I had read and understood the dis-assembling part. Sooo. Let's visualize the mode of operations for this contraption:
We bring in the sections by railroad. That's the easy part.
Then, we assemble it (hopefully not under arty fire), then attack, and if the plan works out, cross the line and advance some.
Then at the first bridge we stop, dismantle it (hopefully not under fire), start laying or re-laying rail tracks, bring in Thomas the Little Engine that Could, plus a few flatcars, load up the sections and cross the bridge (hopefully not under fire), and repeat?
Sorry, but to me this sounds like a zehr kolossale dumme Idee.
Especially if you could produce many dozens of Renault FT-17 clones for the same expenditure and effort....
But I accept that the Prussian Empire preferred Kolossale Finesse.