Mike...Myself, maybe others, would be interested in knowing the timeline and specific areas, steps, of further work needed on the extending mainline. It should help potential track, washout, trestle and slide workers to be available when the time for each project arrives.
I worked for construction companies, estimated for subs. The details, scheduling, coordination are guaranteed difficult.
If we knew more details here, I'm certain your job as overall work superintendent would have fewer wrinkles.