Evan Davis: Warum so viele Menschen die Geschwindigkeitsbegrenzung von 20 Meilen pro Stunde überschreiten

Actually quite a good article but a few issues.

The Belfast study mentioned showed a reduction of casualties on 20mph limits, but spotted an increase overall when you factored in other roads. The main reason for that was thought to be displacement; traffic was actively avoiding the 20mph roads and using other, less suitable roads and having their accidents there at the same/greater rate. Similar thing happened in Manchester a few years previous – in both cases they removed the default 20 in favour of targeted limits.

This displacement is a big issue; I’ve seen some TomTom data on it in Wales where traffic has gone from using a well designed A category road with great active transport infrastructure to an uncategorized road with no pavement and lots of walkers and cyclists using it- it was something like a 250% increase in traffic which is crazy.

The data in Wales is riddled with statistical issues; prior to the limit reduction they found the police weren’t recording speedlimts correctly and most were the default value. It’s a shame, but it makes any comparison impossible.

20 limits are a powerful tool for highlighting dangers, when targeted.

As someone who lives in Wales, firstly there’s decades of the limit being 30 or more so in some places 30 just feels normal, because it was normal. Then there are 20 roads that probably shouldn’t be – things like spinal roads through housing developments that have no actual housing on them.

I think targeted 20mph speed limits are a good thing. But not as a blanket rule that many councils are now implementing.

There are lots of headline stats in there about the roughly one third reduction in collisions as well as deaths and serious injury. But we need a greater understanding of the causes of those accidents. Was it always the driver at fault or did the pedestrian/cyclist do something that meant it was unavoidable. Changing a variable without understanding why it has an effect is not very helpful.

We used to have adverts on the TV all the time for the Green Cross Code Man and ‚Stop, Look, Listen‘ is very familiar to previous generations. Now though there appears to be nothing and by constantly pushing the perception that its drivers that are the only cause of accidents means there are plenty happening that could be avoided by other road users being more aware.

It wouldn’t surprise me in a few years if there isn’t a push to lower them to 15 followed some time later by 10 and eventually someone will say ‚you know the Red Flag Act has a lot of merits so we should bring that back‘.

Is this really limited to people breaking 20mph limits? Or is this just drivers regularly breaking any speed limit?

Collectively, as a majority we abide by laws that seem reasonable.

20mph limits in most scenarios are not reasonable.

It’s as simple as that.

The comment section of that BBC article is rather revealing of the sorts of people we share the road with.

I’m not following laws I don’t agree with unless you make it untenable not to

The statistics in that article are a car crash. The improvement in safety for a reduction from 40mph to 30mph is framed as a ‘relative risk reduction’ of 3.5-5.5 times (let’s call it an average of 4.5 times) and is only discussed in terms of pedestrians (the most vulnerable group). That’s a 78% absolute risk reduction.

Whereas all the statistics for the 30mph to 20mph are given in absolute risk reductions (22-35%, let’s generously call it 30% on average). And relate to all Killed-Seriously Injured (seemingly) which would include other non-pedestrian road users.

These numbers just aren’t comparable at all. Evan Davis is notionally an economist, he should do better than this in terms of presenting data and statistics.

Furthermore there is no consideration of displacement to other roads, nor of negative externalities that might occur due to slower speeds (what impact does it have on fuel economy, emissions and journey times). There has to be a trade off between speed limits and other factors (otherwise we’d limit vehicles to no more than walking speed), but only by looking at the full picture (with comparable data!) can we make that decision.

I sat on a bus in London, just for fun turned on the GPS speedometer.

Of course it was doing 25-30 mph between stops (when it could). Even buses can’t hold those unrealistically low speed limits.

When it comes to speed limits. I get the reason. Safety. Simple as.

But technology has advanced so much that a 20mph speed limit is very redundant.

Exception children and kids are more vulnerable to impact with moving objects.

But take London for instance. A 20mph speed limit EVERYWHERE is stupid.

When they were proposing it in Wales, I posted several times asking to see the studies and proof this works. Zero response. I did see recently a report showing it was working, but just gave numbers, no context – so could just have been Covid – vs normal. And as has been said, no car is designed to go at 20mph, so they’re unpleasant to drive etc. And then there’s the cost, must be £millions, while the roads are so bad you have to drive like a slow motion rally driver to avoid catastrophic damage to ur motor. Absolutely insane times we are living in..

I put my adaptive cruise control on when in 20mph and 30mph limits, it practically drives itself (even stopping and pulling away again) and I don’t get into any trouble. That said, I *feel* like it reduces concentration somewhat as you’re less „actively“ driving which is a topic this article mentions. I *feel* safer judging appropriate speed myself and being a more active driver, but if they’re going to send you to boot camp for doing 25mph I assume they know better than my gut feelings.

What I don’t understand is how Europe manages it? 30 km/h speed limits in urban areas (not wide, segregated main roads) are common in Spain, France, Belgium, Netherlands and Germany. They didn’t seem to have as much whining about not being allowed to kill as many pedestrians and cyclists.

I do wonder if there’s an aggregated economic impact of all vehicles in the UK getting to places 10mph slower than before. One less phone call, one less delivery etc.

I drive 5 different vehicles in a week.

I find that 20MPH work well for electric and hybrid vehicles.

But the work Vans (Diesel) just do not like being under 30 MPH at all.

My little car (petrol) seems to be ok but I’m not a mechanic.

And my motorbike has no worries with that sort of speed.

But there is something very frustrating with going 20MPH compared to 30MPH.