Bridge-Limited Patrol at Dawn
You are the second-in-command of a rifle company at a temporary base in north-eastern Nigeria. The company has 42 soldiers and 6 attached medical personnel. Two vehicles are serviceable: an MRAP with 80 litres of usable fuel and a consumption of 1.6 km per litre, and a covered truck with 120 litres and 2.5 km per litre. The objective is a village 34 km away along one route. At km 21 a bridge is posted at 7.5 tonnes. The MRAP weighs 12 tonnes laden; the truck weighs 6 tonnes laden and can seat 24 personnel. The patrol must spend four hours at the objective, and daylight ends in seven hours. The average speed is 30 km/h. The truck radio has a faulty antenna; the MRAP radio works. Water is 3 litres per person for the entire patrol. One section commander wants both vehicles; another wants the truck only. A local guide says the bridge is inspected monthly.
1. Which vehicle or vehicles can cross the bridge, and how many personnel can the compliant vehicle deliver to the objective in one lift? Show the test you applied.
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Bridge test: compare each laden weight with the posted limit.
- MRAP: 12 t > 7.5 t → cannot cross.
- Truck: 6 t ≤ 7.5 t → can cross.
The truck seats 24, so one lift delivers 24 of the 48 personnel. The remaining 24 cannot reach the objective in the same lift. The MRAP is not a substitute because the binding constraint is the bridge, not fuel or seating. The bridge therefore forces either a reduced deployed party or a transshipment plan; this is not a matter of preference between the two section commanders.
2. Test the truck-only plan against fuel, time and daylight. Show all steps and state whether it is feasible.
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Fuel: round trip = 34 × 2 = 68 km. Fuel used = 68 ÷ 2.5 = 27.2 L. Usable fuel is 120 L, leaving 92.8 L. Fuel is not the binding constraint.
Time: travel = 68 ÷ 30 = 2.267 h = 2 h 16 min. Add four hours at the objective = 6 h 16 min. Add about 20 min for loading and unloading = 6 h 36 min. Daylight available = 7 h.
Conclusion: the truck-only plan is feasible for 24 personnel, with roughly 24 minutes spare, provided it departs immediately and handling takes no longer than estimated. It is not feasible for all 48. The faulty truck radio is a separate communications risk, not a time calculation.
3. Recommend a course of action that respects the bridge limit and maintains communications. State one risk you are accepting.
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Recommendation: send the truck across the bridge with 24 personnel, including the medics and a radio operator. Keep the MRAP on the near side at the bridge as a radio relay and recovery asset. It cannot cross, but it can still communicate and support. Do not overload the truck and do not attempt to cross the MRAP.
Risk accepted: the objective party is only 24 strong, and radio contact beyond the relay may be intermittent. If the truck is delayed, the MRAP cannot cross to assist. Mitigate by setting a firm turn-around time, a radio-check schedule and a pre-agreed return signal. If the task genuinely requires more than 24 personnel at the objective, the plan must change to transshipment or a second lift, which the daylight window will not allow.