The race itself gets under way at 9am, but traffic restrictions along the route will be put in place an hour beforehand.
Gardaí have warned motorists to “expect significant delays” if they’re intending to drive through the city centre, in particular.
They advise the North Ring Rd and South Ring Rd should be used while the Jack Lynch Tunnel remains open all day.
However, a contra-flow will operate in the southbound bore, so traffic flow will be slower than normal. The tunnel should be fully operational by 1pm.
“The south City Link Rd will be operating contra-flow until approximately 1.30pm. Black Ash Park and Ride is also open from 7.30am to 7.15pm,” a garda spokesman said.
Traffic diversions and road closures will be removed by 4pm and later at Inchigaggin Lane (5pm) and St Patrick St (6pm).
Delays are also expected on some bus routes.
Changes have been made this year to the starting point and time of the Tony Brauders Half-Marathon.
The half-marathon will now start on Victoria Rd at 10.45am and participants should assemble at Kennedy Park by 10.30am.
The starting point can be easily accessed from City Hall or Blackrock Rd. There will be no parking available in the area on the day and the road will be closed to traffic from 8am.
During the race itself, many eyes will be on firefighter Alex O’Shea who is attempting to get a Guinness Wold Record Challenge for running the marathon in his full firefighter attire.
This includes steel-toed, reinforced, firefighting boots; fire-retardant pants, and a firefighting jacket along with a 3lb firefighter’s helmet and visor.
The current record for running a marathon in full firefighting gear is 4:45:16 and is held by Niall Crowley who set the record at the 2010 Cork City Marathon.