The government has defended the salaries of HS2 bosses, suggesting "the best engineers in the world" would deliver the high-speed rail project.
Chairman David Higgins is being paid £591,000, while new chief executive Simon Kirby is to receive £750,000.
Mr Kirby's salary will be six times higher than that of current boss Alison Munro, who is to move to a new role.
Transport Secretary Patrick McLoughlin said the salaries were "large" but justifiable for such a major scheme.
The £50bn project to build a high-speed line between London and Birmingham, which will then be extended to Manchester and Leeds, has been criticised for its cost, its environmental impact and business rationale.
Mr Higgins, the former chief of Network Rail, who was also head of the Olympic Delivery Authority before London 2012, has pledged to drive down costs on the project.
He started work on a part-time basis in January and will take on the role full time in March.
One of his first decisions was to hire Mr Kirby as chief executive earlier this month.
Mr Kirby will join in June from Network Rail, where he has been in charge of major infrastructure schemes such as the Forth bridge overhaul and the Thameslink upgrade.
But while Ms Munro, who will take up a new role as director of development for HS2 shortly after Mr Kirby joins, was paid about £115,000, her successor will be paid £750,000.
Asked about the salary on the BBC's Daily Politics, Mr McLoughlin said these "are very big projects and we need to attract the best people we possibly can".
"So we are going for the best engineers in the world to engineer this project," he added.
"It is a large salary but I am rather pleased that engineers, rather than bankers, can be seen to get big rewards for delivering what will be very important pieces of national infrastructure."
The transport secretary said he hoped that Parliament may approve legislation needed to authorise HS2 before the 2015 general election, but would not make any commitment on the time it would take.
The High Speed Rail bill was due to have been debated by MPs for the first time this month but has been delayed after problems with the consultation process on the environmental impact on phase one of the project.
HS2 omitted to include an 877-page document in its submission, which it blamed on a memory stick not being handed over. Mr McLoughlin said the mistake was "unacceptable and should not have happened".
But he said Parliament had more time to debate the bill than normal pieces of legislation and he remained confident it continued to have the support of the majority of MPs.
"The timing that it takes to go through Parliament is a matter for Parliament... The bill will have started its progress through the Commons by 2015 and it may well have concluded."