Plans to extend the line were revived in the late 1980s, prompted by the Canary Wharf development, which massively increased the predicted numbers of jobs in the Isle of Dogs and required a transport network with much greater capacity than provided by the Docklands Light Railway (DLR). Initially, Olympia and York, the developers of Canary Wharf, proposed building the Waterloo and Greenwich Railway from Waterloo through London Bridge to Canary Wharf and then to Westcombe Park in Greenwich, costing £400 million. However, London Transport resisted this, preferring to wait for the results of studies into new railway construction. One of these, the East London Railway Study, recommended an extension of the Jubilee line from Green Park to Westminster, then following the route of the Waterloo and Greenwich Railway, continuing to Stratford via Canning Town alongside the North London Line. This option was adopted, with an estimated cost of £2.1 billion to which Olympia and York would make a £400 million contribution, the original cost estimate of the Waterloo and Greenwich Railway (Mitchell 2003). In the end it cost £3.5bn, partly because of huge cost overruns during construction. Where initially the developers were to pay for a large part of the extension, their final contribution was less than 5%.