Road Trip

by Don Friedman on December 22, 2015

My family went to New Hope, Pennsylvania this past weekend for a trip on the New Hope & Ivyland Railroad. Much fun was had riding on the oldey-timey train, but my attention during our walk across to New Hope from Lambertville, New Jersey was grabbed by a well-preserved Pratt truss bridge.

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[Click to enlarge.]

Our work is almost entirely with buildings, but it’s hard for a structural engineer to ignore bridges. This one dates from 1904 and was restored in 2004.

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Plate-girder bridges have driven out trusses for short spans like this through a combination of lower first cost and less maintenance, but the tension diagonals of a truss have a spidery elegance that girder just can’t match.

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