A busy stretch of University Drive in Amherst is getting a major rebuild starting Monday, so drivers should expect detours. Crews will reconstruct about 1,800 feet of roadway, from the new Amity Street roundabout area toward CVS, in a $1.22 million project. Work is scheduled daily from 6 a.m. to 5 p.m. During construction, traffic will only be allowed northbound from Route 9, while southbound drivers coming from UMass will be detoured through Blue Hills Road to Northampton Road.