There is evidence that 20mph zones do save lives and injuries even if people don’t obey them. This is because they still drive slower than they would in a 30mph zone.
I would agree, however, that if the limit is set to 20mph then the road design needs to be changed to match that, making it uncomfortable for drivers to exceed the limit. Unfortunately the UK is quite institutionally poor at this kind of traffic calming design compared to some of its neighbours.
There is evidence that 20mph zones do save lives and injuries even if people don’t obey them. This is because they still drive slower than they would in a 30mph zone.
I would agree, however, that if the limit is set to 20mph then the road design needs to be changed to match that, making it uncomfortable for drivers to exceed the limit. Unfortunately the UK is quite institutionally poor at this kind of traffic calming design compared to some of its neighbours.