Left Turn in Rain with a Cyclist, a Pedestrian and an Amber Light
Haruto drives a 準中型 truck (車両総重量 7.4 t, 最大積載量 4.0 t) loaded with 3.9 t of steel fittings. It is raining and the asphalt is wet and greasy at the junction. He approaches a signalised crossroads intending to turn left at about 42 km/h. A woman on a bicycle is travelling straight ahead in the same direction, roughly 4 m from the left kerb and slightly behind his cab, on a wobbling line as she avoids puddles. A pedestrian with an umbrella is waiting at the crossing on the road he intends to enter. The light turns amber when his front bumper is 25 m from the stop line. His firm's vehicles have standard all-season tyres and the truck has no load-sensing brake adjustment.
1. List the hazards in this scene in the order they are likely to become critical, and explain which one the vehicle's geometry makes worst.
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- The cyclist on his left rear quarter. She is the most immediate hazard and the one his mirrors are least able to resolve: close to the cab, moving at a similar speed, and weaving.
- The amber light at 25 m. It converts the approach into a stop-or-go decision at exactly the moment his attention is on the cyclist.
- The pedestrian at the crossing he is turning into. The turn exit is where his attention will be least available.
- The wet, greasy surface with 3.9 t aboard, which lengthens every stopping distance and makes a skid more likely under braking or steering.
The geometry makes the cyclist worst: 内輪差 means the rear wheels of a 7.4 t truck track well inside the front wheels on a left turn. If he turns across her line, the rear of the truck sweeps into the space she occupies even though the cab has already passed her - the classic 巻き込み pattern.
2. The light is amber and he is 25 m from the stop line at 42 km/h. Analyse whether he can stop, and state what he should do.
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Amber means stop unless stopping safely is impossible. At 42 km/h (about 11.7 m/s) with a realistic 0.75 s reaction, the 空走距離 alone is roughly 9 m. On wet asphalt a loaded truck on all-season tyres can expect a friction coefficient around 0.4, giving a 制動距離 of about 17 m - a total near 26 m, longer than the 25 m available. So a clean stop is marginal, and a panic stop risks a skid or the load shifting.
The honest answer is that the decision was lost earlier: on a wet road with 3.9 t aboard and a junction ahead, he should have been at 30 km/h or less with the brake covered. Given the situation as it stands, he should apply firm progressive braking without swerving, keep the wheels rolling, and if he cannot stop before the line he must not accelerate through - he continues only after confirming the junction is clear. He must never trade the cyclist's safety for the light.
3. Describe the correct left-turn technique from this point, including how he handles the cyclist and the turning path.
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- Slow before the turn, in the lower gears, so the engine assists braking and the steering is light; signal early and keep the signal on through the turn.
- Position close to the left kerb without mounting it, so no one can come up on his inside.
- Re-check left mirror and blind spot immediately before turning, and again as the cab begins to swing; a mirror check made ten seconds earlier is worthless.
- Let the cyclist go first. She is going straight; if there is any doubt about her line, stop and let her clear the junction rather than trying to out-drag her.
- Follow a path that keeps the rear wheels clear of the kerb and of the crossing, remembering 内輪差, and check the pedestrian on the road he is entering before the cab straightens - the pedestrian crossing is on the exit side, not the entry side, so it is reached last and forgotten most often.