UPSTREAM ANCHORAGE SYSTEMThe upstream anchorage system is the system which holds the bridge in positionagainst the force of the river’s normal current. This system is the bridge’s primaryanchorage system and its design is the most critical. Two types of anchorages can beused for the purpose of upstream anchorage: shore guys and the overhead cablesystem.Although several factors may come into play when determining which of thesetype of anchorage to install, the primary considerations are the current velocity andriver conditions. Table 2 provides guidelines for the selection of an upstreamanchorage system.DOWNSTREAM ANCHORAGE SYSTEMThe downstream anchorage system protects the floating bridge against reversecurrents, tidal conditions, eddies, and high winds or storms which mighttemporarily alter or reverse the natural flow of the river. Shore guys and overheadcable systems can be used as methods of anchoring the bridge downstream. Onceagain, the design of downstream anchorage systems can be based upon severalfactors. River bottom conditions and the velocity of the expected reverse current willbe of primary importance. Table 3 provides guidelines for the design of downstreamanchorage systems.TM 5-5420-278-100035 000035 00-6BRIDGE ANCHORAGE (Contd)APPROACH GUYS (Contd)CURRENT UPSTREAM ANCHORAGE HOLDING THE BRIDGE AGAINST THE RIVER’S CURRENTDOWNSTREAM ANCHORAGE PROTECTING AGAINST TIDES AND WINDSAPPROACHGUYSAPPROACHGUYSFigure 6. Three Components of a Long-Term Anchorage System.
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