Here's information provided by the City of Livermore:
To further improve regional traffic flow through Livermore, Caltrans is widening SR 84 increasing the highway capacity. These efforts would encourage commuters to stay within the state highway system as opposed to using local city streets as by-pass routes. Caltrans will be closing portions of Isabel Avenue between Concannon Boulevard and Jack London Boulevard from 7/16 to 7/21 between the hours of 10 p.m. and 5 a.m. as part of their widening project. Depending on the specific closure location, traffic could be detoured using Jack London Boulevard, Murrieta Boulevard, Stanley Boulevard, Holmes Street, and Concannon Boulevard.