It follows feedback from drivers and passengers
Capacity on some of the Island's bus services has been increased for the rest of TT following concerns that some buses were too full to pick up every passenger.
Passengers have told Manx Radio that single deckers on the main routes have been full by the time they've left Douglas, leaving buses unable to stop to collect other customers.
The Department of Infrastructure says it can be difficult to predict passenger numbers during TT fortnight, particularly following the changes to this year's race schedule.
In a statement, the department says capacity has been increased on some of the main routes following feedback from drivers and passengers, particularly in the evening and early morning.
This could see double deckers replacing single deck vehicles, or duplicate buses as the Department's fleet doesn't have enough double deckers to cover every service.
Between 12,000 and 14,000 passengers use the Island's buses on a typical day, but in TT these numbers can double.