TM 5-5420-278-100035 000035 00-22BRIDGE ANCHORAGE (Contd)LENGTH OF DEADMANDeadmen are designed to have lengths which enable them to resist the breakingstrength of the cable attached to them. The required length and thickness are basedon allowable soil bearing with 1 ft (0.3 m) of length added to compensate for the widthof the cable trench. The formula for the determination of deadman length Dt is:Dt = CC + 1(HP x Df)where CC is cable capacity (breaking strength) HP is the requiredholding power of the deadman.Df is the deadman face in feet (for log deadmen, use log diameter).This is the general formula for the determination of the required deadman length inall circumstances. In Appendix C of TC 5-210, the values for CC and HO have beendivided by 1,000 for ease of calculation. Actual breaking strengths (CC) or cables wereprovided in table 7. The actual holding power of deadmen in loamy soil is provided intable 9.NOTETable 9 assumes the deadman will be buried in loamysoil. For rock or hardpan soil, multiply the values intable 9 by a factor of 5. For fine-grained or sandy soil,multiply these values by a factor of 1/2.The tower-to-deadman slope used in table 9 represents an approximation of theslope of the cable running from the tower to the deadman, as shown in figure 16. Sincethis value cannot be accurately measured until the exact location of the deadman isknown, an estimation is made. The tower-to-deadman slope should fall between a 1:1slope (45 degrees) and a 1:4 slope (14 degrees). If it is not possible to obtain an accurateestimate, then assume the worst case (1:1) slope.REQUIRED HOLDING POWER (HP) IN LB/SQ FTDEPTH OF DEADMAN (DD)TOWER-TO-DEADMAN SLOPE1:1 (45°)1:2 (26.5°)1:3 (18.5°)1:4 (14°)39501,3001,4501,50041,7502,2002,6002,70052,8003,6004,0004,10063,8005,1005,8006,00075,10070008,0008,400Notes: 1. For hardpan or rock, multiply the HP by 5.2. For fine-grained soils with high moisture content, multiply the HP byTable 9. Holding Power of Deadmen in Loamy Soil.