Today we’re launching a very cool feature for customers in Sydney: you can now see how full each Waratah train is. Down to the carriage. In real-time.

When real-time loads are available, you’ll see a colour coded train next to each trip.

Green means lots of seats, orange means you’re going to be standing, red means you’re about to get to know your fellow commuters a bit more than is probably ideal.

We’ve been testing this a while now and it’s incredibly useful. Passengers tend not to distribute evenly between train carriages, so armed with the knowledge of which ones are full and which are empty your chances of getting a seat on your commute just went way up. And if you have some flexibility when you need to arrive somewhere, you’ll find not all trains are as full as each other.

When viewing a trip the live train load is shown in the centre of the screen. Tapping it will show approximately how many seats are free in each carriage. The numbers 1 to 8 represent each carriage from the front to the end of the train in the direction it’s travelling.

Travelling in the rear four cars of the T2 train on the left would be a good life choice

We’ve built a learning algorithm so you can see how full the train will be at your station and along the journey. When you’re looking at your station, the load shown is how full we predict the train to be on departure. This all updates in real-time if conditions change along the train line.

How does it work? The clever folks at Sydney Trains are weighing the train. Under each axle is an airbag with an air pressure meter attached — the psi reading translates to the kilogram weight of the carriage. Each night when the train goes to bed in the yard, it’s like the equivalent of hitting the ‘tare’ button at the fruit market. Then it’s just a matter of dividing that by the average weight of each commuter (which took a bit of trial and error to figure out).

As the doors close at each platform, the carriage weights are recorded and sent over 3G. The carriage weights get through to the app around 10–20 seconds later and we feed it through our algorithm to project seat availability.

Only the newer Waratah trains in Sydney Trains fleet are capable of collecting this data: that means it’s available for most trains on the T1 line and around half the trains on the T2, T3, T5 and T8 lines. 24 new Waratah trains are on the way to improve the number of trains you’ll be able to see this on.

Thanks to the teams at Sydney Trains and Transport for NSW who’ve been quietly working with us behind the scenes for some time now to make this happen.

Real-time train loads are available in NextThere now. Spread the word!