Traffic lights have been installed until further notice.
Midlands drivers are being urged to take extra care on the road between Baylin and Mount Temple in Westmeath.
The road, adjacent to CarnPark, is currently being undermined by a washout of material from underneath the road and nearby lands, resulting in the road becoming deformed.
A similar event happened in 2016 and continued for a number of months.
Westmeath County Council have installed traffic light controls and will monitor all development and respond accordingly.