Belfast and Dublin have been named the 6th and 7th most congested cities in Europe.
TomTom’s annual traffic index has found that traffic in these cities is worse than Paris, London and Rome.
Dublin comes 15th in the worldwide ranking, with 85% of the time spent on journeys during peak morning commutes being spent sitting in traffic.
That figure reduces slightly to 81% at the peak of the evening rush.
The study found that for the average journey 40% of drivers' time is spent sitting traffic - this was an increase of 2% on last year.
Wednesday, November 18th was the most congested day of 2015 in Dublin, as a serious collision at Junction 6 on the M50 caused massive traffic jams.
Mexico City tops the list with peak rush hour waiting-times of 97%. It is followed by Bangkok, Lodz in Poland, Istanbul and Rio.
TomTom uses its real-time feed of live traffic data to compile this report.