How to count turning vehicles at junctions with your own cameras.
A turning count says how many vehicles, of which kinds, went from each road into a junction to each road out of it. Most busy junctions already have a camera that recorded all of it.
What the count is
Every vehicle is followed from the road it came in on to the road it left by. One entry paired with one exit is a movement: north to west, east to south. A junction of four roads has twelve movements, and each is counted by vehicle class for every interval, so signal timing, junction design and traffic models work from what really happened.
Which cameras work
- Any fixed camera that records to a file. Junction and traffic signal cameras, city CCTV and temporary cameras put up for a traffic study all work, at whatever resolution they record.
- A view of every road that meets at the junction. Vehicles must be visible where they come in and where they leave. An elevated view of the whole junction is best.
- More than one camera is fine. If no single camera sees every road, each camera counts the movements it can see. Following vehicles from one camera to the next is available on request.
If you are unsure about a camera, send it: the first 12 hours are free, and the result answers the question.
Setting it up
- Draw an entry area on each road where vehicles come in, and an exit area on each road where they leave.
- Give them the names your report uses, such as North or Road A, because those names come back in the data.
- Keep entry and exit areas apart, and place them where vehicles are fully visible, not behind poles, signs or queues.
- Choose your vehicle classes, or group them into the categories you already report on.
The areas are saved to the camera. The next time that camera's footage arrives, they are already in place for you to confirm. Before anything runs, a trained engineer checks every area you drew, free.
What comes back
A row for every entry, exit, class and interval, in CSV, Excel, JSON or the API:
camera_id,interval_start,interval_end,entry_id,exit_id,class,group,count
JN-4,2024-12-10T17:07:39+04:00,2024-12-10T17:07:49+04:00,Entry A,Exit A,Car,,3
JN-4,2024-12-10T17:07:39+04:00,2024-12-10T17:07:49+04:00,Entry B,Exit B,Car,,1Excel adds a summary sheet: the full entry to exit table by class, ready for a report. Intervals can be 5 minutes, 15 minutes, an hour or a day, so the busiest hour comes straight out of the rows.
Those two rows are real data from the example junction on our home page.
What it costs
A full week of footage from one junction camera, with four entries, four exits and 12 vehicle classes, costs about $32. Processing takes about 17 hours, after the free engineer check. Counting the same junction by hand costs about $1,000 for twelve hours.
Nothing is priced per vehicle or per movement, so a busy junction costs the same as a quiet one.