Figure 12-8.—Grading machine controlled by laser level and laser detector.and tunneling, the operator of the machine can stayon the proper alignment and grade. Figure 12-8shows a laser level mounted on a tripod and a powergrader with laser detectors mounted on each end ofthe blade.5. The laser level shuts off when the laser beamdeflects from horizontal.6. It increases the number of rod readings, aseach rodman can set elevations without waiting forthe instrumentman, thereby increasing the area ofsurvey within a given time frame.QUESTIONSQ1. What two general types of electronic distancemeters are in common use?Q2. Assume that you have used an EDM to measurethe slope distance from points A to B and that youobserved the vertical angle using a separatetheodolite. The slope distance is 730.65 metersand the observed vertical angle is 3°25´30´´. Therecorded heights above the ground for the EDM,reflector, theodolite, and target are 1.75 meters,meters, 1.60 meters, and 1.70 meters, respectively.Calculate the horizontal distance.Q3. You are using a specially designed short-rangeEDM mounted on an optical-reading repeatingtheodolite to locate the position of a point. Towhat class of positioning systems does yourinstrument belong?Q4. For normal leveling operations, in what modeshould the laser detector on your laser rod be set?12-8
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