For the seasoned commuter, the choice of train door is often a strategic pick.
Either it's because they know it's usually one of the emptiest, or because it's nearest the exit at their destination station.
Not everyone pays so much attention though, and often you can get a few carriages crammed with people, while others are considerably less of a squeeze for new boarders.
So, Transport for London (TfL) is trialling out new technology in Shoreditch, which will make use of train weighing systems to actually show passengers how busy certain carriages are in real-time.
A trial of a new green-amber-red info screen at Shoreditch High Str station will show customers which carriages are less busy on next train pic.twitter.com/8ZGs0ABHv2— London Overground (@LDNOverground) October 17, 2017
And it's using the universal traffic light system to signal to people whether they ought to opt for a carriage or not. Green indicates a pretty empty one, yellow rather more full, and red presumably means board at your own peril.
This will be displayed on an information screen at Shoreditch High Street station with real-time information (FYI, you can watch it yourself here if so inclined...).
It's currently just a trial for the next month, but if it proves a success, TfL may well be inclined to roll it out further.
This sort of system is already being used on the new Thameslink trains, where passengers on board can see whereabouts on the train they've actually got on, and how busy different carriages are, in case they fancy shuffling along.
They also feature walkways between carriages so people can actually navigate their way through the train without too much trouble.
Unless it's rush hour of course, in which case you'll probably all be squashed together like sardines anyway, so there'll be no navigating by anyone anywhere.