By Suzanna McLeod
Special to Ontario Construction News
Vessels hover in anticipation. Vehicle traffic is temporarily halted at a safe distance as the counterweight lowers to open the waterway. The boats motor through and the bascule bridge resets, allowing vehicles to cross the bridge. An expert engineer of bridge architecture, Joseph Baermann Strauss built several bascule bridges in Ontario.
Taunted by sports jocks at university for being a smaller man, Strauss (1870-1838) set his sights on achieving something grand and outstanding. “Since a bridge is the biggest thing a man can build, ‘Joe’ Strauss made up his mind to be a bridge engineer,” said A. William Finke in “Joseph B. Strauss: His Life and Achievements,” University of Cincinnati, 1960. On graduation, he leapt into bridge architecture as draftsman, instructor, inspector and designer. By the late 1800s, he learned the design of then-rare bascule bridges.
Submitting innovative ideas to his employer in 1902, Strauss devised ways to reduce costs of counterweight materials by switching from expensive pig iron to concrete. Strauss’s plan allowed the bulky counterweight to operate smoothly and involved “the pin-connected or parallel-link counterweight system, a radical departure from conventional practices,” writes Finke.
The managers ridiculed Strauss. The engineer donned his hat and walked out. Strauss immediately rented an office and put out his sign as a bridge builder.
Strauss’ first customer was the Wheeling and Lake Erie Railroad. The transportation company required a bascule bridge at Cleveland. Since it would be the first of its kind, the agreement stated that Strauss was on the financial hook if it failed. He fearlessly designed “a counterweight of iron-ore slag, carried in a reinforced concrete box or container,” described Finke. “He waited anxiously the day when he could throw the switch and watch the machinery drop the 150-ft. [45.7 m] single-track span into place.”
The simplified construction was a roaring success. Efficient and economical, Finke said, “the Strauss bascule revolutionized bridge building.” There was more ingenuity ahead. For his next project, Strauss developed a concrete beam connected to the counterbalance arm of each truss. The engineer’s precise design was picked up by “all designers of bascule and other types of lift bridges and completely superseded cast-iron counterweights.”
Hitting his stride, Strauss produced a vast range of bridge designs, improving techniques for safety, strength, and affordability. His bascule bridge architecture itself was developed in four versions: the heel-trunnion; single-span; vertical overhead counterweight; and underneath counterweight.
The trunnion was the essential element of Strauss’s architecture. The heavy mechanical component with a bearing is a medieval invention used first on cannon carriages to allow the muzzle to lower and lift. Strauss adapted the trunnion as “the vital element of every bascule, upon which the efficiency of the entire structure depends,” stated The Strauss Bascule Bridge Company in 1920. “The trunnion carries its load in surface bearing,” so it is only necessary to calculate pressure per inch to determine the required size of the trunnion. The calculations ensured that the trunnion would not be overstressed.
An advantage of Strauss’s machinery was that the trunnion and bearing are fully enclosed and protected from the rust, debris, and possible damage. The surface of the trunnion featured three straight grooves, “extending from edge to edge of the bearing, with screw compression grease cups at one end and removable pipe plugs at the other,” described the Company. “These constitute a simple and effective lubricating system.”
Some Strauss-designed bridges were outfitted with “an automatic pressure system whereby lubrication is applied to all trunnions of the bridge simultaneously, from a central control. The lubricants used are ordinary commercial standards.”
Electric motors provided the power for Strauss bridges, but if not available, “direct gasoline engine operation or electric motors supplied from a gasoline generator set, with storage battery is supplied,” the company said. Smaller, less-frequently-used bridges were hand operated. The equipment was rapid. “Designed to overcome the friction, inertia and the wind and the normal speed of opening or closing averages 1 to 2 minutes.”
Strauss bridges were appointed with service brakes and emergency brakes. Manufactured by standard electric motor companies, service brakes were operated by a solenoid and mounted on the motor shaft. Emergency brakes were “were operated either by solenoid, compressed air or by weighted levers,” and were “mounted on an intermediate gear shaft as close to the pinion as convenient.” The air operated emergency brakes were best suited for the heavier bridges. Bumpers and buffers were affixed to stop movement if either brake system failed.
Fully-equipped operator houses were constructed with the bascule bridges. Switches, circuit breakers, controls for roadways and sidewalks, were included, plus signalling devices, and much more for safe and efficient operation.
Considered a premium bridge (though doubtless their competitors would disagree), elegant Strauss bascule bridges were installed in Ontario and around the world. Over a century later, the bridges are gradually being replaced.
© 2024 Susanna McLeod. McLeod is a Kingston-based freelance writer who specializes in Canadian History.
Suggested Image:
“Demolished in 2024, the Strauss single leaf heel trunnion bascule bridge was installed in 1917 over the Cataraqui River at Kingston, Ontario. Counterweight span: 42m, bascule span: 51.8m, roadway width: 7.3m, and sidewalk: 1.21m.”
The Strauss Bascule Bridge Company: Engineers and Designers of Trunnion, Bascule, and Direct Lift Bridges, Chicago, Illinois, 1920, pg. 35. Retrieved from https://archive.org/details/TheStraussBasculeBridgeCompanyInc.EngineersAndDesignersOfTrunnion/page/n7/mode/2up
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