TM 5-5420-278-100035 000035 00-19BRIDGE ANCHORAGE (Contd)TOWER HEIGHTa. Required. To determine the size of the tower which must be built, it is firstnecessary to calculate the required tower height. Because the purpose of the toweris to elevate the overhead cable to a height at least 3 ft (0.9 m) above the waterlevel, the formula for the required tower height (in feet) is:HR = 3 ft (0.9 m) + S – BHwhere HR is the required tower height in feet, S is the initial sag,and BH is the bank height in feet.Because the height of the bank is used in this calculation, determine the requiredtower height separately for both the near shore and the far shore (if the bankheights of both shores are not the same).b. Actual. Once the required tower height (in feet) is calculated, the actualheight of each tower (near and far shore) can be determined. When using the Class60 tower, it is possible to bolt the tower cap directly to the pivot unit to obtain atower height of 3 ft 8 1/4 in. (1.13 m). This is the minimum possible tower height.The tower height may be increased by adding up to six of the 10 ft 10 in. (3.30 m)tower sections. Table 8 provides a list of possible tower heights.TOWER LOCATIONDistance from the tower to the waterline. Before erecting the towers, determineexactly where on each shore to place the towers. Both towers are placed an equaldistance from the waterline. For planning purposes, determine this distance (A) infeet, by using the formula:A = L – G2where L is the distance between towers in feet and G is the riverwidth in feet.This calculation, basically, centers the two towers on the river.NUMBER OF TOWER SECTIONSTOWER HEIGHT (H)Cap, base, and pivot unit3 ft8 1/4 in.(1.13 m)With 1 tower section14 ft6 1/4 in.(4.43 m)With 2 tower sections25 ft4 1/4 in.(7.73 m)With 3 tower sections36 ft2 1/4 in. (11.04 m)With 4 tower sections47 ft1/4 in. (14.34 m)With 5 tower sections57 ft 10 1/4 in. (17.65 m)With 6 tower sections68 ft8 1/4 in. (20.95 m)Table 8. Possible Tower Heights.