Earth's curve tilts bridges

Really. The top of towers of the Verrazano - Narrows Bridge at the mouth of the Hudson river in New York City are tilted almost two inches further apart than the base thanks to the curve of the Earth's surface.

Actually, there are a lot of amazing things about that not-so-famous bridge.

When it opened in 1964, at 4260 feet it was the longest suspension bridge in the world, exceeding the Golden gate completed in 1937, by 60 feet. Today it's the longest single span in North America and the seventh longest in the world. (The longest is the 6,529 foot Akashi-Kaikyo Bridge in Japan, completed in 1998.)

The Verrazano - Narrows Bridge contains enough concrete to construct a single lane highway from New York to Washington, and if the wires that make up the suspension cables were laid end-to-end they would reach 143,000 miles, more than halfway to the moon.

On hot days, the double-decker road bed expands almost six feet and sags 12 feet lower, something that ships passing underneath have to consider. In fact, the Queen Mary 2 had to modify its smokestack to pass under the bridge.



Professor D.C. Warmington said...

Dear Sir

You have an inquiring mind and are a man after our own heart. We congratulate you as the first commentator, and cordially invite you to return at your leisure to assist in the process of peer review.

Thank you for visiting.

Yours faithfully

D. C. Warmington and all the staff at Farthing's Compendium

Dr dpi said...

Hi, Super great post. Brilliant! Except for the fact that you only stayed on topic for the first sentence. But I do enjoy the way you convey the information with authority then back it up with nothing. No sources, not even the train of thought that lead you to post this in the first place.

Besides the fact that most agree the Earth's curve is closer to 8" per mile squared. Beyond that most everyone agrees the curve is imperceptible in the first mile. That is of no concern because your photo clearly shows the closest columns are tapered. It is logical to expect the others to be tapered as well. Poof! There is your two inches.

Dr dpi said...
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Dr dpi said...
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Anonymous said...

I was told that when bridges and railroad tracks are constructed over long distances earth curvature is not used in reality that it is just text book . When laying railroad tract or post fencing on the ranch, just do it in a straight line and don't include the 8 inch per mile square rule, even if the fencing runs over 1 mile. The vertical posts slants on a bridge I was told is done to maintain and support the bridge by redistributing the weight of the bridge and using gravitational forces to do this. Is this true? The longest bridge in the world in China, The Danyang bridge is 102.4 miles. Was the earth curvature rule 8"per mile square rule applied? and if so how much of a drop is it from one end to the other? Thank you for your help.

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Tom said...

You're right, of course; bridges, railroads (and roads) do conform to the curvature of the earth. The bridge in China, does too; there is no ramp at each end to reach a perfectly flat 100 mile roadbed.

You're also right, the vertical bridge posts do support the weight--produced by gravity--of the bridge.

But in some construction it really matters, for example in the tunnels used to enclose the lasers that are part of the LIGO gravitational wave sensors. Light travels in a perfectly straight line, and each leg of the LIGO sensors are 4km long, so each end is about a meter above the ground thanks to the curvature of there earth.

It's a different topic, but you might enjoy thinking about the fact that light doesn't always travel in straight line if passes close to a very massive object such as a star or black hole. Einstein thought about this a lot and the result was his General Theory of Relativity. If you can find the articles he wrote about Relativity, 100 years ago, they're surprisingly readable.

Tom said...

Dr dpi, you're right, it is hard to see the curvature--but whether we can see it or not, it's 8" per mile, not 8" squared (which is 64").

The tapered columns, by the way, have nothing to do with the measurement. They measured from the exact center of each post.

If you're interested in knowing more about the bridge and it's construction I highly recommend Gay Talese's book, The Bridge. It's available on Amazon, and your local library probably has a copy.

Matthew Renaud said...

Then way is the water under the bridge level and not curved....that's because the earth is not a spinning ball....Gravity is a theory.. made up to help and try and explain how stupid of a concept it is.. that we live on a spinning ball. ...Gravity can't be used as an excuse for every theory that is made up to fit a Heliocentric model.... That in it self.. is just a theory.... It seems Gravity is the answer to everything that has not yet once ever been tested... or proven to work in this real world.... Mass, Density, Electrical and Magnetic fields are the only things that have ever been tested to work.... and proven to exist... on this Stationary Flat Plain we call Earth.. So why is it that gravity is always the excuse for every question we have about living on spinning ball ...and all its magical impossibilities. .. Well that's because it's a made up idea fit a Heliocentric model.... that till this day.. still doesn't work.. and never will work in this real world.. .. Welcome to the Flat Earth....(Ptolemy)...had it right all this
time...Geocentricity Rules....

Anonymous said...

Curve is 8" first mile then squared distance not inches.1 mile 1x1x8" 2 miles? 2x2x8" , 3 miles 3x3x8" etc etc because the earth is supposedly round.

Raul De Leon said...

But why isn't there an end to the earth if it's a flat plane? How can you fly from Florida to Japan if there is no curvature?