On August 21, 1960, American professional engineer and bridge designer David Barnard Steinman died. Since childhood, he had loved bridges and the colossal integrated parts that support them. Steinman pursued the studies in mathematics related to bridge building with a doctoral thesis that became the design of New York’s Henry Hudson Memorial Bridge that he built 25 years later!
Bridge collapses were not uncommon events. These often took many lives and terrible injuries to those caught in the crossing. Steinman was determined his bridges would not fail and spent his career improving standards and innovating structure. He could plan projects that allowed for future structural additions as traffic increased. He introduced the use of twisted wire rope-strand cables, led the way with use of lighting on bridges, and, with his keen eye, added colour and sweeping lines that accent the aerodynamic form of his structures.
In studies of environmental factors like airflow and wind velocity, Steinman showed far-sighted respect for sudden and unpredictable extremes and rhythms of nature. His innovations included open-grids along the roadway that minimized wind pressure and extra-stiff 4-way trusses beneath the road instead of solid steel sheets.
On his world-famous Mackinac Bridge that links Lower Michigan to its Upper Peninsula, Steinman’s total structural innovation raised the Mighty Mac’s ability to resist critical wind velocity to approximately 1,000 kph (630 mph)… surpassing the 64 kph (40 mph) standard of the day. He calculated ice pressures and weights of water current against supporting pier structures… then multiplied known maximums by five. His formulas on aerodynamic stability became world design exemplars.
Steinman’s work endures around the globe. The Henry Hudson Memorial Bridge was built in 1936 and still serves fully today. The Mackinac Bridge still holds the longest total suspended length of bridge in North America – over 2500 m (8,300 ft). And those are only two of over 400 of Steinman’s eco-smart bridges.
Along with his legacy of bridges, he not only contributed to his profession, publishing over 20 books and 600 professional papers, he was also a photographer and published poet. He served as President, American Association of Engineers and Founding President, National Society of Professional Engineers, now in its 84th year. Considered one of the most important suspension bridge designers of the 20th century, Steinman received dozens of international awards, honours, prizes, and citations.
B Bondar / Real World Content Advantage