For over 100 years, Chicago has been a leader in drawbridge technology, and in error has occasionally boasted of having the greatest number of drawbridges. In actuality, Amsterdam holds that title, and in classic Second City form, Chicago is second in this regard. Despite being in second place, Chicago can still rightfully claim the title “Drawbridge Capital of the World.”
For it is the young City of Chicago that quickly became the world center for drawbridge innovation, engineering, and design. This is reflected in the number of bridge and bascule bridge patents held by Chicagoans, but more impressively by the great variety of drawbridges that stand in Chicago today. More new and different drawbridge designs were tested, built, and proven here, before anywhere else on Earth. These remnants of past contributions in the development of drawbridge technology strung across city waterways are regularly overlooked and often little understood.
Chicago’s rapid growth spurred frequent moveable bridge replacement and experimentation to meet the needs of the evolving city. The high value of land and concentration of business and industry on the prairie landscape made drawbridges the ideal solution to connect a city trisected by the Y-shaped Chicago River. This river, which acted as both a harbor and waterway, created a natural proving ground for moveable bridge design. Today Chicago still retains more than a dozen unique drawbridge designs despite the passage of more than 100 years since the advent of commercial-grade steel and the great steel ships that gave birth to today’s modern moveable bridge designs.
Today’s bridges are the result of trying and testing a variety of private and public bridge designs that ultimately led to the development of what is now know as the Chicago-type bascule bridge. This design invented by city engineers near the turn of the last century and is the pre-eminent design for most of today’s downtown bridges.
[Insert image of simple bascule]
Bascule is a French term meaning “seesaw” that for centuries has described the simple principle of using a counterweight to balance a bridge, making it easier to open and close.
Beginning in the 1850′s and through the 1890′s, the dominant moveable bridge design in Chicago, and for the nation, was the swing bridge. This design operated on a horizontal plane by rotating on a central pier, similar to the way a lazy susan works.
As these bridges evolved, the bridge superstructure transitioned from simple wooden construction to wood and iron, to all-iron and eventually steel. With the growing availability of commercial steel in the 1870′s and 80′s, new, larger and wider ocean and Great Lake ships made of steel required better drawbridges that could offer an 80- to 150-foot-wide “draw” or opening.
In 1890 in Chicago, there were 48 swing bridges with meager 50- to 80-foot-wide draws to either side of their center piers. And the narrow Chicago River was at best only 200-feet wide. Clearly a new design that opened the full river channel to ships was required. The inadequate swing bridge design would have to be replaced.
The evolving crisis prevented the new ships of the Great Lakes from navigating the Chicago River and main harbor because of the obstructing swing bridges. Continued prosperity and growth, and lobbying from industry and shipping interests brought new federal oversight to force the introduction of new bridging solutions. Efforts toward solving this problem lead to the trial and development of many new drawbridge designs.
What follows is a virtual tour of the many unique designs and engineering solutions gracing Chicago’s waterways. These designs were built in an earlier era, when ships were the pre-eminent means of travel.
Thankfully Chicago’s history as a center of bridge innovation is gaining recognition, and many of these bridges, through Mayoral and City Council approval, have been designated Chicago Landmarks. This status ensures permit review by the city Landmarks Commission prior to significant alterations or removal. Such protection should help preserve Chicago’s fantastic drawbridge legacy.
The oldest design still existing is the swing bridge design, of which there are three variations.
The first is the traditional center-pier swing bridge, demonstrated by three railroad bridges crossing the Sanitary & Ship Canal. These are the Chicago, Madison, & Northern Bridge, which received Chicago Landmark status in December 2007; the Chicago & Western Indiana Bridge; and Santa Fe Railroad Bridge, also known as the Illinois Central Railroad Bridge, which was landmarked in December 2007.
The Sanitary District, now known as the Metropolitan Water Reclamation District, built these in 1899 to carry the railways over the newly completed canal that reversed the flow of the Chicago River. These bridges are now owned and maintained by the respective railroad companies and for several decades have been treated as fixed spans.
As one can imagine, massive swing bridges like these, stretching 334- to 479-feet across the canal, large enough to allow the passage of large ships, would be prohibitive on the 200-foot wide Chicago River. Especially given the high value of downtown real estate. Such considerations well illustrate the fatal flaw of center-pier swing bridges in many applications.
The second swing bridge variation is the bobtail swing bridge on Chicago’s north side, located just south of North Avenue at the river. Referred to as the Cherry Street or Z-2 Bridge, it is now treated like a fixed bridge. In decades past, it operated by rotating on the circular pier and turntable along the northeast river bank. The name bobtail comes from the shortened end of the bridge containing the large concrete counterweight that is used to balance the bridge.
Landmarked in 2007, this bridge connects a railroad spur to Goose Island, and still occasionally carries freight in and out. Built in 1902 by the Chicago & North Western Railway, it was refurbished by the City of Chicago in 2008-09 to double as a bicycle and pedestrian bridge.
The third swing bridge variation is the Z-6 Bridge, roughly a block south of Cortland Street. This bridge was built and designed by the Chicago & North Western Railway in 1899 to replace and old center-pier swing bridge. This steel-plate bobtail swing bridge is unique as it only turns 57° to open and close. Instead of a full turntable, this bridge rotates utilizing two semi-circular racks and a cluster of steel rollers.
Placed on a bend in the river, it is normally open with the entire span resting over the east bank. This bridge still occasionally carries freight cars to move scrap metal from recycling dealers on the east side of the river. More detail on each of these swing bridges is available in a related article titled Railroads and Chicago Swing Bridges on the ForgottenChicago.com website.
Another early solution used to replace the swing bridge design was the vertical-lift bridge invented by J.A.L. Waddell, a Kansas City, Missouri engineer. Waddell won a bridge design contest in Duluth, Minnesota, but that design was never built. So Chicago seized the opportunity, and built the world’s first modern vertical-lift bridge at South Halsted Street and the Chicago River in 1894.
These bridges employ large concrete counterweights suspended by steel cables which run over large pulleys (or sheaves) atop the supporting towers and down to the bridge roadway. They balance the bridge, allowing it to be operated using just two small steam engines. In 1907 those were replaced by two 65-horsepower electric motors.
This first vertical-lift bridge was removed in 1934, but a half-dozen of these bridges still stand over Chicago waterways. The best known is the Pennsylvania Railroad Bridge in Chinatown, near 18th Street crossing the South Branch of the Chicago River. Built in 1916, it is now used by Amtrak and is monitored 24 hours a day, seven days a week due to its low river clearance. The bridge is opened remotely from a train switching tower at 14th and Lumber Streets. It is required to open on demand, but river traffic is frequently delayed by train traffic running in and out of Chicago.
Five other vertical-lift bridges cross the Calumet River between Lake Michigan and 130th Street. In the early 1900′s, the design was further refined and patented in partnership with engineer John Harrington, and thereafter railroads used the Waddell-Harrington vertical-lift designs extensively across the nation.
The Scherzer rolling-lift bridge was the design that quickly surpassed the vertical-lift bridge. Invented by Chicago engineer William Scherzer, the rolling-lift bridge operates similar to a rocking chair by rolling up and back away from the waterway.
Two instances of this bridge remain in Chicago—at Cermak Road crossing the South Branch, which received Chicago Landmark status in 2006; and the Eight-Track Bridge west of South Western Avenue over the Sanitary and Ship Canal.
The Eight-Track Bridge is a series of four alternating, single-leaf Scherzer rolling-lift bridges that carried two sets of railway tracks on each bridge. Now only the two easterly bridges carry train traffic, as the rail lines approaching the western bridges have been abandoned.
The downfall of Scherzer bridge was that its foundations, like those of earlier bridges, did not rest on bedrock. That was part of the Scherzer Rolling Lift Bridge Company’s low-cost advantage. But as a result, it was soon discovered that wind caused it to wag while it was operating. This wag, though slight, caused significant deterioration of the huge curved or segmental steel girders supporting the bridge. The foundations could move as much as an inch or more per year toward the center of the river. Thus within a short period of time, maintenance of these bridges could become a significant burden. The bridge might not close properly as the bridge leaves would bang up against each other. Once, at State Street, an inch or more of steel had to be cut off the ends each leaf so the bridge would close properly.
The problems, maintenance costs, and royalties associated with private bridge engineering solutions pushed City of Chicago engineers to develop their own design. With little or no budget available, a literature review was conducted and engineers seized on the simple fixed trunnion bascule design modeled on the Tower Bridge in London, England.
Three bascule bridge designs were drawn up and reviewed by an independent panel of bridge engineers. Incorporating many of their suggested changes, City of Chicago engineers soon had a bridge design that became known as the Chicago-type drawbridge.
The first of these was completed at Courtland Street crossing the North Branch of the Chicago River in 1902. This more than one-hundred year old bridge still stands today and received Chicago Landmark status on July 24, 1991.
Ten of these first-generation bridges were built, approximately one per year. Those that remain include three that cross the North Branch of the Chicago River at Division Street, connecting the east and west side of Goose Island (completed in 1903 and 1904); and at Kinzie Street where there is a single-leaf bridge, completed in 1909.
The advantage of these bridges was their simple, royalty-free design, which required less maintenance, met the requirements of the Chicago River, and proved reliable for decades and in some cases one-hundred years or more.
Twenty-eight second generation Chicago-type bridges followed between 1911 and 1938. These were the most decorated and architecturally interesting of all the Chicago-type bridges past or present. The two finest examples are the LaSalle Street Bridge and the double-deck Michigan Avenue Bridge crossing the Main Channel of the Chicago River.
Further refined, these bridges began to integrate the bridge houses into the approach and made concerted effort toward architectural design. For example, both of these double-leaf bridges require only two bridge houses—one for each leaf. With four bridge houses on the Lake Shore Drive, Michigan Avenue, and LaSalle Street Bridges, it must be recognized that two of the bridge houses are completely superfluous and added purely for architectural effect.
The second generation bridges up until 1930 featured the Beaux Arts architectural style as represented by the Michigan Avenue and La Salle Street Bridges above.
After the Great Depression, the bridges moved away from expensive ornamentation and the simpler Art Deco style was employed. This style is best shown at the North Ashland Avenue Bridge, and was strongly featured on the Ogden Overpass Bridges that were removed in 1998.
One of the most significant innovations in the Chicago-type drawbridge during this period was the development of the double-deck bascule bridges. In Chicago there are three Chicago-type double-deck bridges: At Lake Street, built in 1916; Michigan Avenue, built in 1920; and Wells Street, built in 1922 and completely rehabilitated in 2013.
However the Chicago-type bascule was not the only design in town. Chicago’s fourth double-deck, bascule bridge at Lake Shore Drive is a patented Stauss design. A talented engineer, Strauss also designed the below-deck truss, bascule bridge at Jackson Boulevard.
Born and educated in Cincinnati, Ohio and transplanted to Chicago, Joseph B. Strauss became an internationally known engineer and bridge designer holding more than 40 U.S. patents, including 14 bridge patents. Strauss, who founded the Strauss Concrete and Bascule Bridge Company, with offices in the famous Monadnock Building, is best know as the Chief Engineer of San Francisco’s Golden Gate Bridge.
Both the Jackson Boulevard and Lake Shore Drive Bridges are Strauss fixed trunnion bascule bridges, which employ a parallelogram configuration below the roadway to connect the counterweight that balances against the bridge structure. This arrangement has the advantage of having a smaller footprint to fit the constrained spaces between the river and the railroad tracks leading to Union Station, and was the only choice for Jackson Boulevard.
Strauss and his firm were well know for successfully designing the largest bascule bridges and were therefore selected to design the massive Lake Shore Drive Bridge built in 1937.
Another Strauss patented bridge well known to Chicagoans is the Strauss heel-trunnion bascule railroad bridge near Kinzie Street. It is easily identified by its awkward and imposing counterweights suspended above the east bank of the river, a design frequently used by the railroads. A steel parallelogram mechanism connects the bridge structure and counterweight, allowing it to operate using a set of small electric motors.
Constructed for the Chicago & North Western Railway in 1908, the railroad bridge near Kinzie Street received Chicago Landmark status in December 2007, and has been perpetually raised to the heavens since 2001. This was after the last commercial customer of that rail spur, the Chicago Sun-Times, moved newspaper printing into a new south side production building.
This bridge is a frequently the backdrop for still and moving pictures and is now considered an iconic Chicago bridge.
Chicago of course was home to many other important and less well-known engineers and bridge designers who made their mark on the changing urban landscape. Chicagoans Theodore Rall and John W. Page both of who received bridge patents still have examples of their innovative designs in Chicago.
One Rall bridge stands in Chicago inconspicuously crossing a slip off the Sanitary & Ship canal near 33rd Street, east of Kedzie Avenue. This is one of only five Rall bridges in existence. The Chicago-based contractor, the Strobel Steel Construction Company, built this bridge for the Chicago & Illinois Western Railway in 1914.
Viewed in profile with its lone strut and large steel wheel outside the steel plate superstructure, it is hard to imagine this bridge opens at all. Counterweights, motors, and gears hidden behind the steel plates at the heel of the bridge operated the rolling trunnion (or axle) held by the large steel wheel. It rolls the bridge back and rotates up to open. It’s been decades since the bridge was last opened, it is now treated as a fixed span. This single-leaf Rall bascule bridge received Chicago Landmark status in December of 2007.
The lone example of a Page bascule bridge in Chicago, and possibly anywhere in the world, is the Chicago & Alton Railroad Bridge built in 1906. This unique bridge was designed and patented by Chicago engineer John W. Page, who founded and was president of the Page Engineering Company until his death in 1967.
Better know for inventing and designing dragline excavators, based on his early work experience with the Chicago Sanitary District, he also invented two different bascule designs.
The first was a cantilever bascule bridge that was constructed in 1902 at South Ashland Avenue, but was replaced in 1936. His second design crosses the South Fork of the Chicago River’s South Branch next to the CTA Orange Line. It is a single-leaf, through-truss bascule bridge. The superstructure features an elongated S-shaped rack that meshes with a pinion gear to drive the tail-end of the bridge down and back to open.
Counterweights incorporated into the heavy superstructure’s tail-end balance the bridge and make counterweight pits unnecessary. The span is no longer required to open is treated as a fixed span, but it does still carry train traffic and was granted Chicago Landmark status in December, 2007.
Drawbridge evolution is continuing today, albeit at a slower pace. So one should also recognize the newest of Chicago’s bascule bridges.
First and foremost is the Columbus Drive Bridge. It is currently the world’s second-largest bascule bridge, and was built in 1982 at Columbus Drive. This modern welded box-girder bridge is a significant innovation in design.
The main structural components of the bridge, the eight box-girders that give it a clean, streamlined feel, avoid the numerous rivets of early bridges. These welded box-girders reflect an accumulated technological advance in welding techniques, allowing the fabrication of massive load-bearing structures that are practical, safe, and reliable.
Each of these girders, four for each leaf of the bridge, were fabricated in Pittsburgh, Pennsylvania and shipped by barge to the construction site and assembled in the upright position. When the two leaves were lowered nose-to-nose for the first time, the fit was off by a mere two-centimeters.
This raised the level of precision in construction, fabrication, and design to new heights as the configuration allows only two points of adjustment of the bridge. Earlier bridges, with their hundreds of steel members bolted and riveted together, allow many more points of adjustment. The fabrication of welded-box girders at the factory delivered a significant cost-savings and took another significant step forward in bascule bridge design.
Three such box-girder bridges reside in Chicago, starting with the prototype bridge at Loomis Street, built in 1978; the previously mentioned Columbus Drive Bridge; and the last new bascule bridge at Randolph Street, opened in 1984. There has not been a new drawbridge built in Chicago since.
This inventory chronicles a dozen unique drawbridge designs from the three swing bridge variations, single-leaf to double-deck Chicago-type and Strauss bascule bridges, to the vertical-lift, rolling-lift, heel-trunnion, Rall, and Page bascule designs. This concentration, found nowhere else, of varied approaches and evolutionary moveable bridge designs is not just important to Chicago, but reflects a significant slice of engineering history and heritage of the built environment. It is hoped over time these bridges may grow in significance, gain popular support, and be preserved as important structures in Chicago and the world’s history of bridge and engineering design.
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