Public transport companies face one big problem: accuracy of the estimated static time. This is the symptom of a bigger problem: transit lag times. The first train of the day has bigger chances of respecting the timetable than the thirtieth train of the day during rush hour. A major factor contributing to the problem is the context: most of the trains need to serve most of the stations, if not all of them. The time required for the train to stay at the platform for passenger boarding is important. It cannot be compressed or eliminated, unless the train skips (or hops) serving that station. The process is called station hopping.
Let’s look at the line presented in the image. Statistically speaking, half of the passengers boarding between End Station A and Station 3 are likely to get off at Station 4, and the rest of them will disembark at stations between Station 5 and End Station B. That means that maybe, the train does not need to stop in all the stations.
Instead of having all the trains stop in all the stations, we could have, at rush hour, two types of trains:
- type one who skips red stations
- type two, who skips brown stations.
The rationale behind this is to avoid losing time during deceleration, stop, and acceleration phases, for every station.
Type one trains will serve on average half of the stations plus the central blue station. The time gained will allow the train to better follow the schedule. After all, half of the potential issues have been eliminated.
The same way, type two trains will serve on average the other half of the stations plus the central blue station. There will be a gain of time too.By interweaving type one with type two, most of the passengers will travel to their destination without the need to make all the unnecessary stops.
There is the problem of passengers wanting to travel only a few stations. They represent a small part of the whole. There are several possible solutions, like:
- having a few rare trains that stop in all the stations. This reintroduces the initial problem, so it is not an option.
- having several key stations where all the trains stop and the passengers can change the train from one type to another.
- have the passengers travel to the central station and take the other type of train in the opposite direction. While this maintains the speed of the trains, it forces people to have a longer travel time. It might work around the central station and the two end stations.
Today, the transit companies don’t have the right answer to the problem. But they are aware that rush hour traffic is far from perfect.