You're on the side of a highway and someone needs to know exactly where you are: the office, a traffic controller up the road, the person writing the incident report. "Just past the servo" doesn't cut it. The road, section and chainage does. Here's how to get that from your phone in a few seconds, and how to check it's right before you read it out.
Why chainage beats a street address
Most of Queensland's state-controlled road network has no street numbers. A highway can run for 100 km between towns, and the landmarks people use ("the big tree", "the second culvert after the bridge") mean nothing to someone who hasn't been there.
Chainage is the distance along the road from the start of its road section, as recorded by the Department of Transport and Main Roads (TMR). A reference like Bruce Highway, section 10A, chainage 25.306 km points to one spot that anyone with TMR's data can find. That's why it's used in traffic guidance schemes, permit applications, maintenance defect reports and contract documents. If chainage is new to you, start with What is chainage?
Before you start: location access and a good GPS fix
Chainage uses your phone's location, so two things matter:
- Allow location access. The first time you tap Find my chainage, your browser asks for permission. Say yes. If you said no by mistake, the app shows step-by-step instructions for iPhone and Android to turn it back on.
- Give the GPS a moment. Phones are most accurate with a clear view of the sky. The US Government's GPS site puts typical smartphone accuracy at about 5 metres under open sky, and it gets worse next to tall buildings, in deep cuttings, under heavy tree cover and inside vehicles. If you've just got out of the car, wait a few seconds for the fix to settle.
You don't need an account to find a chainage. You only need one to save points to a project.
Step by step: find your chainage with GPS
- Open chainage.com.au in your phone's browser. Nothing to download. To open it like an app next time, add it to your home screen (Safari: Share, then Add to Home Screen; Chrome: ⋮ menu, then Install app).
- Tap Find my chainage. The map zooms to you and your chainage appears on the button.
- Read the result card. It shows the road name, the TMR road section (for example 10A), the chainage in kilometres (for example 25.306 km, also written CH 25+306), the carriageway and how far you are from the road centreline. It also shows your GPS accuracy.
- Keep moving if you need to. The chainage keeps updating as you walk or drive, which suits a passenger recording chainages during a drive-through inspection. If you pan the map, following pauses; tap the button again to re-centre.
Never use a phone while you're driving. Let a passenger run the app, or pull over somewhere safe first. On the roadside, work from a safe position, wear your high-visibility clothing and follow your site's traffic management.
What the result is telling you
Chainage compares your position with TMR's reference points along every state-controlled road and tells you how close you are:
| You see | What it means |
|---|---|
| You're on [road] at chainage … | You're within about 30 m of the road's centreline. The chainage is for the point on the road nearest to you. |
| You're about … from [road] | You're off the road but within 500 m of it, for example in a compound, a side street or a property. You get the nearest chainage on that road. |
| You're not close enough to a Main Roads road | The nearest state-controlled road is more than 500 m away. You're probably on a council road. See how to tell who manages a road. |
Make sure it's the right carriageway
On a two-lane country highway there's only one carriageway, so this step is easy. On divided roads, interchanges and anywhere with ramps or service roads, there can be several carriageways within a few metres of you, each with its own TMR carriageway code. The chainage can differ between them, especially on ramps.
- Check the carriageway on the card. A single, undivided road is code 1; the two sides of a divided road have their own codes, and ramps and service roads have others.
- If it's picked the wrong one, zoom in and tap directly on the carriageway you mean. The pin snaps to that road and shows its chainage.
- Use Street View on the card to confirm you're looking at the right side of the road before you commit to a location for signs or a work zone.
Reading it out over the radio or phone
A chainage on its own isn't enough. Give the whole reference, in the same order every time:
- Road name and section: "Bruce Highway, section ten-A".
- Chainage: "chainage twenty-five point three zero six", or "twenty-five plus three zero six". Say each digit after the point so nobody hears 25.36.
- Carriageway or direction if it's a divided road: "northbound" or "carriageway two".
- What's there: "vehicle on the left shoulder", "pothole in the left wheel path".
If the other person has a smartphone, it's quicker and safer to send a link than to read numbers. Tap Share on the result card for a link and QR code that open the map at your exact point. See sharing exact road locations with your crew.
Save it, copy it or send it
- Copy: the copy icon next to the chainage copies it, and Copy coords copies your latitude and longitude for a form or message.
- Save chainage point: keep it in a project with a title, notes and photos taken on the spot. Points sit in phases and layers, so a site walk can be sorted into signs, hazards, access points and so on.
- Make a chainage range: for a stretch rather than a point, such as a lane closure or a section of damaged pavement.
- Share: a link and QR code for anyone, no account needed.
How accurate is it?
Chainage works from TMR's published reference points, which sit about every 10 m along each carriageway, and calculates your exact position between them. The result is within a few metres of TMR's data. The bigger variable is usually your GPS fix and where you're standing relative to the road.
Treat the result as a reliable working location, not a survey. Where position is critical, such as setting out structures, confirm against survey marks, design drawings or TMR records.
Frequently asked questions
Do I need an account to find my chainage?
No. Finding chainages is free and doesn't need an account. You only need a free account to save points, photos and projects.
Why does the app say I'm not near a Main Roads road?
TMR chainages only exist on state-controlled roads. If the nearest one is more than 500 m away, you're most likely on a council-managed local road, which has no TMR chainage. The app still tells you the nearest state-controlled road and how far away it is.
Can I use it while driving?
Only if someone else is holding the phone. A passenger can leave it running during a drive-through inspection and read chainages as you go. The driver should never use the phone while driving.
Does it work without mobile reception?
Your phone's GPS works without reception, but Chainage needs an internet connection to look up the chainage and load the map. In patchy areas, results can take a little longer. See our guide to pinpointing your location on remote roads.
Why is my chainage a few metres different from a roadside marker?
GPS error, which carriageway you snapped to, and how recently the roadside markers and TMR's digital network were updated can each shift the result by a few metres. For precise work, confirm critical chainages on site or with TMR.
Sources
- GPS.gov (US Government), GPS accuracy.
- Queensland Department of Transport and Main Roads, Road Location and Traffic Data definitions (open data).
- Chainage user guide: find a chainage.