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By
JAMES VINCENT CARROLL
Dr. James
Vincent Carroll, a senior engineer at the U.S. Department of
Transportation's Volpe National Transportation Systems Center, is the
project-team engineer responsible for the design, development, and
installation of a modern GPS navigation system at the Panama Canal.
Ninety years
ago, the United States built the Panama Canal by combining innovative
engineering strategies with state-of-the-art technology. Now, on the eve
of the Canal's transfer to the Republic of Panama on 31 December 1999, a
prototype GPS (Global Positioning System) navigational system enables
safer and more efficient operations--thanks to the technical know-how of
an engineering team assigned to the Department of Transportation's Volpe
National Transportation Systems Center in Cambridge, Mass.
A
Lesson in Geography
The continuing
importance of the Panama Canal to international commerce and U.S.
national-security affairs may be demonstrated by the school child's
exercise of tracing the alternate route around South America and north
again on a globe--a lengthy transit of thousands of miles each way,
avoided by a 45-mile canal across a narrow strip of land. The lesson of
this simple demonstration is borne out by the 13,000 oceangoing vessels
that use the Canal every year. Even in today's "information
age," livelihoods around the globe depend on the oceanic movement
of sugar, steel, oil, and ores. Fortunes rest on the time it takes for
goods to move from one part of the world to another.
While transits
through the Panama Canal save considerable time and fuel, navigating
this narrow waterway also presents many challenges. Canal navigation is
such a complex affair that all vessels transiting the Canal (even U.S.
Navy warships) are directed by a Canal pilot who is responsible for the
vessel's movements until the transit is completed.
As pilots
direct ships past landslides, around corners, and over submerged rocks,
they navigate by a system of buoys and land-based markers. Relying
primarily on visual cues and experience, a pilot aligns the ship within
the channel and recognizes when to adjust ship heading or speed.
Unfortunately, when rain or fog obscures visual navigation aids, a pilot
may be unable to determine if the ship is on course, drifting perilously
close to the bank, or heading into the path of an oncoming vessel.
The Canal's
navigation difficulties are closely tied to the impediments that
hindered its construction, such as the fractured geology that causes
recurring landslides. Today, dredges are regularly at work, clearing the
channel of rocks and mud. Torrential rainstorms previously caused floods
that swept away construction equipment and laborers; now the floods are
tamed by two dams, but the daily downpours can reduce visibility to
barely the width of a vessel. The fog that develops almost every night
was once thought to be the precursor of malarial fever; now sailors know
that the real danger of fog is the thoroughness with which it obscures
navigation aids.
With the aid of
the Volpe National Transportation Systems Center, Canal pilots have a
new piloting tool: a CTAN (Communications, Traffic Management, and
Navigation) system. This new system, developed for the PCC (Panama Canal
Commission) by Volpe Center staff in the Center for Navigation, makes
the Canal safer and more efficient by using satellite data to create a
real-time display that shows the location of every vessel within the
Canal. This bird's-eye view gives Canal pilots and traffic managers an
entirely new all-weather perspective from which to view the complex
choreography of 50,000-ton vessels slipping into narrow locks and
passing one another around tight corners.
"A
Stupendous Undertaking"
Ever since
Vasco Núñez de Balboa crossed the Central American isthmus and named
the Pacific Ocean in 1513, seafaring countries have dreamed of a passage
that would broach the narrow strip that separates the world's two
greatest oceans. Engineers soon began to explore the challenge. Where to
build such a canal? How shall it be excavated? What shall be done with
the rock? The first real effort to build a canal began during the 1880s,
when French entrepreneur Ferdinand DeLesseps, having just completed the
Suez Canal, turned to Panama--pouring billions of francs and 25,000
lives into an unsuccessful attempt to build a sea-level canal. The
French effort was thwarted by plagues, unreliable machinery, and almost
a billion cubic yards of rock.
The failed
canal sat idle until the turn of the century, when the United States
turned its gaze in earnest towards Panama. President Theodore Roosevelt,
influenced by Alfred Thayer Mahan's book The Influence of Sea Power on
History, realized that a Central American canal would be an important
strategic asset to a country that bordered both oceans and whose
international reach extended both east and west.
The U.S.
construction effort used technology in unique and innovative ways to
make construction of the Panama Canal possible. It was truly "a
stupendous undertaking," in the words of the day. One by one, U.S.
engineers solved the major challenges that had thwarted French efforts.
The engineers instituted a massive mosquito eradication and sanitation
program to protect laborers from malaria and yellow fever; they used a
flexible system of movable railroad tracks and one-sided boxcars to
ferry away excavated material and dump it quickly; and, rather than dig
a sea-level canal, they built a dam and locks to lift vessels up to the
level of a new man-made lake.
The key
features of the Canal are its three monumental locks. In order to
accommodate two-way traffic, each lock has two lanes. Individual lock
chambers are 1,000 feet long and 110 feet wide--large enough to hold the
Titanic, had it ever reached the isthmus, or an Iowa-class battleship.
Vessels must pass through three such chambers, each chamber changing
elevation by 28 feet, in order to reach the elevation of Gatun Lake, 85
feet above sea level. All water moves by gravity--flowing from the lake
through the locks and into the oceans.
About one third
of the vessels that use the Canal are known as "Panamax"
ships--those up to 970 feet long and 105 feet wide, with a 39-foot
draft. For these behemoths, transiting the Canal is a complicated
endeavor. Slipping into a lock, navigating the Gaillard Cut, and
encountering oncoming vessels present challenges for the Canal pilot and
strain navigation and propulsion systems designed for sailing the open
seas.
Navigational
Improvements
Since its
inauguration in 1914, more than 700,000 vessels have used the Canal. In
accordance with the Panama Canal Treaty of 1977, the U.S. Canal Zone was
disestablished in September 1979. Full responsibility for the Canal's
administration, operation, and maintenance will shift to Panama when
ownership is transferred on 31 December of this year. A related
Neutrality Treaty guarantees that the Canal shall remain open, safe,
neutral, and accessible to vessels of all nations. Treaty provisions
stipulate that the United States has the right to "expeditious
transit" through the Canal in times of conflict. It also reserves
the right for the United States or Panama to intervene militarily should
it be necessary to reopen the canal or restore its operations.
Recognizing the
Canal's role as a key link in the world's economy, the PCC continuously
seeks ways to make the Canal more efficient and safer. As the volume of
ship traffic hovers near Canal capacity, better scheduling and traffic
control are key elements of the proposed improvements. Canal traffic is
so consistently near or over capacity that even slight complications can
cause expensive delays. Canal authorities recently installed
closed-circuit-television cameras at strategic vistas along the Canal in
order to monitor traffic, but these cameras are limited in their
usefulness, and their imagery is not helpful to Canal pilots on board
ships.
In 1995, the
PCC requested Volpe's Center for Navigation, a known leader in the
development of radio-navigation systems, to design a satellite-based
system that would track the location of transiting vessels and PCC tugs,
launches, and dredges. The Center for Navigation was the logical choice
to develop such a system, having already proven its ability with a
similar system it developed for the St. Lawrence Seaway Development
Corporation. That system utilized GPS navigation satellites to determine
vessel location, which was transmitted to a shore-based control center
and then rebroadcast to all participating vessels.
While the
Center for Navigation's experience in the St. Lawrence Seaway was
important, the scale of the Panama system was considerably larger.
Furthermore, the new system utilizes DGPS (differential GPS) to produce
even more precise navigation data. The two DGPS reference stations built
at the Canal can pinpoint a ship's location in the Canal to within three
meters. These stations conform to U.S. Coast Guard specifications for
its Maritime DGPS system for U.S. waterways.
Thanks to the
technical and management expertise of the Center for Navigation staff, a
high level of collaboration between the Volpe Center, PCC engineers, and
Canal pilots was nurtured and maintained throughout the design and
development of the navigation project. This collaboration often prompted
the development of new design features that were not envisioned when the
system was first planned. One such feature is the system's ability to
predict the meeting point between two vessels. Using this information,
pilots can modify their ship's speed in measured ways--adjusting the
meeting point to a more desirable location, if necessary.
The result of
this collaborative effort is a coordinated system composed of more than
150 mobile units--about half installed on PCC tugs, launches, and
dredges--that enable communication with six shore-based stations and a
master communications center. The system provides for redundant coverage
of the entire Canal. The mobile units consist of a GPS receiver and
antenna, a notepad computer, and a UHF digital radio. Once the mobile
GPS unit has determined a vessel's location and speed, it transmits this
information on the two-way UHF data link to the communications center,
from which it receives navigation and other useful data on the other
vessels in the Canal--updated approximately once per second.
A
System for Today and Tomorrow
In August 1998,
the new navigational system proved its worth by preventing a potentially
serious accident. A 740-foot-long bulk carrier in Gatun Lake, transiting
north from the Pacific, lost rudder control just as a heavy rainstorm
developed. The vessel grounded crosswise in the channel. Meanwhile, a
600-foot car carrier traveling south was not aware of the situation just
around the bend. However, both pilots used their CTAN units to avoid
what they later said would have been a certain collision had CTAN
equipment not been on board.
The CTAN
system, while addressing today's navigational requirements, also was
designed for adaptability, flexibility, and utility in the future. The
Panama Canal will continue to present navigational challenges during the
years ahead. Its construction baffled engineering minds for centuries,
ruined one of the world's foremost entrepreneurs, and killed thousands
of laborers. This epochal engineering achievement demanded the full
attention of the United States for almost 10 years; 80 years later, it
continues to give heartburn to seasoned Canal pilots.
Throughout the
Canal's history, great minds have turned their attention to the
challenges of the day; when the time is right, as it was in 1908, the
confluence of innovation and technology yielded remarkable results. Now,
the Volpe Center's engineering team--partnering with the Canal's
administrative staff and pilots--has added its names to the list of
noteworthy engineers, technicians, and laborers who have successfully
tackled an endless parade of formidable technical hurdles for more than
eight decades.
The Canal's
modern DGPS navigational system has reinvented the experience of
navigating a vessel through the Canal. Much as those pioneers of 80
years ago who planned the Canal, operated the steam shovels, designed
the locks, poured countless tons of concrete, and dredged the channel,
they have made a new Panama Canal--one that is designed to serve the
world's maritime transportation and commercial needs efficiently and
safely well into the 21st century.
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