a joint line between Hawick and Carlisle. The line would be built in two equal parts by the companies which would be responsible for its management; free interchange of traffic would be allowed on the NBR lines north and west of Hawick and on the lines south and west of the Caledonian main line. The proposal gained no traction with the Caledonian, leading the NBR to publish details of its proposed scheme, to be known as the Border Union Railway, on 17 December 1858. The line would cost £450,000, of which £337,500 would be raised by shares and the remainder by a loan. Authorisation was given on 21 July 1859 when the Border Union (North British) Railway Act provided for the construction of a long line to Carlisle. The main line opened throughout to passengers on 1 July 1862. A celebration was held on 1 August when a special train ran from Edinburgh and a dinner was held in the carriage shed at Carlisle for around 700 guests. The Waverley Route was not however complete until the final section on the branch from Canonbie to Langholm opened on 18 April 1864 after completion of a 12-arch viaduct over Tarras Water. Comprised within the Border Union Railway Act were powers allowing the NBR to cross the Caledonian Railway's main line and join the Carlisle and Silloth Bay Railway at Rattlingate, as well as the granting of facilities at Carlisle Citadel railway station. The NBR would take a 999-year lease of the Silloth line from 1 August 1862. This brought two advantages: firstly, the NBR had access to Carlisle and Silloth harbour with access to Ireland and Liverpool and, secondly, it allowed freight to be sent by sea without having to work through Carlisle and thus not be subject to the Anglo-Scottish traffic agreement which set the rates for goods workings via Carlisle. Topography and construction At , the alignment chosen for the Waverley Route was considerably longer than the direct route as the crow flies between Edinburgh and Carlisle, around . However, the course was chosen to navigate a careful path around the formidable natural barriers south of Edinburgh in the form of the Southern Uplands and the summits at Whitrope () and Falahill (). Although advantage was taken of the easy conditions offered by the numerous river valleys, these two areas of high ground had to be tackled head-on, and