The span of the bridge was assumed as 100 feet. The type ofbridge used is the timber Howe Truss. The height of truss was takenas 20 feet between center lines of top and bottom chords. The widthwas taken as 18 feet center to center of trusses. The truss wasdivided up into five panels 20 feet long.
It was designed according to the "General Specifications forSteel Highway Bridges" by Ketchum. For the live load for the floorand its supports, a load of 80 pounds per square foot of totalfloor surface or a 15 ton traction engine with axles 10 feet centersand 6 feet gage, two thirds of load to be carried by rear axles.
For the truss a load of 75 pounds per square foot of floor surface.
For the wind load the bottom lateral bracing is to be designedto resist a lateral wind load of 300 pounds per foot of span; 150pounds of this to be treated as a moving load.
The top lateral bracing is to be designed to resist a lateralwind force of 150 pounds per foot of span.
The timber to be used in the bridge is to be Douglas fir.
The unit stresses used for timber are those of the AmericanRailway Engineering Association.
