Road closure signs were posted at Highway 33 and 46 in Kings and San Luis Obispo counties.
Cal Trans says the 30-45 minute delays were necessary to help pave the roads, mow the grass and fix guard rails.
Some people got caught off guard and the detours ended up being a nightmare.
"No stop your vehicles just take off and go," Doug Hitchen said. "And we've been wandering around this mountain and you couldn't believe it unless you had been there. But it was a different one I hope we never see it again."
Some local businesses were also affected by the highway closure that started at eight o'clock Wednesday morning.
Cal Trans also worked on another construction project in Reef City that caused an additional 15 minute delay.