The live cameras may be down for the count, but aerial images from architectural photographer Hunter Kerhart showcase progress on the Sixth Street Viaduct replacement. Crews are currently in the process of demolishing the 3,500-foot long bridge, which was compromised by an alkali-silica reaction.  Past studies indicated that the condition put the 1932 structure at a high risk of collapse during a major seismic event. One of the bridge’s iconic metal arches was removed earlier this month, and will eventually be incorporated into a park that is planned beneath the viaduct. The $449-million replacement, designed by Michael Maltzan Architecture and HNTB, is slated for completion in 2019.