Traffic restrictions will be in place within 30 miles of the site of the National Ploughing Championships which will open near Carlow on Tuesday.
A special Garda traffic plan will be put in place to facilitate the 200,000 people who are expected to visit the event, the largest of its kind in the world.
An early visitor to the 500-acre site on Tuesday will be the Taoiseach, Mr Ahern, who will be accompanied by the Minister for Agriculture and Food, Mr Walsh, who will be performing his final ministerial function as the Cabinet changes will be announced the following day.
The President, Mrs McAleese, will be visiting the site on Thursday. There will be over 600 trade stands, 70 major ploughing competitions as well as livestock and machinery exhibitions on display.
The event, which is staged by the National Ploughing Association, is being held at Grangeford, between Tullow and Carlow town in what is known as the "Irish tillage triangle".
People attending the event are being accommodated as far as 30 miles from the site and the organisers have asked the public to contact them if they have surplus accommodation in their homes.
Traffic problems may increase later in the week when a major international golfing tournament takes place in Mount Juliet, Co Kilkenny.
The Garda traffic plan is:
Route A: From the south and south-east via Kilkenny.
Travel north on the N9 to Milford Cross. At Milford Cross divert right via Hayes Cross and Ballybar Cross towards the N80. Divert left on N80 and travel north towards Carlow town to Walls Forge. Divert right onto R725 to car-parks numbers 3 and 4.
Route B: From the south-east via Wexford, Enniscorthy and Bunclody.
Take the N80 through Ballon village to Kilnock junction (2 miles north of Ballon village). Divert right onto a minor road through Rathoe village to car-parks numbers 5 and 6.
Route C: Approaching from the south and mid-west via Abbeyleix.
Approach along the N8 via Abbeyleix - divert right in Abbeyleix onto the R430 towards Carlow. In Carlow, at Castlecomer roundabout divert left along the Northern Relief Road towards Hacketstown roundabout. Divert left onto R726 for 4 miles to car-parks numbers 1 and 2.
Route D: From the west, north-west, midlands via Portlaoise.
Divert at Portlaoise onto N80 towards Carlow via Stradbally. In Carlow, at Portlaoise roundabout divert left onto the Northern Relief Road towards Hacketstown roundabout. Divert left onto R726 for 4 miles to car-parks numbers 1 and 2.
Route E: From the midlands via Edenderry, Monasterevan, Athy.
Divert left in Athy onto the N78 towards Dublin. Divert right onto R418 to Castledermot. At the bottom of Main Street, Castledermot divert left and continue on the R418 to Killerig Cross. Divert right at Killerig Cross onto R726 to car-park number 8.
Route F: From Dublin and the north-east.
Travel along the M7 and divert onto M9 just after Naas.
Travel south towards Castledermot. In Castledermot village divert left onto R418 to Killerig Cross. Divert right at Killerig Cross onto R726 to car-park number 8.
Route G: From Dublin and north-east via Blessington.
Using the N81 travel through Baltinglass. At Bough Cross continue along R726 to Straboe Cross. From Straboe Cross go along minor road to R418 and follow sign posts to car-park number 9.
Route H: From east Wicklow and north Wexford via Tullow.
Travel through Tullow town along R725 to car-park number 7.