Regulations
Laws & Standards
Lawful operation of trailer houses on public roads
To enhance the safety and social trustworthiness of trailer houses, the Association promotes proper manufacturing, sales, and transport in compliance with the relevant laws and regulations.
1. Basic policy
When moving a trailer house on public roads, it is important to confirm the necessary procedures—such as vehicle inspection, relaxation certification of the safety standards, and special-vehicle passage permits—according to the vehicle’s structure, dimensions, weight, braking system, and so on.
2. Promoting vehicle inspection
For trailer houses that are within 2.5 meters in width and that conform to the safety standards for length, height, weight, braking devices, lighting devices, and the like, the Association’s basic policy is that they be operated on public roads only after undergoing the required inspection and registration.
Being within 2.5 meters in width alone does not allow a determination that vehicle inspection can be obtained.
3. Gross vehicle weight of 3.5 tons and the O2/O3 categories
The international classification of towed vehicles includes O categories based on vehicle weight.
| Category | Maximum weight |
|---|
| O1 | 750 kg or less |
| O2 | Over 750 kg to 3.5 tons |
| O3 | Over 3.5 tons to 10 tons |
| O4 | Over 10 tons |
O2 and O3 differ in the technical standards required for braking devices and the like. In particular, for trailer houses exceeding 3.5 tons, a general inertia-brake system alone may be insufficient to meet the standards, so confirming the vehicle structure, including the braking system, becomes important.
O2 and O3 are international vehicle classifications, and this distinction alone does not determine whether vehicle inspection and registration are possible within Japan. A gross vehicle weight exceeding 3.5 tons alone does not uniformly make inspection and registration impossible.
4. Relaxation certification of the safety standards
For trailer houses that do not conform to the ordinary safety standards for road transport vehicles, there is a system under which, if the prescribed requirements are met, they may be temporarily operated after receiving standard-relaxation certification from the District Transport Bureau. The certification review covers the vehicle structure, the purpose of operation, the route, safety measures, and so on.
For the standard-relaxation certification concerning temporary operation of a trailer house, a separate temporary operation permit is required.
5. Special-vehicle passage permit
Vehicles exceeding the general limit values set out in the Road Act require, in principle, procedures such as a special-vehicle passage permit. The general limit values include the following.
- Width: 2.5 meters
- Length: 12 meters
- Height: 3.8 meters (4.1 meters on certain designated roads)
- Gross weight: 20 tons in principle (with exceptions depending on road designation, etc.)
In addition, axle weight, wheel load, minimum turning radius, and the like are also subject to review.
Standard-relaxation certification and the special-vehicle passage permit are procedures with different purposes. Obtaining one certification or permit does not make the other unnecessary.
6. Thorough safe operation
In transporting trailer houses, the Association promotes the following.
- Advance confirmation of the vehicle’s dimensions, weight, and braking performance
- Obtaining the necessary vehicle inspection, registration, and permits/approvals
- Confirmation of road width, bridges, and height restrictions along the passage route
- Deployment of guide vehicles in accordance with the permit conditions
- Compliance with the designated route, time periods, speed limits, and so on
- Inspection of the coupling between the towing vehicle and the trailer house and of the safety devices
7. The Association’s initiatives
Through proper acquisition of vehicle inspection, the reliable completion of necessary permits and approvals, and thorough safe operation, the Association aims for the sound development of the trailer house industry as a whole. We will also strive to provide information to member businesses and to raise awareness of legal compliance, promoting the spread of safe and trusted trailer houses.
* The inspections, certifications, permits, etc. actually required differ depending on the individual vehicle specifications and operating conditions. Confirmation with the competent District Transport Bureau, road administrator, and the like is necessary before operation.
Where to confirm installation and road operation
Building classification at the installation site and conditions for travel on public roads must be checked separately.
Building Standards Act
Consult the building authority before installation
Building classification depends on equipment that obstructs movement, utility connections, size and installation conditions. Consult the building authority responsible for the site before installation.
Road Transport Vehicle Act
To travel lawfully on public roads
Check with the transport office and road administrator about inspection, registration, safety standards or exemptions, and procedures for the planned route. A standards exemption does not replace vehicle inspection or road-access procedures.
General limits under Article 2: width up to 2.5 m, height up to 3.8 m and length up to 12 m. Semi-trailer length is measured differently; specified semi-trailers have a 13 m exception.
MLIT: Relaxation of standards for trailer houses (press release, Japanese)
MLIT: Special vehicle passage system (Japanese)
The following 13 items are the Association's checklist. They do not replace legislation or administrative approvals. Meeting all items does not guarantee that a unit is exempt from classification as a building.
