The TT course will be opened during rush hour throughout Manx Grand Prix race week.
If racing is delayed, all but one road will open to all traffic between 5pm and 6pm to avoid the congestion seen during last year's event.
The Snaefell Mountain Road between the Hairpin and Creg ny Baa will remain closed.
Practice sessions for the Manx Grand Prix begin this Saturday, with races scheduled from August 31.
During TT only small sections of the course are opened as crossing points at major junctions.
On the Wednesday of last year's Manx Grand Prix, the Island became gridlocked when the course remained closed during rush hour after racing was delayed because of bad weather.
Latest information will be on the Road Closure Information Line, which is 685888.
The TT Festival and Motorsport Arrangement Group hopes this will minimise inconvenience for local residents.