Height and stagger surveys are essential for ensuring the safe and efficient operation of electrified trains by measuring the exact positions of overhead line equipment (OLE). They are performed using Height & Stagger Gauge, which allow for rapid and accurate measurement of the height of the contact wire above the track and its horizontal distance (stagger) from the centerline of the track.

What is measured?
Height: The vertical distance between the contact wire and the running rail. This is a critical safety measurement to ensure the pantograph on the train can maintain contact with the wire.
Stagger: The horizontal distance of the contact wire from the centerline of the track. This ensures the wire is positioned correctly to make consistent contact with the pantograph as the train moves through curves and straights.