The group said it was now forming a management team to oversee the scheme. The team is expected to involve key personnel from framework contractors working on the project.
Work is expected to start next, spring after government approval for the much-delayed scheme, which is expected this summer.
Project director Norman Haste said the complexity of the project ruled out the use of an external firm.
Haste said: "A project manager could not come into the T5 situation and pick up the pieces without having knowledge of the projects and all the stakeholders.
"This is a fairly wide-ranging operation, which includes the airport, a transport interchange, retail operations and maintenance." Eryl Smith, managing director of T5, said it was better for BAA to take the risk than a contractor. He said: "BAA believes it has to manage the whole process and take the risk." Smith said that a cost plan for the scheme would include incentives to make savings, which in turn would ensure that there was pressure on the management team to reduce the likelihood of disputes.
The incentivised cost scheme envisaged is similar to the one being used on the £55m Stansted Airport extension. Under the scheme, BAA and its suppliers share any savings.
Smith said: "This is not a panacea but we are trying to learn from other big projects such as the Jubilee Line Extension. We want to give everyone the potential to win." There will be six delivery teams under top management. They will work in the following areas: above ground buildings, rail and tunnelling, civil engineering, substructure, IT systems and baggage handling.
Preparations for the project are being stepped up with the design team set to double this year, from about 200 to 500-600. BAA expects to employ a workforce of 2000 if construction starts next year and 5500 at its peak in 2005.
The design team includes architect Richard Rogers Partnership, and engineers Mott MacDonald and Arup.
BAA also has 31 first-tier suppliers, including Amec (civil engineering and M&E), O'Rourke and Laing. Its main QSs are EC Harris and Turner & Townsend. Haste said that BAA was staying with Laing, despite uncertainty over its construction arm, put up for sale last year.
Haste said: "Clearly there is a concern. The view that BAA has is that we will support Laing in this process. We are happy with the people we have from Laing and have a clear undertaking from the John Laing board that it supports them."