What exactly is it about 40mph?

[Johnnytheboy]

I've become vaguely obsessed about this, but please feel free to tell me I'm wrong.

I drive approx 40k miles a year, an awful lot of them on unclassified rural roads.

I spend a lot of those miles stuck behind one of the South West's finest numpty slow drivers.

I'm not massively impatient, if someone wants to go slowly I've just got to put up with it until I can get by, or they turn off.

What does astound me is how frequently, when I'm following someone slow down an NSL road, they are doing an exact, constant, 40mph.

This raises several questions.

1. Have they chosen 40 mph consciously?
2. If so, why?
3. If not, why do so many drivers seem to default to 40mph?

I know I am starting to sound a bit tin-foil-helmet, but the frequency I encounter people doing a steady, exact 40mph leads me to believe either

1. They mistakenly believe 40mph is the limit on unclassified roads.
2. They believe 40 SHOULD be the limit on unclassified roads.

I sincerely hope I'm not the only one that has observed this phenomenon...

[soad]

Who cares? Why get frustrated? Or try to understand these fkers?
Overtake and be done with it. Life's too short.

[matthias73]

Try driving a non PH car in a most relaxed fashion with absolutely no care for how fast you drive along an NSL and you will probably find yourself doing about 40mph.

Whenever I find myself driving with my dad down an NSL I do between 40 and 50mph. Granted in my e39 its quite easy to get up to 60mph but I find it's generally more pleasant for the old man and myself if I don't have to keep speeding up and then slowing down for corners. Will happily pull over for someone to overtake, mind.

[Zwolf]

Johnnytheboy said:

This raises several questions.

Just one? With 20mph of legal leeway, why don't you overtake slow drivers more often instead of sit there getting frustrated at them?

The person behind you might be thinking the same of you as after all you're happy to do the same, meaning they have to overtake two if they want to, which could be riskier, so they don't.

Et voila! The 40 mph rolling roadblock on an NSL road that you just joined - it's not all the fault of the driver at the front...

[Sheepshanks]

Johnnytheboy said:

I drive approx 40k miles a year, an awful lot of them on unclassified rural roads.

Do you really mean unclassified roads? Not A or B roads?

I do a lot of miles, and live in a rural area, but still don't do any distance on unclassified roads.

People doing 40 on single carriageway rural A roads is pretty common, but the HGVs are limited to that speed and many drivers would never overtake them so they get in a "window" in the traffic and just sit there.

[anonymous-user]

i see this all the time on b roads, i am guessing 40 is to to them 60 to a norm, so think they are doing a normal speed.

Edited by The Spruce goose on Friday 20th June 21:34

[Johnnytheboy]

I'm as ever genuinely impressed by posters ability to misread the OP's post.

1. I'm not making a point about people driving slowly, just that the distribution of slow people's speed seems to exhibit a pronounced spike between 39 and 41 mph.
2. I have already mentioned that I am not frustrated at being stuck behind them and, yes, I realise that overtaking them is the ideal outcome.
3. Most of the time I observe this I am driving a 104hp van, so driving a non-PH car is already covered.

[siovey]

Yep, you follow them into a 30mph and they still stay at 40 mph. Yet, they never seem to get caught. Just another example of moronic driving on Britain's roads.

[mp3manager]

Zwolf said:

Johnnytheboy said:

This raises several questions.

Just one? With 20mph of legal leeway, why don't you overtake slow drivers more often instead of sit there getting frustrated at them?

The person behind you might be thinking the same of you as after all you're happy to do the same, meaning they have to overtake two if they want to, which could be riskier, so they don't.

Et voila! The 40 mph rolling roadblock on an NSL road that you just joined - it's not all the fault of the driver at the front...

I will quote this every time some car-driving numpty on here thinks that I as a truck-driver, should pull into laybys, despite travelling at 40mph, which is the maximum speed for a truck on a single-track A-road.

[Johnnytheboy]

Sheepshanks said:

Do you really mean unclassified roads? Not A or B roads?

I do a lot of miles, and live in a rural area, but still don't do any distance on unclassified roads.

Yes.

Many of Dorset's non-trunk A and B roads are a disaster of 30 and 40 limits, so - barring the numpties this thread's about, if you know the minor roads you can often make better progress on minor roads.

[alpha channel]

siovey said:

Yep, you follow them into a 30mph and they still stay at 40 mph. Yet, they never seem to get caught. Just another example of moronic driving on Britain's roads.

Just about to say this myself, all of those that I come across doing forty simply carry on doing forty when they hit a thirty limit with very few exceptions.

[Jasandjules]

Zwolf said:

Just one? With 20mph of legal leeway, why don't you overtake slow drivers more often instead of sit there getting frustrated at them?
..

Well I don't know about the OP's route but many roads around here have very limited opportunities to overtake, straights are few and far between.

[Johnnytheboy]

mp3manager said:

Zwolf said:

Johnnytheboy said:

This raises several questions.

Just one? With 20mph of legal leeway, why don't you overtake slow drivers more often instead of sit there getting frustrated at them?

The person behind you might be thinking the same of you as after all you're happy to do the same, meaning they have to overtake two if they want to, which could be riskier, so they don't.

Et voila! The 40 mph rolling roadblock on an NSL road that you just joined - it's not all the fault of the driver at the front...

I will quote this every time some car-driving numpty on here thinks that I as a truck-driver, should pull into laybys, despite travelling at 40mph, which is the maximum speed for a truck on a single-track A-road.

You really are a one trick pony, aren't you?

Just because you don't have to doesn't mean you morally shouldn't.

Anyway, back on topic....

[Johnnytheboy]

Jasandjules said:

Zwolf said:

Just one? With 20mph of legal leeway, why don't you overtake slow drivers more often instead of sit there getting frustrated at them?
..

Well I don't know about the OP's route but many roads around here have very limited opportunities to overtake, straights are few and far between.

If Zwolf re-reads my first post he'll see I've already covered that anyway.

It's not about my desire to get by them, it's my mystification at the frequency of 40mph being the speed of the car in front.

[Zwolf]

Jasandjules said:

Well I don't know about the OP's route but many roads around here have very limited opportunities to overtake, straights are few and far between.

Which possibly answers the question where that is the case as to why ~40mph is chosen - with straights few and far between, maintaining a constant lower speed likely has a similar journey time overall as one where 60mph is reached for short spells, more braking is required and a less smooth and more effortful and less economical drive overall for no appreciable gain in average speed from A to B. Most people don't like effort, especially when it comes to driving, so just "go with the flow". Hence the situation the OP describes arising - maybe.

[redtwin]

matthias73 said:

Try driving a non PH car in a most relaxed fashion with absolutely no care for how fast you drive along an NSL and you will probably find yourself doing about 40mph.

Whenever I find myself driving with my dad down an NSL I do between 40 and 50mph. Granted in my e39 its quite easy to get up to 60mph but I find it's generally more pleasant for the old man and myself if I don't have to keep speeding up and then slowing down for corners. Will happily pull over for someone to overtake, mind.

That about sums what I think happens.

There are quite a few NSL B roads I have been on where anything even approaching the 60MPH limit feels way too fast to be travelling when you can't see past the next corner or over the brow of a hill. I tend to find myself dropping to a speed where I know I can safely stop should I go round the corner and find a tractor stopped in the middle of the road.

That "comfortable" speed is probably right around 40MPH.

[Johnnytheboy]

At the risk of repetition I'm not referring to people defaulting to 'about' 40mph, but more or less exactly 40mph.

Irrespective of road conditions, these are frequently minor roads I'll do 70 down the straights on.

[LHD]

40mph.

It's fast enough to kill you but it's slow enough to make you think you're safe.

[Sheepshanks]

Johnnytheboy said:

At the risk of repetition I'm not referring to people defaulting to 'about' 40mph, but more or less exactly 40mph.

Irrespective of road conditions, these are frequently minor roads I'll do 70 down the straights on.

They're probably scared of meeting van drivers like you coming the other way.

[Johnnytheboy]

Sheepshanks said:

Johnnytheboy said:

At the risk of repetition I'm not referring to people defaulting to 'about' 40mph, but more or less exactly 40mph.

Irrespective of road conditions, these are frequently minor roads I'll do 70 down the straights on.

They're probably scared of meeting van drivers like you coming the other way.

If that was the case, and they had more cognitive capacity than I imagine, they'd adjust their speed to take account of the distance ahead of them they could see, rather than driving at a constant 40mph just in case someone materialised ahead of them on a straight, clear road.