Flooded Dip After Heavy Rain
It is 8:30 p.m. during a tropical storm. You are driving a low-clearance sedan from Mandeville toward Treasure Beach. At a dip in the road, muddy water covers both lanes for about 25 metres. A small car is stalled in the middle with its hazard lights on; the water is at its door sills. On the far side, a pickup truck is waiting. You cannot see the road edges or any markings, and there are potholes known to be in this section. Rain is still falling heavily, and the wind is gusting. Your phone battery is at 15%. A detour would add 40 minutes on unlit rural roads. Another driver flashes headlights and shouts that it is 'not deep'.
1. How should you decide whether to drive through? What checks and what decision rule apply?
Read the worked answer
Do not drive in. At night you cannot see the road edges, the markings or the potholes, and the stalled car shows the water is at least at door-sill height. For a low-clearance sedan, 15–20 cm of water can already affect control; moving water around 30 cm can float many cars and 60 cm can sweep one away. The other driver's shout is not evidence of depth. The decision rule is: if you cannot see the bottom or judge the depth, or if the water is moving, turn around. A 40-minute detour on unlit roads is less costly than a flooded engine, a stranded car or drowning.
2. What should you do about the stalled car and its occupants?
Read the worked answer
Do not wade in to push the car. Call 110 and 119, give the location and say a car is stalled in floodwater. From the bank, shout to the occupants to stay with the car if the water is not rising and the car is stable; if water is rising or the car shifts, tell them to get out through a window and move to high ground, keeping away from the downstream side. Do not add a second casualty by entering moving water. If they are in immediate danger, throw a rope or float rather than swim.
3. If you ignore the warning and stall in the water, what should you do?
Read the worked answer
If you stall in water, switch off the ignition and do not try to restart - restarting can hydraulic-lock the engine and, more importantly, you may need to leave quickly. Unfasten your seatbelt, open or break a window if the door will not open because of water pressure, and get out towards high ground. Do not stay with the car to save it. Call for help and keep your phone dry. Prevention is the real answer: do not enter floodwater you cannot assess.