fast. Satnav generally gives a more accurate reading, but can fluctuate at times.

The one in my holiday hire car last year read 3 mph less than Emily the SatNav's figure, which I found curious.  Unless she's got Droid Rot.

[Cunobelin]

Speedos are not allowed to read slower than true speed, but can be up to 10% fast. Satnav generally gives a more accurate reading, but can fluctuate at times.

The one in my holiday hire car last year read 3 mph less than Emily the SatNav's figure, which I found curious.  Unless she's got Droid Rot.

'tis a Conspirusy, I tell you

The exil anti-speeding Elite have got to the SatNav companies and forced them to reduce the speed  - hence depriving motorists even further of teh right to drive like muppets

[Ben T]

A6097 NE Of Nottm was the first non smart motorway roadworks average sp cam route I've driven on, last yr.  I can't see any disadvantages.

The nearby A614 which also has them, is fairly straight but undulating with lots of blind summits. There used to be a lot of dangerous overtaking but with the average cams there is hardly any overtaking now.

[hellymedic]

The capacity of a road is greatest at speeds of between 35 and 50mph, as faster traffic has longer gaps between vehicles.

When I calculated these things as a 6th former, using stopping distances from the Highway Code, flow was best at something under 20mph....

[jsabine]

18mph is the speed usually quoted, I think.

[Gattopardo]

Can cycle faster than that.

[Gattopardo]

The capacity of a road is greatest at speeds of between 35 and 50mph, as faster traffic has longer gaps between vehicles.

Supposed to have longer gaps.

[hellymedic]

Well yes, that's the point! The traffic flow 'sweet spot' is between 15 and 20mph, a speed many cyclists will use.

Most petrolheads won't accept the simple mathematical truth!

[orienteer]

The capacity of a road is greatest at speeds of between 35 and 50mph, as faster traffic has longer gaps between vehicles.

These are the figures for motorways, and would think dual carriageways are similar.

[hellymedic]

I don't think the maths or physics vary with the type of road!

[Kim]

I don't think the maths or physics vary with the type of road!

The conditions do, though.  Dual cabbageways often have features that motorways don't - traffic lights, roundabouts, junctions without sliproads, etc. which are likely to affect the sweet spot for traffic throughput.  Probably in the downwards direction.

[ian]

I don't think the maths or physics vary with the type of road!

The conditions do, though.  Dual cabbageways often have features that motorways don't - traffic lights, roundabouts, junctions without sliproads, etc. which are likely to affect the sweet spot for traffic throughput.  Probably in the downwards direction.

Indeed, it just gets you to the next stopping point (or traffic) sooner, when the slower vehicles catch up. While using far more fuel and putting far more stress on your car. But no, there's convincing many drivers of this, despite the fact they experience it every time they get in their car.

[DaveReading]

https://web.engr.uky.edu/~rsouley/CE%20331/Part%20III%20F13/Traffic-4-TrafficFlowFundamentals.ppt

[arabella]

Well yes, that's the point! The traffic flow 'sweet spot' is between 15 and 20mph, a speed many cyclists will use.

Most petrolheads won't accept the simple mathematical truth!

So that means that to make best use of our roadspace we should time traffic lights etc for traffic speeds of 15-20mph.  I'm not sure what that will do to bus speeds, mind.
And demand that vehicles are most efficient/quiet and least polluting at those speeds.
And restore the element of axle weight to the vehicle excise duty and link payment thereof to mileage completed so that as the vehicle produces emissions and causes wear to the roads, so shall it be charged theretofore.
Just have to encourage the proto-cyclists until they can match vehicular speed.  Maybe that mamil film ...

[Mr Larrington]

Back in the 1970s I read an interview with a chauffeur from Victor Britain, which was basically a mega-posh minicab outfit run by Avis, who reckoned that if you timed it just right you could cruise down the A4 from the Chiswick roundabout to Piccadilly Circus at a steady 20 mph and not have to touch the brakes.  His company car was a Rolls-Royce Phantom VI weighing about three tons so as well as being more comfortable for the posho in the back the fuel savings were considerable.

[Asterix, the former Gaul.]

I don't think the maths or physics vary with the type of road!

The conditions do, though.  Dual cabbageways often have features that motorways don't - traffic lights, roundabouts, junctions without sliproads, etc. which are likely to affect the sweet spot for traffic throughput.  Probably in the downwards direction.

Indeed, it just gets you to the next stopping point (or traffic) sooner, when the slower vehicles catch up. While using far more fuel and putting far more stress on your car. But no, there's convincing many drivers of this, despite the fact they experience it every time they get in their car.

Years of driving long distance have made me slow down long before I reach the roundabout.  The idea being to reach it when there is no queue and the car in front of me is just entering the roundabout.  Because my speed is low and I am in the right gear I have plenty of time to observe traffic and can frequently enter the roundabout without needing to brake (I don't brake a lot - it puzzles my garage when they check the pads).   It is far less tiring doing it that way.