Quadruple Track Layouts
As it can be seen from the pictures below in the Gallery of diagrams, the four tracks can be paired either by direction (slow/fast in each pair) or by purpose (speed or direction in each pair).
Read more about this topic: Quadruple Track
Famous quotes containing the word track:
“What is the use of going right over the old track again? There is an adder in the path which your own feet have worn. You must make tracks into the Unknown.”
—Henry David Thoreau (1817–1862)