The Columbia River Longview bridge has a cantilever span 1200 feet long and a clearance of 196.5 feet above mean low water of Columbia river. The maximum height above mean low water is 330 feet and the length, including wooden approaches, is 8289 feet.
Beginning with the Longview or north side, the bridge has 2620 feet of wooden approach trestle; two 40 foot and one 168 foot steel approach spans, a 760 foot anchor arm; a 1200 foot cantilever central span (which includes one 440 foot suspended span); a 760 foot anchor arm; two 337 foot, one 84 foot, one 168 foot and one 28 foot approach span; and 1800 feet of wooden approach trestle. It also requires 600 lineal feet of concrete paving on the Longview end and three fourths mile of paving on the Rainier end.
The roadway is 27 feet wide; there are two 3 foot sidewalks.
The bridge is designed for two 20 ton trucks passing abreast and for standard specifications of the American Association of State Highway officials. The main trusses are designed for 60 pounds per square foot of roadway and for 40 pounds per square foot of sidewalk. Secondary stresses were figured throughout. Carbon and silicon steel members are employed; the silicon being used where enough weight is saved to pay for its added cost.
The substructure contains 25,000 cubic yards of concrete, of which 20,000 cubic yards was a tremied 1:2:4 mix with one extra bag of cement per batch and 5000 cubic yards was a straight 1:2:4 mix, poured in the dry; 124,000 cubic yards of excavation; 350 tons of reinforcing and 63 tons of structural steel embedded in the concrete; one million board feet of timber cribbing; 10,000 cubic yards of riprap around piers; and 436 piling. There are 1100 cedar piling and four million board feet of local red fir in the timber approaches. The superstructure contains 12,500 tons of structural steel, of which about 6,000 tons was fabricated in the Bethlehem Steel company plant at Steelton, Pa., and the remainder in the Seattle plant of the Wallace Bridge and Structural Steel company.
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