and construction of the remaining two lines was split into four phases: Phase 1a from Newhaven to Edinburgh Airport via Princes Street, combining parts of lines 1 and 2 Phase 1b from Haymarket to Granton Square via Crewe Toll, comprising most of the remainder of line 1 Phase 2 linking Granton Square and Newhaven, completing the line 1 loop Phase 3 extending the airport line to Newbridge, completing line 2 The future of the scheme came under threat in 2007, when the Scottish National Party (SNP) published its manifesto for the Scottish Parliamentary election. The party made clear its intention to cancel the scheme, along with the Edinburgh Airport Rail Link, to save £1.1 billion. Following a lost vote in the Scottish Parliament, the SNP-led minority Scottish Government agreed to continue the line from the airport to Leith on condition that no more public money would be supplied. A report by Audit Scotland, commissioned by the Scottish Government, confirmed that the cost projections were sound. The cost of the scheme in 2003 was estimated at £498 million, £375 million in funding from the Scottish Government and £45 million from Edinburgh Council. On 25 October 2007, the council approved the final business case. Approval was given on 22 December 2007 for TIE to sign contracts with CAF to supply vehicles and BBS (a consortium of Bilfinger Berger and Siemens) to design and construct the network. Contract negotiations finished in April 2008, and construction started in June 2008. By this stage the cost of the project was estimated at £521 million. Funding problems and political disputes led to the scaling back of the original plans. In April 2009, the council cancelled phase 1b, citing revenue shortfall created by the economic slowdown to save an estimated £75 million. The Granton extension was also cancelled. Construction: 2007–2012 Until August 2011, the project was overseen by Transport Initiatives Edinburgh (TIE), a company wholly owned by the City of Edinburgh Council, who were responsible for project-managing the construction of the tramway. After the draft business case was accepted by the Scottish Government in March 2007, initial construction work commenced in July 2007, with the diversion of underground utilities in preparation for track-laying in Leith. These works followed a plan by System Design Services (SDS), a joint design team led by Parsons Brinckerhoff and Halcrow Group. In May 2008, final contracts to build the tram system were