The NCR would have started in Harlesden with its western end having a junction to the east of Willesden Junction station with the West Cross Route, the western section of Ringway 1 coming north from Shepherds Bush. Also connected to the junction here would have been Harrow Road (A404) and an unbuilt motorway that would have headed south-west along the National Rail North London Line to meet the M4 at Gunnersbury. A spur from this motorway would have connected to the Western Avenue (A40) near Gypsy Corner.
Heading east, the NCR would have run in a cutting along the north side of the North London Line to Brondesbury and Kilburn High Road (A5) . To accommodate the motorway cutting, most of the houses on the south side of the roads lining the railway would have been demolished. Roads that crossed the railway line, such as Willesden Lane, would have also bridged the sunken motorway.
Between Kilburn High Road and West End Lane a major Y-shaped junction would have been constructed where the NCR was to meet the intended end of the M1 motorway. This was originally planned to be continued south of its Staples Corner junction with the North Circular Road (A406) (Ringway 2) along the east side of the St. Pancras mainline through Cricklewood. The M1 junction would have been provided with slip roads allowing traffic movements between the M1 and NCR in each direction and the NCR would also have been provided with additional lanes between this junction and a roundabout to have been built at Finchley Road (A41) between Finchley Road Underground station and Finchley Road & Frognal National Rail station.
East of Finchley Road there were three alternative routes towards Camden Town:
Despite the destruction involved in constructing the tunnel through Belsize Park, the preferred route appears to have been alternative 1 as this provided the best means of creating an interchange with the planned Camden Town by-pass which would have connected Albany Street (south-west of Camden Town) to Camden Road (north-east of Camden Town).