Commuters using the M7 motorway, one of the busiest in the country, face up to 24 months of disruption due to expansion roadworks.
The works will add a third lane along a 14km stretch, from Junction 9 at The Ball (Maudlins) in Naas to the M7/M9 interchange at Junction 11.
A revised speed limit of 60km/h will apply for the duration of the works.