The Mountain Road will close at 9.30am on Friday 29 May to enable preparation work to take place ahead of the 2015 TT Races.
When the road reopens at 4.30pm on Friday it will be one-way for the duration of the festival.
The Mountain Road will close again at 9.30am on Monday 15 June and when it reopens at 4.30pm that day it will revert to two-way traffic.