A 239-million-dollar rebuild of Interstate 35-W from downtown Minneapolis to 46th Street starts today. The project begins as commuters still are slogging through construction in the Lowry Hill Tunnel and on Interstate 94 out to Brooklyn Center, but MN-DOT says motorists on I-35W won’t be affected much until next spring — although work affecting city streets begins immediately. The whole project will be done in five phases and take four years, and includes new pavement, a new transit station and replacing or refurbishing 18 bridges. The real pain begins next spring when access to westbound I-94 plus the major exits to downtown Minneapolis will be closed for reconstruction.