|Location Map ( geo)|
|Distance:||11.3 miles (18.2 km)|
|Meets:||A467, A472, A4048, B4254, A4048, A467|
|Former Number(s):||A4048, A472|
|Route outline (key)|
The B4251 is a circuitous B-road in south Wales.
In 1922 it started on the A467 in Cross Keys and headed west then north to end on the A472 in Pontllanfraith. By 1932 all this had been renumbered as an extension of the A4048 but the B4251 had been extended via Oakdale to the then-A4044 in Crumlin.
This situation lasted until the 2000s (although slight reroutings, such as an Oakdale bypass, did take place). Then the opening of the A4048 Blackwood bypass to the east of the town (and along a small section of the 1930s route of the B4251) changed things somewhat.
The B4251 was extended along the pre-bypass A4048 along almost all its original route back to Wattsville and also gained two spurs in Pontllanfraith. One is the pre-bypass A472 leading back to the A4048; the other is all that remains of the road's 1932 route in Pontllanfraith itself.
The present route of the B4251 thus connects the A467 to itself, needing twice the distance to get there!