ARMY TM 5-5420-212-10-1 MARINE CORPS TM 08676A-10/1-1 TABLE 6-24. Central and eccentric deflections - Double Story Bridges SPAN feet (meters) DEFLECTION inches (mm) DEAD LOAD DEAD LOAD DEAD LOAD + + LIVE LOAD LIVE LOAD (CENTRAL) (ECCENTRIC) 37 (11.3) 0.5 (13) 0.75 (19) 0.75 (19) 43 (13.1) 0.5 (13) 1 (25) 1 (25) 49 (14.9) 0.75 (19) 1.5 (38) 1.5 (38) 55 (16.8) 1 (25) 2.0 (51) 2.25 (57) 61 (18.6) 1.25 (32) 3.25 (70) 3.0 (76) 67 (20.4) 1.5 (38) 3.75 (83) 3.75 (95) 73 (22.3) 2.0 (51) 4.25 (108) 4.75 (121) 79 (24.1) 2.5 (64) 5.25 (133) 6.0 (152) 85 (25.9) 3.0 (76) 6.5 (165) 7.25 (184) 91 (27.7) 3.5 (89) 8.0 (203) 9.0 (229) 97 (29.6) 4.0 (102) 9.5 (241) 10.5 (273) 103 (31.4) 4.75 (121) 11.5 (292) 13 (330) Tracked vehicle of maximum load class allowed. 6-14. ASSEMBLY a. Assembly Using a Launching Nose With launching noses, an overbridge is built as if it was being put across a gap.  The roller beam closest to the existing bridge must be positioned so that it does not touch the existing span.  Also, the roller beam height should be kept high enough to prevent the launching nose, or far bank end of bridge, from coming into contact with the existing span. (1) Set up rear roller beam/front roller beam clear of the span to be bridged. (2) Assemble and launch bridge as though bridging a gap. b. Assembly Without a Launching Nose (2E + 3 through 2E + 12 bay double story) Without launching noses, an overbridge is built in place over the existing span.  Ensure that the existing span is capable of supporting the weight of the overbridge during construction, particularly if it is being constructed over a long, low class bridge. 6-68