ROADS in JAPAN

Vehicle size and weight

Road-related Systems in Japan

Roads are designed to ensure safe and smooth traffic for vehicles with certain specifications. In principle, vehicles that do not meet size and weight requirements are not allowed to be on the road, because they can potentially damage the road’s structure or disrupt traffic.
However, road administrators are empowered to give permission to the vehicles that exceed the size or weight regulations to use the road, but only if the road administrator acknowledges that there are no alternatives after examining the vehicle’s structure and the cargo. In these cases, the road administrator will put certain conditions in place to protect the road structure and prevent potential dangers to road users.


■On general roads

General limit (upper limit) of vehicles according to Article 3.1, Vehicle Size and Weight Restriction

●Typical special vehicles

■On expressways

Dimension & weight limits for specified
vehicles are more lenient than on general roads
  Length
Semi-trailer 16.5m
Full-trailer 18.0m
Greatest axle
distance
8m
or
more
9m
or
more
10m
or
more
11m
or
more
12m
or
more
13m
or
more
14m
or
more
15m
or
more
15.5m
or
more
Gross weight 25t 26t 27t 29t 30t 32t 33t 35t 36t

●Specified vehicles

Approval system for the use of special vehicles on roads

Road administrators are authorized to permit the drivers of vehicles that exceed the size or weight regulations to use the road, but only after the road administrator examines the vehicle’s structure and the cargo and determines that there are no alternatives. In these cases, the road administrator will put certain conditions in place to protect the road structure and to prevent any potential dangers to other road users. Road fatigue, which is caused by vehicle traffic that is over the weight or size regulations, has a significant effect on road structures and pavement. In order to utilize our road stock effectively in the future, it is important to ensure that road structures are properly maintained now.

Controlling illegal vehicles

1. Instructive enforcement
Drivers are told to pull over at "instruction stations", where vehicle weights and sizes are measured. If the vehicle exceeds the size or weight regulation, the drivers are ordered or warned to reduce the weight and size of the vehicle by splitting the cargo.

2. Weigh-in-motion (WIM)
A WIM device automatically measures a vehicle’s gross weight as the vehicle drive over a measurement site. If the vehicle is over the weight regulations, it then determines if the overweight vehicle has a permit by accessing the database. Based on the results, repeated violators will be given an instructive warning.

■Weigh-in-motion

 
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