surveying iii (topographic and geodetic surveys) - Modern Prepper

e. The rear stretcher man holds the rear stretcher in position while the tension is applied, so that therear terminal mark on the tape is opposite to or slightly forward of the mark on the copper strip on therear stake. He approaches the rear stake and places the staff firmly in the ground at the proper distance,directly in line with the other stakes, while he simultaneously slips on the leather loop to the properheight on the staff. To maintain steady pressure on the staff, the rear stretcher man should have the topback of the staff resting on one of his shoulders, with his body leaning forward. With full tensionapplied, the tape should be a few millimeters above the top of the stake.f. The middleman is primarily concerned with the intermediate stakes along the baseline. He mustmove forward, carrying the tape, and place it on the middle support as tension is applied. If a nail isused as a middle support for the tape, he must rapidly and lightly tap the underside of the tape to reducethe friction at the moment of the reading. He must also ensure that the tape is not in contact with weeds,brush, or other obstructions and that the middle support is not more than 10 centimeters from the middlemark on the tape at the time of the reading.The middleman also notifies the recorder of all middle supports marked broken grade. A brokengrade is an intermediate support which is not on grade. If the intermediate support between the tapeends cannot be placed so that it will be down to grade with the terminal posts, it should be numberedwith colored chalk and marked with a piece of cloth so that it is noticed and touched upon by the levelman. All stakes should be numbered with colored crayon as they are driven. Intermediate supportsabove grade should be given a fractional number.3-8. Run a Baseline. The top of a rail of a railroad track or the surface of a concrete roadway ofuniform grade may be used for baseline measurements. However, these surfaces should not be usedwhen their temperatures are appreciably different from that of the surrounding air.a. If the baseline is over uneven ground, provide supports for the tape using substantial posts, 2 by 4inches or 4 by 4 inches, driven firmly in the ground. To run a baseline, the first task is to set these posts.Clear the baseline so that the ends are intervisible. Set up the theodolite at one end of the line, and setthe sight (range pole) at the terminating end of the baseline. Carefully adjust the theodolite to theforesight. Drive the posts on the line, accurately spaced 50 meters between centers. The tops of thestakes should not be less than 10 inches or more than 24 inches above the surface of the ground andshould be driven to a firm footing. Halfway (25 meters) between terminal posts, drive a 2- by 4-inchstake. Offset the face of the stake 1 inch from the line of sight. All stakes should be offset on the sameside of the line of sight.3-7 EN0593