sentences:  The fitting and calibration of gauging plates was done at a gauging station or indexing station.On the Birmingham Canal Navigations (BCN) Main Line the Smethwick Gauging Station near the Engine Arm Aqueduct was on an island, with a covered gantry in a centre channel where boats were loaded with weights, plated and calibrated.The channels either side allowed two-way traffic and possibly the collection of tolls.