A few months back I was looking around the internet looking for photos of through girder turntables. I don't remember right now where they are (maybe the Santa Fe modelers web site) but I did find pictures of a couple of Santa Fe turntables that had been extended. It looks like the people working on it basically lifted the turntable out of its pit, tacked an extension on to both ends, and then dropped it back into its pit, which of course had also been expanded.
David
I don't know the answer to this, but I could see an engineering team and construction gangs doing it in stages. First, the TT doesn't need a vertical retaining wall all around it, but it does need a clear rail and tracks properly supported at the radial ends. The rest of the TT can be broken up, expanded, and the working parts stay in place to service engines. Later, over perhaps a week, a well-organized gang comes in to tear out the remaining ramparts, pit wall, lift out the bridge, build a new circular rail, and insert the new bridge. The remaining radials are cut short as the bridge wall is newly established. Eventually the new bridge, rail, and those last radials are serviceable once again. The crew can then go about restoring the remaining perimeter of the pit and other tracks.
Crandell
Planning in advance and having assemblies ready for installation made the delays as short as possible. Wyes and balloon tracks would be used for turning locos and cars. Other facilities nearby would take the pressure off the blocked roundhouse and storage was outside. Armies of men and equipment were brought in and work was done in shifts of 12 hours each until the job was done.
It was not limited to turntables. Round house and locomotive building facilities were constantly upgraded and expanded. The same could be said of the rail road as a whole. As locomotives got bigger they also got heavier and bridges and track structure also needed to change. Clearances were also checked to make sure a locomotive of a certain size was limited from going somewhere it would not fit.
Pete
I pray every day I break even, Cause I can really use the money!
I started with nothing and still have most of it left!
As loomotives got ever bigger in the 1910s and 1920s the railroads found it necessary to increase the length of (some of) their turntable bridges. How did the railroads expand a turntable without disrupting the whold operation at that point?
From the far, far reaches of the wild, wild west I am: rtpoteet