A bridge under construction creates an optical illusion of slanted roofs

This type of optical illusion is no doubt obsolete 
with modern bridge construction techniques.

Popular Mechanics magazine from October, 1912:
Bascule bridge provides optical illusion

A 102-foot bascule bridge recently under construction in Milwaukee Wis., drew much attention because of the peculiar optical illusion provided by it when raised to a vertical position for the passage of shipping. The sections of the under layer of planking were laid at an angle, and the surface layer, but partially done, as shown in the illustration, is laid straight. The illusion of gabled roofs was startling when the bridge was raised.
A bascule bridge, as you can probably figure out, is another name for a drawbridge. I don't know if this bridge still exists, but if you'd like to drive over it, you can try looking for it at Bridgehunter, a database of historic bridges of the U. S.

Popular Mechanics, October 1912, Google Books>>


  1. Yes it does look like a optical illusion when they're just building the bridge.

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  2. This is something new to me, why does it really look like a roof rather than a bridge? Either way, they still manage to build a strong bridge.
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