The Department of Infrastructure says it carried out just under £484,500 worth of work on the TT course after inspections with race organisers.
A Freedom of Information request asked how much it had cost to get the Mountain Course ready for this year's race festival.
In its response, the DOI said the one-way system on Snaefell cost £3,100 in staff time, while £7,650 was spent on preparation work such as signs and barriers.
And it added surfacing works cost £573,885, with £484,470 of the work done after inspections with race organisers.
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