R377 road (Ireland)  The R377 road is a regional road in north County Roscommon in Ireland. It connects the R367 road at Castleplunket to the N60 road at Castlerea. The R377 is long (map of the road). The government legislation that defines the R377, the "Roads Act 1993 (Classification of Regional Roads) Order 2012 (Statutory Instrument 54 of 2012)", provides the following official description: