A double-track railway usually involves running one track in each direction, compared to a single-track railway where trains in both directions share the same track.
A double-track railway line running through a wooded area.
Driving Creek Railway, New Zealand
Brough station, Yorkshire, UK. Platform 1 is for trains north and east bound (Down trains), platform 2 is for trains south and west bound (Up trains)
Partially restored double-track section south of Wymondham Abbey, Norfolk, UK, on the Mid-Norfolk Railway
A single-track railway is a railway where trains traveling in both directions share the same track. Single track is usually found on lesser-used rail lines, often branch lines, where the level of traffic is not high enough to justify the cost of constructing and maintaining a second track.
A Class 158 DMU on the Kyle of Lochalsh Line, a primarily single-track railway in Scotland
A train on the Long Island Rail Road's single-tracked Central Branch
A train on the Jinhua–Wenzhou Railway, a single-track railway in Southern Zhejiang Province, China
Single track on the Stony Point Line in the Australian state of Victoria