The main railway from Belgrade to Constantinople skirts the Maritza and Ergene valleys, and there is an important branch line down the Maritza valley to Dedeagatch, and thence coastwise to Salonica.
There is a branch line from Inverurie to Old Meldrum, 54 m.
A third line of great importance is the junction line between the Transcaucasian railway - which runs from Batum and Poti to Baku, via Tiflis, with a branch line to Kars - and the railway system of Russia proper.
The points over which a train travels when directed from the main to a branch line are called " facing points " (F P), while those which it passes when running from a branch to a main line are " trailing points " (TP).
To avoid the delay thus caused the branch line which would occasion the diamond crossing if it were taken across on the level is sometimes carried over the main line by an over-bridge (" flying junction ") or under it by an under-bridge (" burrowing junction ").
