The Tarmonbarry Triathlon is taking place the weekend of June 23rd and gardaí are warning motorists to expect delays.
From 9am-12pm, there will be traffic delays on the N4 and N5 approaching Longford town, Clondra village and Tarmonbarry village.
Separately, there will be delays on the Aughreagh Fiddlers roundabout on the N5 and Charlotte Brooke roundabout on the N4.
This is to facilitate the safe passage of competitors, which is anticipated will be in the region of 250 people.
Motorists are advised to approach with caution and co-operate with An Garda Síochána and the stewards.