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By KIM GIFFORD
If you’ve seen someone in an orange safety vest with
a tripod near a roadway or open field, you’ve seen a
surveyor at work. For many, this is the only
knowledge they have of what a surveyor does. Unless
you’re building, buying, selling or subdividing, you
probably haven’t benefited from the services of a
surveyor.
“Surveyors are on site before any construction
happens — before the ground is broken or a twig is
moved,” explains Tim Rockwood, vice president and
director of Surveying Services at Pathways
Consulting in Etna, N.H. “Surveyors provide boundary
and topography in detail. They’re the first ones and
last ones on site, coming and going throughout the
whole process.”
Why Survey?
Surveying is the art and science of accurately
determining the form, extent and position of
something (such as a tract of land) by taking linear
and angular measurements and applying the principles
of geometry and trigonometry. That’s the definition
from Merriam-Webster, but better descriptions of
this technique can be found throughout history.
Did you know that the Egyptians were early
surveyors, re-establishing boundaries by using
simple geometry after the Nile River overflowed its
banks each year. There was Daniel Boone, a famous
pioneer and frontiersman who blazed the Wilderness
Road in 1775. In 1791 Benjamin Banneker, with his
knowledge of astronomy and mathematics, was
instrumental in surveying the District of Columbia.
The Lewis and Clark expedition (1804-1806) was the
first United States overland expedition to the
Pacific coast and back. Later, surveyor and road
builder Len Beadell opened up the last remaining
isolated desert areas of central Australia in the
1940s and 1950s. He built the Gunbarrel Highway by
pushing through raw scrub with a Land Rover and
using Celestial navigation for latitude and
longitude measurements.
“Surveyors provide boundary and topography in
detail. They’re the first ones and last ones on
site, coming and going throughout the whole
process.”
Surveying, in fact, has been an essential element in
the development of the human environment since the
beginning of recorded history, and it is a
requirement in the planning and execution of nearly
every form of construction. According to Wikipedia,
whenever there are roads, dams, retaining walls,
bridges or residential areas to be built, surveyors
are involved.
Pathways on the Job
Rockwood is a licensed surveyor at Pathways
Consulting, a 30-person firm that provides services
in several areas, including planning, civil and
environmental engineering, geological consulting,
surveying and construction assistance. Clients
include King Arthur Flour in Norwich; businesses
within Centerra Resource Park in Lebanon; Home Depot
in West Lebanon; Twin State Sand & Gravel in Vt. and
N.H.; City of Lebanon; Town of Hanover; Dartmouth
College; Kimball Union Academy in Meriden; and
Dartmouth-Hitchcock Medical Center (DHMC), to name a
few.
Engineers, after they have developed a concept plan
for a construction project, call a surveyor to get a
base sheet. “A base sheet includes all the site
features above and below ground,” explains Rockwood.
“This includes everything outside the building:
Drainage, utilities, ground contours (elevations),
slope changes, wetlands, tree lines, roads, signs,
guard rails — all the features you see when you
drive by a site. Sometimes these features go right
down to parking, striping and minute details.”
At DHMC’s new Doctor’s Office building, surveyors
were on site as concrete was poured for each new
floor. Surveyors used coordinates to re-establish
gridlines on the next floor. Surveyors also helped
add two more floors to the Cancer Center building.
Although there was a site plan for the original
building, engineers needed some updated information
before they started the addition.
“Perpendicular steel moves, so it can be tricky to
find the beams,” says Rockwood. “Once the roof was
cut off and the beams were exposed, a surveyor maps
the beams, which may have expanded structurally.”
Surveyors frequently help bridge the difference
between the design world and the real world, working
behind the scenes to document that a building
location is on — or off — track.
“We’re experts in measurement,” says Rockwood. “But
we also know a bit about boundary law, research
(historical research on a boundary can lead you back
to the 1800s), investigation for evidence on the
ground (finding the location), drafting (creating a
document on paper so someone can write a deed) as
well as state and local regulations (which
constantly change from town to town and state to
state).”
Decisions are made based on multiple sources of
information: What is on site, what people are using
(possession line) and what the record says. Rockwood
notes that “surveyors can only offer their
professional opinion on where the lines are, and two
surveyors can disagree where a line is. The surveyor
is impartial as to how he determines a survey; we
just put what has been determined back on the
ground. Only the owners or the court can actually
move or fix a boundary line.”
The Tools of the Trade
The basic principles of surveying have changed
little over the ages, but the tools have evolved
tremendously.
“We used to measure with plumb bobs and tapes,” says
Rockwood, who has been a licensed surveyor for 26
years. “But the technology has changed because of
NASA. Now we have electronics, hand-held data
collectors, hand-held PCs and GPS [global
positioning system]. Batteries have become our most
important tool.” (See sidebar on “Surveying Tools.”)
Whether conducting a boundary and topographic
survey, construction layout or specialty survey such
as flood insurance certifications, Pathways provides
a “level of comfort that the professional they are
hiring is capable of doing the task,” says Rockwood.
“All projects don’t go smoothly for various reasons
— we may find a boundary issue that no one knew
about and it may affect the timeline of the project.
But our seal is on the plan — and there is no
statute of limitations on boundary surveying — so we
do the best job we can for each and every survey.”
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Surveying Tools |
Early surveying was conducted with a
chain (usually made up of 100 links and
a hook on each end), a compass and the
stars. But today’s surveyors have access
to the latest technology. Wikipedia, the
free online encyclopedia, and Trimble, a
leading innovator of Global Positioning
System (GPS) technology, provides
definitions for these must-have tools of
the trade.
The GPS is a satellite navigation system
used for determining one’s precise
location and providing a highly accurate
time reference almost anywhere on Earth
or in Earth orbit. Developed and
operated by the U.S. Department of
Defense (DOD), GPS permits land, sea and
airborne users to determine their
three-dimensional position, velocity and
time 24 hours a day, in all weather,
anywhere in the world.
GPS Surveying Systems typically have
wireless technology (from Bluetooth) to
receive up-to-the-minute GPS data — and
transmit it — while in the field.
A theodolite (also called a transit) is
an instrument used to measure horizontal
and vertical angles. It consists of a
telescope mounted movably within two
perpendicular axes — the horizontal axis
and the vertical axis.
Electronic distance measuring devices (EDM)
send out narrow beams of sound waves
that bounce off solid objects back to
the hand-held receiver. Custom
electronics and a microprocessor then
convert elapsed time into a distance
measurement and display it on the LCD.
A total station is an optical instrument
used in modern surveying. It is a
combination of an electronic theodolite,
an EDM and software running on an
external computer. A surveyor uses a
total station to determine angles and
distances. Then, with the aid of
trigonometry, the angles and distances
are used to calculate the coordinates of
actual positions of surveyed points (or
the position of the instrument from
known points) in absolute terms. The
data may be downloaded from the
theodolite to a computer, and
application software will generate a map
of the surveyed area.
Satellite navigation systems use radio
time signals transmitted by satellites
to help mobile receivers on the ground
to determine their exact location. The
relatively clear line of sight between
the satellites and receivers on the
ground, combined with ever-improving
electronics, allows satellite navigation
systems to measure location right down
to the meter.
A controller is an advanced handheld
field computer. Many include software
packages such as the Microsoft Windows
Mobile for Pocket PC operating system;
hardware like removable memory; and
communication technologies including
cell phone integration. |
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