For projects such as this, the EA surveyor is oftenrequired to perform as-built surveys to determine thework in place for each of the construction activities.These surveys are usually performed on a periodicbasis, such as biweekly or monthly. The results ofthese surveys are then used to determine thecompletion percentage of the project.When doing as-built surveys for the purpose ofmonitoring and reporting progress, the techniques, ormethods, that you use are nothing unique. Simply usethe method that is best suited for the job at hand. Also,for this type of as-built surveying, extreme accuracyis usually not required; for example, if you aredetermining how much of a total road surface has beenpaved, measurements to the nearest foot are usuallysufficient.Now let’s look at some stakeout surveys.Culverts and BridgesAs in other types of layout for construction, thestakeout of culverts and bridges generally includesproviding line and grade. The procedures andprecision required will vary with the magnitude andcomplexity of the job.DITCHES AND CULVERTS.— For minor opendrains or outfall ditches a few feet deep, a single lineof stakes will serve for both alignment and grade. Byrunning profile levels, you can determine theelevations of the tops of the stakes. As a guide to theconstruction workers, mark the cut on each stake toshow the depth of drain below each station.For drains that are very deep, you must cross-section the line and set slope stakes. The grade for aditch is measured along the flow line; that is, along thebottom of the ditch.When pipe culverts without wing walls and apronsare staked, only the alignment and invert grade arerequired; however, when head walls, wing walls, andaprons are used to intercept drainage water, to retainearthwork, and to prevent erosion, grade stakes, aswell as horizontal alignment stakes, will be required.Large bridge culverts and box culverts require stakesand hubs for batter board alignment similar to thoserequired for a building layout.Figure 10-11 illustrates the stakeout of a boxculvert that crosses below an airfield taxiway. Theangle at which the culvert crosses below the taxiwaymay be written on the plans, or it may be taken fromthe plans.Assume that this angle is 84°30´, as shown. To runthe center line of the culvert, setup the transit at A andturn the 84°30´ angle from the center line of thetaxiway.Place reference stakes at B, C, D, and E along theculvert center line far enough beyond the limits of theculvert to make sure they are not disturbed by theconstruction work. In this case, points B and D are setarbitrarily at 5 feet (measured at right angles) from thelocation of the outside face of the culvert headwalls.Figure 10-11.—Stakeout of a box culvert.10-15
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