RENOVATION OF RAILWAY INFRASTRUCTURE

The infrastructure of the railway system consists of earthworks; bridges, viaducts and tunnels; the permanent way; and stations. Other elements which are not specifically covered in this paper are depots, signalling, and electric traction fixed equipment, including overhead line and conductor rail systems. Railways were generally constructed in the period between 1830 and 1900 and the original earthworks are mostly still standing. These consist of embankments and cuttings in a variety of materials, retaining walls, coastal defences, etc. The earliest railway in the North West, the Liverpool-Manchester line, includes fine examples of high embankments, the well-documented problem of building a railway across Chat Moss, and the rock cutting with vertical faces at Olive Mount. The "flying arches" between retaining walls just north of Chorley Tunnel on the Bolton-Preston line are an interesting early structure. Sea defences can be seen on the Cambrian and Cumbrian coastal routes. The original major structures