Bridges over competing company's lines

[Chris M]

When a railway company built a bridge over a pre-existing railway line, presumably (in at least some cases) closures of the lower line were required to facilitate construction? How was this arranged when the older line belonged to a competing company, who had motive to make life difficult for the new builders? I presume objections would be raised when the line was being planned, so parliamentary approval meant they were not allowed (legally) to block construction, but were "unofficial" means of doing so attempted?

 

[Cowley]

When a railway company built a bridge over a pre-existing railway line, presumably (in at least some cases) closures of the lower line were required to facilitate construction? How was this arranged when the older line belonged to a competing company, who had motive to make life difficult for the new builders? I presume objections would be raised when the line was being planned, so parliamentary approval meant they were not allowed (legally) to block construction, but were "unofficial" means of doing so attempted?

I may be wrong but wouldn’t they have built a wooden frame with working platforms to start assembling the parapets and arch to avoid having to close the line below?

In the case of girder bridges it would be possible to crane the parts in piece by piece maybe?

 

[Class15]

AIUI when the route out of Marylebone was built they had to be very careful not to intrude too much on the LNWR line at South Hampstead.