science

Transcontinental Traverse

Transcontinental Traverse is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Transcontinental Traverse rather than just read about it. In short: The Transcontinental Traverse (TCT) was a geodetic survey traverse conducted in the continental United States by the United States Coast and Geodetic Survey between 1961 and 1970 and the U.S. National Geodetic Survey between 1970 and 1976.

Key takeaways

Transcontinental Traverse belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Transcontinental Traverse to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Transcontinental Traverse from memory before moving on to harder problems.

Reference excerpt

The Transcontinental Traverse (TCT) was a geodetic survey traverse conducted in the continental United States by the United States Coast and Geodetic Survey between 1961 and 1970 and the U.S. National Geodetic Survey between 1970 and 1976. It was the most accurate large-area survey ever done prior to Global Positioning System surveys. TCT included over 2,700 survey stations, covered over 13,600 miles (21,900 km), and passed through 44 U.S. states. This nationwide survey increased the accuracy of the existing U.S. survey network. It was also fundamental to the sophisticated mathematical readjustment of the nation's survey network known as the North American Datum of 1983. It was the "end of an era" as the last conventional, purely terrestrial large scale survey.

Forerunner surveys The first major transcontinental survey was the Transcontinental Arc of Triangulation, completed in 1896 along the 39th parallel north with coastal endpoints at Cape May Lighthouse at Cape May, New Jersey, and Point Arena Light near Point Arena, California. It established the Meades Ranch survey marker, also called the Geodetic Center of the United States. The Transcontinental Traverse, commonly known as the "TCT", grew out of smaller surveying projects that the U.S. Coast and Geodetic Survey (USC&GS) conducted for the United States Air Force missile-tracking program in an area near Cape Canaveral, Florida, during the 1960s. The USC&GS developed unique specifications for this work that resulted in one part in 1,000,000, exceeding Air Force requirements. This led USC&GS officials to conclude that applying the same specifications to a nationwide traverse, a surveying method, would dramatically improve the scale of the entire U.S. survey network. Soon after completing its work for the Air Force in Florida in 1961, the USC&GS embarked on the TCT.

Route and history The Geodimeter electronic distance measurement device was rapidly tested and adopted by U.S. national agencies for long-distance mapping. The last base line to be measured with tape happened near Salmon, Idaho, in 1958. The survey began in 1961 in Florida and ended in 1976 in Michigan. It crisscrossed North America along three east–west and five north–south corridors. A portion that had been planned to traverse the U.S.-Canada border to Maine was canceled due to advances in satellite geodesy.

Equipment and methods

The traverse made use of the Geodimeter, a lightwave phase electronic distance measurement instrument that had just been invented when the traverse began. The instruments were located atop Bilby towers many meters above ground level to avoid obscuring objects and to get a smoother air temperature profile for accuracy. Due to the light source then in use, the Geodimeter could only be operated at night.

Satellite triangulation

Photographic satellite triangulation stations were tied in to the traverse at Moses Lake, Washington; Chandler, Minnesota; Beltsville, Maryland; and four other locations. The Moses Lake and Beltsville sites became part of a worldwide satellite geodesy network.

See also Geodetic control network Great Trigonometrical Survey of India

References

Sources Wilford, John Noble (2001), "Baselines across a continent", The Mapmakers, Vintage Books, pp. 353–366, ISBN 0375708502 Committee on the North American Datum, National Academy of Sciences / National Research Council / National Academy of Engineering (1971), "Appendix D: High-precision transcontinental traverse surveys in the United States and Appendix E: Satellite Triangulation for North America", North American Datum: A Report, Issue 81, U.S. Government Printing Office, pp. 73–80, LCCN 72-608706 This article incorporates public domain material from The High-precision Transcontinental Traverse: Improving the Scale of the U.S. Survey Network. United States Geological Survey. in NOAA Celebrates 200 years

Further reading Geodesy for the Layman, USAF via NOAA, 1959, mentions this traverse planned at the time C. Barton Crattie, Surveying and Towers for Triangulation With an Emphasis on the Bilby Steel Tower (PDF) James K. Richards (1965), Bilby Steel Tower for Triangulation (PDF), United States Coast and Geodetic Survey, Publication 62-3, archived from the original (PDF) on 2019-06-17

External links Media related to Transcontinental Traverse at Wikimedia Commons

Illustrations

Worked examples

Example 1 — a first encounter with Transcontinental Traverse

Start with the simplest possible case. Write down what Transcontinental Traverse claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Transcontinental Traverse before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Transcontinental Traverse ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Transcontinental Traverse

In research: Transcontinental Traverse appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Transcontinental Traverse in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Transcontinental Traverse is common in secondary-school and first-year university syllabi. It links to neighbouring topics Geodetic surveys, United States Coast and Geodetic Survey, so understanding it makes those chapters shorter.
In everyday life: Look for Transcontinental Traverse outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

Affiliate

Preply — study more efficiently by working with a personal tutor. 50% off.

How to study Transcontinental Traverse in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Transcontinental Traverse means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Transcontinental Traverse out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Transcontinental Traverse in simple terms?

Why does Transcontinental Traverse matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Transcontinental Traverse?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Transcontinental Traverse.