An Bord Pleanála has given the go ahead for the €810 million upgrade of the M50 motorway.
The upgrade will involve the addition of a third lane in each direction, together with modification to ten interchanges and the upgrade of the Westlink toll bridge to a fully electronic free-flow facility.
The board said that it had concluded the development would not have significant adverse effects on the environment and would not be contrary to the proper planning and sustainable development of the area.
An Bord Pleanála received more than 250 submissions on the plans - most of them objecting to the scheme.
The Minister for Transport, Martin Cullen, has welcomed An Bord Pleanála's decision.
A spokesman for the minister said that while the upgrade would not solve all traffic problems on the M50, it would deliver real benefits to road users.
Initial work on the first phase of the upgrade between the N7 (Naas Road) and the M4 (Lucan Road) will begin in the autumn. Construction work will begin early next year.
