As discussed everywhere, ministers are looking to increase the motorway speed limit to 80mph:

[Transport Secretary Philip Hammond] added: “Now it is time to put Britain back in the fast lane of global economies and look again at the motorway speed limit which is nearly 50 years old, and out of date thanks to huge advances in safety and motoring technology.

“Increasing the motorway speed limit to 80mph would generate economic benefits of hundreds of millions of pounds through shorter journey times.”

By generating ‘economic benefits’, he presumably means financial benefits to King Abdullah or the head of any other oil producing nation; as anyone knows that the faster you drive, the more fuel you rip through.

The high priest of petrol-heads, Jeremy Clarkson, writing in a post last month on the Top Gear site, had a rather surprising take on this:

It is, however, not fine to have an 80 limit in Britain because then, the police will turn a blind eye to those doing 95. And 95 on British motorways is too fast. There are too many other cars, too many Nissans, too many pensioners coming the other way on the wrong side of the road.

But what about the other impacts? Damian Carrington, writing in the Guardian, summarises neatly:

More people will die and be injured in crashes: more work for doctors, nurses and ambulances. More cars will be written off or damaged: good news for motor manufacturers and mechanics. And the biggest, most profitable companies in the nation – BP and Shell – will have yet more money poured into their coffers as drivers pump more petrol into their tanks. The fact that emissions of climate-warming carbon dioxide will leap too seems, astonishingly, a secondary concern in the short term.

I’ve not actually looked too closely at the NO2 increases this would entail (though presumably they would also go up, as would the likelihood of photochemical smog etc). The point about road deaths is not to be ignored either.

A few years ago, I crashed my car. As was a standard thing at the time, I had to go on a road safety course. It was actually pretty useful and taught many interesting things; most memorably was how just a small increment in speed at the point of impact can cause a shocking effect on the human body. The odds of people walking away from a higher-speed crash are greatly diminished, as revealed in the gruesome photos we were shown.

So then: just another typical, ill-thought-out, cheap attempt at winning popularity from a backward-looking government.

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About Mark Newton

Born in 1981, live in the UK. I write about strange things.


  1. most memorably was how just a small increment in speed at the point of impact can cause a shocking effect on the human body. 

    Indeed. But this is most relevant at suburban speeds. By the time you get to motorway speeds, the difference in survival rates between 70 and 80 is … not negligible, but not very large.

    I’m not really sure how I feel about this policy. A lot depends on whether it is actually enforced, I think. If 80 is enforced, then it seems more like a shift in image rather than reality, since that’s the speed a lot of motorway traffic flows at now; it could even be a net benefit, since I would bet you a reasonable amount of money that most motorway accidents are caused by people doing a fair bit more than 80. On the other hand, if it’s not enforced, and 95 does become the new normal, that’s not so good.

    And it will be paired with an expansion of 20 zones. This is an unqualified good thing. And to be callously utilitarian about it, I suspect the lives saved by more 20 zones will massively outweigh the lives lost due to an 80 limit. Last year’s stats show that there were 1,551 accidents in 20 zones (6 fatal), 5443 accidents in 70 zones (150 fatal), and 100,174 accidents in 30 zones (545 fatal).

    In an ideal world we’d expand 20 zones, cut most country A-roads to 50 (since that’s where a lot of fatal accidents happen), and not increase the motorway speed limit. On balance, though, I think I’m comfortable with 20 for 80 as a trade-off.

    (It would be helpful to know the hours of travel per year for each road type, so that we could work out the number of accidents per hour of travel and make the numbers more directly comparable. Any idea whether that sort of information is available anywhere?)

  2. As much as people love to hate on Clarkson (Who at the very least helps fund the BBC with the sheer popularity of Top Gear), he’s a very sensible man and that quote just shows that he has his head screwed on. Raise the speed limit, people are going to push it further. There’s enough dangerous drivers on our motorways – such as people doing 50 on the motorway in normal traffic – without needing to add more.

    As for the increase in fuel usage, I’m kinda confused. If you’re going 80mph for an 80 mile journey, you’re burning fuel for less time than you are if you do 70 for that journey. I’d have thought that being on the road for less time would at least partially counter-balance the decrease in efficiency but no-one seems to be mentioning that. Maybe it’s insignificant? I don’t know, I’m not a car boffin.

    P.S. Boo cars, yay public transport!

  3. “Indeed. But this is most relevant at suburban speeds. By the time you get to motorway speeds, the difference in survival rates between 70 and 80 is … not negligible, but not very large.” 

    Well, I can only speak for the few incidents we were shown on the road safety course. For its ‘showpiece’ on deaths, it mainly focussed on the damage at higher speeds and, well, you’d be surprised that a 10mph difference can make – though of course it depends on what you have behind your seat (one driver was beheaded by a large tool box), breaking distances, technology, who’s in the car, what distractions there were, and so on. 
    Incidental stuff aside, point 7 here reveals interesting results. It briefly shows where there have been marginal increases in speed limits in a couple of different countries, and the increase in fatalities that followed. What’s defined as an ‘accident’ re: the DoT incidentally? I’m wondering if a crash in slow-moving rush-hour traffic on a motorway has parity with a high-speed crash.Regarding that final point, I’m afraid my Google-Fu is weak this afternoon…

  4. Who would have thought Clarkson made sense for once?

    To my knowledge, each car has an optimal speed at which its engine is working as good as it ever will. Go above this speed, and you’re burning far more fuel than you would have if you had continued at your optimum. Even 70 is probably above the optimum for many cars.

  5. I’ve been on one of those courses too, a couple of months ago, and they made a big deal out of the difference between 25 and 30 compared to 70 and 75. Of course, my course was designed to encourage slower driving in suburban areas, so it’s not a surprise that’s where they put their emphasis…

    Your point 7 seems to reinforce my point above. If the number of motorway deaths increased by 40%, it would go from 150 a year to 210 a year. Based on the rates in the UK spreadsheet I linked, going from 30 to 20 in a substantial number of areas would probably save a couple of hundred lives. (And of course the differential for less severe types of accident would be even greater.)This PDF (linked from the bottom of the spreadsheet) has the definitions of accident severity.

    “Accident: Involves personal injury occurring on the public highway (including footways) 
    in which at least one road vehicle or a vehicle in collision with a pedestrian is involved 
    and which becomes known to the police within 30 days of its occurrence. One accident 
    may give rise to several casualties.  “Damage-only” accidents are not included in this 

    “Slight accident: One in which at least one person is  slightly injured but no person is killed or seriously injured.”

    “Serious accident: One in which at least one person is seriously injured but no person 
    (other than a confirmed suicide) is killed. “

  6. Yes, per the graph you linked from your post. Of course it’s also true the other direction — the optimum for most cars is somewhere in the region of 40-55, if you go more slowly than that you’re also operating below peak efficiency.

  7. Thanks for the definitions – very useful.

    So, given that there would be an estimated extra 60 people killed on the roads (and presumably 7500+ accidents) with this limit increase, and assuming that data is transferable to the far busier motorways we have in the UK, would you still support that increase along with the trade-off?For me, irrespective of a trade-off against lowering the limit in urban zones, anything that means this number lives are lost (and of course, there are all the injuries to add to the tally), then that’s surely a bad thing. Why should there be a trade-off at all? Then you have to add that to the other environmental costs involved and health impacts from increased car emissions, which haven’t improved for many years, and which also contribute to deaths, illnesses and so on…

  8. Why should there be a trade-off at all?

    Because this is the real world. 🙂 As I said in my first comment, ideally, sure, we wouldn’t increase the motorway speed limit. But we’re not being offered the policy in isolation, and if we’re getting more 20 zones out of it, with the likely much bigger reduction in accidents and fatalities that entails, therefore reducing the *overall* numbers of accidents and fatalities, I think I can live with it.

    Of course, clearly environmental reasons are much lower down my list of reasons for changing speed limits than they are yours; increasing the 20 zones will also have negative environmental costs per the discussion about engine efficiency upthread, but that doesn’t bother me, because it is likely to save a lot of lives.

  9. Well, the real world has managed for 50-odd years without requiring the trade-off! Few people (other than the odd motoring lobby group, but not even Clarkson) have been asking for it. It smacks of trying to appease voters on the right (this was announced alongside an equally pointless weekly rubbish collection piece). And 60 people extra will die each year because of it (the speed limit, not the rubbish collection!).

    There are possibly more complex issues with the many thousands of deaths attributed to pollution from car exhausts, too, but that’s another can of worms entirely…! Do you listen to Costing the Earth on Radio 4? If you don’t, there was a fascinating look at this very subject a week or so ago. 

  10. Well, the real world has managed for 50-odd years without requiring the trade-off! 

    Hmm, has it? Road safety has improved steadily, but the 30 limit has seemed pretty sacrosanct in my lifetime. I’m glad to see that eaten into. If I thought this government could be shamed into only passing the 20 part of these changes, I’d be all for it; but I suspect that if this backfires they’ll drop *all* the changes.

    (I don’t think weekly rubbish collection is pointless, but I do agree it’s an absurd thing to prioritise given their self-imposed financial constraints.)

    I’ve listened to Costing the Earth occasionally, but not regularly. Is it available as a podcast, or only via iPlayer?

  11. It’s available as a podcast, yes – weekly for the most part, with the occasional extra production. It’s probably the best environmental issue news programme out there: remarkably balanced, and is in-depth whilst coming across as entertaining (which is a difficult job to pull off).