radio equipment manufacturer Sepura. Another major business is Marshall Aerospace located on the eastern edge of the city. The Cambridge Network keeps businesses in touch with each other. Transport Air Although Cambridge has its own airport, Cambridge City Airport, it has no scheduled services and is used mainly by charter and training flights and by Marshall Aerospace for aircraft maintenance. London Stansted Airport, about south via the M11 or direct rail, offers a broad range of international destinations. Cycling The city lies on fairly flat land and has the highest level of cycle use in the UK. According to the 2001 census, 25% of residents travelled to work by bicycle. Furthermore, a survey in 2013 found that 47% of residents travel by bike at least once a week. Rail Cambridge railway station was opened in 1845. Trains run to and (via the Fen Line), (via the Breckland Line), , , , , , , and railway stations. Lines open throughout the 19th century, included the Cambridge and St Ives branch line, the Stour Valley Railway, the Cambridge to Mildenhall railway, and the Varsity Line to Oxford lines were closed during the 1960s. The station has direct rail links to London with termini at (via the Cambridge Line and the East Coast Main Line), (on the West Anglia Main Line) and (on the Thameslink line). Fast trains to London King's Cross run every half-hour during peak hours, with a journey time of 53 minutes, and these are supplemented by semi-fast trains to Brighton via London St Pancras, and slow trains to London King's Cross. The station's original line to London was to , via . A second railway station, Cambridge North, opened on 21 May 2017, having originally planned to open in March 2015. A third railway station, , near Addenbrooke's Hospital is now under construction; it is expected to open in 2025. The former station of for Cherry Hinton operated when it was separate village to Cambridge. Road Areas outside the centre are car dependent causing traffic congestion in the drivable parts of centre. The M11 motorway from east London terminates to the north-west of the city where it joins the A14, a road from the port of Felixstowe to Rugby. The A428 connects the city with the A1 at St Neots as the A421 (via Bedford and Milton Keynes) on to Oxford. The A10 connects via Ely to King's