1. From BMs, turn levels on the center-line hubs or on the ground next to a grade stake at each station.

2. Reduce the notes to obtain hub-top or ground elevation.

3. Obtain the finished grade elevation for each station from the construction plans.

4. Compute the difference between finished grade and the hub or ground elevation to determine the cut or fill at each station.

5. Go back down the line and mark the cut or fill on each grade stake or guard stake. The elevations and the cuts or fills may be recorded in the level notes, or they may be set down on a construction sheet, as explained later in this chapter.

Another procedure may be used that combines the method listed above so that the computations may be completed while at each station; then the cut or fill can be marked on the stake immediately. As before, levels are run from BMs; the procedure at each station is as follows:

1. Determine the ground elevation of the station from the level notes to obtain HI.

2. Obtain the finished grade for the station from the plans.

3. Compute the difference between the HI and finished grade; this vertical distance is called grade rod.

4. Read a rod held on the hub top or ground point for which the cut or fill is desired. This rod reading is called ground rod.

5. Determine the cut or fill by adding or subtracting the grade rod and the ground rod, according to the circumstances, as shown in figure 14-36.

During the final grading, you will most likely be working with hubs called BLUE TOPS (fig. 14-31). These hubs are driven into the ground until the top is at the exact elevation of the finished grade as determined by the surveying crew. When the top of the stake is at the desired finish grade elevation, it is colored with blue lumber crayon (keel) to identify it as a finished grade stake. Other colors may be used, but be consistent and use the same color keel throughout the project so as not to confuse the Equipment Operators. Blue tops are normally provided with a guard stake to avoid displacement during construction work. The guard stake usually shows the station and the elevation of the top of the hub. The elevation and station markings may be required only at station points; otherwise, all that is needed is the blue top and the guard stake with flagging.

The procedure for setting blue tops lends itself primarily to final grading operations. It is carried out as follows:

1. Study construction plans and center-line profiles for each station to determine (1) the exact profile elevation and (2) the horizontal distance from center line to the edge of the shoulder.

2. Measure the horizontal distance from the center line to the shoulder edge at each station, and drive a grade stake at this point on each side. Sometimes it is advisable to offset these stakes a few feet to avoid displacement during construction.

3. Set the top of the stake even with the grade elevation, using both the level and the rod. This is accomplished by measuring down from the HI a distance equal to the grade rod (determined by subtracting grade elevation from the HI). The target on the rod is set at the grade-rod reading; the rod is held on the top of the stake; and after a few trials, the stake is driven into the ground until the horizontal hair of the level intersects the rod level indicated by the target. Color the top of a stake with blue crayon (keel).

4. Where the tops of stakes cannot be set to grade because grade elevation is too far below or above the ground line, set in ordinary grade stakes marked with the cut or fill as in rough grading. However, for final grading, it is usually possible to set mostly blue tops.

Where grade stakes cannot be driven, for example, in hard coral or rock areas, use your ingenuity to set and preserve grade markings in a variety of conditions. Markings may often be made on the rock itself with a chisel or with a keel.