ARMY TM 5-5420-212-10-1MARINE CORPS TM 08676A-10/1-13-4 PRELIMINARY STUDIES A thorough evaluation of information from preliminary studies may aid the reconnaissance by limiting it to a few suit-able sites. Sources of preliminary information are intelligence studies and reports, interviews with local civilians, maps,aerial photographs, and personal aerial reconnaissance.3-5 SITE SELECTIONWhenever possible, aground reconnaissance is made to find a site that has selection factors desirable for construc-tion of single story and double story MGBs, with and without reinforcement. Following are the factors that must be con-sidered during the reconnaissance.a. Access RoutesAccess routes at each end of the bridge that tie in to the main road network. These routes should not require too muchmaintenance or preparation.b. Approaches(1) Single and Double Story MGBApproaches requiring little preparation. Should be two lanes wide and straight for 160 ft (48.8 m) at each end of thebridge. Slope of the approach should not exceed 1 in 10. Transverse (side to side) slope should not exceed 1 in 10 (upto 5 bay SS) or 1 in 20 (all other bridges) in the first 60 ft (18.3 m) measured from the A’ peg. See Figures 3-1, 3-2 andChapter 1, Table 1-1.(2) Link Reinforced MGBApproaches requiring little preparation. Should be two lanes wide and straight for 160 ft (48.8 m) at each end of thebridge. Slope of the approach should not exceed 1 in 20. Transverse (side to side) slope should not exceed 1 in 20 inthe first 60 ft (18.3 m) measured from the A’ peg. See Figure 3-2.3-8 Change 2
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