I think we had a thread on bypasses that had been bypassed. That's similar, but obviously not the same thing.ajuk wrote: ↑Tue Aug 10, 2021 02:43 I'm not sure if this has been discuses before. I know there are plenty of sections of A road that were later superseded by motorways that contain online upgrades, or bypasses, in some cases the upgrade may have occurred after the motorway was build because the old A road remains locally significant ie the Marshfield bypass. I'm not talking about roads superseded by motorways here.
I'm talking about A roads that were given online upgrades only to be abandoned as the main road at a later date.
On that thread I mentioned that - aside from the A38 in Gloucester (bypassing the city, and then itself bypassed by the M5) - the original A40 was diverted to bypass its original route through the city centre via Escourt Road-St Oswalds Road, before again being diverted to bypass that via its current alignment.
I don't know how old the crawler lane on Castleford Hill (original A48 from Chepstow to Tutshill) would be, but it was pretty old and I'm not sure that it wasn't like that from the time that the A48 number took over from the original A437 in 1935.So you now have a seemingly insignificant road with a crawler lane.
Examples I can think of at the old A30 through Blackwater, sections of the old A40 in Pembrokeshire, the old A48 out of Chepstow and I seem to remember a crawler lane somewhere near Frome, but can't remember where I was, not sure if it was ex A361.
There is a similar example not far away in Lydney, where the old NSL signs coincided almost perfectly with the beginning of the S2+1 alignment up Highfield Road in the direction of Gloucester. That was possibly a more recent upgrade than Castleford Hill, but it's still as old as I can remember and was nonetheless bypassed completely (and speed limit reduced to 40) in the 1990s; there are still green signs on the old A48 through the town centre, implying that the road is still more important than it actually is.
As for Frome, the modern bypass that it shares with Beckington and the A36 has plenty of S2+1, but the original route (now B3090 through Frome, and unclassified through Beckington) has nothing that looks like it would ever have been S2+1. For your Frome example, might you be thinking of another town near the Somerset-Wiltshire border?
Cirencester does of course have a dualled bypass (currently A429) that follows the course of the River Churn closely, and that bypass was itself bypassed by the much more modern A417/A419 identity crisis (i.e. the bit of dual carriageway where it's not clear which number applies) much more recently.