Prior to the construction of the M6 motorway the R446 formed the main N6 road connecting Dublin and Galway (via the N4 at Kinnegad).

From Kinnegad the road travels in a westwards direction passing through the midland counties of Westmeath & Offaly.

It crosses the River Shannon at Athlone and continues into counties Roscommon and Galway.

The road passes through the following towns and villages en route to Galway City from Kinnegad; Milltownpass, Rochfortbridge, Tyrrellspass, Kilbeggan, Horseleap, Moate, Athlone, Ballinasloe, Loughrea, Craughwell & Oranmore (bypassed).

The road ends at the Coolagh Roundabout with the junction of the N6 east of Galway City.