The N4 is the only one of the main inter-urban national routes whose dual carriageway section runs right into the city centre.

Congestion is frequently reported on the route's single carriageway sections.

A single carriageway section runs from the city centre to a large roundabout at the Barnes.

The only dual carriageway section is along Sketty Lane.

The single carriageway sections of this road are dangerous, and local people hope for a new dual carriageway.

This dual carriageway section ends in a one-way system marking Stratford town centre.

In 1999 the A30 through Fairmile was re-routed to a newly built dual carriageway section, about mile to the north of the previous road.

The remaining single carriageway sections are due for upgradeing with construction due to begin in 2011.

This stretch of motorway will replace a single carriageway section of the N11.

The new two-lane dual carriageway section of the A14 would run parallel with the A1 on this section.