ARMY TM 5-5420-212-10-1
MARINE CORPS TM 08676A-10/1-1
k.
Slope check.
(1)
Longitudinal: Ensure that the difference in elevation between the F’ (use elevation of CRB) and F peg
does not exceed 1/10 th of the total bridge length. If it does, either crib up, undertake a major construction project, or find
another centerline.
(2)
Transverse/cross: Ensure that the transverse slope on both banks does not exceed 1/10th of the bridge
width (4.0 m), regardless of MLC.
I.
Calculate H and G
Calculate the far bank height (H) and the ground (at tail of bridge) clearance (G) for later comparison against N (nose lift)
and T (tail lift). The value of N, H, T and G are relative to a baseline drawn through the CRB and RRB.
H = Elev F + Elev RRB x (L - 0.5m)
13.7m
G = Elev O - Elev RRB x R Distance
13.7m
FIGURE 3-14. DS 13-22 BAY w/o LRS-Distance R,T,G,H,& N
m. Rule 1
Use a LNCG setting from Table 3-26, columns (g), (h) or (i). Both roller beams are in the low position.
(1)
Choose a LNCG setting from Table 3-26, columns (g), (h), or (i) which gives an N greater than H. If
none of the three choices meet the criteria, choose the highest value available.
(2)
Check to see if the T value from Table 3-26, column () is greater than G.
(3)
If N is less than or equal to H, or if T is less than or equal to G, proceed to Rule 2.
(4)
If N is greater than H and T is greater than G, the LNCG setting chosen has adequate nose lift and the
bridge selected has adequate tail clearance, proceed to loads required.
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