How the limit on a marker is worked out

Each camera marker shows a number in km/h. That number is the limit the map believes is in force at that point, at the moment you open it. The steps below are the same ones the daily build and the phone use.

Posted limit

The usual number comes from OpenStreetMap, from the maxspeed tag on the road next to the camera. Transport agencies publish camera sites. They rarely publish the limit on that stretch, so the map reads the road data.

If OpenStreetMap has no limit there, the marker shows a question mark. The camera is still on the map. You then use the sign on the road.

School zones and other timed limits

OpenStreetMap also stores timed rules as maxspeed:conditional. A common NSW school zone looks like 40 km/h on weekdays from 08:00 to 09:30 and from 14:30 to 16:00, with school holidays off.

The daily build turns those rules into time windows in each state's time zone. The map then picks the window that covers now. During a lower window the ring stays red and the disc turns yellow, so the drop is visible at a glance.

NSW camera files mark some sites as school zones with no hours of their own. For those the map uses the statewide NSW school zone hours above.

What updates, and when

• Camera list a job runs every day, reads the official files again and writes cameras.json.
• The website downloads that file when you open the map, so a visit after the job sees the new sites.
• The Android app ships with the list from the day it was built, then tries the website copy and falls back to the copy inside the app.

Mobile cameras planned for today

Some police forces publish which roads will have a mobile camera on a given day. The map draws a purple glow on those markers for that local date. The glow means a published plan. It does not mean a van is on that corner this second.