SportsTurf provides current, practical and technical content on issues relevant to sports turf managers, including facilities managers. Most readers are athletic field managers from the professional level through parks and recreation, universities.
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The most basic laser is the level laser. This laser is typically used to document existing relative elevations within an area. This laser is designed to send out a flat "level" beam of light. That is, the X axis and the Y axis are both level creating a level plane above the area being documented. Example: The laser transmitter is set up in a location within view of the area to be documented. The laser has to be set up in "plane" sight, pun intended. Anyway, the operator uses a grade rod marked off in feet and inches or other measurement such as tenths, meters etc. The grade rod is equipped with a laser re- ceiver. The operator can document the relative elevation at any location within the proposed area. First, he or she positions the grade rod perfectly vertical on that location. Then, by maneu- vering the receiver up or down on the grade rod to intersect with the beam sent by the laser transmitter, the operator can read the corresponding measurement on the grade rod; the higher the corresponding measurement, the lower the actual ele- vation. By documenting the relative elevations over a grid work of locations the operator can chart the surface contours or to- pography of a given area. Once the operator has done this, he or she can develop a better understanding of water movement and use this information to develop an effective grading plan. EVERYTHING IS RELATIVE It is important to note that when documenting relative ele- vations, these elevation readings are only relative to the height or elevation of the laser transmitter at that time. If the transmit- ter is repositioned, the operator will come up with totally differ- ent readings on the grade pole. To allow for this, a benchmark is established at the time the elevations are documented. A bench- mark is a location within plane site of the transmitter that is a permanent elevation such as a concrete pad, footing, or possibly the base of a fencepost. By establishing a benchmark, the opera- tor can reposition the transmitter on a day to day or even year to year basis as long as the elevation of the benchmark doesn't change. By documenting the new reading for the benchmark, the operator can translate the new readings to correlate with those documented in the past. The benchmark is used as the reference elevation when posi- tioning the receiver on the mast above the laser grading equip- ment. First the laser transmitter is positioned, turned on and programmed to the desired slop. The cutting edge of the grad- ing blade directly below the receiver is positioned on the bench- mark elevation. The receiver is raised or lowered on the mast to intersect with the laser bean. The receiver will remain in this po- sition as long as the transmitter is not repositioned. Whenever the laser transmitter is repositioned, the laser receiver must also be repositioned to correlate with the elevation of the new trans- mitter location. The same process is carried out to position the receiver correctly when a grade rod is used. A single plane laser has the ability to slope the Y axis while the X axis always remains level. This creates a flat plane but not a level plane. It is important to note that the terms "flat" and "level" are many times used interchangeably. In reality they can www.stma.org SportsTurf 19