When the French A1 was widened to D3M between Lille and Paris this canal bridge posed a problem - their fix was to just split the southbound carriageway: https://goo.gl/maps/WL18yyK7qFdNbuueAKeithW wrote: ↑Thu Jun 17, 2021 13:55Well given that a cut and cover tunnel would require demolishing properties and be highly disruptive during construction this seems to me to be somewhat unlikely.JammyDodge wrote: ↑Thu Jun 17, 2021 13:24I think the best solution for widening the Doncaster Bypass is to build a cut & cover tunnel under J36, through the residential area, to D3M spec. A tunnel should start North of Broomhouse Ln and just south of the Don Bridge. The Don Bridge would be replaced with a new "twin" D4M, with the A1(M) reducing to D3M north of the Don Bridge
Looking from the A630 overbridge I think there would be room to squeeze 3 lanes in especially using ALR.
As for the Don Bridge providing its structurally sound I would expect a new bridge for the southbound carriageway would be built east of of the existing bridge and the northbound traffic would use the existing structure.
It's probably likely unless they fully redeck and plug that gap in the Don Bridge central reservation that they'd need to do similar. Not a great hardship apart from it's not in the DMRB so they'll have a fit at the idea.