To facilitate the stakeout, set a stake at point h.From h the locations of pointsj and k may be measuredand staked. The distance used is one half of the lengthof the headwall as that length is shown on the designplans. Set stakes at points F and G directly oppositeand on lines at right angles to the ends of theheadwalls. Set stakes similarly at L and M. Set gradeFigure 10-12.—Ditch inlet and pipe culvertstakes near B and D for the invert or flow line of theculvert.The stakes set in this way are sufficient to locatethe forms for the headwalls and for the barrel of theculvert. Figure 10-12 shows one of a number of typesof pipe inlets and culverts. The type shown is suitablefor picking up side-surface drains adjacent to a landingstrip or roadway embankment. Stakes for bothhorizontal alignment and elevations are required.Figure 10-13 shows the stakeout of a pipe culvert,wing wall, and apron.BRIDGE SUBSTRUCTURES.— As you knowfrom chapter 2 of this TRAMAN, the substructure ofa fixed bridge consists of the end and intermediatesupports and their foundations. Bridge substructuresare divided into two main types of supports: endsupports called abutmentsand intermediate supportscalled bents or piers.Abutments.— The ground support at each end ofa bridge is called an abutment. Construction plans willshow the details of the abutments. Check the layoutafter excavation and before pouring the concrete. Youmust check abutment elevations, and when concrete isused, establish lines for setting forms. Abutmentsmust be staked by following the construction plans,Figure 10-13.—Stakeout of a pipe culvert, wing wall, and apron.10-16
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