The Longfellow Bridge will be closed to public traffic Saturday and Sunday and again the weekend of Nov. 2-3, according to the state Department of Transportation. Red Line service will be suspended between the Kendall and Park Street stations, MassDOT announced. Shuttle buses will be available for Red Line passengers between the stations, and will also stop at Charles/MGH Station. The buses will be the only motor vehicles allowed over the bridge during the closures. All other traffic will be diverted to a detour via Leverett Circle. Pedestrians and bicyclists will be allowed to cross the bridge, but cyclists must walk their bikes. The bridge closures are necessary so state contractors can perform work near the Red Line tracks as part of the ongoing Longfellow Bridge rehabilitation project, MassDOT said.