Motorists were warned of worse to come on the roads after the return of children to school this week.
AA Roadwatch said traffic volumes were notably heavier this morning.
"Heavy volumes were experienced on key commuter routes and on local roads near primary and secondary schools from very early this morning" said Emma Caulfield.
Gardaí were on point duty at key junctions in the main cities, but Ms Caufield said the roads would get busier over the coming weeks as mornings get darker and third-level institutions return for the new term.
"As always at the start of a new school year we see a dramatic transformation take place on our roads as thousands of vehicles, pedestrians and cyclists begin the school run," she added.
"The safety of our children travelling to and from school whether they are passengers, pedestrians or cyclists is of paramount importance".
