The safety of motorway speed restrictions
Discussion
Hi all
I don't do much motorway driving these days but the other day I was on a stretch with a considerable weight of traffic and the overhead restriction signals were active but not in a way which I would consider a safe way of slowing traffic to a potential hazard ahead; ie: 60 to 50 to 40
I witnessed them changing with random speeds ( I guess of numerous problems ) which I adhered to as quickly as possible without braking too hard. With this in mind I believe the cameras above send out fines for speeding motorists which seems not only unfair but if the cars break suddenly to conform to changing speed limits then safety has to jeopardised surely?
Is there anyone on here with experiences and/or facts about how these situations work in regard to speeding fines vs motorist safety?
Furthermore, who is in charge as I would like to write to them asking for the official stance?
Cheers and good luck to all who drive on motorways
I don't do much motorway driving these days but the other day I was on a stretch with a considerable weight of traffic and the overhead restriction signals were active but not in a way which I would consider a safe way of slowing traffic to a potential hazard ahead; ie: 60 to 50 to 40
I witnessed them changing with random speeds ( I guess of numerous problems ) which I adhered to as quickly as possible without braking too hard. With this in mind I believe the cameras above send out fines for speeding motorists which seems not only unfair but if the cars break suddenly to conform to changing speed limits then safety has to jeopardised surely?
Is there anyone on here with experiences and/or facts about how these situations work in regard to speeding fines vs motorist safety?
Furthermore, who is in charge as I would like to write to them asking for the official stance?
Cheers and good luck to all who drive on motorways
mgsontour said:
Hi all
I don't do much motorway driving these days but the other day I was on a stretch with a considerable weight of traffic and the overhead restriction signals were active but not in a way which I would consider a safe way of slowing traffic to a potential hazard ahead; ie: 60 to 50 to 40
I witnessed them changing with random speeds ( I guess of numerous problems ) which I adhered to as quickly as possible without braking too hard. With this in mind I believe the cameras above send out fines for speeding motorists which seems not only unfair but if the cars break suddenly to conform to changing speed limits then safety has to jeopardised surely?
Is there anyone on here with experiences and/or facts about how these situations work in regard to speeding fines vs motorist safety?
Furthermore, who is in charge as I would like to write to them asking for the official stance?
Cheers and good luck to all who drive on motorways
As far as I know, the variable speed limit signs do not monitor your speed, so no fines etc will be triggered by them. The speed cameras on motorways are separate.I don't do much motorway driving these days but the other day I was on a stretch with a considerable weight of traffic and the overhead restriction signals were active but not in a way which I would consider a safe way of slowing traffic to a potential hazard ahead; ie: 60 to 50 to 40
I witnessed them changing with random speeds ( I guess of numerous problems ) which I adhered to as quickly as possible without braking too hard. With this in mind I believe the cameras above send out fines for speeding motorists which seems not only unfair but if the cars break suddenly to conform to changing speed limits then safety has to jeopardised surely?
Is there anyone on here with experiences and/or facts about how these situations work in regard to speeding fines vs motorist safety?
Furthermore, who is in charge as I would like to write to them asking for the official stance?
Cheers and good luck to all who drive on motorways
SS2. said:
Dingu said:
It’s pretty widely accepted, even here, that a period of grace exists once the speed limit changes.
It's more than widely accepted, it's legislated that a lower speed limit cannot take effect for at least 10 seconds after the signs have changed.
The trouble is that just lifting off and coasting often doesn’t reduce speed quickly enough for the required reduction.
Variable speed limits are a nonsense and cause miles of jams - especially when they change for no apparent reason
It would be a great experiment to turn them all off for a week and change the signage to say “drive in left lane unless overtaking” at every gantry. Would be fascinating to see how the traffic flows like that.
Wouldn’t raise so much money from fines of course, which is the real aim.
Variable speed limits are a nonsense and cause miles of jams - especially when they change for no apparent reason
It would be a great experiment to turn them all off for a week and change the signage to say “drive in left lane unless overtaking” at every gantry. Would be fascinating to see how the traffic flows like that.
Wouldn’t raise so much money from fines of course, which is the real aim.
livinginasia said:
The trouble is that just lifting off and coasting often doesn’t reduce speed quickly enough for the required reduction.
Variable speed limits are a nonsense and cause miles of jams - especially when they change for no apparent reason
It would be a great experiment to turn them all off for a week and change the signage to say “drive in left lane unless overtaking” at every gantry. Would be fascinating to see how the traffic flows like that.
Wouldn’t raise so much money from fines of course, which is the real aim.
If you can’t lift in time for variable limits then either your eyesight is dreadful or your anticipation and road planning is woeful. Either way, not very PH.Variable speed limits are a nonsense and cause miles of jams - especially when they change for no apparent reason
It would be a great experiment to turn them all off for a week and change the signage to say “drive in left lane unless overtaking” at every gantry. Would be fascinating to see how the traffic flows like that.
Wouldn’t raise so much money from fines of course, which is the real aim.
The rest of your post is based on the above poor driving, so not even worth bothering with.
oyster said:
If you can’t lift in time for variable limits then either your eyesight is dreadful or your anticipation and road planning is woeful. Either way, not very PH.
The rest of your post is based on the above poor driving, so not even worth bothering with.
So you can be driving at 70, suddenly have a sign come on at 50 a few yards before you are at the gantry with a camera, and by lifting off you can refuse speed by 20mph before you reach the gantry?The rest of your post is based on the above poor driving, so not even worth bothering with.
You must have a car with amazing engine braking, mine only slows gently as it takes the lightest touch of throttle to cruise at 70.
As for the rest of my comment, it’s about MLM causing jams which I assume you think is nonsense?
Ok then ! Good luck with that.
livinginasia said:
oyster said:
If you can’t lift in time for variable limits then either your eyesight is dreadful or your anticipation and road planning is woeful. Either way, not very PH.
The rest of your post is based on the above poor driving, so not even worth bothering with.
So you can be driving at 70, suddenly have a sign come on at 50 a few yards before you are at the gantry with a camera, and by lifting off you can refuse speed by 20mph before you reach the gantry?The rest of your post is based on the above poor driving, so not even worth bothering with.
You must have a car with amazing engine braking, mine only slows gently as it takes the lightest touch of throttle to cruise at 70.
As for the rest of my comment, it’s about MLM causing jams which I assume you think is nonsense?
Ok then ! Good luck with that.
You also suggested it's all about raising money from fines, which can't be true as I often see variable speed limits on sections without a camera and then see the national speed limit sign as I approach a gantry with a camera.
As to braking, I've never seen a variable speed limit drop 20mph before. It goes 60>50>40. I might be wrong of course.
In any case it's a moot point as you are allowed a certain amount of grace after the limit change. More than enough time for your engine braking to have an effect.
I am absolutely certain that most braking seen in variable limit zone is NOT because of a lack of engine retardation. It's a different sort of retardation entirely!
The speed limit signs on motorways are 2 distinct types.
1) Any speed set that has yellow flashing lights is an advisory speed limit, not compulsory. Although if you were to be involved in an incident within the area controlled by those signs, and proved to have been going faster, then you risk a more sever penalty.
2) Any speed limit within a red circle (Normally found on Smart Motorways), are compulsory, as is a red 'X'. You must NOT exceed the posted sign, and there are now cameras that can pick up offenders, followed by a letter in the post.
Signs & signals on the motorway are either set automatically by MIDAS (Go google it) or set manually by a control room operator.
The system will not allow a speed restriction more than 20mph less than the flow of traffic immediately prior to that signal. IE. Apart from a lane closure, the lowest speed settable is 20, Setting that on a gantry would automatically set a 40 on the nest upstream gantry, and 50 or 60 on the one in front of that. Also if you set a low speed or even a red 'X' the system initially will set 50's, then steps down showing slower speeds allowing a few seconds between each change until the required setting is showing. So there is no excuse saying that "A 20mph speed limit just popped up" It can't do that!
MIDAS is controlled by electronic sensors buried in the tarmac on each lane (usually very close to the signal, look for an area of a square cut with still saw, the wires buried, then the slot filled with tar) MIDAS picks up the average speed of vehicles passing over the sensors and sets the gantry. It sets say 50's if the average speed has dropped to 45, once the average speed reaches 50 for a controlled time, it will up the speed to 60. This is why you can get a mixture of speeds due to bunching, slow HGVs, congested exits etc.
With MIDAS there is usually a VMS (Variable Message Sign) with a message of "Congestion" "Queue" etc. Anything more specific would be set by a control room operator.
1) Any speed set that has yellow flashing lights is an advisory speed limit, not compulsory. Although if you were to be involved in an incident within the area controlled by those signs, and proved to have been going faster, then you risk a more sever penalty.
2) Any speed limit within a red circle (Normally found on Smart Motorways), are compulsory, as is a red 'X'. You must NOT exceed the posted sign, and there are now cameras that can pick up offenders, followed by a letter in the post.
Signs & signals on the motorway are either set automatically by MIDAS (Go google it) or set manually by a control room operator.
The system will not allow a speed restriction more than 20mph less than the flow of traffic immediately prior to that signal. IE. Apart from a lane closure, the lowest speed settable is 20, Setting that on a gantry would automatically set a 40 on the nest upstream gantry, and 50 or 60 on the one in front of that. Also if you set a low speed or even a red 'X' the system initially will set 50's, then steps down showing slower speeds allowing a few seconds between each change until the required setting is showing. So there is no excuse saying that "A 20mph speed limit just popped up" It can't do that!
MIDAS is controlled by electronic sensors buried in the tarmac on each lane (usually very close to the signal, look for an area of a square cut with still saw, the wires buried, then the slot filled with tar) MIDAS picks up the average speed of vehicles passing over the sensors and sets the gantry. It sets say 50's if the average speed has dropped to 45, once the average speed reaches 50 for a controlled time, it will up the speed to 60. This is why you can get a mixture of speeds due to bunching, slow HGVs, congested exits etc.
With MIDAS there is usually a VMS (Variable Message Sign) with a message of "Congestion" "Queue" etc. Anything more specific would be set by a control room operator.
Edited by Gafferjim on Thursday 22 September 14:51
livinginasia said:
So you can be driving at 70, suddenly have a sign come on at 50 a few yards before you are at the gantry with a camera, and by lifting off you can refuse speed by 20mph before you reach the gantry?
You must have a car with amazing engine braking, mine only slows gently as it takes the lightest touch of throttle to cruise at 70.
Your scenario doesn't bear much resemblance to real life.You must have a car with amazing engine braking, mine only slows gently as it takes the lightest touch of throttle to cruise at 70.
At 70mph you are travelling at over 30m per second. If the lower limit sign comes on a "few yards" before you are at the gantry, you will be well past the gantry within a few seconds, long before the speed cameras actually switch on to monitor the lower limit, so there's no need for any braking at all.
oyster said:
livinginasia said:
oyster said:
If you can’t lift in time for variable limits then either your eyesight is dreadful or your anticipation and road planning is woeful. Either way, not very PH.
The rest of your post is based on the above poor driving, so not even worth bothering with.
So you can be driving at 70, suddenly have a sign come on at 50 a few yards before you are at the gantry with a camera, and by lifting off you can refuse speed by 20mph before you reach the gantry?The rest of your post is based on the above poor driving, so not even worth bothering with.
You must have a car with amazing engine braking, mine only slows gently as it takes the lightest touch of throttle to cruise at 70.
As for the rest of my comment, it’s about MLM causing jams which I assume you think is nonsense?
Ok then ! Good luck with that.
I've never seen a variable speed limit drop 20mph before . It goes 60>50>40. I might be wrong of course.
-CB
Edited by chickenbarns on Thursday 22 September 16:18
I've only ever seen one person pulled for hogging the middle lane - I was behind him on a 2 lane section of the southbound A1, just past Peterborough services it goes to 3 lanes. Cockstand in front pulls to the middle lane so I move to lane 3 to overtake. I'd seen plod on the slip road joining and after passing said MLM went back to lane 1 - idiot boy (with plod now behind him) stays in lane 2 for 2-300m, no other traffic in the vicinity. I couldn't help but laugh when the blues n 2s came on.
Brilliant to see, only that once though...
Brilliant to see, only that once though...
It's certainly not a safe way of controlling a motorway. Most people are bunched up and panic brake when they see these variable limits.
Whether thats right or wrong it's simply how it is and slamming the brakes on at 70/80mph is best avoided IMO. They would be better off advising the limit will change in a mile giving everyone chance to slow down gradually.
Whether thats right or wrong it's simply how it is and slamming the brakes on at 70/80mph is best avoided IMO. They would be better off advising the limit will change in a mile giving everyone chance to slow down gradually.
8IKERDAVE said:
It's certainly not a safe way of controlling a motorway. Most people are bunched up and panic brake when they see these variable limits.
Whether thats right or wrong it's simply how it is and slamming the brakes on at 70/80mph is best avoided IMO. They would be better off advising the limit will change in a mile giving everyone chance to slow down gradually.
The actual speeds are readable from at least 300 yds probably more, but you can see that there is something on the gantries / signs from a good half a mile away, is your brain that slow to understand that you'll need to slow down for some reason.Whether thats right or wrong it's simply how it is and slamming the brakes on at 70/80mph is best avoided IMO. They would be better off advising the limit will change in a mile giving everyone chance to slow down gradually.
Gafferjim said:
8IKERDAVE said:
It's certainly not a safe way of controlling a motorway. Most people are bunched up and panic brake when they see these variable limits.
Whether thats right or wrong it's simply how it is and slamming the brakes on at 70/80mph is best avoided IMO. They would be better off advising the limit will change in a mile giving everyone chance to slow down gradually.
The actual speeds are readable from at least 300 yds probably more, but you can see that there is something on the gantries / signs from a good half a mile away, is your brain that slow to understand that you'll need to slow down for some reason.Whether thats right or wrong it's simply how it is and slamming the brakes on at 70/80mph is best avoided IMO. They would be better off advising the limit will change in a mile giving everyone chance to slow down gradually.
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