Are all modern passenger and freight railroads operated by universal standards? I’m aware of CTC (Centralized Traffic Control) is that how they run all modern railroad operations? What about interlocking towers. Are they integrated with CTC? What if a CTC control personal falls asleep on the job, how are train collisions prevented from malfunction of switches or signals? How are flat multi tracked interlocks set up to prevent collisions? How the heck did they wire the rail lines with signals and hooked them all up with CTC? I will concentrate on the Northeast Corridor Line. Where and how can I find information regarding how they operate the line the engineering, authority ,etc.
Not all tracks are controlled by CTC. Out here, and I suspect across the US, it is common for low traffic short lines and branch lines to have no signals. There probably is considerable ABS and DTC.
Your question is rather broad and niave…railroad operations from railroad to railroad are slightly different but there is a NORAC Code or rules which deifines certain ways things are done. The answer to you question is impossible…you have to find books on the history of railroads in general followed by books on individual railroads of your choice. Then follow railroads in magazines like Trains comparing the past throught Classic Trains. Single track, double track, CTC, ABS, dark, Class One, Short Line, branch line…the answer is as open as your question.
First let’s separate your question in two: How does a train get permission to use a main line track? And, how do “automatic” systems such as CTC control train movements to prevent two trains from occupying the same track at the same time?
Permission is granted with either a piece of paper (track authority, track warrant, etc.) or a trackside signal (CTC, etc.) Almost all of the permission systems are now computer controlled. The dispatcher chooses a route for a train on the computer and the computer reserves that piece of track for the authorized train only. There are ways to authorize two or more trains on the same track, but that is still under “computer” control at the dispatcher’s desk. Rules for “permission” are given in the railroad’s rule book and there are three in the U.S.: NORAC, USOR, and GCOR. Each railroad’s timetable will have a note next to each section of mainline track telling you how to get permission to be on that track.
Now once you have permission there are many “automatic” systems out there that give you trackside signals. The signal system detects the presence of each train and relays that information to the dispatcher. It will also set the signals in front (for oncoming trains) and behind (for following trains) to approach (yellow) or stop (red) to prevent trains from occupying the same ditch (after the collision) at the same time. Some automatic systems do not give you permission (Automatic Block System for example) but tell you if the track ahead is occupied. Automatic interlocks give proceed signals (green) only if the track is aligned for your movement. Again, the railroad’s timetable will tell you what sort of signals (CTC, ABS etc. ) you will encounter and how they are controlled. In addition, the rule books, and railroad “special instructions” will give additional details
Copies of the rule books are available on-line (google GCOR or USOR) as a starting place for how things are run. The best way is to start with one piece of track you know a
Many of the answers to your questions can be found here under the Trains “Railroad Reference” heading (below) at the link for “ABC’s of Railroading” at:
http://trn.trains.com/home/railroad%20reference/abcs%20of%20railroading.aspx
Specifically, try these articles (after the 1st one, in no particular order):
Transforming the Corridor - CETC (Centralized Electrification and Traffic Control) by DiCenso, Al, from Trains, June 1991, p. 58 (AMTK control signaling technology)
CTC: Remotely directing the movement of trains - http://trn.trains.com/en/Railroad%20Reference/ABCs%20of%20Railroading/2006/05/CTC%20Remotely%20directing%20the%20movement%20of%20trains.aspx
Railroad signals - http://trn.trains.com/Railroad%20Reference/ABCs%20of%20Railroading/2006/05/Railroad%20signals.aspx