Night Patrol Plan That Visits Q Too Early
You are the range officer's patrol planner for a night patrol in Bhimgad area. There are four checkpoints: P, Q, R and S. Road distances are P–Q 8 km, Q–R 6 km, R–S 5 km, S–P 9 km, Q–S 7 km and P–R 10 km. A vehicle averages 20 km/h on these roads. Each checkpoint needs a 20-minute check; S also needs a 45-minute foot patrol. Checkpoint Q is high-risk and must be visited twice, with the second visit after midnight. Two guards and one vehicle are available. The vehicle fuel limit is 40 km for the night. A proposed plan is: start at P at 18:30, follow P–Q–R–Q–S–P, and finish by 22:30. The planner claims this meets all requirements because Q is visited twice-once at the start and once on the way back.
1. Test the proposed plan against every requirement. Identify the exact failure and any other weakness.
Read the worked answer
Route length = 8 + 6 + 6 + 7 + 9 = 36 km, so the 40 km fuel limit is met.
Timing:
- 18:30 P, check to 18:50; P→Q 24 min, arrive Q 19:14; check to 19:34.
- Q→R 18 min, arrive R 19:52; check to 20:12.
- R→Q 18 min, arrive Q 20:30; check to 20:50 (second visit).
- Q→S 21 min, arrive S 21:11; 20 min check + 45 min foot patrol to 22:16.
- S→P 27 min, arrive P 22:43.
The failure is clear: the second visit to Q is at 20:30, not after midnight. The plan also finishes later than claimed (about 22:43, not 22:30). Fuel and coverage of all four checkpoints are otherwise satisfied. The planner has confused “visited twice” with “visited twice with the second visit after midnight.”
2. Propose a corrected schedule that keeps the fuel within 40 km and makes the second Q visit after midnight. Show the key times.
Read the worked answer
Reorder to P–R–Q–S–Q–P so that Q is visited near the end rather than in the middle.
Route length = P–R 10 + R–Q 6 + Q–S 7 + S–Q 7 + Q–P 8 = 38 km, within the 40 km limit.
Schedule:
- 21:30–21:50 P check; depart P.
- P→R 30 min, arrive R 22:20; check to 22:40.
- R→Q 18 min, arrive Q 22:58; check to 23:18 (first Q visit).
- Q→S 21 min, arrive S 23:39; check 20 min + foot patrol 45 min to 00:44.
- S→Q 21 min, arrive Q 01:05; check to 01:25 (second Q visit, after midnight).
- Q→P 24 min, arrive P 01:49.
All checkpoints get the required time, Q gets a post-midnight visit, and the vehicle stays within fuel. The cost is a later finish, which is acceptable within the 18:00–06:00 window.
3. The vehicle develops a starting fault at Q at 23:00, before the second Q visit. What is the best judgement call, and what should be recorded?
Read the worked answer
Safety and communication come first. Do not force the vehicle to continue on a suspect battery or starter in a forest road at night. Park it safely off the carriageway, switch on hazard lights, and inform the control room and the Range Officer. If radio or mobile coverage is weak, send one guard on foot to the nearest known signal point or patrol hut while the other remains with the vehicle.
Operationally, the second Q visit has not yet been completed. The remaining requirement is to visit Q after midnight. If the fault can be fixed within a reasonable time, continue with the same plan. If not, request a relief vehicle and record the delay. Do not mark Q as “checked after midnight” unless someone actually reaches it. Record the odometer reading, fault time, persons informed, relief arrangement and any missed checkpoint. The report should distinguish “planned,” “attempted” and “completed” checks.