As of August 6, Blackwatch Pass will be closed for construction works for “an extended period of time”.
The Ministry of Public Works said the closure begins next Monday.
A spokeswoman advised people to seek alternative routes to avoid delays.
“While Blackwatch Pass is closed the public is encouraged to seek alternative routes to avoid delays,” she added.
“The Ministry takes this opportunity to thank the public in advance for their cooperation and patience while these necessary construction works are conducted.”