Motorway "Active traffic management"??

Paradigm

Barneysmom wrote: »

Not all the gantrys have cameras, my satnav picks them out. But no point trying to speed anyway in the mornings, it's just too heavy, they'll never solve the traffic problem.

You took the words out of my mouth

The sheer volume of traffic during busy periods has it's own calming effect on speed, it regulates itself! You don't need an overhead sign (installed at how much cost?) to tell you the speed limit is 50 when thats's all you've been doing for miles!

flang

The signs (signals) displaying the variable speeds are set automatically according to the traffic speed/flow detected by inductive loops in the road surface.
Speeds cameras (HADECS) are installed at several sites on the M42 and can be set as low as +10mph of the set speed indicated on the above lane signal. When no speed limit is displayed HADECS is usually set to 90mph although can be set as low as 80mph by the police.

The same applies on the M25/M1 & M20

gilbert_and_sullivan

Having been a regular M42 user since it opened i viewed the Active traffic scheme through horrified eyes especially the irregular use of the hard shoulder between junctions.

Well egg truly on face, yes it might be frustrating for those that want to belt along at 90 for half a mile then brake hard at the back of the next bunch, but in practice it works.

I can't quote figures but i haven't seen the aftermath of half as many accidents since it started, the constant speeds mean any accidents tend to be fairly trivial (with exceptions) and my horror at hard shoulder use unfounded.

Junction bunching where huge volumes of vehicles entered the motorway don't cause quite the same problems as before, partly because the undertaking gang won't be risking blasting down the 'clear spot' between exit and entry which occurs at junctions in the nearside lane where before some would undertake at breakneck speeds to gain a dozen spaces and have to brake sharply to avoid cars entering the motorway.
Now that exiting and entering cars have their own lane for a short time those momentary clearings of inside lane don't occur the same way.

Overall i reckon it works, if we had unrestricted roads and 20 lane motorways there'd still be some idiots fighting over the outside lane for 'king of the road' merit badges.

mikey72

I use the M42 reguarly, active traffic mangement keeps the traffic moving, it's a much better motorway than it used to be.

Kite2010

neilmcl wrote: »

I know how they work but what I'm saying is they haven't been active below 70mph since day one.

Also to pick up on another point you made, there isn't cameras behind every sign, you can tell where the cameras are by looking at the oncoming lane opposite, if there are cameras on that gantry there'll be ones on yours as well.

Do you know if the same is true with the M25 "variable speed-limit" zone?

neilmcl

Kite2010 wrote: »

Do you know if the same is true with the M25 "variable speed-limit" zone?

Couldn't tell you I'm afraid, I'm not even sure they use the HADECS system but I'd imagine there would be more traffic cops on the M25 anyway so I wouldn't risk it. One thing I do know is the Highways Agency actually openly admitted that they had no plans to use the M42 cameras for enforcement under the national speed limit and anything over that would be at the discretion of the police.

flang

not going into to much detail on the subject but the M25 cameras do work and are enforcing traffic at a min of +10mph. (set by the police)
The problem with the HADECS system is it requires all the signals on the gantry to be 100% working with no faulty LEDS. (Hence the new signals being installed). The same problem lies on all Controlled Motorways and Active Traffic Mangement motoways.

rev_henry

flang wrote: »

not going into to much detail on the subject but the M25 cameras do work and are enforcing traffic at a min of +10mph. (set by the police)
The problem with the HADECS system is it requires all the signals on the gantry to be 100% working with no faulty LEDS. (Hence the new signals being installed). The same problem lies on all Controlled Motorways and Active Traffic Mangement motoways.

So, as soon as they notice a dodgy matrix speed limit sign they have to turn the cameras off? That must be pretty often then no?

flang

rev_henry wrote: »

So, as soon as they notice a dodgy matrix speed limit sign they have to turn the cameras off? That must be pretty often then no?

Yes each signal indicator above each lane has a physical connection into the HADECS enforcement camera. (per gantry) whenever a fault is detected on anyone of the signals the camera switches off enforcement and alerts the maintenance engineer. The camer(s) will still operate and flash etc but no fines would be issued.
All cameras are digital and do not require the changing of film.

MonkeySaving?

Just to add to this conversation, the cameras on the M42 don't operate unless there is a visible matrix sign