Wondering how the SR 99 closure from January 11, 2019 through early February will affect traffic? As we saw in 2016, closing a major highway significantly affects local and regional traffic patterns. The data in WSDOT’s report comes from the full closure of the Alaskan Way Viaduct from April 29 through May 8, 2016. SR 99 was closed between the south end of the Battery Street Tunnel to South Spokane Street. The Battery Street Tunnel and associated ramps remained open to traffic. Since the 2016 closure, Seattle’s population has grown by more than 40,000.