The dual carriageway continues in the Republic of Ireland as the N1, which from Ballymascanlon in County Louth onwards is under motorway regulations and signed as the M1 motorway. The road follows the M1 south to Dublin, where, in the northern suburbs, it meets Dublin's ring road, the M50 motorway. It follows the M50 through the outer suburbs of Dublin until it meets the short M11 motorway near Shankill. The M11 continues as a dual carriageway, the N11, south of Bray in County Wicklow. This section passes through the Glen of the DownsNature Reserve. Apart from a section of standard highway (single carriageway road) between Rathnew and Arklow in County Wicklow, the road is dual carriageway or motorway to south of Gorey in County Wexford. Following this, the remainder of the route in Ireland is single carriageway and passes through several towns and villages. The N11 continues to Wexford, where at a junction outside the town it meets the N25 road from Cork. The route follows the N25 to its final destination in Ireland of Rosslare Europort.
All remaining sections of the N11 (and therefore E01) outside of Dublin are due to be replaced by motorways or dual carriageways.
The E 01 has two sections in Spain. The northern section is between Ferrol and Tui at the Portuguese border. It follows the motorway AP-9, aka The Atlantic Axis, which connects the Galician cities of Ferrol, A Coruña, Santiago de Compostela, Pontevedra and Vigo, continuing south towards Tui. The E 01 follows the motorway A-55 near the city of Tui to the Portuguese border at the river Minho.