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accompanying the equipment. Any adjustment instrument should not be attempted in the field.






(c) Care and Calibration of Electronic Distance Measuring Instruments (EDM). EDMs and the accompanying reflecting prisms and data collectors should be handled with the same degree of care as is required for transits and levels. In addition, the calibration of these instruments should be checked annually and kept on file.

In order to properly calibrate EDMs, both horizontal and angular measurements must be checked. A traverse has been established around the Central Office Complex for this purpose, however a closed traverse may be ran in the field if it is not convenient or feasible to use the established traverse.

Either of the closed traverses should be run on the ground and the closure calculated. All angles should be turned four times (twice normal and twice inverted) and averaged to obtain the angle measurement. A project centerline traverse can be used to check the instrument by running two or three tangents along the centerline, but on a different alignment, back to the point of beginning. If the computed traverse closes to a minimum of 1:10,000 using hand-held prism poles, your instrument calibration is considered acceptable.

If a traverse will not close, the horizontal distance measuring function of the instrument should be checked at a calibration range using the procedure described in file EDMI-CAL.DOC located in the Construction Directory of the LAN (CSD4:\doc\edm\). The range locations and point data are contained in file NOAA-BL.DOC under the same directory. If either the angular or distance measuring device is not functioning properly, the instrument should be brought to the Construction Office for repair or adjustment.

(d) Transporting Instruments. Transits and levels should be carried in their cases when being transported by car or truck over any appreciable distance. A special protective holder within the vehicle is desirable for these cases. Instruments may be carried out of case over short distances, provided they are carefully held in someone's lap.

NEVER carry an instrument on the tripod with the tripod resting on the back of the seat and the instrument unsupported.

When it becomes necessary to ship an instrument, it should be packed securely in its case and arrangement made for the instrument to be transported by AHTD personnel.

(e) Care of Miscellaneous Surveying Equipment. Expendable items, as listed in Part II of the Survey Inventory sheet, are considered as such for the reason that they depreciate rather rapidly with normal use. The fact that these items are expendable does not relieve the Resident Engineer or the Resident Engineer’s personnel of the responsibility for their proper care and conservation.

Chains are easily damaged by kinking and by the action of traffic. When wet or muddy, chains should be cleaned and dried before rolling. Chains should be cleaned, oiled and inspected occasionally and all kinks removed by hammering on a flat wood surface. Splice kits are available for use in repairing broken chains. NEVER permit traffic to travel over chains or tapes.


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