TM 5-5420-203-14
1-8. EQUIPMENT DATA - CONT
b. Load and Use Limitations. The MLC 60 bridge can support up to Class 70 under "risk"
conditions. This means that although the bridge can support a crossing weight of Class 70, it does so
with the risk of failure if care is not taken. FIGURE 1-7 indicates the highest speed a vehicle should
travel when crossing the bridge and also shows limitations for caution and risk crossings.
Approach speed is no greater than maximum vehicle crossing speed.
Three miles per hour (3 MPH) is maximum speed crossing under risk conditions.
No turning, positioning, or jerking of vehicle allowed on the bridge.
Align vehicle straight down the center line of bridge prior to crossing.
No course corrections allowed on bridge. Course corrections create sideways stress that could
structurally damage the bridge and cause a failure.
No stops allowed on the bridge.
No more than one vehicle allowed on bridge at one time.
Calculate Military Load Class (MLC) for each crossing vehicle. Refer to TM 5-312 and FM 5-
36 for instructions on how to calculate or figure MLC.
All vehicles heavily laden with weapons, equipment, and/or tools shall cross under "risk"
conditions. Accompanying troops on such vehicles shall unload and walk across the bridge, if
mission permits (troops are not under fire).
c. Safety in Use. Structural and curb damage to the bridge has been attributed to speeds at which
tanks are crossing the bridge. Structural damage also has been attributed to stopping, starting, and
course direction adjustments made on the bridge. Any of these actions exert a serious increase of forces
on the bridge. These forces can cause structural failures, warping, twisting, and component breaks.
Bridges which will be used to support MLC 60 thru 68 are to be inspected by an engineer officer and
marked as follows: Inspect bridge panels for structural damage, weld repairs, and center panel hinge
wear. Center panels having hinges with less than 1 7/8 inches of material remaining between the outside
of the hinge pin hole and the outside edge of the hinge must be replaced. Only the four hinges on the
female center panel need to be measured. However, if any of the male hinges appear to be worn more
than the corresponding female hinges, than both the female and male must be measured. Dismantling
the bridge is not required to conduct these measurements. Any bridge panel showing signs of structural
damage is to be repaired or replaced as necessary. Repair by welding is not authorized as it will weaken
the panel. Bridges are to be marked with paint to identify a 50 ft span. This is to be done by measuring
25 ft in each direction from the center panel hinges and painting a vertical yellow stripe on both sides of
the bridge at both ends. When the bridge is to be utilized for a crossing of vehicles with a MLC 60 thru
68, the operator must ensure that there is a solid foundation under the panels to at least the painted stripe
on both sides of the bridge.
1-16 Change 2
