Garda statistics show the number of detections for some road traffic offences have dropped significantly during the first six months of this year.
This is despite additional resources being made available for roads policing.
Figures published on the website of An Garda Síochána show that 1,602 arrests were made for dangerous driving between January and June, a more than 48% decrease on the same period in 2017.
There were 3,116 arrests in the same period last year.
Arrests for driving while intoxicated during the first half of the year fell by 3.74% - down from 4,440 to 4,274.
The statistics for fixed charge notices are available for the first five months of this year.
Speeding notices issued between January and May were down by 28% compared to the same period last year (46,969 in 2018 down from 65,303 in 2017).
Notices issued for not using a seatbelt have fallen by 28% from 5,045 in 2017 to 3,618 in 2018.
Fixed charge notices for using a mobile phone while driving were down by 14% from 12,900 to 11,095.