Initial analysis of traffic speeds on Welsh roads where there’s been a drop from 30mph to 20mph suggests vehicles are travelling around three miles per hour slower.

Analysis by statisticians Agilysis suggest speeds on the roads it looked at dropped from 22.67 mph the week before the change to 19.77 the week after.

The company used TomTom data to check 261 miles of roads in ten Welsh towns and cities in Wales.

In the report, spotted by nation.cymru, Agilysis concludes “the change in traffic speeds on urban roads in Wales has been dramatic following the implementation of widespread 20mph limits. Reductions of 2.9mph are similar to those achieved in other areas such as Scottish Borders but on a much wider scale.

“Compliance using the chosen median speed metric is very good, with half of drivers sticking to the
new limit. There has been a very significant reduction on the length of roads where speeds are well above 24 miles per hour, the speed at which enforcement would typically take place.”

(Graphic – Agilysis)