Learner drivers are facing waiting times of up to seven months to sit their tests.
New figures released by the Road Safety Authority (RSA) under the Freedom of Information Act show 19 centres around the country have waiting lists of over 12 weeks.
They show nearly 46,500 people are waiting to sit their driving test.
Nearly 33,000 have received no test appointment at all, while almost 14,000 have appointments scheduled for the coming weeks.
There is a backlog of 31 weeks in Killester in Dublin, 25 weeks in Drogheda in Co Louth, and 18 weeks in Deansgrange/Dún Laoghaire in south Dublin.
Three areas have waiting times of 14 weeks: Carrick-on-Shannon in Co Leitrim, Togher in Co Cork and Tallaght in Dublin.
The shortest estimated waiting times is Kilrush in Co Clare, at just three weeks.
Dublin driving instructor Ian Daly said there should be extended hours to clear the backlog.
"People have to take a day off work if they work 9 to 5.
"So if they had the option to do an evening test, or a weekend test of course.
"During the summer with climate change, weather has been much better - obviously it's bright later at night time - it'd be perfect."
Sinn Féin's transport spokesman is Darren O'Rourke.
"We need to have a fit-for-purpose system of driver training and of licencing.
"And it's clear that, in terms of the testing service, it's not fit for purpose at this time".