What's the "real" speed limit on the motorway?

[whoknows212]

I don't drive much on the motorways, but when I do, I set my cruise control to the 70mph limit and it seems that nearly every other driver overtakes me

So what's the "real" speed limit on the motorway? Because it sure as hell isn't the posted 70mph one

The flow doesn't go at anything like that speed around here (M6, M61, Manchester area) some in the overtaking lane may do if conditions allow.

In NSL stretches it's mostly a mix of some going about the speed of trucks and others going pretty near true 70 ie reading 75ish on the speedo. But in many stretches it's slower.

Speed awareness courses are full of people who think speed limits are for guidance. Yes, they walk and drive amongst us.

Google Maps and because of science.

So true - this is a huge problem.

Nope. I asked that at a speed awareness course and they said it might be a common misconception but it's not right. The limit is 70.

Edit: I was on the course for doing 34 in a 30 mph limit

This. The standard of driving on our roads has dramatically decreased in the past 5 years.
tail gating, lane hogging, no regard for lane discipline or priority on round abouts. People are getting away with it because of driver aids, not through skills. Touch screens on cars and mobile phones are massive distractions.

It’s like the little boy who cried wolf isn’t it. One day they will be there

There’s discrepancies naturally in your car, discrepancies on what size wheels you’ve had fitted etc.

gps is more accurate but also glitchy in itself

Its meant to be up to 70mph.
There is always the moron doing 58mph in the middle lane so you have to go up to 75 ISH to overtake in the right to get past the middle lane hogger!!

One thing to note is that if your Speedo says 70, then you're probably only going at 65 - 67mph.

Most Speedos under report by a bit, as they're not that accurate and it's better to under report than over report. If you have Google maps, that'll show you what you're actually going at.

There a big long stretch of 50mph average speed cameras by me. I set my cruise control at 53mph, because that's actually 50 in my car, and generally end up sailing past everyone else.

There’s discrepancies naturally in your car, discrepancies on what size wheels you’ve had fitted etc.

@BourbonsAreOverated there are only discrepancies if you have a wheel size that wasn't on the car when it was built such as buying bigger alloys for your first car. Manufacturers don't have discrepancies in the cars they build. They know the wheel size that model and spec will have and it's not out on a whim. It's calculated.

You know perfectly well what the fast lane means. But it's lane 3 or 4 if you want to nitpick.

I'm also aware of the speed limit. But what I see with my eyes is that people are generally driving faster than that.

The thing is there's a bigger picture. It's not just cars that are designed for a speed limit. The speed affects the design of the whole road: slip road length, sign sizes and lettering, distances between junctions, curves. Lots of older junctions are substandard. The national speed limit has to work for the whole network, all cars and all drivers. Obviously a few mph (on your speedo) won't make much difference but much over that will be increasing the risk especially with all the phone users/tailgaters in the mix.

I think speeding in roadworks is worse. Road works tend to use fixed (metal) signs rather than Electronic ones. Having crews out changing all those signs every night and weekend between shifts would put more humans at risk. Putting cones and signs out is one of the riskiest jobs in the network.

Traffic management doesn't put speed limits on for fun but the logistics mean that there has to be a safety margin and you might not see the hazard yourself.

Of course lots of people exceed the limit without any problems but don't complain if a HADECS camera gets you or you break down and nobody bothers to observe the gantries because they can't see the problem.

In case of doubt look up the statistics for probability of having a crash with increasing speed and then driver/passenger fatalities with speed in modern cars.

Modern cars don’t always feel like they’re going as fast as they are (better noise insulation, suspension etc) but that doesn’t make reaction times any better - at 90mph you have a lot less time to react than at 70mph. The type of car also matters - not just for your survival but also for that of whatever you hit. In a high speed accident, the driver in a tank like SUV doing 95mph might survive, but the Corsa it hits will be shredded.

It’s really common on my commute to have signs showing 40mph where there are no works and no congestion.

So... The 40mph is working at smoothing out the traffic flow at peak time then isn't it?

Depends on your personal risk assessment and degree of legal compliance:

70mph legally correct answer (unless it's a lower signed limit)

77-78mph - 10%+1mph leeway before you get a ticket (most locations, at discretion of chief constable). Also why many trucks go through the 50mph zones still on their speed limiter (i.e. 56mph).

<90mph - worst case is only 3 points (Band A)

<=99mph - unlikely to end up in court below 100mph (provided conditions clear / dry and road not too busy, and you pass the 'attitude test' when stopped). Likely, at worst, to be 6 points unless other aggravating circumstances.

Obviously the above is a bit flippant because with increasing speed comes greater risk of killing yourself or (worse) someone else. I'm just articulating how I think other drivers may think about their speed.

The real limit is 70. People who go faster always run the risk of being stopped or being arrested if they’re involved in an accident.

@DoctorAngelface calling it "the fast lane" suggests that there are different speed limits applied to each lane, similar to a swimming pool. The outside lane is unambiguous.

At the time I pass through the relevant stretch of road virtually everyone is driving at a significantly higher speed. So any necessary smoothing has happened and drivers are freely going at the speed the conditions allow. Why are the signs not updated to reflect that? The limit is clearly artificially low as there is no congestion despite almost total noncompliance.

I’m prepared to find out I’m missing something here, but from my perspective as a driver the only things this 40mph stretch adds is a dilemma about how to approach it.

I think if I were getting it wrong I’d have had some speeding tickets by now. So I’d say the police one is scoring the same as my satnav.

Calling it the outside lane is also not strictly correct, if you want to be petty. It's lane 3 or 4.

I hardly think people are putting their foot down purely based on semantics either.

Some areas it’s to reduce pollution for local residents- where air quality has been particularly poor. There’s a stretch of motorway in the Birmingham area. Much too close to housing.

My speedometer reads about 4mph lower than my Google maps, so when I am travelling at 70 on the speedometer lots of people overtake me.

I think that OP’s question stems from the fact that it’s possible to be doing 70-73 in the outside lane (while overtaking a line of slower vehicles ahead of you in the middle lane, so no possibility to pull in) and invariably someone will come up behind you going much faster and flash or tailgate you. The message being that they consider that they have the right to go faster and you are slowing them down. It takes a lot to stand your ground in those circumstances and often the only option is to exceed the speed limit until you are level with a gap in the middle lane.

I know the areas you mean, @SensibleSigma . My experiences with variable speed around Birmingham have been pretty good as you can see how it’s used to improve the flow of traffic and, yes, air quality.