You cannot see a carrier's workshop from your desk, and "our trucks are well maintained" costs nothing to say. What you can see is the state's inspection, which every truck on a transport licence has to pass to be registered and to renew.
It is a real test with numbers in it. It is also a snapshot taken once a year. Knowing exactly what it measures tells you what you still have to check yourself, and that is the whole article.
What the law requires of a for-hire truck
Four sections of the Land Transport Act do the work.
- Section 71. A vehicle used for transport must be sound, carry the equipment and fittings the ministerial regulations set, and be registered and taxed.
- Section 72. A vehicle must pass inspection before it is registered and taxed. The inspection is done by a Department inspector or by an authorised inspection station, and a pass produces a certificate.
- Section 77. The registration book is valid for four periods, which are quarters starting in January, April, July and October. That is one year. The section applies Sections 71 to 73 again to a renewal, so a renewal means a new inspection.
- Sections 83 and 84. A transport inspector, a different officer from the one at the test station, who finds a truck unsound reports it. If continued use is clearly dangerous the inspector can suspend it temporarily and must report within 24 hours. The registrar can order the licence holder to send the truck for inspection and to stop using it until cleared.
So the default is one inspection a year, at any Department office, branch or authorised private station, and the Department's own service description puts it at about 30 minutes, not counting the wait.
One limit on that default. Section 72 lets a ministerial regulation exempt some vehicle types from inspection from time to time. This article could not read that list, so do not assume every truck on your account was inspected this year. Ask to see the certificate. Section 83 is the other limit: it depends on a transport inspector actually seeing the truck.
What the inspection measures
The Department's work manual sets the pass lines for goods vehicles. These are the ones that bear on maintenance.
| Check | Pass line |
|---|---|
| Foot brake, all wheels together | Brake force at least 50% of the vehicle's weight |
| Foot brake, left against right | Difference no more than 25% of the stronger side on that axle |
| Handbrake | At least 20% of the vehicle's weight |
| Trailer or semi-trailer | Total brake force at least 50% of the load on its axles. On a tractor and trailer the air line is unplugged, and the brakes must lock at once so the trailer does not move |
| Air pressure gauge or warning | Must work |
| Tyres | Tread at least 1.6 mm, no tear over 20 mm that reaches the fabric layer, no bulge |
| Wheels | No cracks or bends, no loose or missing wheel nuts |
| Front wheel alignment | Within 5 metres per kilometre either way on a side-slip tester |
| GPS link | Connection checked on trucks that must carry a recorder |
A worked example of the brake line. A truck with a registered weight of 6,000 kg must show total foot brake force equal to at least 3,000 kg. Suppose its front wheels give 900 and 650. The gap is 250, which is 27.8% of the stronger wheel, so it fails even if the total is fine. At 900 and 700 the gap is 200, which is 22.2%, and it passes. A truck that pulls to one side under braking is exactly what that line is built to catch.
A truck that fails does not simply get turned away. It is given a printed certificate of what to fix, and the process carries on once the work is done. A failure is therefore a normal event. What matters is whether the carrier fixed it and kept the record.
What it cannot tell you
- It is one day a year. A truck can pass in January with a tyre close to the 1.6 mm line and wear past it within weeks. The next planned look is a year away.
- It reads condition, not history. Nothing in those checks asks what was replaced, when, or why. Two trucks with the same pass can have very different service histories.
- It depends on the registration type. The Department's online tax page requires a private truck to pass inspection before tax only once it is more than 7 years from first registration. A carrier running your goods on a truck registered as private is outside the licence anyway. How to check that is in how to check a Thai carrier is properly licensed.
- The exemption list is unread. See above.
What the accident record says
The Ministry of Transport counted 22,139 accidents in 2023 reported from the Department of Highways, the Department of Rural Roads and the Expressway Authority, and recorded a presumed main cause for each.
| Presumed main cause | Accidents | Share |
|---|---|---|
| Speed over the limit | 15,118 | 68.29% |
| Worn or burst tyre | 555 | 2.51% |
| Brake system fault | 117 | 0.53% |
| Vehicle equipment defect | 116 | 0.52% |
| Vehicle electrical fault | 20 | 0.09% |
| Vehicle condition, the last four lines added | 808 | 3.65% |
Three readings, none of them comfortable for a maintenance sales pitch and all of them useful.
- Condition is a small cause of accidents. 808 of 22,139 is about one in 27. Speed is 18.7 times larger. Maintenance is not the main safety lever, and a carrier that talks about it as if it were is changing the subject.
- Inside that small share, tyres dominate. 555 of the 808 is 68.7%, and tyres are 4.7 times as common a cause as brake faults. If you check only one thing at your dock, check tyres.
- This counts accidents, not breakdowns. The figures cover all vehicle types, not only trucks. They say nothing about how often a poorly kept truck simply fails to arrive, which is the cost a shipper feels first.
The voluntary check: Q Mark
The Department runs a quality standard for truck operators called Q Mark. One of its five areas is vehicles, described as sound condition, checks at set intervals, and GPS and safety equipment fitted. What makes it different from the yearly inspection is that an independent body visits the operator's actual premises.
The Department's page counts 458 non-fixed-route truck operators holding it, with 63,675 vehicles between them, about 139 each. It is voluntary and it is a large-fleet badge. Holding it is a good sign. Not holding it says little, as covered in the licence article above.
A two-minute check at your own dock
You do not need a workshop to apply the state's own pass lines. When the truck arrives, before loading:
- Match the plate and the operator mark to the vehicle list the carrier gave you.
- Look at every tyre. Tread above 1.6 mm (a depth gauge settles it), no bulge, no deep tear.
- Look at the wheel nuts. None missing, none visibly loose.
- Check the lights work.
- Ask to see the latest pass certificate, or the registration book page, for that plate.
Do this on the first load from a new carrier and on a random one in ten after. A carrier whose trucks pass it every time is showing you something no promise can.
What to ask for once, and keep on file
For each truck that will run your account:
- The date of its last inspection pass and the date its registration next renews. Put the renewal in your calendar.
- Its service record by plate. The dates of the last brake work and the last tyre change are enough. A carrier that cannot produce two dates for a truck has told you something.
- Where the trucks are kept and repaired. The licence file names that place, as covered in the licence article above. Ask to see it.
- A short breakdown log for your lanes, because the accident report cannot give you that.
Then write it into the contract. A short clause that trucks on your account hold a current inspection, that the certificate is shown on request, and that you may refuse a truck that fails the dock check, with the carrier replacing it at its own cost, is one of the clauses in what a road freight contract should say. The inspection also checks that a recorder is connected where one is required, and what that recorder can and cannot tell you is in what GPS tracking on a truck shows.
What each check proves
| Check | Proves | Does not prove |
|---|---|---|
| Pass certificate dated this year | The truck met the pass lines on one day | That it still does |
| Renewal date in the future | The registration has not lapsed | That the truck was inspected, if its type is exempt |
| Service record by plate | Work was done and recorded | That it was the right work |
| Dock check of tyres and nuts | The visible condition today | Anything inside the brakes |
| Q Mark | An outside body saw the operation | That every truck on your account is in the audited fleet |
| Breakdown log | How often trucks fail on your lanes | Why |
What to do this week
- Ask each carrier for the latest inspection certificate for every truck on your account, with dates
- Put each registration renewal date in your calendar
- Ask for the service record by plate, at least the last brake work and the last tyre change
- Buy a tyre depth gauge and keep it at the dock
- Run the two-minute dock check on the next arrival from each carrier
- Start a breakdown log for your own lanes, since nobody else will give you one
- Add the inspection and refusal clause to the next contract renewal