The biggest reason for these delays I've found over the years it the signaling system and headway spacing. Blocks on a railway system are designed to provide e

The biggest reason for these delays I've found over the years it the signaling system and headway spacing. Blocks on a railway system are designed to provide enough space and warning so that trains do not crash into each other. However, when you use line side signals and CTC (Centralized Train Control) to dispatch them, you end up with a set of rules that create spaces for occupancy that can easily be longer than the trains themselves. In the NYC subway, speaking as an observer as opposed to an insider, the signaling and dispatching requires certain distances between trains and headways (time between trains) to provide safety of 2-4 minutes. However, this results in the cascading delays as one train that dwells too long in a platform can have a stacking effect on trains behind. For example, if your minimum block distance is 1000 feet, and a max length train is 500 feet, a stack of five trains waiting to enter a station would actually occupy 5,000 feet of track. This could stretch to previous stations along the line. The best solution would be dynamic blocks and cab signals, where the system itself defines spaces occupied by trains and only allows a train into a space where it can occupy safely, but also can make the distances dynamic based on conditions. Cab signals would be required as you can't have dynamic blocks with line side signals. However, to do this requires a massive investment in new equipment both line side and on the trains that would take years to implement, along with a massive amount of painful work that would cause even more issues while it is being set up. Sadly, running more trains probably won't cut it as the system literally cannot handle more safely.