STOCKTON — San Joaquin Regional Transit District will close its administrative offices, call center and Downtown Transit Center on Sept. 3 in observance of Labor Day. In addition, RTD will not operate its regular fixed-route bus services — Stockton Metro, Metro Express, Intercity, Hopper and San Joaquin Commuter — or its Dial-A-Ride services.A limited, demand-response service that starts at 8 a.m.