The original 489 feet (149 m) viaduct was built in timber to the designs of Isambard Kingdom Brunel, but it was replaced in 1888 by a masonry structure. The line had until now been just a single track with a passing loop in the station, but the new viaduct was wide enough for two tracks once the 7 ft 0 1⁄4 in (2,140 mm) gauge rail was no longer required following the abandonment of broad gauge services in 1892. The second line was brought into use in February 1894; a second line was laid eastwards from the station in 1911.
The original Hayle Railway station became a goods depot when the new station opened, access to it being controlled by 'Redruth Junction' signal box which also controlled access to the goods branch line to Tresavean mine. Goods sidings were also provided on both sides of the line at the new station, with a large goods shed on the north side of the line. A new goods depot was opened at Drump Lane, east of the tunnel, in 1912.
Historical text taken from Wikipedia.