The private company which has been carrying out driving tests to help reduce waiting lists has had to reschedule tests due last Saturday and this Saturday because of heavy traffic.
SGS says the measure was taken because some tests were taking longer than necessary and other candidates were left waiting around.
All of the cancelled tests have now been rescheduled.
160 people who were due to sit their tests at centres in Citywest, Fonthill, Northpoint and Deansgrange have been affected by the cancellations.
SGS says this represents about 7% of the tests due to be carried out over that two-week period.
Some of the rescheduled tests will take place before the end of the month, while others will be carried out in the New Year.
SGS was hired by the Government in October to help clear the waiting list for driving tests, which is currently at an average of eight months.
In order to meet its target of 40,000 tests over 18 months, SGS scheduled some tests to take place on Saturdays.
But the company was forced to cancel all tests in Dublin last Saturday and this Saturday because of heavy traffic on some of the test routes.
It says some of the test centres are located very close to retail parks and industrial estates which have been attracting high traffic volumes in the run-up to Christmas.
