Capacity - Catherine

CE 515 Railroad Engineering
Operations of Railways
“Transportation exists to conquer space and time -”
• FRA responsible for safety
• Safety never deregulated
• All accidents reported
• Safety and Loss Control Department
• Main tracks: governed by one or more methods of control.
Should not be occupied without permission or authority
• Other than main tracks: occupancy without authority, the
locomotive engineer should look for other movements,
usually max 20mph
• Higher speed: improve capacity and productivity
but also risk and maintenance cost
• Separate speed according to the type of train
• Temporary Speed Restrictions (TSR) and
Permanent Speed Restrictions (PSR)
Rail Traffic Control Systems
• Track Warrant Control (TWC)
• Direct Traffic Control (DTC)
• Automatic Block Signal (ABS)
• Centralized Traffic Control (CTC)
Rail Traffic Control Systems
• TWC, DTC: Non-signalized systems
• Use radio communication and computers
• Rail Traffic Controller (RTC): order transferred
by radio and written by crew
Automatic Block Signal (ABS)
• Series of consecutive blocks governed by block signals, cab
signals, or both. Signals activated by a train moving through
the block, or by certain conditions that affect the block use.
• Developed in 1872, Dr. William Robinson
• Divide “tracks” into blocks, only one train per block
• Directional operations, two or more tracks
• Designated current of traffic, low-density single tracks
Automatic Block Signal (ABS)
• Track circuit
• Fail-safe design
• Length of block: equal to longest normal
stopping distance
• “Two-block, three-indication”, “Three-block,
• Remained ABS systems: operated by TWC
Automatic Block Signal (ABS)
Centralized Traffic Control (CTC)
• Track territories, double track sections: crossing
over is allowed.
• Rail Traffic Control Center: all track circuits
connected, controlled together
• Panel: showing position of each train
Centralized Traffic Control (CTC)
Centralized Traffic Control (CTC)
Centralized Traffic Control (CTC)
• Authority to enter a CTC main track: by signal.
• Crew requests for permission by radio
• Opposing movements: not allowed, only
following train movements
• “Intermediate signals”: facilitate fleeting of trains
Centralized Traffic Control (CTC)
• Single track: 70% of capacity of double track
with ABS
• Railways: shift to CTC: excess capacity

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