Derbyshire County Council has scrapped plans to trial 20mph zones in three places.
In 2016 it was proposed to pilot 20mph speed limits - reduced from 30mph - in Brassington, Fritchley and Ilkeston.
These pilots would have followed on from a trial in Padfield, where the 20mph zone was marked by road signs only.
Data from the trial in Padfield, which ran from 2015 to 2018, showed that on average motorists travelled only 1mph slower than before the signs were put up.
Councillor Simon Spencer, the council's cabinet member for highways, transport and infrastructure, said: "The point of reducing speed limits is to reduce road speeds so that we reduce casualties. Findings from the trial in Padfield show that average speeds only reduced by 1mph, and in fact the number of collisions increased.
"These results were broadly similar to other national trials, which is that just putting up 20mph signs do not make a significant difference to how fast people drive on the road.
"We have to use our limited resources where they are going to have the most effect, which means that we won’t now be introducing 20mph signed zones in the three areas, Brassington, Fritchley and Ilkeston.
"There's also no evidence from the Padfield trial that lower speed limits encourage wider health benefits."