A tracking screen looks like the truth. There is the truck, there is the road, there is the customer's gate. It is easy to treat it as a record of what happened.
It is not quite that. The device on a Thai truck records a short list of things: where it was, how fast it moved, what time it was, whether the engine was on, and whose licence card was in the reader. Everything else people read off the map, such as "arrived at the customer", "waited two hours", "went back empty", is worked out from those few facts by somebody's rules. Change the rules and the answer changes.
This article sorts the two apart, so tracking data can settle an argument instead of starting one. How to use the live feed to run the day is a separate subject, covered in running the day when the plan meets the road.
Which trucks must carry one, and which do not
The Department of Land Transport requires a certified journey data recorder, connected to its GPS centre, on these vehicles. The scope is narrower than most people assume.
| Vehicle | Required? | Since |
|---|---|---|
| Dangerous goods trucks, and tractors pulling dangerous goods semi-trailers | Yes | All fitted by 1 January 2014 |
| Tractor units | Yes | New registrations from 25 January 2016. Older ones before their 2017 renewal inspection |
| Trucks with at least 3 axles, 6 wheels and 10 tyres: cargo tray, box, tanker and special purpose bodies | Yes | New registrations from 25 January 2016. Older ones before their 2018 renewal inspection on a for-hire licence, 2019 on a private licence |
| Six-wheelers (2 axles) and four-wheel pickups, unless they carry dangerous goods | No | |
| Trailers and semi-trailers themselves | No. The tractor carries the device |
The rule covers for-hire trucks on a non-fixed-route licence and trucks on a private licence alike. So a manufacturer's own ten-wheeler needs one just as much as a carrier's does.
Three things follow for a buyer.
- The urban end is the least covered. Six-wheelers and pickups often do the city delivery work, and nothing requires them to be tracked. If a carrier tracks them, that is its own choice, on its own system, to its own standard. Ask.
- A parked trailer is invisible. The device is on the tractor. A loaded semi-trailer dropped at a yard overnight has no record of its own once the tractor leaves.
- "Required" means connected to the Department. It does not mean you can see it. That comes later.
What is actually in the record
The Department's 2015 specification lists what the device must record and send. Read in Thai, each record carries:
- Which device: the vendor's certification number and the unit's own number
- When: the time the device took the reading, and separately the time the tracking provider received it
- Where: latitude and longitude, with a horizontal error of no more than 20 metres
- How fast: speed to 1 km/h, with a value every minute
- Engine status, GPS fix status and data status
- A record sequence number
- The driver: licence type, number and issuing province, from the licence card swiped in the reader
- External power status, which shows if the device was unplugged
Data must go out in real time or at least once every five minutes, with detail every minute. If there is no signal, the device keeps at least 24 hours of records and sends them later. The provider must keep the data for at least six months.
Now look at what is not on that list. Nothing says whether the truck is loaded or empty. Nothing says the doors opened, what the temperature was, what it weighed, which drop it was on, or that anyone signed for anything. Some carriers add sensors for those. They are extras, and the Department's standard says nothing about them.
Measured, or worked out
Everything anyone reports from tracking falls into one of two columns.
| Measured by the device | Worked out from the measurements |
|---|---|
| Position, to within 20 metres | Arrived at a customer |
| Speed, each minute | Waiting against unloading |
| Time | Loaded or empty on a leg |
| Engine on or off | Rest stop or work stop |
| Which licence card was swiped | Who was actually driving |
| Device unplugged | Followed the agreed route |
The right-hand column is always somebody's rule applied to the left-hand column. That is not a flaw. It just means a number from the right-hand column is only as good as the rule behind it, and the rule should be agreed before the number is used for money.
Researchers working on the Department's national truck feed show how much rule-making it takes. To find where trucks actually did something, they:
- Ignored any stop shorter than 20 minutes, to filter out traffic
- Merged stops less than 2 km apart, because trucks shuffle around inside industrial estates
- Labelled each remaining stop as a rest or a load-unload by probability, using only how long it lasted and how far it was from the nearest road
- Inferred loaded or empty from the sequence of places visited, and could fit 72% to 90% of trips to a known pattern
Even with that care, the answers vary widely. Average loading and unloading stops ran from about 74 to 151 minutes depending on the commodity, some lasted up to 1,050 minutes, and the provincial average ran from 143.5 minutes in Rayong to 249.5 in Nan.
You have an advantage the researchers did not. You know your own addresses and your own orders. So you can replace their guesswork with plain rules about your own sites. The next two sections are those rules.
The line you draw decides the number
"Arrived at the customer" usually means the truck's position entered a zone drawn around the site on a map, called a geofence. Where that line goes changes the answer more than any accuracy problem does.
Take one visit:
| Time | What happened |
|---|---|
| 08:00 | Truck joins the queue on the road outside the customer |
| 09:30 | Passes the gate |
| 09:45 | Reaches the dock |
| 11:05 | Leaves the dock |
| 11:15 | Leaves through the gate |
Draw the zone around the whole site, including the road where trucks queue, and the tracking shows 3 hours 15 minutes on site. Draw it around the gate only, and it shows 1 hour 45 minutes.
With two hours of free time, the first line gives 1 hour 15 minutes of chargeable waiting. The second gives none. Same truck, same morning, same data. The only difference is a line somebody drew. How much waiting is reasonable, and how the charge should work, is in what a waiting time charge is, and how much waiting is reasonable. The point here is narrower: agree in writing where the zone is, for each site, before the first invoice.
Where the dot can be wrong
The Department's standard allows up to 20 metres of horizontal error. Where the truck stands matters too. The US government, which runs GPS, says a typical phone is accurate to about 4.9 metres under open sky, and that accuracy gets worse near buildings, bridges and trees, and indoors. On a Thai route that means under an expressway, inside a covered loading bay, and between tall factory buildings: exactly the places where trucks wait.
Two practical rules come out of that.
Two gates less than 40 metres apart can be confused. At 20 metres of error, a truck standing at one gate can be recorded 20 metres towards the next. If the gates are closer than 40 metres, that point can land nearer the wrong one. Factories that share a road in an estate often sit this close. Use one zone per site, drawn around the site, not a pin on each gate.
The gap between records limits the timing. A stop measured from records one minute apart can come out short by up to 2 minutes: up to a minute at each end, before the first reading inside and after the last. From records five minutes apart it can come out short by up to 10 minutes. That does not matter for a two-hour free time. It matters a lot for a 30-minute delivery window. The rule lets a device send its records in five-minute batches, and a tracking screen may show fewer points than were recorded, so for a dispute, ask for the one-minute records, not the screenshot.
Three fields that settle arguments
Most arguments about tracking come down to whether the record is complete. The standard already includes the fields that answer that. Few people look at them.
- Record sequence number. Each record is numbered. A gap in the numbers means missing records. No gap means the trace is complete, even if the map shows a jump.
- Reading time against received time. A signal dead zone looks like a truck that vanished and reappeared. If the reading times run every minute but the received times arrive in one burst later, the device was buffering, which it must do for up to 24 hours. The truck did not vanish.
- External power status. Records whether the device was disconnected, so "the tracker was not working" is something you can check.
One field looks stronger than it is. The driver field records which licence card was swiped, not who was driving. If two drivers share a truck and only one swipes, all the driving hours land on that one licence. It is a good record of the card. It is not proof of the person.
Getting the data when it is not your truck
If you hire a carrier, nothing in the tracking rules gives you access to its data. The standard sends records to the Department and requires the provider to keep them. It says nothing about the carrier's customers. Access is whatever your agreement says. So put it there:
- Which vehicles are tracked on your work, including six-wheelers and pickups, which the rule does not cover
- How you see it: a live share link, or a daily file of the one-minute records
- The zones for each of your sites, drawn and agreed, and who may change them
- The dispute window. The provider must keep data for at least six months. Raise any claim that depends on tracking inside that period, or agree a longer retention
- Device changes. The installation certificate names the device, its number and the vehicle's plate. Ask for it when a truck joins your work and when its device is replaced
- What counts as arrived, unloaded and left for your sites, stated as rules on the data rather than left to the screen
The Department's GPS centre publishes a list of certified device models on its website. It takes a minute to check that the model in a carrier's certificate is on it.
What to set up this month
- List the vehicle types on your work and mark which ones the rule covers. The six-wheelers and pickups are the gap.
- Draw a zone around each of your top twenty sites. Include the queue road if waiting is going to be charged. Get it agreed.
- Write down the event rules: arrived when the truck enters the zone, left when it exits, with a minimum stop length so a truck passing the gate does not count.
- Ask each carrier how you will get one-minute records for a disputed day, and test it once before you need it.
- Check the sequence numbers and power status before accepting or rejecting a tracking-based claim.
- Diarise the six-month limit. A claim built on tracking data after the data is gone is just an opinion.
- Keep the driver's own status messages. Tracking will never tell you the goods were signed for or why a stop took an hour. The driver can.
The one line worth keeping
The tracker measures position, speed, time and a card in a slot. Everything else is a rule someone applied to those facts, so agree the rules before the data is used for money.