Or, alternatively narrow and calm the road, because something is wrong with it. If a 20mph limit is set, there's probably a good reason, but it's not good enough to just put up the signs, you need to make people feel uncomfortable driving more than that on the road via calming measures.
Noise concerns is a joke. I drive a truck in Germany. In many villages and some areas of towns/cities, trucks are to drive at 30 kph instead of 50 kph at night to reduce noise levels.
The joke is, when I drive at 30, the truck is in a lower gear than at 50, making more noise, passing more slowly (noise duration longer) and putting out a higher volume of CO2 for the duration.
Cars with fart cans and motorbikes with their loud exhausts are way louder than my truck could ever be driving those roads - at any speed.
But it's only trucks that have to slow down, and my truck - like most modern trucks - has an 'L' classification for Austria, which stands for 'Lärmarm' which translates to 'Quiet'.
Speed limits are set based on safety considerations. We don't change safety rules based on what some people find convenient. If 85% of drivers can't follow the law, then 85% of drivers can pay a fine / have their licence suspended.
@CorruptBuddha@emergencyfood A 20mph speed limit is based on momentum the human body can withstand without a high likelihood of death.
Every mph over the limit increase the likelihood of a human being dying in a collision.
Speeding in a 20mph zone is very specifically choosing to increase the likelihood of killing someone.
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.