Hi Blackthorn,
Just picked up your thread.
If you contact the Heritage Centre in Dursley, they sell a DVD called 'End of the Line', I bought one last year from there,it was £5 and was a seven minute silent home cine film, in colour of the Dursley Branch, the last passenger train complete with carrots on the engine, a footplate ride and shots of Dursley, Cam and Coaley Stations and the bridge you mention, It is a gem, a nice bit of photography and a mine of information for a model and well worth the money.
Trust this helps,
John