The Rathbride road has been closed for emergency repairs.
Kildare County Council said the R415 is closed from Kildare town to Milltown at the cattlegrid.
Diversions are in place for traffic in both directions and delays are to be expected.
Alternative routes are as follows:
Traffic travelling from Kildare town to Milltown will be diverted along the R401, onto the Dunmurray Road and back onto the R415.
Traffic travelling from Milltown to Kildare Town will be diverted from the R415, onto the Dunmurray road and will continue onto the R401.