the future, a line may be built as single-track but with earthworks and structures designed for ready duplication. An example is the Strathfield to Hamilton line in New South Wales, which was constructed as mainly single-track in the 1880s, with full duplication completed around 1910. All bridges, tunnels, stations, and earthworks were built for double track. Stations with platforms with 11' centres had to be widened later to 12' centres, except for Gosford. The former Baltimore and Ohio Railroad (B&O) line between Baltimore and Jersey City, now owned by CSX and Conrail Shared Assets Operations, is an example of a duplication line that was reduced to single-track in most locations, but has since undergone re-duplication in many places between Baltimore and Philadelphia when CSX increased freight schedules in the late 1990s. Also: Smardale Gill viaduct. Westerham line. The Menangle Bridge was single track (1863) but built for double track (1890s). A second track was laid temporarily to allow testing both tracks at once. The Long Island Rail Road's Ronkonkoma Branch was originally single track for most of its length, but land for a double track was purchased as part of a project to electrify part of the line in the 1980s. A double track was laid along the rest of the segment in 2018. Never-used provision for duplication Some lines are built as single-track with provision for duplication, but the duplication is never carried out. Examples include: Swanage Railway Bluebell Railway: Horsted Keynes to Culver Junction (Lewes). Keighley and Worth Valley Railway – including bridge and tunnels and a deviation. Westerham in Kent. Mid-Wales Railway (parts). Neath and Brecon Railway Monkerei Tunnel in New South Wales – double track size at summit reduces fume problem in tunnel. Golgotha Tunnel near Eythorne on the East Kent Light Railway was only partly excavated for the second track. Skitube Alpine Railway – A provision for a second 300-metre-long passing loop has been made inside the tunnel. New Jezreel Valley railway – Planned as a double-tracked line, but only a single track has been constructed due to budgetary issues. Linha do Leste and Linha do Alentejo in Portugal. The embankments in all bridges were built to double track but the second one was never installed. West Coast Line (Sweden). The line through Varberg is single track but prepared for double track with long enough bridges over the track. The national traffic administration (and predecessor)