Quadruple Track - Quadruple Track Operation

Quadruple Track Operation

In quadruple track, trains are sorted in various ways in order to make maximum use of track capacity. These can include one or a combination of:

• Sorting by speed

A faster express line and a stopping local line are separated, with each having a separate pair of tracks. Construction of new double tracks dedicated to high-speed rail alongside existing conventional double track used by regional and local passenger trains and freight trains is a form of quadruple track. It increases the capacity of that route significantly, and allows for significant increases in inter-city high-speed train frequency with reduced travel times.

• Sorting by distance

Long distance inter-city rail and freight trains are separated from short distance commuter rail. This helps to prevent delays on one service affecting the other, and is commonly seen in metropolitan areas. Quadrupling may be necessary when a new commuter rail service begins to operate on an existing line. Sometimes the local trains have separate technology, such as electrical system or signalling, which requires strict separation, for example in Berlin or Copenhagen.

• Sorting by destination

When a quadruple track line divides to different destinations part way along, trains need to be sorted by their destination.

• Sorting by passenger/ freight

Passenger trains and freight trains can be separated with each different track.

A variation of this can be found on the quadruple track section of the Main North railway line in New South Wales between Waratah and Maitland where one pair of tracks are used exclusively for coal trains and the other pair are used for passenger trains and general freight. A similar process, but with all intercity and commuter passenger trains on the outer tracks and thru-freight trains on the inner tracks, was done by the Pennsylvania Railroad on its New York-Washington and Philadelphia-Pittsburgh mainlines prior to the takeover of operations by Amtrak and Conrail (and later Norfolk Southern). This is somewhat still done to this day by NS, CSX, and Conrail Shared Assets trains on Amtrak-owned trackage in the Philadelphia area.

• Other modes

Two double track lines along opposite sides of a river can operate as a quadruple track. Examples of this can be found in Rhone in France and Rhine in Germany.