Arkansas River Crossing - Bridge 474.7 and 474.7 A - Tulsa, OK, MP 423.5 - Cherokee Subdivision Frisco railroad bridge Tulsa, OK. FM Edit 1/31/2024: This postcard image depicts the early through truss bridges at this location. The 9 through pin connected trusses (TPCT) each measured 155'-4". They stood on stone piers. The total bridge length was 1,242'-8". This span was originally replaced in 1912 with a bridge made from deck plate girders (DPG). The new bridge included 18 shorter spans that measure 77'-8". Alternating concrete piers were placed between the original stone piers to support the shorter DPG spans. For a period a staff system was used to dispatch trains over the bridge. With this system a train crew must be in possession of the staff or rod for authority to enter or be in the controlled block. The staff was dispensed by a machine that was analogous to a vending machine. Interlocked the machines would not dispense a staff on one end of the controlled block until an authority staff was inserted on the other end of the same controlled block. Only one staff could be issued at a time. This provided absolute authority to occupy the block over the bridge. Capacity was further increased in 1923 when a companion parallel adjoining span, bridge 474.7A, was added. It was built like the original replacement bridge, also resting on the original stone and new intermediate concrete piers. Added bridge narrative, body of water, bridge numbers, mile post and subdivision. MKD
