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What trailer tracking is for once the tractor pulls away
Tracking each trailer tells you which ones are in the yard and which sit at a customer dock. It shows how long each one has sat there, and where one went if it left without a driver you sent.
The tracker on your tractor cannot tell you this. Trailers spend most of their life unhooked. They wait at a shipper, sit in an overflow lot, or leave with a carrier you hired. The tractor's telematics sees none of it.
This page covers dry vans, flatbeds, reefers, chassis and lowboys, and the utility, dump and enclosed trailers towed behind a pickup. Shipping containers and returnable packaging have their own container tracking guide. If you track trailers alongside machines and generators, the equipment tracking system guide covers the rest of the fleet. The tool tracking system guide covers the tools inside.
What a GPS tracker for trailers needs, and why a tag needs neither
Any GPS tracker for trailers needs two things: power and a data plan. On a dry van or a flatbed, power usually comes only through the 7-way connector while a tractor is coupled. The rest of the time a trailer GPS tracker runs on its own battery, which drains faster the more often it reports. It also sends every position itself, so each unit carries its own data plan.
A crowdsourced tag needs neither. It has no GPS receiver and no data plan. It broadcasts a Bluetooth signal, and any phone that passes reports where it heard the tag. These networks are large (Apple counts over a billion iPhone, iPad and Mac devices, and Google over a billion Android devices).
The tag runs on its own battery for up to six years, depending on its size. It never touches the trailer's wiring, so it fits a flatbed, a dry van or a utility trailer the same way.
Updates follow people. A trailer at a busy distribution center updates often. One on a quiet rural lot updates when someone passes, or when the trailer moves somewhere busier. With no wiring and no data plan per unit, trailer tracking can cover the whole fleet, from the newest reefer to the oldest flatbed.
Where to hide a tracker on a trailer: six spots that keep reporting
Hide a trailer tracker out of sight, where its signal still has a way out through plastic, wood, a seam or a vent. A tag near an opening reports more often than one sealed in a steel or aluminum box. The figure marks six spots that are hidden and still near an opening, three on a flatbed and three on a dry van.
Anywhere road spray reaches, use a sealed tag rated IP68. Asset tracking tags covers what is inside a tag, mounts and IP ratings.
Before you fit the whole fleet, test one mount in the quietest lot the trailer visits. A busy yard makes almost any mount look good.
Trailer yard audits without walking the yard
With a tag on every trailer, a yard audit starts from a list instead of a walk. Walking the rows and reading unit numbers covers only the trailers on the lot. It says nothing about the ones that are not.
Sort the list by the time since each trailer was last seen, and the ones that need a look rise to the top. That might be a unit that has sat at one customer for three weeks, or one not seen in your yard lately.
At the gate, draw one geofence around the yard, wide enough that normal position drift inside it does not trip an alert. The geofence setup guide covers drawing and tuning. The exit alert comes with the tag's first report from outside the fence, which is quick where people pass.
Detention and drop-trailer time you can put on an invoice
Trailer tracking supplies the dates a detention invoice needs: when the trailer reached the customer's facility and when it left. A trailer dropped at a customer earns nothing while it waits. Your contract or tariff sets the free time and the rate.
Draw a geofence around each customer site you deliver to. Every arrival and departure is then recorded with a time. The history exports as a spreadsheet for the invoice or the customer's accounts payable team (data export and API).
The arrival time is the first report from inside the fence, and the departure time is the first report from outside it. The real drop and pickup happened at or a little before those times. At a busy distribution center the gap is small, and at a quiet dock on a Sunday it is wider.
The record shows the facility, and the dock log shows the door. In a detention dispute, the record answers two questions: was the trailer on the customer's property, and for how many days?
Tracking a stolen trailer: what the history gets you
Trailer tracking history gives you a starting address and a dated trail. A thief with a tractor still has to crank up the landing gear and connect the air lines. With a pickup and a ball-hitch trailer it is quicker. The alert comes with the first report from outside your yard, and the record after that is what gets the trailer back.
Wherever the trailer is taken, the tag keeps reporting as people pass, and each report gives police an address and a time. Busy places give fresher updates, and the last report from a quiet lot still marks where to start.
On tagging day, photograph the VIN plate, the license plate and the unit number. The FBI's NCIC Vehicle File records a stolen vehicle's VIN, make, model, year, owner-applied number and plate. A separate NCIC License Plate File lists stolen plates by type, trailer plates included (FBI NCIC privacy assessment). Have those details ready when you call.
On a lowboy, the machine chained to it is often worth more than the trailer. A loaded lowboy needs only a tractor to leave. The 2016 equipment theft report from NER and NICB says equipment should never be left on trailers. Tag the machine as well (GPS tracker for construction equipment).
Hand the address, timestamps and history export to police. Do not go and collect the trailer yourself. The stolen tool and equipment recovery playbook covers the report, the registries and the insurer.
For prevention, use a kingpin or gladhand lock on a semi trailer. On a towable, use a coupler lock and a wheel lock (theft prevention).
What to expect from tag-based trailer tracking
A crowdsourced tag keeps a location record for every trailer and helps you get one back.
- Updates come from passing phones. Any phone that passes reports the tag. A trailer on a busy site updates often. One on a remote drop lot or a rail siding updates when someone passes, or when the trailer moves somewhere busier.
- Lot-level position. The position comes from the phone that heard the tag. It gets you to the right lot, and the unit number does the rest (how accurate tag locations are).
- Location only. A tag reports where the trailer was heard. Reefer temperature and door status need sensors of their own.
- A hidden tag stays on. A tag in plain view can be pulled off. The spots above keep it out of sight.
Frequently asked questions
What is the best tracking device for a trailer?
For most trailers, a crowdsourced tag. A GPS tracker for trailers needs power and a data plan on every unit, and most trailers have power only while hooked up. A tag needs neither: it runs on its own battery for up to six years, depending on its size. Any phone that passes reports where it is, and a trailer moving between yards, truck stops and docks passes people every day.
Can I use an AirTag to track my trailer?
Yes. An AirTag is a crowdsourced tag: any phone that passes reports it, so it needs no power from the trailer and no data plan. Apple rates it IP67, so mount it out of direct road spray, and out of sight so it stays on. On its own it shows the trailer's last reported location, and a tracking dashboard adds the history and an exit alert.
How much does a trailer tracking system cost per trailer per year?
It comes down to what each trailer carries. A GPS tracker means the hardware, often an installer, and a data plan for every unit. A crowdsourced tag means the tag and the tracking software, with no wiring and no data plan per trailer. That is why a tag can go on every trailer, where GPS tracking was kept for the most valuable ones.
Can you track a stolen trailer?
Yes, if it carries a tag before it is taken. The exit alert comes with the first report from outside your yard: quick in a busy area, slower on a quiet street at night. After that, each report from a passing phone gives police an address and a time. A kingpin or coupler lock deters the theft, and the location history is what gets the trailer back.
Does a trailer tracker need power from the trailer?
A crowdsourced tag does not. It runs on its own battery for up to six years, depending on its size, and never draws on the trailer's power. On a small towable with electric brakes, never wire an always-on tracker into the breakaway battery. That battery exists to apply the brakes if the trailer comes off the hitch.
Will a tracker work inside an enclosed trailer?
Yes, but the walls weaken the signal. A tag deep inside a steel or aluminum box reports less often than one on a flatbed. Mount it near an opening, behind a plastic liner or a door seam, rather than deep in the box. Test it in a quiet lot before fitting the fleet.
How accurate is a trailer tracker?
Accurate enough to take you to the right yard, lot or customer dock. A crowdsourced tag's position comes from the phone that heard it, and the unit number shows which trailer to walk to. Each position is dated, so you can see how recent it is.
Can I prove how long a trailer sat at a customer dock?
Yes, to the facility and within the time between reports. Put a geofence around the customer site, and each arrival and departure is recorded with a time. The history shows the stay and exports as a spreadsheet for the invoice. At a busy dock the recorded times are close to the real ones, and at a quiet dock the gap is wider.
Know what is on the lot before you walk it
Tell us how many trailers you run and where they park. We will suggest a tag for each and tell you what updates to expect at your yard and your customers' docks.