page_title: South Eastern main line
section_title: Construction
hierarchical_section_title: South Eastern main line / History / Construction
caption_attribution_description: Railways in the South East of England, authorised and/or under construction in 1840
context_page_description: The South Eastern main line is a major long-distance railway route in South East England, UK, one of the two main routes crossing the county of Kent, going via Sevenoaks, Tonbridge, Ashford and Folkestone to Dover. The other route is the Chatham main line which runs along the north Kent coast to Ramsgate and Dover via Chatham.
context_section_description: The line was built by the South Eastern Railway (SER), which was in competition with the London, Chatham and Dover Railway (LCDR), hence the duplication of routes in Kent.
  The original main line was given sanction by Act of Parliament in 1836. The route first authorised was from London Bridge via Oxted, Tunbridge, Maidstone, Ashford and Folkestone. The route was to make use of the existing London and Croydon Railway and London and Greenwich Railway companies tracks. The SER was not a company that had a large amount of capital to spare. As a cost-cutting measure, authorisation was secured in 1837 to make the junction with the London and Croydon Railway at Norwood, Surrey. instead of at Corbett's Lane. However, the London and Brighton Railway were authorised to build from Norwood southwards in 1847. It was suggested by Parliament that further savings could be made by avoiding having lines running in parallel valleys for 12 miles (19 km) if the SER were to make its junction further south. The London and Brighton were to construct the line, and the SER were to purchase it at cost on completion. Both companies would operate trains over the route. The London and Brighton took advantage of this to ensure that gradients would be kept as shallow as possible, even at the expense of substantial earthworks and a mile-long tunnel at Merstham. The SER main line diverged from the London and Brighton's line at Reigate Junction, which the London and Brighton opened to traffic on 12 July 1841.
  Leaving the Brighton line, a beeline was made for Folkestone, plans to serve Maidstone having been abandoned. A branch line was to be built from Maidstone Road instead. The line was almost direct between the two points, not varying by more than 0.5 miles (800 m) in either direction between Redhill and Ashford. The engineer was Sir William Cubitt. To facilitate fast running, Tunbridge, Maidstone Road and Ashford stations were built with through roads. Headcorn station was to be rebuilt on a similar plan in 1924. Construction began in November 1837 from Reigate Junction eastwards, and in both directions from Tunbridge. The line from London Bridge to Tunbridge opened on 26 May 1842. The line between Tonbridge and Ashford opened on 1 December 1842.
  No major engineering works were needed until Folkestone was reached, where a 100 ft (30 m) high viaduct was needed to cross the Foord Gap. A temporary station was provided at Folkestone, which opened on 28 June 1843. With the completion of the viaduct, Folkestone station opened on 18 December 1843. East of Folkestone, a hard gault ridge was bored through by the Martello Tunnel, which took its name from a nearby Martello Tower. Between Folkestone and Dover, there were three headlands, Abbott's Cliff, Round Down Cliff and Shakespeare's Cliff. The first and last were of sound chalk, but Round Down Cliff's chalk was of a different character, being found to be unstable. Cubitt sought the advice of Lieutenant Hutchinson, RE, who had experience in using dynamite in the clearing of the wreck of HMS Royal George in 1840. It was decided to blow the cliff away over a distance of 500 ft (150 m). On 18 January 1843, a total of 18,500 lb (8,400 kg) of gunpowder was used in three charges to blow away the cliff face. An estimated 1,000,000 tons of chalk being dislodged. As the chalk in Shakespeare's Cliff was not as strong as that of Abbot's Cliff, two single line tunnels were bored. East of Shakespeare Tunnel, a low trestle bridge was built across the beach to gain access to Dover. The line between Folkstone and Dover opened on 7 February 1844.
  In 1843, permission was obtained to build the branch line from Paddock Wood to Maidstone. It opened on 25 September 1844. In May 1844, permission was gained to build a railway from Ashford to the Isle of Thanet, serving both Margate and Ramsgate. The line opened as far as Canterbury on 6 February 1846. In 1845, permission was obtained to build a branch line to Tunbridge Wells. This line opened on 19 September 1845. It would later be extended to Hastings, East Sussex in 1852. Also in 
caption: Railways in the south east that were built, authorised or under construction by 1840
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