The Student Room Group

M25 variable speed limits

I understand that by law, the speed limit posted by the last sign applies until you have passed the next one. On most of the M25, there is a variable speed limit and if it is higher on one screen than the previous screen, I always wait until I have gone past it until I speed up. However, nearly every other driver seems to speed up as soon as they see the higher speed limit (perhaps because the next speed camera will be set to this?). I find this very frustrating as it means that to avoid lane hogging, I find myself moving into a slower lane before a speed limit increase, only to move out again after I have passed the sign. I would be interested to hear what other people do.

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Reply 1
Thanks I didn't realise those stickers are available for free. It is particularly worrying sometimes when there is someone tailgating me and the speed limit goes down, that they may go into the back of me, especially when the new speed limit sign is hard to see as it is partially covered! The fact that most people speed makes speed limits dangerous sometimes :confused:
Reply 2
Original post by maths42
I understand that by law, the speed limit posted by the last sign applies until you have passed the next one. On most of the M25, there is a variable speed limit and if it is higher on one screen than the previous screen, I always wait until I have gone past it until I speed up. However, nearly every other driver seems to speed up as soon as they see the higher speed limit (perhaps because the next speed camera will be set to this?). I find this very frustrating as it means that to avoid lane hogging, I find myself moving into a slower lane before a speed limit increase, only to move out again after I have passed the sign. I would be interested to hear what other people do.

Just speed up like everybody else..

You'll reach a point in your driving career when you realise that doing everything by the book is wrong - keep with the flow of traffic.
Reply 3
Only on a motorway.
Reply 4
Original post by IWMTom
Only on a motorway.

I disagree. Motorway speeding is treated very seriously with a potential fine of up to £2500 (depending on income) on top of the points (incidentally, how do they calculate the fine if you are self-employed and your income varies?). The time saving of speeding up before you have passed the sign is negligible.

In some situations it is clearly ridiculous that a speed limit sign is not posted earlier (particularly on slip roads!) but at the end of the day I don't think it's ever worth the risk of speeding.
Reply 5
Original post by maths42
I disagree. Motorway speeding is treated very seriously with a potential fine of up to £2500 (depending on income) on top of the points (incidentally, how do they calculate the fine if you are self-employed and your income varies?). The time saving of speeding up before you have passed the sign is negligible.

In some situations it is clearly ridiculous that a speed limit sign is not posted earlier (particularly on slip roads!) but at the end of the day I don't think it's ever worth the risk of speeding.

Sigh.. you'll learn one day.
Reply 6
Original post by IWMTom
Sigh.. you'll learn one day.

Or you will if you get caught speeding...
What is shocking is when professional drivers try to make you break the law. I was going at 20 in a 20 speed limit recently and a taxi behind was flashing at me madly...I wasn't going slowly because I wanted to, it's the law!
Reply 7
Original post by maths42
Or you will if you get caught speeding...
What is shocking is when professional drivers try to make you break the law. I was going at 20 in a 20 speed limit recently and a taxi behind was flashing at me madly...I wasn't going slowly because I wanted to, it's the law!

You probably weren't doing 20 - taxis tend to have GPS speedos so they can take advantage of the tolerances.

It's the way of the world, mate - you can't follow every rule every day of your life - driving requires common sense.

Don't forget, the holy highway code also states not to flash your headlights to convey any messages, and yet that's one of the most helpful things on the road!
Reply 8
Original post by IWMTom
You probably weren't doing 20 - taxis tend to have GPS speedos so they can take advantage of the tolerances.

Even so, it's not reasonable to flash at someone for going at slightly less than the speed limit. I'm sure that he realised that my speedo was probably reading 20.

Also the speed limit is a limit, not a target. Whilst 20 is sometimes a ridiculously low limit, it is acceptable to be going a little bit slower than the speed limit! Imagine if I had been flashed at for going a 60 on my speedo in a nsl!
Reply 9
Original post by maths42
Even so, it's not reasonable to flash at someone for going at slightly less than the speed limit. I'm sure that he realised that my speedo was probably reading 20.

Also the speed limit is a limit, not a target. Whilst 20 is sometimes a ridiculously low limit, it is acceptable to be going a little bit slower than the speed limit! Imagine if I had been flashed at for going a 60 on my speedo in a nsl!

Given good conditions, it absolutely is a target. Unless there are good reasons to the contrary, you should be on or very very close to the limit of the road. The mantra that "it's a limit not a target" is absurd given the DVSA throw faults for failing to make progress.
Reply 10
Original post by IWMTom
The mantra that "it's a limit not a target" is absurd given the DVSA throw faults for failing to make progress.

I would imagine that you would fail a driving test for going a bit over 20 in a 20 zone though, but not for going a little bit under 20.

Also clearly there are many situations in which it would be very dangerous to attempt to go at the speed limit, albeit not often when it is only 20.
Original post by maths42
I would imagine that you would fail a driving test for going a bit over 20 in a 20 zone though, but not for going a little bit under 20.

Also clearly there are many situations in which it would be very dangerous to attempt to go at the speed limit, albeit not often when it is only 20.


How long have you had your licence for? It sounds like you’ve had it for a maximum of 24 hours :laugh:
Reply 12
Original post by RoyalSheepy
How long have you had your licence for? It sounds like you’ve had it for a maximum of 24 hours :laugh:

A few years actually but no one is allowed to speed, however much experience they have had!
Reply 13
Original post by maths42
I would imagine that you would fail a driving test for going a bit over 20 in a 20 zone though, but not for going a little bit under 20.

Also clearly there are many situations in which it would be very dangerous to attempt to go at the speed limit, albeit not often when it is only 20.

It really irritates me when people do 28 in a 30 (indicated) because below 30, I need to change down from 4th to 3rd.. then they'll speed up a bit.. then slow again.. then up.. then down.. then up.. then down.. constantly hovering within the 28-32 range, but never staying consistent. Constant gear changes.. pain in the arse.

**** other drivers.
Reply 14
Original post by IWMTom
It really irritates me when people do 28 in a 30 (indicated) because below 30, I need to change down from 4th to 3rd.. then they'll speed up a bit.. then slow again.. then up.. then down.. then up.. then down.. constantly hovering within the 28-32 range, but never staying consistent. Constant gear changes.. pain in the arse.

**** other drivers.

I do find it very irratating when people go slowly in NSL when the road is straight and the conditions are good. This happens all the time, only for them to get well ahead of me when the speed limit drops to 30, at which point others start to tailgate me.

Going slightly below the speed limit is sensible though, to reduce the risk of speeding by accident. I'm sure that you could manage to drive at 32 in the same gear that you use at 28 :confused:
Reply 15
Original post by maths42
I do find it very irratating when people go slowly in NSL when the road is straight and the conditions are good. This happens all the time, only for them to get well ahead of me when the speed limit drops to 30, at which point others start to tailgate me.

Going slightly below the speed limit is sensible though, to reduce the risk of speeding by accident. I'm sure that you could manage to drive at 32 in the same gear that you use at 28 :confused:

Yeah, I could use third above an indicated 30, but it's uneconomical in my car. I shouldnt have to sacrifice fuel economy because some old biddy infront can't manage a stable speed.
Reply 16
Original post by IWMTom
Yeah, I could use third above an indicated 30, but it's uneconomical in my car. I shouldnt have to sacrifice fuel economy because some old biddy infront can't manage a stable speed.

You could just stay at 28 then?
Reply 17
Original post by maths42
You could just stay at 28 then?

I shouldn't have to if the limit is 30 and the conditions are perfectly acceptable.
Reply 18
Original post by IWMTom
I shouldn't have to if the limit is 30 and the conditions are perfectly acceptable.

I shouldn't have to stop walking through a shop because someone decided to steer their trolley into my path! I shouldn't have to ask staff to bring out more clean glasses at a hotel breakfast! Yes there are things that we all "shouldn't have to" do because of other peoples' actions but we have to live with it.
I don't mess with variable speed limits on motorways, after I pass the NSL sign is when I'll start planting it back up to 70-75. I keep all the way to the left and everyone else can frankly do what they want.

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