matrix speed signs and specs
Discussion
I'm sure I read a while back that if the matrix signs on the M25 read below 70mph, all the speed cameras adjust to that speed.
Just driven round the M60 and there's specs from J1-J3 and a 40mph limit. However, today the matrix signs were showing a 30mph limit. Is it likely that the specs would then have an upper limit of 30mph average speed??
Just driven round the M60 and there's specs from J1-J3 and a 40mph limit. However, today the matrix signs were showing a 30mph limit. Is it likely that the specs would then have an upper limit of 30mph average speed??
The HDS (Highest Displayable Speed) in the matrix signs are set 10 mph below the speed limit in the area. So...........
On a "normal" section of the motorway, they are set at 60mph.
Where roadworks are, that aren't showing any speed limit, they are set to 50mph.
And where there are speed restrictions set (ie 50 mph round signs with red boarders) they are set to 40 mph.
This is so that if an incident/accident happens in that location, when signals are put on, it can't put anything higher than the HDS set.
So if on a normal motorway incident, 50's would be set (that's 20 mph below the highest speed you're supposed to be doing) In the roadworks it will automatically set lower than 50, depending on what the HDS is set at.
Any speed signal with a RED circle around it is mandatory, and you can get booked for going faster than the posted speed.
Any speed signal that doesn't have a red circle, is advisory, but should you cause/have an accident by ignoring that speed, you are liable for "dangerous driving" or "careless driving"
NOTE; Any signal with a red X, or a "wicket" "IIT"(lane 3 closed) "TII" (lane 1 closed) "TTT" (all lanes closed) is a lane closure, is mandatory, and you commit an offence if you ignore that and continue in the closed lane (The BiB around our area are now clamping down on people doing that)
An diagonally pointing down arrow over a lane, is a "lane divert" and could point either way, and is usually automatically set before a lane closure, this gives you time to move over, before you get to the actual lane closure.
On a "normal" section of the motorway, they are set at 60mph.
Where roadworks are, that aren't showing any speed limit, they are set to 50mph.
And where there are speed restrictions set (ie 50 mph round signs with red boarders) they are set to 40 mph.
This is so that if an incident/accident happens in that location, when signals are put on, it can't put anything higher than the HDS set.
So if on a normal motorway incident, 50's would be set (that's 20 mph below the highest speed you're supposed to be doing) In the roadworks it will automatically set lower than 50, depending on what the HDS is set at.
Any speed signal with a RED circle around it is mandatory, and you can get booked for going faster than the posted speed.
Any speed signal that doesn't have a red circle, is advisory, but should you cause/have an accident by ignoring that speed, you are liable for "dangerous driving" or "careless driving"
NOTE; Any signal with a red X, or a "wicket" "IIT"(lane 3 closed) "TII" (lane 1 closed) "TTT" (all lanes closed) is a lane closure, is mandatory, and you commit an offence if you ignore that and continue in the closed lane (The BiB around our area are now clamping down on people doing that)
An diagonally pointing down arrow over a lane, is a "lane divert" and could point either way, and is usually automatically set before a lane closure, this gives you time to move over, before you get to the actual lane closure.
Vaux said:
gafferjim said:
The HDS (Highest Displayable Speed) in the matrix signs are set 10 mph below the speed limit in the area.
Who sets them Jim? I have had to call the HATO RCC once as a wicket was showing 50 in a roadworks section with a mandatory 40.
Now that's confusing!
That's a cock-up. Someone has forgotton to change the HDS or the system has reset and the new HDS hasn't been entered (assuming the RCC knew about it in the 1st place of course!)
There are a number of reasons that could cause this, faulty signal, human error, or system fault. once known, the system is checked to see when it happened, and why, the police are then informed so that anyone caught during that time for speeding under the incorrectly posted speed, will not be prosecuted. Then the investigation into the cause is examined and hopefully corrected.
gafferjim said:
The HDS (Highest Displayable Speed) in the matrix signs are set 10 mph below the speed limit in the area. So...........
On a "normal" section of the motorway, they are set at 60mph.
Where roadworks are, that aren't showing any speed limit, they are set to 50mph.
And where there are speed restrictions set (ie 50 mph round signs with red boarders) they are set to 40 mph.
The Motorway Matrix Indicators (and those for dual carriageways) and the Variable Speed Limit signs (e.g. on the M25, J10-15) can be set to any figure. The VSL signs are often set to different speeds and a common "trick" on the M25 clockwise carriageway is to stick a 50 in between two 60s (usually where the gantries are close together) - Streaky On a "normal" section of the motorway, they are set at 60mph.
Where roadworks are, that aren't showing any speed limit, they are set to 50mph.
And where there are speed restrictions set (ie 50 mph round signs with red boarders) they are set to 40 mph.
FYI The variable limit on the M42 near the NEC has switchable red rings around the numbers. When first introduced, the numbers had a white ring around them, when the cameras were switched on they had a red ring around them.
Colleagues have seen it with red rings during busy periods and a few times a 60 limit with white rings when less busy - no idea if this relates to the status of the cameras though.
Local theory is that the limit must legally be displayed inside a red ring - otherwise it is just advisory, like tho old ones in the middle of motorways used to be.
Colleagues have seen it with red rings during busy periods and a few times a 60 limit with white rings when less busy - no idea if this relates to the status of the cameras though.
Local theory is that the limit must legally be displayed inside a red ring - otherwise it is just advisory, like tho old ones in the middle of motorways used to be.
Goochie said:
Local theory is that the limit must legally be displayed inside a red ring - otherwise it is just advisory, like tho old ones in the middle of motorways used to be.
Yep, the law (as I understand from some training by a serving police officer) is very clear. Red circle with number - Enforced speed limit. Anything else - advisory....
So yes, if you have a sign with a speed limit shown with a red circle and there are cameras then expect that they are active, though there is no guarantee that they actually are, but they could be.
To be honest though, it still amazes me the number of people I see getting flashed (but not necessarily prosecuted) on the M25 in the variable speed section! 99% of the traffic is doing 50 or there abouts, car zips through at 70 - flash.... er, were you not expecting that then? Was it a complete surprise that you got flashed? The fact there are massive gantries with numbers on them and that almost all of the traffic is going the same speed not give you a clue? Maybe they are too busy on the phone to notice....
streaky said:
gafferjim said:
The HDS (Highest Displayable Speed) in the matrix signs are set 10 mph below the speed limit in the area. So...........
On a "normal" section of the motorway, they are set at 60mph.
Where roadworks are, that aren't showing any speed limit, they are set to 50mph.
And where there are speed restrictions set (ie 50 mph round signs with red boarders) they are set to 40 mph.
The Motorway Matrix Indicators (and those for dual carriageways) and the Variable Speed Limit signs (e.g. on the M25, J10-15) can be set to any figure. The VSL signs are often set to different speeds and a common "trick" on the M25 clockwise carriageway is to stick a 50 in between two 60s (usually where the gantries are close together) - Streaky On a "normal" section of the motorway, they are set at 60mph.
Where roadworks are, that aren't showing any speed limit, they are set to 50mph.
And where there are speed restrictions set (ie 50 mph round signs with red boarders) they are set to 40 mph.
streaky said:
gafferjim said:
The HDS (Highest Displayable Speed) in the matrix signs are set 10 mph below the speed limit in the area. So...........
On a "normal" section of the motorway, they are set at 60mph.
Where roadworks are, that aren't showing any speed limit, they are set to 50mph.
And where there are speed restrictions set (ie 50 mph round signs with red boarders) they are set to 40 mph.
The Motorway Matrix Indicators (and those for dual carriageways) and the Variable Speed Limit signs (e.g. on the M25, J10-15) can be set to any figure. The VSL signs are often set to different speeds and a common "trick" on the M25 clockwise carriageway is to stick a 50 in between two 60s (usually where the gantries are close together) - Streaky On a "normal" section of the motorway, they are set at 60mph.
Where roadworks are, that aren't showing any speed limit, they are set to 50mph.
And where there are speed restrictions set (ie 50 mph round signs with red boarders) they are set to 40 mph.
We don't have any mandatory variable speed limit gantires in our patch, so can't really talk about them, only confirm that if they have a RED ring around them, they are mandatory,
As to seting the speeds on the matix to different readings, this can be regular with the MIDAS system setting them automatically, as it monitors the speed of traffic passing over the "pads" in the road, and adjusts the signals accordingly, usually with a VMS sign saying "queue ahead" or similar, This is all automatic. (PS. No! it doesn't monitor individual speeds, just average speeds)
The only other time it can happen, is if a lower speed is set for an incident (usually 30's or 50's) and Midas is still active after the incident. We would NOT set a lower speed between ganties showing one particular speed. (mind you, what the police did previously I can't comment on)
On the variable speed limit signs on the M25 often you see 3 of the 4 lanes with a speed limit inside a red circle (mandatory) however the other lane just has a number with no Circle.
This happens on a gantry with a cameras whcih are operating so do the cameras/authorities know that if you are in the lane where the speed limit isn't mandatory and therefore don't enforce any images taken by the system?
This happens on a gantry with a cameras whcih are operating so do the cameras/authorities know that if you are in the lane where the speed limit isn't mandatory and therefore don't enforce any images taken by the system?
gafferjim said:
The only other time it can happen, is if a lower speed is set for an incident (usually 30's or 50's) and Midas is still active after the incident. We would NOT set a lower speed between ganties showing one particular speed. (mind you, what the police did previously I can't comment on)
MIDAS itself will smooth out the speed settings so that you don't get 50/60/50/60, but rather 50/50/50/50 or 60/60/60/60 depending on the circumstances.
Signal speed settings emanating from MIDAS are also subject to signal sequencing rules which can mean that although MIDAS may request a 60, it's a 50 that gets set on street.
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