Safe Speed Forums

this is coming as a car driver rather than a trucker.

how fast do you consider to be a safe speed to travel on the motorway? taking circumstances into account, we are talking about a relatively clear road, clear conditions and you are not in a hurry.

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Richie

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If you can see well enough, far enough ahead, and the car's safely capable of it, as fast as you like. I could certainly imagine a situation in which 250 mph would be ok.

In most conditions though, 100 is too fast And probably per vehicle-mile, 50 is about the limit.

i normally sit at 65. the reason for this is so that the cars can fly past without a problem and i am not getting in the way of the trucks. i do accelerate to overtake but 65 leaves me cruising along not bothering anyone and i find it relaxing

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Richie

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On my bike 95mph is what I would want to do if the conditons allowed it. It's the middle of the rev counter, peak torque and still very little buffeting from the wind. A very comfortable cruising speed and, as far as I can tell without the benefit of all the groovy digital distractometers available in cars these days, also the best fuel consumption.

I would say that, to me on that particular vehicle, above about 125 it starts to feel 'deliberately fast'.

I also think that if I owned and rode something different, the answer would probably be different too.

There's really no 'one clear answer' to this question. It's highly dependent on vehicle, driver and subtlties of conditions. Assuming good traffic conditions, good weather and good road surface conditions, a very capable vehicle and no fear of speed enforcement, my speed would probably vary between 60 units and 150 units. I wouldn't pass another vehicle in an adjacent lane with more than about 30 units speed differential, and usually less.

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Paul Smith
Our scrap speed cameras petition got over 28,000 sigs
The Safe Speed campaign demands a return to intelligent road safety

thats why i specified normal driving conditions and not in a rush. not the fastest safe speed on the motorway. this question is aimed at individual responses rather than an average opinion

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Richie

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When I'm in my own motor I do like to get where I'm going pretty quickly, because I drive all week for a living and have no desire to do it in my spare time as well. If the conditions allow, I usually sit at 85-90mph on motorways and keep a good look-out for pigs. If I do any less than 80mph, I feel like I'm not getting anywhere and that does annoy me.

But there's no 'one clear answer' for an individual car and driver combination either. Perhaps if we asked about a 'personal comfort zone' we might get a different answer. I do believe that everyone tends towards 'comfortable speeds' but that individual 'comfortable speeds' are quite variable from individual to individual.

Or perhaps: "What's your personal perfect cruising speed in perfect motorways conditions?" If we can get the question really right, let's run a poll.

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Paul Smith
Our scrap speed cameras petition got over 28,000 sigs
The Safe Speed campaign demands a return to intelligent road safety

Still too many variables.

Dead straight motorway (or one with a good sightline), no junctions, no traffic and in an ideal world with no enforcement then it would depend on the car but certainly 100mph+ in an average family car.

More realistic, some traffic, possible enforcement, junctions, bends then 80 to 100 depending on the car. Adjusting speed for the conditions.

Normal motorway conditions, as fast as the car 2 seconds in front is going.

I usually mooch along at an indicated 65 - 70 if it's clear (in my car), about 5 to 10 mph slower if we are in my wife's MPV. I sort of got used to being the slowest car on the road a long while ago (my car is capable of much more - I think a handy power reserve is a useful thing).

I do believe the maximum limit on the motorways should be raised, although I don't think I would drive much faster if the speed limit went up by 10 mph. At an indicated 70, I can get from my southern office to home in 3.5 hours if there is no major hold up, that's fast enough not to worry me that I'm not making progress.

wrt the poster earlier who suggested some roads would support 250 mph - is there any really straight stretch (4+ miles, perhaps) of motorway in the UK? I heard an urban myth some years ago that the reason Burtonwood airbase did not have a runway anymore was because they had enough earth moving machinery to turn the M62 into a runway in the time it would take to fly from the US to the UK - my guess is that was not true in the first place and even less true now, with more bridges and roadside furniture / development close by.

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COAST Not just somewhere to keep a beach.

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Well, I can't claim to have driven at anything like 250 mph, but there's no reason that I can think of the road has to be straight - you simply need to be able to see far enough ahead to stop. An example of this would be the A1(M) between Peterborough and Huntingon, where at night the minimum speed limit is 90mph... any slower and you get pulled over for acting suspiciously.

(It's lit by the way. IMO I don't think it's reasonable to exceed 90mph on an unlit road at night, at least with normal car headlights).

well of course this is going to be relative.

on a regular basis on open roads i think 100 is plenty.... things happen pretty quick at those speeds no matter how ideal you think the conditions may be.

100+ (ish) rightly takes alot of prep even in a closed road controlled environment.

A 'straight' calulation indicates the following overall stopping distances (including thinking distance) from 250mph:

at 0.9g (emergency braking): 865 yards
at 0.45g (planned braking): 1,639 yards

I haven't allowed for aerodynamic assistance to braking which will be pretty significant in the 150mph+ segment.

FWIW

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Paul Smith
Our scrap speed cameras petition got over 28,000 sigs
The Safe Speed campaign demands a return to intelligent road safety

As a pedantic bastard with a GPS and a strong desire to go as fast as possible without putting myself at risk of prosecution, I find people who do this incredibly annoying.

L2 is too slow and L3 is too fast.

Anyway, to answer the original question. I'd go with 90-100 in the Legacy, possibly increasing after I get enough time to explore how the vehicle responds at thos speeds, and probably around 85 in the Passat.

....and the acceleration distance

down the slip road.... hoping someone gives way as you pull between two artics at 120...

Octavia 2.0Tdi

140bhp

236ft/lb of torque

M6 Toll which is usually 3 lanes of tranquility (comparatively speaking)...

Indicated 85

M6 J10A to 6, speed varies between 45 and 80 according to traffic (0 to 5mph in rush hour).............

Although given a completely clear stretch of 3 lane motorway that is straight for a couple of miles, 135 indicated

Although that was in Austria!

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Safe yet Swift.

Does it have to be arrow straight for the entire length, or would it be permissible to also include curves so gentle that they can be treated as a straight for the speeds being discussed? A quick scan of the UK in Google Earth with the roads layer turned on suggests there are several 4+ mile stretches of motorway which could do the job.

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Chris

There's also a chunk of (I think) the A50 in Lincolnshire that could do the job. I remember overtaking a 40mph queue of about 20 or 30 cars and a few HGVs in a single manouvre without exceeding the speed limit on that stretch once (went through several cameras too)

I took the question to mean something like...

"If there were no legal speed limit, what speed would you tend to find yourself travelling at, on a clear motorway?"

My answer would be about 90mph. Fast enough to keep you alert and feeling like you are making progress, but slow enough that (most) overtakes wouldn't require a massive speed adjustment, nor for driving generally to become stressful.

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In the conditions above I find 110 units to be just about ideal: I am on peak torque for my engine, which means not much pressure on accelerator pedal and therefore more mpg than at, say 90 units.

I also find it fast enough to get places in good time without stress and also slow enough to enable me to slow down for traffic ahead, overatake and than get back up to speed again.

Of course if I do want to shave off some time than 130units is just fine, but does require a little more effort on my part.