I believe this is one end of the lift span, with the electrically operated locks which are engaged when the Corps of Engineers lowers the bridge. In the event there is no power, the lift span can be manually cranked up or down by a single person due to precise counterbalancing. The locks can be manually engaged on each end, but if power comes back on they may disengage and train must wait for Corps to remotely operate them. I got to experience this in 1988 while riding the cab on the Fort Smith turn.
Thanks for the information.......I didn't know exactly how it functioned, just that it's a cool bridge...........
