CONSTRUCTION (GRADE) STAKES

Grade work is the plotting of irregularities of the ground (making cuts or fills) to a definite limit of grade (elevation) and alignment. This is performed by reading information placed on construction (grade) stakes.

Figure 15-20.-Area of trapezoid.

Figure 15-21.-Computing cubic yards of cross sections. 15-15

Construction stakes, sometimes referred to as grade stakes, are the guides and reference markers for earthwork operations to show cuts, fills, drainage, alignment, and boundaries of the construction area. The number of stakes and the information contained on them will vary with the project as to whether they are temporary or permanent. Stakes are usually placed by a three- to five-person survey party using a level, a level rod, a tape, and range poles.

A "stake" is defined as any wooden lath, stake, or hub. "Hub stakes" are 2 inches by 2 inches by approximately 12 inches and are used primarily for well-defined surveyors' reference points, with the red and blue tops used in finished grade work. Stakes will vary in shape and size according to their use and the materials available for their manufacture. Several stakes are shown in figure 15-22. Stakes range in size from the ordinary rough plaster lath to 1- by 2- by 3-inch cross-sectional lumber with lengths varying from 18 inches to 48 inches.

All reference hubs, markers, and bench marks established by the Engineering Aids (EAs) for project control or alignment are protected by guard stakes. Guard stakes are used as a means of locating the points needed. Some color of bunting or flagging (a narrow strip of cloth or plastic) may be tied around the top of the stake. Station identification is placed on the front of the stake and any other pertinent data on the back.

In some situations, the survey crew will establish grades only on the centerline stakes, while edge-of-road and slope stakes are set by the project supervisor and helpers. Alignment, shoulder, and slope stakes should be 1 inch by 2 inches in cross section, smooth on four sides, and about 2 feet in length. Actual grade desired is indicated by a reference mark, called a crowfoot, and numbers to show the amount of cut or fill.

These stakes should be marked with the following information: 

. The stationing or location of any part of the road, runway, or taxiway relative to a starting point or reference 

. The amount of cut and fill from the existing ground surface or reference mark on the stake 

. The distance from the center line to the stake location and from the center line to the ditch line

In most earthwork, measurements are made and written by the decimal system as used in construction engineering. Most markings on construction stakes will be in feet and tenths of a foot. A stake marked C35 means that a cut must be made 3.5 feet. To convert .5 foot to inches, multiply the decimal fraction by 12. For example: .5 x 12 inches = 6 inches; .25 x 12 inches = 3 inches.