It’s 20mph for a reason

Road safety 20mph

It feels like many critics of 20mph zones would have been the same people who railed against seatbelt legislation and the introduction of the 70mph motorway limit; a barking at the moon that’s soon forgotten by history.

In 1967, a noisy crowd marched through London protesting against Barbara Castle’s Road Safety Act because it included restrictions on drink driving. It’s likely that objections to 20mph limits will one day be viewed as a similarly curious historical footnote.

However, in the meantime, the fact  towns and cities are cleaner, safer for walking and cycling, and generally nicer places to spend time when car speeds are reduced rankles with those who’d prefer to prioritise driving at any cost. No surprise then that some resort to flimsy arguments in favour of the status quo. Here are three:

20mph speed limits force me to drive in a lower gear

This might be the case if you’re driving a high-revving classic sports car, but if you’re behind the wheel of a modern car you’ll be able to comfortably maintain 20mph in third or even fourth gear. If you don’t believe us, then watch our our video. We drove a little city car with a one-litre engine on 20mph-limited streets to see how it performed.

20mph limits mean I’ll use more fuel

Reducing peak road speeds in areas where people live, work or play saves energy and cash. Research into typical stop/start urban traffic by Future Transport reveals fuel efficiency peaks with speed capped at 20mph. Drivers  benefit from up to 10p per mile in fuel savings without trips taking longer. That’s a 30 per cent saving in urban fuel costs.

In built-up towns and villages, the key factor in fuel consumption is the number of times you accelerate back up to the speed limit after slowing down or stopping – the higher the speed limit then the greater that acceleration influences fuel consumption.

Engineering consultants at Future Transport modelled the fuel efficiency in accelerating from stopped to between 5 and 40mph. For a typical urban drive cycle – with repeated acceleration and deceleration – fuel efficiency peaks at a top speed of 15-20mph.

To drive at 20mph I need to keep my eyes focussed on the speedo and that’s not safe

If you’re unable to maintain a particular speed without your eyes glued to the speedo, driving’s not for you. One of the things learner drivers master early on is the ability to keep to a particular speed while occasionally glancing at the speedometer to check their speed hasn’t crept up. It’s a basic skill that’s assessed by examiners as part of the driving test. After all, driving steadily at 20mph is no different from maintaining 30, 40 or 70mph.

Reducing road harm

The most compelling argument in favour of 20mph limits is the reduction in road harm. When a person is struck by a car they are 7 times more likely to die if the vehicle is travelling at 30mph.

20mph poster

The ethical choice

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  1. Vinnie


    I have a 1ltr car and can’t drive at 20mph in 3rd gear. It’s quite hilly were I live so I’d stall. Also the 20mph speed bumps often have to be taken much slower because of parked cars and general giving way to others. I do quite enjoy driving at 20mph when in a 20 zone, it’s amazing how many people overtake or look really annoyed in the rear view ; yep that’s how close they get.

  2. Steve Connolly


    In our Cornish village we want 20mph signs but have now been told that this won’t even be considered until 2025. This is madness considering the tiny cost to change a few signs.

  3. David Bowen


    20mph is fine in purely residential streets and outside pedestrian intense places such as schools but in a road which links two separate residential areas flanked by a few set back dwellings ànd where sighting a pedestrian is a great rarity 20mph is already causing long tail backs, frustration and dangerous overtaking. More commonsense applied to when and where would win public support far more easily

    • The ETA


      As a matter of interest, what is it about the 20mph that you think is causing tailbacks as generally speaking reduced speeds often help traffic flow

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