Municipal Ring: Railroad Permit, Critical Path, and a Third Drill Crew
A city is building a 42 km fiber ring linking nine traffic cabinets and three schools. The contract is 12 months with liquidated damages of $2,500 per day after day 365. Resources: two directional-drill crews, three splice/test crews, and one OTDR/loss-test set. Four state highway crossings need permits (90–120 days); one railroad crossing needs 6–9 months. Baseline: drill months 1–6, cable pull months 4–7, splice months 6–9, test months 8–10, cutover months 10–12. At the end of month 5, drilling is 60% complete (14.4 of 24 km), the railroad permit is still pending, and the splice crew has been idle 30% of the time waiting for cable. The project manager proposes adding a third drill crew and starting splice work on the sections already cabled.
1. Identify the critical path and explain how the pending railroad permit affects the completion date and liquidated damages.
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The critical path runs through the railroad crossing permit, the crossing installation, cable pull through that segment, splicing, end-to-end testing, and cutover. Drilling is a predecessor, but at month 5 it is not the only gating activity. The splice crew idling 30% while waiting for cable shows that cable pull, not drilling, is currently feeding the downstream work.
The railroad permit is the highest-risk item because its 6–9 month range can consume the entire 12-month contract before installation starts. If the permit is issued at month 9, the crossing, pull, splice, and test sequence cannot finish by day 365. Liquidated damages of $2,500 per day then accrue immediately after day 365, so a 30-day slip costs $75,000.
The correct response is not to assume the permit will arrive on the optimistic date. Treat it as a decision gate: if the permit is not issued by month 7, activate an alternate route or a temporary leased path for the affected cabinets.
2. Evaluate the proposal to add a third drill crew: what schedule benefit, if any, and what resource conflicts could it create?
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A third drill crew does not automatically recover the schedule. At month 5, the two crews have completed 14.4 km against a plan of roughly 20 km, so drilling is behind. But the downstream constraint is cable pull and splice/test, and the splice crew is already waiting on cable. Adding drilling capacity only helps if specific unfinished bores are blocking cable pull on segments that can be spliced and tested.
A third crew also adds real conflicts: additional locates and traffic control, more supervision, more spoil and restoration, and possible congestion in the same rights-of-way. It may pull resources from cable pulling or force the city to issue more permits at once.
A better test is to map the unfinished bores against the cable-pull sequence. Add the third crew only for the two or three bores that gate the next splice sections, and set a stop date. In parallel, add a second OTDR/test set, because testing is likely to be the end-of-project bottleneck.
3. Recommend a recovery plan and the message to the city, including what you would not promise.
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Recovery plan:
- Split the ring into segments and splice/test the completed sections now instead of waiting for full continuity.
- Add a second OTDR/loss-test set and cross-train a third tester; the single test set is a schedule risk.
- Assign a dedicated permit expediter to the railroad crossing and pursue a directional drill under the railroad with flagging, if the railroad allows it.
- Prepare a temporary leased-fiber or wireless path for the cabinets isolated by the railroad crossing so cutover can proceed in phases.
- Use six-day shifts on splice/test only, not on all crews, to avoid burning cost without schedule benefit.
Message to the city: give a range, not a false date. State that the railroad permit is outside the contractor's control, show the decision gate at month 7, and present the temporary-path option and its cost. Do not promise day 365 until the railroad permit is in hand. Do not absorb acceleration costs without written direction, and do not let the city treat a permit delay as contractor delay without a documented notice.