|From:||Brynmill, Swansea (SS642922)|
|To:||Neath Abbey (SS735974)|
|Distance:||4.4 miles (7 km)|
|Meets:||A4067, A4118, A483, M4, A465, A4230|
|Old route now:||A4067, A483|
|Route outline (key)|
The B4290 is now in two separate parts – one in Swansea and one southwest of Neath. As originally defined it was a continuous route from southeast Swansea to the western outskirts of Neath, more or less paralleling the course of the Tennant Canal, east of the River Tawe. Only the eastern half of that one-time seven-mile-long route is still numbered B4290, however, while a subsequently added section running through central Swansea west of the Tawe is now separated from the eastern B4290 by a gap of four and a half road miles.
Numerous changes to Swansea's central road layout resulted from Swansea's post-Blitz reconstruction; furthermore, today's B4290 and A4067 have largely swapped their respective earlier courses between the point on the seafront known as The Slip, near the Guildhall, and the western bank of the River Tawe. The original number of the road along Oystermouth Road was actually the B4293. This later became the B4290 – and then that number swapped routes with the A4067 at some point no earlier than the 1970s.
Consequently it is now the B4290 that runs towards the city centre from The Slip, skirting the north side of the Sandfields district, while its former route passing the south side of HM Prison and extending to the river crossing to St Thomas has been taken over by the A4067.
Before the designation of the route between Swansea St Thomas and the new 1950s road crossing of the lower River Neath at Briton Ferry as a part of the A483, the route from southwest Swansea to Neath Abbey was numbered B4290 all the way. Today, only the section running north- and then northeastward from Crymlyn Burrows, immediately south of Jersey Marine, retains the number B4290. A spur leads to M4 J43, after which the road passes through the suburb of Skewen to end on the A4230 in the Neath Abbey area of town.
An amended OpenStreetMap trace for this route awaits uploading to the SABRE Wiki.