This is very clever and useful – commuters travelling on the rail network in Sydney, Australia can now make informed decisions on where to stand on a platform for the best shot at getting a seat.
The rail authority, Transport for NSW, now has digital signage on platforms that shows which rail cars have seats available, have standing room only or are completely full.
I assumed this was all done with cameras or some sort of density sensor, but the transport system reports occupancy based on carriage weight data, which flows to Sydney Trains from in-built sensors under the axle of each train. So more people > more weight = higher occupancy.
The sensors are just some of the more than 300 on each rail car set that generate data every 10 minutes.