Locations arrive in all sorts of shapes: a Google Maps pin in a text message, coordinates in an incident report, a photo location from a drone survey, a line in a spreadsheet. But permit applications, traffic guidance schemes and defect reports on Queensland's state-controlled roads usually want the TMR road, section and chainage. This guide shows how to convert one into the other, and the mistakes that put a point on the wrong road.
Formats Chainage understands
Paste any of these into the search bar in Chainage:
| Format | Example |
|---|---|
| Decimal degrees | -27.4705, 153.0260 (latitude first; a comma, semicolon or space between) |
| Degrees, minutes, seconds | 27°28'13.8"S 153°01'33.6"E |
| Degrees and decimal minutes | 27°28.230'S 153°01.560'E |
| Google Maps link | A maps.app.goo.gl/… share link from the app, or a full google.com/maps/… address from a browser |
Grid coordinates (MGA eastings and northings), what3words addresses and plus codes aren't read directly. Convert them to latitude and longitude first (see MGA coordinates below).
Convert coordinates to chainage
- Copy the coordinates from wherever they are: an email, a report, a GPS unit's screen, a spreadsheet cell.
- Open chainage.com.au and tap the search bar (or press / on a keyboard).
- Paste. A pasted coordinate jumps straight to the point. If you type it instead, tap Go to map point.
- Read the result card: road name, TMR road section, chainage (for example 7.314 km or CH 7+314), carriageway and the distance from the point to the road.
If the point is right on a state-controlled road, the pin snaps to the road. If it's off the road, for example a driveway, a compound or a sign location on the verge, Chainage keeps a dropped pin exactly where the coordinates say, draws a dotted line to the nearest road and shows that road's nearest chainage with the offset distance. That's usually what a permit or access application needs: the precise point plus the chainage it's adjacent to.
Convert a Google Maps link to chainage
Someone sends you a pin from Google Maps on their phone. The link looks like https://maps.app.goo.gl/AbCd… and hides the coordinates. You don't need to open it first:
- Long-press the link in the message and copy it.
- Paste it into Chainage's search bar. Chainage reads the location from the link and goes straight there.
- Check the pin landed where the sender meant, then read off the chainage.
Links copied from Google Maps in a desktop browser work too. If a link from another app won't read, ask the sender for coordinates instead, or open it, copy the coordinates and paste those.
Getting coordinates out of Google Maps yourself
- On a computer: right-click the spot on the map. The coordinates are the first line of the menu; click them to copy.
- On a phone: touch and hold the spot to drop a pin. The coordinates show in the search box or in the pin's details, where you can copy them.
The other way: chainage to coordinates
Got a chainage from a TGS, a work order or a defect list and need to find it on a map or send coordinates to someone?
- Search the road name or section number, for example Bruce Highway or 10A, and open the road.
- In Find another chainage on this road, enter the distance (switch between km and m) and tap Go.
- Tap Copy coords for the latitude and longitude, Share for a link, or Google Maps or the directions buttons to navigate there.
Five mistakes that put the point on the wrong road
- Missing minus sign. Queensland is in the southern hemisphere, so decimal latitudes are negative:
-27.47, not27.47. Without the minus, the point lands in the northern hemisphere. - Latitude and longitude swapped. Queensland latitudes run from about −10 to −29; longitudes from about 138 to 154. If the first number is in the 140s, it's the longitude.
- Too few decimal places. A degree of latitude is about 111 km, so each decimal place matters: four places (
-27.4705) is good to about 11 m, six places to about 10 cm. Three places can put you on the wrong road at an interchange. - Minutes mistaken for decimals.
27°28.23'(degrees and minutes) is not27.2823°. Keep the degree and minute symbols when you paste, or convert carefully. - The wrong carriageway. On a divided road or at an interchange, a point between carriageways can snap to the wrong one. Check the carriageway on the result card and tap the one you mean.
MGA coordinates and datums
Survey and engineering drawings in Queensland often use grid coordinates: eastings and northings on the Map Grid of Australia (MGA), in a numbered zone. Those need converting to latitude and longitude before you can paste them. Most GIS and CAD software will do it, as will the online coordinate converters published by Geoscience Australia. Make sure you know the zone (Queensland spans MGA zones 54, 55 and 56) and the datum.
On datums: Australia's current datum, GDA2020, moved coordinates by about 1.8 m compared with the older GDA94, because the continent drifts north-east by about 7 cm a year. Phone GPS works on a global datum that's closely aligned with GDA2020. For finding a chainage the difference doesn't matter, because it's well within normal GPS error. For survey set-out, it does, so use the coordinates from the drawing's stated datum.
Keeping the result
Nothing is saved when you look up a point. To keep it, tap Save chainage point (or Save dropped pin) and add it to a project with a title and notes. Every saved point stores both forms: its latitude and longitude, and its road, section, carriageway and chainage. When you export a project to CSV, each row includes the coordinates and the chainage side by side, which is handy for registers, permit schedules and GIS.
Frequently asked questions
Can I paste a Google Maps link straight into Chainage?
Yes. Paste a Google Maps share link (maps.app.goo.gl) or a full google.com/maps address into the search bar and Chainage reads the location from it and shows the nearest TMR chainage.
Which way round do latitude and longitude go?
Latitude first, then longitude, for example -27.4705, 153.0260. In Queensland the latitude is negative (south of the equator) and the longitude is between about 138 and 154.
Can I convert MGA eastings and northings?
Not directly. Convert them to latitude and longitude first with GIS or CAD software or Geoscience Australia's online tools, then paste the result. You'll need to know the MGA zone and datum.
What if the coordinates aren't on a state-controlled road?
Chainage keeps the point exactly where it is as a dropped pin and shows the nearest state-controlled road, its chainage and the distance to it. Council roads don't have TMR chainages.
How do I get coordinates from a chainage?
Search the road or section, enter the chainage under Find another chainage on this road, tap Go, then tap Copy coords on the result card.
Sources
- Intergovernmental Committee on Surveying and Mapping, GDA2020.
- Google Maps Help, Find and enter coordinates.
- Queensland Department of Transport and Main Roads, Road Location and Traffic Data definitions (open data).
- Chainage user guide: search.