Police say the Mountain Road has now reopened - and are reminding people it's one-way.
The route closed this morning while the Department of Infrastructure laid out cones and signs.
For the duration of the TT festival, it'll be one way from Ramsey to Douglas.
Cyclists are also banned from using it while the system is in place.
Scientist announces run for Onchan Keys seat
Fog and mist could disrupt flight schedules, says airport
Bottleneck parking "limited" during TT, says council
Dispose of your vapes properly, say firefighters
Play equipment review for Onchan
TT's fastest woman "gutted" to miss festival after crash
Merseyside Police launch TT bike safety operation
VAT slashed for kids' activities this summer