In July 2014, the Chicago Department of Transportation undertook an emergency $6 million project to replace the 111-year-old East Division Street Bridge. In June 2013, the biennial inspection determined the bridge was, in engineering terms, “structurally deficient.” It does not mean unsafe, rather, it means the bridge “requires significant maintenance and repair to remain in service and eventual rehabilitation or replacement to address deficiencies.”1
Given the heavy traffic crossing the bridge, CDOT began monthly inspections while working up the engineering and environmental impact studies necessary for bridge replacement. A December inspection determined its deterioration had accelerated due to the severity of the winter. The vacillating temperatures causing expansion and contraction of the bridge, and extreme cold and snow, had exacerbated the decline in the bridge’s condition. Thereafter weekly inspections followed as CDOT fought through the myriad of regulations, reviews, environmental studies, state, and federal agencies to shepherd approval for emergency replacement.
Normally this process takes 2-3 years, however in this case significant delay could be disastrous. In April the bridge was restricted to carry trucks of 5 tons or less, forcing semi-truck traffic to find alternative routes as pressure mounted to secure emergency funding and approval to erect an interim bridge.
Division Street features two bridges running across the North Branch of the Chicago River: on the west and North Branch Canal, and on the east to connect Goose Island. The North Branch Channel, dug in the 1860s, created the only island in the Chicago River as part of an early land development scheme led by William B. Ogden, Chicago’s first mayor.
The second East Division Street Bridge, which opened in 1903, was the second ever Chicago-type bascule bridge. Eight months earlier the world’s first Chicago-type bascule bridge was completed at Cortland Street. It is protected by Chicago landmark status granted in July 1991.
In 2010 both East and West Division Street Bridges received a new open-grate deck, but by 2014 the supporting truss superstructure of the East Division Street Bridge had deteriorated to the point that complete replacement for it was necessary.
On June 30, the street was closed to traffic so that the 111-year old bridge could be removed, the abutments revitalized, and new supporting piers added. A new, interim, East Division Street Bridge was constructed to restore traffic over the North Branch Canal on September 30. The interim bridge was purchased from and installed by the Acrow Bridge company. It’s a Bailey-type bridge designed for three lanes of traffic. However, it actually carries two lanes of automobile traffic and two bike lanes, with sidewalks cantilevered off each side of the roadway. It was the lowest cost and most efficient solution for restoring the street crossing until the engineering work could be done and the funding found for the permanent replacement of the old East Division Street bascule bridge.
First invented by Donald Bailey, Bailey bridges gained popularity during World War II for their portability and ease of assembly. Donald Bailey was a civil servant in the British War Office and a model bridge hobbyist, who presented his design to the higher ups during the war. The advantage of his design was quickly recognized as the components are pre-fabricated. They’re typically small enough to be carried by truck, light enough to be lifted in place by hand, and require little or no special tools to construct. The resulting assembly creates a truss bridge that capably carries armored tanks and trucks across rivers or ravines.
1 Bridge Inspection Definitions, American Association of State Highway and Transportation Officials (AASHTO) website: http://www.iowadot.gov/subcommittee/bridgetermspz.aspx#s
Special thanks to Chief Bridge Engineer Luis D. Benitez, P.E., S.E. and Civil Engineer Emilie Giraudon, Ph.D., P.E. at DCOT for insights on the bridge and the replacement process.