Civil Engineering Reference
In-Depth Information
In many instances, the location of a boundary corner is not suitable for a per-
manent marker. As an example, the preceding paragraph described a stone wall
made from small, easily moved stones. In such cases it is often a greater service to
the surveyor's client to set a permanent marker in a large immovable stone in the
vicinity of the corner. The survey plan can then show the relation between the cor-
ner and marker with a bearing and distance. If the permanent marker is relatively
near the lot corner, the corner can be easily replaced at any time in the future. This
method is arguably much better than relying solely on an impermanent marker set
at the corner which is very likely to become disturbed or lost.
15.3 Using Global Positioning for Setting Corners
The widespread use of GPS has the potential to make reestablishment of lot cor-
ners less costly than traditional methods. Once a survey has been tied into a state
plane coordinate system, replacing a missing lot corner can be much less time con-
suming than when using traditional techniques, if a long traverse must be run to
control monuments (Fig.
15.7
). Using RTK GPS, the rover only requires an occu-
pation time of a few seconds or minutes. Because of the accuracy limitations dis-
cussed earlier, RTK may not be suitable for boundary establishment if the required
level of accuracy is not attainable. It must be kept in mind that the receivers are
still subject to accuracy limitations caused by objects between the antenna and the
satellites so it may still be necessary to use conventional surveying techniques to
set some of the lot corners (Fig.
15.7
).
Having the boundaries related to fixed datum certainly makes sense, particu-
larly for large parcels of land. For small lot surveys, the cost may still be pro-
hibitive, but that is rapidly changing as technology improves and equipment cost
decreases. Although GPS may make it easier to replace missing lot corners it
will still be desirable to set permanent markers at as many lot corners as possible
because doing so will almost certainly be more cost effective than paying a sur-
veyor every few years to replace missing or disturbed corner markers. In summary,
while tying a survey into a state plane coordinate system is desirable, it does not
take the place of on-site permanent markers.
