All surveyors should be registered in the state where the Construction Manager/General Contractor (CM/GC) is performing the work. In most states, the surveyors must pass a state exam in order to qualify as a registered surveyor.
Site layout flowchart.
Owner's engineer lays out the property line on the site plans
CM/GC surveyor lays out the property lines
Subcontractor's surveyor lays out the excavation plan
Site is excavated
CM/GC and subcontractor determine the elevation _of the floors_
Surveyor checks alignment of the structure
Site is excavated
CM/GC surveyor and subs
surveyor locate the footings
Foundation is placed
The owner's civil engineers prepare the site plan for the project, indicating the boundary of the property either by meets and bounds or by bearing and distance. Meets and bounds tend to be used in the urban environment because the reference points are the major buildings and streets in the area. So the boundary descriptions are tied into the address of a building and the associated streets. This would not be true if a project were being constructed in the farm land of Kansas. In this particular case, the surveyor would use compass points and distance to determine the property lines for a potential project. The two types of methods for indicating property boundaries are noted on Exhibit 7-6 and Exhibit 7-7.
The owner's design team will indicate the location and elevation of the footings and will note the elevation of each floor. The CM/GC's surveyor takes the basic information from the construction documents and lays out the property lines. See Exhibit 7-8 and Exhibit 7-8A for the photograph of a property line indicated on a sidewalk. When excavation starts, the surveyor determines the elevation of the excavation and the location and elevation of the footings.
Meets and bounds.
The zoning lot on which the premises are located is bounded as follows: BEGINNING at the point on the South side of Main Street distant 150.10 (East) of the corner formed by the intersection of Main Street and 57th Street running thence 110.50 (east) feet; thence 110.50 (west) feet thence feet;
to the point of beginning.
thence 100 (south) thence 100 (north)
thence thence feet feet feet feet feet
Bearing and distance.
After the CM/GC's surveyor lays out the basic parameters of the site, the subcontractor's surveyor takes over and establishes benchmarks (elevations) for the components that have to be constructed. Thus, the concrete subcontractor will lay out the location of the footings in relation to the property line of the building. In addition, stakes (wooden slates) will be driven into the ground at the lowest point of the excavation. These stakes will note location of the footing and the bottom elevation of the footing. As the excavation of the footing continues, the subcontractor's surveyor will constantly check the location and elevation of the footings.
Property line to face of steel.
Surveying by trigonometry.
Elevation of floor
Elevation of floor
The subcontractor's surveyor again establishes the elevations of each floor of the building. Thus, for a steel structure the steel subcontractor will have their surveyor determine the elevation of the top of steel at each floor. This is usually done by trigonometry as noted in Exhibit 7-9. When the concrete has to be poured over the metal deck of a steel structure, the concrete subcontractor's surveyor establishes the top slab elevation. In most cases, the elevator sill height is maintained as the benchmark for the floor.
The use of trigonometry for determining the elevation can be used for all floors. As the surveyor starts determining the elevations of higher floors, the calculations may be affected by temperature differential and the curvature of the Earth. In addition, the compression of the structure has to be taken into account. The owner's design team should determine potential compression for a steel or concrete structure.
Elevations at a site are measured from established datum. Most datum use the average (mean) sea level as "0" datum. The mean sea level (0 datum) is determined by measuring tide gauges (high and low tides) at the seacoast city you are using for a period of 19 years. For inland areas, the mean sea level is "brought" to the interior land area that is being considered. Most cities have monuments established by the National Geodetic Survey (NGS), which is part of the U.S. Department of Commerce, National Oceanic and Atmospheric Administration. Information on NGS can be obtained from their Website www.ngs.noaa.gov.
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What you need to know about… Project Management Made Easy! Project management consists of more than just a large building project and can encompass small projects as well. No matter what the size of your project, you need to have some sort of project management. How you manage your project has everything to do with its outcome.