Just looking at the Edinburgh study it is almost comically bad: > 4.5 ‘Before’ and ‘after’ surveys were also carried out at a selection of locations where the

Just looking at the Edinburgh study it is almost comically bad: > 4.5 ‘Before’ and ‘after’ surveys were also carried out at a selection of locations where the 30mph speed limit was retained. At these locations, average ‘after’ speeds in 2021 fell by 2.32mph compared with average ‘before’ speeds in 2016. This is a further decrease of 1.83mph since average ‘after’ speeds were recorded in 2019. Although many factors may have influenced this speed reduction, it could in part be attributed to the effect of speed reductions on surrounding streets, with drivers slowing their driving behaviour throughout Edinburgh. So the "control" streets also saw a decline in average speed, and the conclusion wasn't that the primary effect was due to increasing congestion over time, but instead clearly the speed limits just magically work everywhere. And the highest average speed on these streets was 32 mph to start with, before setting the speed limits. The roads already were doing the work there. That doesn't compare with the ~40 mph stroads we have around here that they've slapped a 25 mph sign onto and called it a day.