ARMY TM 5-5420-212-10-1MARINE CORPS TM 08676A-10/1-1(3)A’ Peg-Edge of firm ground on the near bank.(4)AR Gap-The distance measured between the A and A’ pegs. This is the actual gap to be spanned by thebridge.(5)F’ Peg-Designates the location of the near bank end of bridge (outer edge of bankseat beam). Thedistance (determined later), from the A’ to F’ peg is the amount of bridge that will bear on the near bank, known as nearbank bearing. The minimum acceptable near bank bearing is 1.4 m.(6)CRB Peg-Designates the position of the capsill roller beam (CRB). The distance from the A’ peg to thecenter of the CRB can not be less than 0.9 m, and from the CRB to the F’ peg can not be less than 0.5 m. The placementof the CRB is determined by using the length of bridge (L), AR Gap, far bank bearing, and bridge overhang (0.5 m) toobtain an X distance (from A’ to CRB). Placement of the CRB in this manner will ensure minimum effort during the jackdown operation.(7)FRB Peg-Designates the position of the front roller beam (FRB). The distance from the CRB to thecenter of the FRB (measured center to center) must be 9.1 m.(8)RRB Peg-Designates the location of the rear roller beam (RRB). It is placed 4.6 m from the FRB(measured center to center).(9)O Peg-Marks the clear distance behind the capsill roller beam required to construct the bridge. It ispositioned by measuring the R distance, Table 3-24, column (e), behind the CRB peg.g.Calculate bearingThe minimum and maximum bearings for all DS bridges are shown in the Table 3-25 and Figure 3-13.To calculatethe actual locations of the F and F’ pegs, the following procedure is used: Near bank bearing = bridge length (L) - (ARGap + 0.6 m) Where: Bridge length is obtained from column (d) of Table 3-24. The AR Gap was measured in the firststep of the design procedure. An assumption of 0.6 m is made at this point in the calculation sequence because this is inthe minimum acceptable bearing allowed on the far bank.TABLE 3-25. Bearings DS 13-22 Bay w/o LRSBearingsNear BankFar BankMinimum1.4 m0.6 mMaximum2.3 m2.3 mh.Check bearing(1)If the near bank bearing is within the minimum and maximum bearing limits, it will not be necessary toshift the position of the F and F’ pegs. The position will be initially determined, F peg 0.6 m from A peg and the F’ peg willbe placed the distance determined as near bank bearing measured from the A’ peg.(2)If the near bank bearing is more than the maximum bearing allowed (2.3 m), it will be necessary to shiftthe bearing.i.Shift bearing(1)Determine the amount of excess near bank bearing by subtracting the maximum bearing allowed fromthe amount calculated. At this point decide how to use the excess bearing as follows:either3-36