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Figure 10-12.Ditch inlet and pipe culvert - 14071_216
Figure 10-16.Staking out abutment wing walls. - 14071_218

Engineering Aid 2 - Intermediate Structural engineering guide book
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and  abutment  stakes  should  be  tied  to  the  horizontal control  system  to  meet  accuracy  requirements. The following is a typical procedure for survey- ing an abutment that is to be at right angles to the center  line  of  the  bridge.  In  figure  10-14,  the foundation of a concrete abutment, ABDC, is shown in the plan. AB is the face of the abutment foundation. Establish two convenient points,  H and J, near the abutment CD, on the bridge center line. Set a stake at E (station  41  +  37.50)—the  station  designated  on  the plan for the abutment face. Set up the transit at E, train on H, match the zeros, and turn 90° angles to locate A and B at the correct distance  from  E. Reference  the  line  AB by  setting stakes at F and G at the indicated distances from  A and B. Set temporary stakes at  C and D to mark the other corners  of  the  foundation. Sometimes the alignment of a bridge is not at right angles to the center line of the stream or road it crosses. When this occurs, the abutment is askew (other than a right angle) to the center line of the stream or road. Then slight modifications are necessary to stake out an askew abutment. Figure  10-15  shows  the  plan  for  an  askew near-side   abutment   of   a   railroad   bridge   over   a highway. The outside line of the foundation is  ABCD. The neat line of the face of the abutment is MN. Set stakes to define the direction of  MN and ends AD and BC. The stakes P, S, U, R, V, and T are offset from the abutment  so  they  will  not  be  disturbed  by  foundation excavating. The general procedure is as follows: Figure 10-14.—Staking a right-angle abutment. Figure 10-15.—Staking an askew abutment. 1. Take the dimensions for setting necessary stakes from the abutment plans. Set the temporary point O at the  station  location  indicated. 2. With the instrument at O, sight along the center line of the railroad, turn the skew angle (71°45´), set the permanent  stakes  P and R, and set points  M and N. 3. With the instrument at  M, sight R, turn 90°, and set permanent stakes S and T. 4. With the instrument at N, sight P, turn 90°, and set permanent stakes  U and V. The face of the abutment is defined by P and R. Stakes S, T, U, and V define the face of the end forms. When construction begins, set stakes at A, B, C, and D by  measuring  from  the  offset  stakes.  (These  stakes are  knocked  out  as  the  excavation  progresses.) Concrete  for  the  foundation  is  poured  into  the excavation; if forms are needed for the foundation, measure  the  distances  from  the  reference  offset  stakes. Set  the  elevations  of  the  top  and  bottom  of  the foundation from bench marks outside the excavation area. When the foundation has been poured to grade and has had a day to set, mark temporary points on the top at M and N by measuring 10 feet plus the distance AM 10-17







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