Institute of Welsh Affairs calls for national 20mph urban default

The Institute of Welsh Affairs in its recent report on “Decarbonising Transport in Wales”[1] has called for a default 20mph urban limit as a key recommendation to enable Wales to meet its projected energy demands entirely by 2035.



The report notes in its foreward that:-

Decarbonising transport will make a huge contribution to Wales’ success in meeting its projected energy demands entirely from renewable sources by 2035. The transport sector has considerable potential to address pressing concerns relating to health, the economy, climate change and equality. Transport also has a massive impact on the way we plan our lives; more sustainable choices could be our route to a healthier and happier lifestyle.”

With regard to 20mph limits the report states :-

“Speed limits of 20mph have been shown to have a significant impact on the extent of injuries arising from collisions between motor vehicles and pedestrians or cyclists. Slower traffic also encourages more people to take up walking and cycling as the perceived danger from traffic is reduced.”


“A report by Public Health Wales[1] examined the case for 20mph speed limits in the context of the Well-being of Future Generations Act goals. It included a table assessing the range of benefits:

Table 5: The case for 20mph speed limits

Road traffic casualties 

  • Decreases in injuries, crashes, pedestrian and child pedestrian injuries of 17 to 70%

Air pollution                               

  • 12% reduction in gear changes, 14% in braking and 12% in fuel use; transport emissions reduced in residential areas by 12%
  • 32% reduction in NOx when average speeds drop from 31 to 19mph
  • 48% reduction in NOx emissions with a calmer driving style
  • Acceleration accounts for 35-55% of pollutants
  • Decrease in NOx emissions of 24-31%                                                                                                                   

Active travel

  • 12-25% increase in walking and cycling (Bristol)
  • Three fold increase in cycling to schools (Edinburgh)                                                                                                                   


  • 2dB reduction in traffic noise


  • Narrowed, differences across areas equalised

Social inclusion                          

  • Improved and enhanced

Community cohesion               

  • Increased, communities improved

Local business viability             

  • Improved; people using active travel to visit shops spend more money”

The Institute of Welsh Affairs report recommended that “Welsh Government should impose a default 20mph limit in urban areas, allowing local authorities discretion in exempting routes where justified.

Rod King MBE, Founder and Campaign Director for 20’s Plenty for Us commented :-

“We agree. Wales clearly has aspirations in Well-Being, Public Health and Energy Savings that a default 20mph limit can address. It now has the devolved power to set a national 20mph limit. Our forthcoming 20’s Plenty for Wales for Healthy and Liveable Streets[2]conference on Oct 2nd in Cardiff will be an excellent opportunity to learn why and how this could be accomplished.”

Open PDF



Showing 5 reactions

Please check your e-mail for a link to activate your account.
  • Rod King
    commented 2019-05-13 07:35:22 +0100
    Thank you Pascal

    Its always interesting to hear from any “faster is safer” proponents.

    The knowledge that being hit by a bus at 20mph is life threatening was not news to us. As a pedestrian I have never felt that a 20mph vehicle was an equal match for a human body in a crash. Neither have I found any others sharing that view.

    You comment on 3am in the morning surely applies to any speed limit.

    Have a good day.
  • Pascal Prince
    commented 2019-05-12 22:10:26 +0100
    The problem is not just mathematical. Huamn reacts differently then numbers…

    Here a study that show taht the TTC is not better iat 30 then at 50.

    First the drivers are more concentrated on the road and on the potential danger on 50 then on 30. The pedestrian just don’t care anymore about safety when the authorities are giveing a blank check on safety just because of the speed reduction. And even if they deny it, the poeple don’t care and consider then per default the driver as guilty. That a car will always be less impacted physically then their body don’t seems to get in their views. A canadian study revealed that birds where flowing away from the side of the roads faster or later in conjonction with the local speed “limits”, meanwhile , as the car “usually” high or low speed goes (the flow away much faster near highways then in 20 MPH Zone). They have the same way acting as humans: they “know” that the car drives slow here, so they take much more risks"…. Pedestrians think then: anyways, if I get hit by a car at 20, I don’t get hurt, and therefor they don’t take anymore a look at what happens. Lately, in Switzerland, an old lady on a bike in a 20 MPH didn’t looked at all while getting on the road on her bike…She didn’t saw the bus coming, and of course, even the bus was not even at 20, she died on the spot! Another three years girl was left driving alone on her tricycle in a “safe” 20 MPH zone but got killed by a car that was not even driving at 15!!!! The parents let her “play” on a road! How can they just be so unaware? Because of the 20MPH Propaganda!

    Any speed limit that is not “natural” will also not be respected. And on friday, they aired on the TV the unsolvable problem those 20 MPH zone are for the Ambulances… 20 MPOH zone are more killing poeple’s then the “problem” they are mean to reduce!

    Furthermore, they are permanently, and this is unsane. There is NO RISK to drive 50 at 3’00 in the morning, but you can lose your driving license, theb your job and your family…

    To me, 20 MPH are making poeple going down to a 20 IQ -level!
  • Rod King
    commented 2019-05-12 20:21:08 +0100
    Hi Pascal

    Your Rosen research paper actually concludes :-
    “a strong dependence on impact speed is found, with the fatality risk at 50 km/h being more than twice as high as the risk at 40 km/h and more than five times higher than the risk at 30 km/h. "

    I also note that 80% of casualties in Graz are on 50km/h roads.

    There is no evidence that 20mph limits increase any “not paying attention” by pedestrians. Tests by Imperial College London have shown an 8% reduction in NOX and PM10s from diesel vehicles in a 20mph cycle compared to 30mph. And most modern cars will return in excess of 90mpg at 20mph constant speed. Its the acceleration that kills the fuel economy, not the specific speed.

    But thank you for your contribution

    PS Yes, the AMC Pacer was a revolutionary car. Do you still have one?
  • Pascal Prince
    commented 2019-05-12 20:00:15 +0100
    The Driver are more attentive to pedestrian at 50 then at 30, making the “speed at crash time” lower at 50 then a 30… All those illusions of political narrow minded are not applicable to humans!
  • Pascal Prince
    commented 2019-05-12 19:42:15 +0100
    All those stats are fake-news! In Graz (Austria), after the first 18 years of general 20MPH, there was a decrease of…. 2 accident (less then 1%!) while in the european median accident rate decreased by 30%! All the pretention of decreasing injuries are based on non-scientific oriented studies. The real impact on safety by droping the speed isn’t significant (Rosen 2009, The most part of accident take place at 30kmh speed as the pedestrian, the bicycle and the drivers do not consider traffic as dangerous anymore at 30 and do behaive light minded, not paying attention any more to each other… For the environemental issue, modern engines are polluting the less at constant speed between 50 and 60. A lower speed INCREASE pollution. For the noise, the 2 db decrease is at least not relevant as human ear can make a difference with at least a decrease of 5 to 10 db. And the decrease is not gained if there are bumps, slaloming parking fields or other left priority… All that 20 MPH is pure religious alike dogmatic political illusion!