Abstract:
An apparatus for checking elevation between reference markers. The apparatus includes a measuring device (e.g., a tape measure) that can measure the distance from an elevated location to the ground immediately below the location. A sighting device and a leveling device (e.g., a hand level) are secured to the distance-measuring device so that a remote reference marker can be sighted. The distance-measuring device is calibrated such that it measures the distance from the ground to the centerline of the sighting device.

Description:
This application claims the benefit of prior filed co-pending provisional patent application No. 60/123,210 filed on Mar. 8, 1999. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates generally to instruments used during preparation of the ground surface of a site prior to building or landscaping. More specifically, the present invention relates to leveling instruments that can check elevation changes of a ground surface. 
     BACKGROUND OF THE INVENTION 
     When a site is being prepared for a project, it is important that the ground surface be properly graded according to the designer&#39;s specifications. For example, building sites must be properly graded to obtain the proper elevation of the building relative to the surrounding landscape, and landscaping sites (e.g., parks, golf courses, etc.) must be properly graded to ensure that certain aesthetic and drainage goals are achieved. 
     Grading projects are commonly started by surveying the site using a transit. During the surveying, markers are set into the ground to establish reference elevations. These reference markers are typically placed in a widely-spaced, grid-like pattern. The markers provide enough information to perform rough grading of the site. 
     An elevation map and hand level (sometimes referred to as an eyelevel) are then used to establish the proper elevation of the ground between the markers. The elevation map is used to determine the desired elevation of a chosen location. The actual elevation of that location is then determined in relation to one or more of the reference markers. More specifically, the worker will typically set a grading stake into the ground at the chosen location. A wooden rule is then unfolded, and one end of the wooden rule is rested on the ground with the wooden rule positioned vertically. Using the wooden rule as a vertical guide, the worker then uses a hand level to sight a nearby reference marker. The worker then approximates the position of the hand level on the wooden rule and uses this information to determine whether the chosen location is at the desired elevation. Any required change in elevation is marked on the grading stake. This process continues until enough locations have been staked to enable final grading of the entire site. 
     Because of the length of time and skill involved in using a transit to establish elevations, the number of reference markers established by the transit is typically maintained to a minimum by widely spacing them. The above-described grading stakes are then used to fill in the gaps. Although not as accurate as a transit, the use of a hand level and wooden rule to establish elevation is much quicker than a transit. This is important due to the large number of measurements that must be made on a typical site. 
     SUMMARY OF THE INVENTION 
     The present invention provides an improved apparatus for checking elevation between reference markers. The apparatus significantly reduces the amount of time required to establish the elevation of a location, and therefore can save considerable time in mapping desired elevation changes of a site. 
     The apparatus includes a measuring device (e.g., a tape measure) that can measure the distance from an elevated location to the ground immediately below the location. A sighting device and a leveling device (e.g., a hand level) are secured to the distance-measuring device so that a remote reference marker can be sighted. The distance-measuring device is calibrated such that it measures the distance from the ground to the centerline of the sighting device. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an exploded perspective view of a device embodying the present invention. 
     FIG. 2 is an assembled side view of the device of FIG.  1 . 
     FIG. 3 is a side view of a worker using the device of FIG. 1 to measure the elevation of a chosen location relative to a reference marker. 
    
    
     DETAILED DESCRIPTION 
     The illustrated elevation checking apparatus  10  includes three main components: a sighting device  12 , a leveling device  14 , and a measuring device  16 . The sighting device  12  is used to align the apparatus  10  with a reference marker  18  at a distance. The leveling device  14  insures that the apparatus  10  is level when being used. When the reference marker  18  is sighted and the apparatus  10  is level, the sighting device  12  is at the same elevation as the reference marker  18 . The measuring device  16  is used to provide an instantaneous measurement of the apparatus  10  away from a known surface. 
     Referring to FIGS. 1 and 2, the illustrated sighting device  12  comprises a standard hand level  20 , which are well known in the surveying field. The hand level  20  is design to be mounted in a support  22 . The support  22  is made of a plastic material that will flex when the hand level  20  is pressed into the support  22 . The support  22  is sized such that it will securely hold the hand level  20 . A strap  24  is provided to insure that the hand level  20  stays securely fastened to the support  22 . It should be appreciated that the sighting device  12  of the present invention can be any appropriate device that performs the required function of aligning the apparatus  10  with a reference marker  18 . For example, instead of a visual device such as the illustrated hand level  20 , the sighting device  12  could utilize light beams (e.g., lasers) or other suitable mechanisms. 
     The illustrated leveling device  14  is a bubble level incorporated into the hand level  20 , as is well known in the art. The bubble level is visible when looking through the hand level  20  so that the user can insure that the hand level  20  is level when sighting the reference marker  18 . It should be appreciated that the leveling device  14  of the present invention can be any appropriate device that performs the required function of leveling the sighting device. For example, instead of a bubble level, the leveling device  14  could utilize a plumb bob or other suitable mechanisms. 
     The measuring device  16  of the illustrated embodiment is similar to a common tape measure and includes a housing  26  having a slotted opening  27 , a tape  28  wound within the housing and positioned through the slotted opening  27 , and a footplate  30  secured to the outer end of the tape  28 . As with a standard tape measure, there is a biasing mechanism inside the housing  26  to provide a constant biasing force that pulls the tape  28  into the housing  26 . Also similar to a standard tape measure, the housing  26  includes a locking device (internal to the housing) that can lock the position of (i.e., inhibit movement of) the tape  28  relative to the housing  26 . The locking device is biased to the locked position and can be released by pressing on the release button  32 . Such devices are well known in the tape measure field. It should be appreciated, however, that the measuring device  12  of the present invention could be any appropriate device that performs the required function of measuring the distance between the sighting device and the desired location to be measured. For example, instead of a tape measure, the measuring device  16  could utilize light beams (e.g., lasers or infrared), sound waves, or other suitable mechanisms for measuring distance. 
     Unlike a standard tape measure, the tape  28  includes both front markings  34  (on the radial inner surface of the tape) and back markings  36  (on the radial outer surface of the tape), and the housing  26  includes a visual opening  38  that allows visual access to the back markings  36 . The visual opening  38  can be positioned in any suitable location on the housing  26 . The back markings  36  are calibrated such that they indicate the distance from the end of the tape  28  to the center of the hand level  20  when mounted in the support. Preferably, the back markings  36  are expressed in tenths of a foot, which corresponds with standard surveying practice. A transparent window  40  covers the visual opening  38  to inhibit contamination of the inside of the housing  26 . 
     The footplate  30  provides a surface that can be stepped on in order to position the end of the tape  28  against the ground  42 . The footplate  30  also includes a notch  44  that can be wedged into a grading stake to secure the end of the tape  28  relative to the grading stake. 
     A belt hook  46  is provided so that the apparatus  10  can be secured to a user&#39;s belt. 
     FIG. 3 illustrates the apparatus  10  in use. Using an elevation map, the user first determines the desired elevation of a location spaced from the reference marker  18 . A grading stake  48  is inserted into the ground  42  at that location. Standing behind the stake, the user presses the lock release button  32  and pulls the tape  28  from the housing  26 . The user then places the footplate  30  on the ground  42  and puts one foot on the footplate  30 . If desired, the notch  44  of the footplate  30  can be embedded into the stake  48 . The user looks through the hand level  20  and, using the bubble level, holds the apparatus  10  level while moving it vertically. Once the reference marker  18  is sighted, the lock release button  32  is released, thereby locking the tape  28  relative to the housing  26 . By viewing the back markings  36  through the visual opening  38 , the user is given an accurate reading of the position of the ground  42  relative to the reference marker  18 . This information can be written on the grading stake  48  for use in the fine grading operation. 
     The foregoing description of the present invention has been presented for purposes of illustration and description. Furthermore, the description is not intended to limit the invention to the form disclosed herein. Consequently, variations and modifications commensurate with the above teachings, and the skill or knowledge of the relevant art, are within the scope of the present invention. The embodiments described herein are further intended to explain best modes known for practicing the invention and to enable others skilled in the art to utilize the invention in such, or other, embodiments and with various modifications required by the particular applications or uses of the present invention. It is intended that the appended claims be construed to include alternative embodiments to the extent permitted by the prior art.