engineering

Parshallburg Bridge

Parshallburg Bridge is a engineering 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 Parshallburg Bridge rather than just read about it. In short: The Parshallburg Bridge, also known as the Ditch Road Bridge, was a bridge that originally carried Ditch Road over the Shiawassee River near Oakley, Michigan. It was listed on the National Register of Historic Places in 1994.

Key takeaways

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

Reference excerpt

The Parshallburg Bridge, also known as the Ditch Road Bridge, was a bridge that originally carried Ditch Road over the Shiawassee River near Oakley, Michigan. It was listed on the National Register of Historic Places in 1994. It was the only known Thacher through truss bridge in Michigan, and one of only a few remaining in the nation. In 1999, the bridge was moved to a new location, and in 2008 was washed off its piers and destroyed.

History In 1855, Israel Parshall dammed the Shiawassee River at this location and constructed saw and grist mills located on opposite banks. A hamlet sprang up around the mills, originally called Havana but later known as Parshallville or Parshallburg. It is likely that the first bridge at this location was constructed soon after the mills, and that the original bridge was replaced at a later date, perhaps in the 1870s. An 1889 edition of the Chesaning Argus describes this second bridge as an "iron bridge put up on piles only a few years ago." However, by 1889 this bridge had grown dangerous, and the local highway commission decided to replace it. They contracted with the Wrought Iron Bridge Company of Canton, Ohio to construct a new iron bridge. New abutments were constructed in the summer of 1889, and assembly of the bridge began soon after. The bridge remained in service until the 1980s. In 1986, it was identified as critically in need of replacement, and in 1992 it was closed to traffic. In 1999, the bridge was relocated to Chesaning, Michigan. However, the piers at the new location were too low for the surrounding area, and in late 2008, the bridge was washed away off its piers by flood and ice, and completely destroyed.

Description The Parshallburg Bridge was a single-span, Thacher metal through truss bridge, likely made of wrought and cast iron. The Thacher through truss was invented in 1883 by Edwin Thacher, who was then chief engineer of the Keystone Bridge Company of Pittsburgh. Thacher described the truss design as a "combination of the triangular [Pratt/Warren] and suspension [Bollman/Fink] systems," and was designed to eliminate stresses (and subsequent maintenance issues) due to temperature changes. The Parshallburg Bridge was as eight-panel structure with a length of 140 feet (43 m) and a deck width of 17.8 feet (5.4 m) sitting on rubble fieldstone abutments. The bridge's end and upper chords are constructed from parallel channels riveted to cover plates above and lattice bars below. The vertical posts and struts are constructed from two riveted angles connected by lattice bars. The center ties, inclined suspenders, and the lower chords are constructed from eyebars. The top lateral bracing is made of tie rods with turnbuckles. On each end of the bridge was a cast-iron plaque with the words "WROUGHT IRON BRIDGE CO., BUILDERS, CANTON, OHIO."

See also List of bridges documented by the Historic American Engineering Record in Michigan

References

External links Historic American Engineering Record (HAER) No. MI-127, "Parshallburg Bridge, Spanning Shiawassee River, Chesaning, Saginaw County, MI", 25 photos, 5 data pages, 3 photo caption pages Images of bridge from HistoricBridges.org

Illustrations

Worked examples

Example 1 — a first encounter with Parshallburg Bridge

Start with the simplest possible case. Write down what Parshallburg Bridge claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In engineering, 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 Parshallburg Bridge 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 Parshallburg Bridge 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 Parshallburg Bridge

In research: Parshallburg Bridge appears in engineering 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 Parshallburg Bridge 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: Parshallburg Bridge is common in secondary-school and first-year university syllabi. It links to neighbouring topics 1889 establishments in Michigan, 1999 disestablishments in Michigan, Bridges completed in 1889, so understanding it makes those chapters shorter.
In everyday life: Look for Parshallburg Bridge 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.

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How to study Parshallburg Bridge in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Parshallburg Bridge 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 Parshallburg Bridge out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Parshallburg Bridge in simple terms?

Why does Parshallburg Bridge matter?

Because it connects several engineering 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 Parshallburg Bridge?

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 Parshallburg Bridge.