the extended East London line. There are also sidings at Silwood Triangle (just north of New Cross depot), built in 2013–14. Satellite locations for stabling trains include Stratford, London Euston and sidings (mainly used by London Northwestern Railway), and c2c's East Ham Depot. Train crews are based at stations including Euston, Willesden Junction, Watford Junction, New Cross, Stratford and Gospel Oak. Until recently London Overground operated with a conductor or guard on its North London, West London and Gospel Oak services. With the other 60% of Overground services already operated by only a driver, it was decided in 2013 to convert these remaining two-person operated trains to driver only. Operator London Overground is operated by a private company, Arriva Rail London. Following a model similar to that used for the Docklands Light Railway, TfL invited tenders for operation of the Overground. Unlike other National Rail operators under the franchise control of the Department for Transport, TfL sets fares, procures rolling stock and decides service levels. The operator takes only a small element of revenue risk, with TfL taking 90% and the operator 10%. The first operator, London Overground Rail Operations, a 50:50 joint venture between Laing Rail and MTR Corporation, was chosen by TfL on 19 June 2007. The contract was signed on 2 July 2007 for seven years with the option of a two-year extension. In preparation for the launch of the Overground, MTR Laing renamed itself London Overground Rail Operations. In February 2013, it was awarded a concession extension until 14 November 2016. In April 2015, TfL placed a notice in the Official Journal of the European Union, inviting expressions of interest in operating the next concession. In March 2016, TfL announced that Arriva Rail London had won the right to operate the London Overground concession, starting from 13 November 2016. Ticketing Ticketing is a mix of paper, Oyster cards, electronic smart cards and contactless payment cards for "pay-as-you-go" travel. As with all National Rail and TfL services in London, passengers can use a Travelcard (daily, seven-day, monthly or annual); as on other National Rail services in London, paper single, return and cheap day return tickets priced under the zonal fare scheme are also available. As part of an effort to improve safety and protect revenue, TfL has announced that it will introduce ticket barriers at a number of stations. The stations that did not have barriers when