Award winning bridge reaches milestone
Wells Street bridge, a 2016 National Steel Bridge Alliance award winner, will mark 95 years of service on February 11.
The Merit Award for Reconstruction recognized the innovative engineering solutions used to rebuild and rehabilitate the bridge in-place. The fact that the bridge carries a busy L line with approximately 70,000 riders per day complicated matters. Severing this tie into the city would have had a large negative economic impact on the city. Additionally, at least one leaf had to be operational from March to October. Construction work began on October 30, 2012 and the bridge was officially re-opened November 21, 2013.
To minimize the impact on the L, bridge leaves were rebuilt one at a time with the heels rehabilitated in place and the river arms completely replaced. While pedestrian and auto traffic was interrupted for the duration of the project, L traffic was disrupted for only two nine day periods.
The new river arms were fabricated off-site and then floated to the bridge on a barge. Then the old arms were cut off and floated to the side and eventually dismantled on-site. Next, the new arms were floated into place, raised to bridge height and bolted on.
Mechanical and electrical equipment used to operate the bridge was completely rehabilitated, as well as bridge houses, bridge pits, and counterweight boxes. Care was taken to maintain the historic look of this bridge.
In the award the The National Steel Bridge Alliance cited, “The Wells Street Bridge project demonstrates than in-situ rehabilitation of movable structures nearing their useful life can be a viable alternative to replacement.” The project was managed by CDOT; designed by AECOM, Chicago; built by Walsh Construction and II in One (JV), Chicago; the steel fabricator was Munster Steel Company, Inc., Hammond, IN; and the steel detailer was Candraft Detailing, Inc., Canada. The award is well deserved recognition of the innovation and ingenuity used in this project and an appreciation of the quality of the final product.
Movable bridges have crossed the Chicago River at Wells St. for 176 years. This rich bridge history includes floating pontoon bridges and center pier swing bridges. In 1896, a second deck accommodating the Northwestern Elevated Railroad was added to the existing swing bridge. In 1922 the current double decked bascule was officially opened to traffic.
Engineering innovation and ingenuity has been a hallmark for this bascule. In the early 20th century, N. Wells St. was (and continues to be) an important thoroughfare connecting the north and south sides of the Chicago River. Maintaining both traffic and rail service for the six years the new bridge was under construction was a primary requirement.
The leaves of the bascule were built in the raised position while the existing bridge stayed in service. At the point the new bridge was almost complete, the old swing bridge was rotated open, cut up, and floated away. The leaves were then lowered, and the new bascule completed. Trains were stopped on the old swing bridge at 8 P.M. on Friday December 18, 1921. Trains resumed crossing the new bascule bridge only 59 hours later at 7 A.M. on Monday December 21. A remarkable feat of engineering. The official dedication of the bridge took place on February 11, 1922.
This bridge provides a special treat during its operation. At the sidewalk gate you are a few inches from the bridge which allows a great view into the gear room and counterweight pit as the bridge rises. Bridge statistics are interesting, but actually having this close up view is awe inspiring.
The Wells Street bridge has been a workhorse for 95 years and is ready for the next 95 years.