ARMY TM5-5420-212-10-1
MARINE CORPS TM 08676A-10/1-1
Section VI. ANCHORAGE - SINGLE STORY
This section provides the information used to determine if anchorage is needed, types of anchorages, and
procedures for installation. The components used are listed in Appendixes D and E of this TM.
5-15.
BASIC CONSIDERATIONS
a.
The requirement for anchorage will be determined during site reconnaissance. Factors such as, slope of
finished bridge, volume and type of traffic, and bank conditions will be used to determine if anchorage is required.
b.
Slope of Finished Bridge. The steeper the slope of the finished bridge, the greater the possibility that
anchorage is needed. Consider crossfall of bridge along with slope from end to end. Do not consider the above to mean
that completely level bridges will not need anchorages, as the volume and type of traffic and bank conditions must also be
considered. Bridges constructed on solid banks or on packing may creep under a high volume of traffic (especially
armored, tracked vehicles). If anchorage is not installed, a bridge should be checked during crossing of traffic for any sign
of creeping. If creeping is detected anchorage should be installed.
c.
Volume and Type of Traffic. Heavy wheeled and tracked vehicles may cause the bridge to creep. This is the
result of impact loads against the end of bridge, and braking/accelerating on the bridge. Control of vehicle approach
speed and movement across the bridge will reduce these loads. High volume of medium to heavy vehicles in one
direction may cause creeping. Stop vehicles prior to impact on the end of bridge and instruct drivers to maintain a
constant safe speed, not to shift gears, and not to make any sudden stops.
d.
Bank Conditions. Banks that will allow slow settling of the end of the bridge will probably reduce the amount
of creeping. Firm, solid banks will increase the need for anchorage.
e.
Final Determination. After considering the basic factors, the final determination if anchorage is needed will be
made by the bridge commander. If anchorage is not installed, the bridge will be checked regularly for any sign of creeping.
If detected, the severity of creeping will be determined, and anchorage will be installed if deemed necessary.
5-16.
TYPES OF ANCHORAGE
The types of anchorage used for MGB are Picket and Approach Guy.
a.
Picket type. Consists of pickets driven into the bank along the outside of the bankseat beams. Picket type
anchorage is installed after the bridge has been put on the ground at both ends, and before ramps are added. During
crossing of traffic, check bridge for any sign of creeping.
b.
Approach Guy Type. Consists of anchorage cables attached to holdfasts at the near bank end and to
anchorage pins in the bridge at the other end. Two or four cables can be used at each end of the bridge. Use of this
anchorage must be determined prior to construction as the anchorage pins can only be inserted during construction.
NOTE
Anchorage Installation should not Increase building time by more than one half of an hour.
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