Three-Lane Expressway at Night in the Rain: Speed, Lane and Fatigue Decisions
Kenji, 28, has held a 準中型 (quasi-medium) licence for 14 months. He drives a company 準中型貨物 truck: 車両総重量 6.8 t, 最大積載量 3.5 t, currently carrying 3.0 t of packaged freight. At 21:40 in light rain he joins a 片側3車線 expressway with a posted limit of 100 km/h and settles into the leftmost lane at 78 km/h. Two kilometres ahead, lane 1 is blocked by a column of trucks running at 55 km/h. Lane 2 is moving at about 75 km/h. Lane 3, the rightmost, is almost empty. Kenji's delivery exit is 6 km ahead on the left, and his tachograph shows 3 hours 40 minutes of continuous driving. He considers moving to lane 2 to pass, then staying out in lane 3 to run clear of the traffic all the way to the exit, which would save him roughly four minutes.
1. What is the highest speed Kenji may legally travel at on this expressway, and may he use lane 3 as a running lane? Explain the rules that apply to this vehicle class.
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Speed. A 準中型貨物 is a 貨物自動車. On 高速自動車国道 the statutory maximum for goods vehicles is 80 km/h, and that class limit binds him regardless of the 100 km/h posted for the road. His 78 km/h is therefore lawful, but matching lane 2 at 90 km/h or more would not be.
Lane. Where a carriageway has three or more lanes, 大型貨物自動車等 - a category that includes 中型貨物 and 準中型貨物 - may not use the rightmost lane as a cruising lane; it is available only for overtaking and similar temporary movements. Staying out in lane 3 to "run clear" is a 通行区分 violation even at a legal speed.
Correct plan. Remain in lane 1, signal, move to lane 2 only to pass the 55 km/h column, then return to lane 1 well before the exit.
2. Describe the observation and signalling sequence for the lane change from lane 1 to lane 2, and the space margins he should keep in rain at night with 3.0 t aboard.
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- Mirrors, then a direct look. Interior mirror, left mirror, and a shoulder check into the blind spot beside the cab; a loaded truck's blind area on the left is wide enough to hide a car.
- Signal about 3 seconds before moving (進路変更の合図は3秒前). Signal after checking, not before, so the lamp does not invite someone into the gap.
- Match speed before moving. Accelerate gently to close on lane 2 traffic rather than cutting across at 78 km/h into a 75 km/h stream.
- Margins. On a wet surface the braking distance grows and 3.0 t of freight adds momentum; keep at least 3 seconds behind the vehicle ahead, more if spray reduces visibility, and leave a gap behind the vehicle he passes so it does not have to brake.
- Smooth inputs. No abrupt steering or throttle at 78 km/h in rain with a high centre of gravity.
3. It is now 3 hours 40 minutes into continuous driving and he plans roughly another 90 minutes to finish the run. How should this factor into his decision, and what does the rule for commercial goods transport require?
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Fatigue degrades exactly the skills this manoeuvre needs: hazard search, distance judgement and reaction time. His spare four minutes is not worth any of that.
For commercial goods transport, the 改善基準告示 caps continuous driving at 4 hours before a break of at least 30 minutes. At 3 h 40 min he is close to that ceiling, and adding 90 minutes would plainly breach it.
The judgement call is therefore: make the legal lane change, take the exit, and stop at the next SA/PA for a rest of at least 30 minutes before continuing - or hand over to another driver. The lane-3 shortcut is doubly wrong: it is a 通行区分 violation and it prolongs a stint that is already at the limit.