The 14-kilometre (8.7 mi) Ennis Bypass opened to traffic as a standard dual carriageway section of the N18 on 26 January 2007, after a construction period of almost three years.

[3] The construction of this section of the motorway gained international attention in 1999 as a result of the Latoon fairy bush, a tree of supernatural significance which folklorist Eddie Lenihan demanded must be saved as it was in the path of the intended route.

This scheme, known as 'Gort to Crusheen', connects to the northern end of the Ennis bypass and provides a continuous motorway just north of Gort in County Galway.

The project involved the construction of a motorway from Gort to Athenry, extending in the process the total length of the M18 by 27 km (17 mi).

[11][12][13][14] Initially, none of the proposed dual carriageway between Limerick and Galway outlined in the Transport 21 programme was to operate under motorway restrictions.

However, the National Roads Authority (NRA) decided late in 2008 to include all sections of grade separated N18 – whether built, under construction, or still at the planning stage – in its second tranche of motorway redesignation proposals.