This bridge was constructed in 1969 and it contains built-up end posts and top chords which use rivets for fasteners. All primary truss connections are bolted. Diagonal and vertical members are rolled. With a 1969 construction date, and no innovative or distinctive details, a strong argument could be made that this bridge has no historic value, and also that its lack of attractive v-lacing or lattice that was found in truss bridges of decades past gives it little aesthetic value. However, this bridge is far more attractive than even today's modern truss bridges which are even more simple and plain in appearance. And certainly, this bridge is far more attractive than a typical modern pre-stressed concrete bridge. While indeed, the 1960s truss bridges found on the Calumet Sag Channel do not have a large amount of historic or technological significance, the group of bridges does offer one of the best looks available at an important event in bridge history, which is the end of the use of the rivets in bridge construction. The use of rivets rapidly faded in the 1960s as bolts and welds quickly became the dominant and preferred fastener type, and rolled beams became preferred over built-up beams as well. By 1970, rivets were rarely if ever used. The Francisco Avenue Bridge, built in 1969 typifies this trend, with only a limited use of rivets and a significant use of rolled beams. Rivets had been used since the early years of metal bridge construction in the 19th Century, and so the abandonment of rivets is a major event in the overall history of bridge construction. Further, the abandonment of rivets is perhaps the most recent major change in bridge construction to date, especially with metal truss bridges. The lack of development in the design of metal truss bridges since 1970 also means that even as these post-1970 bridges age, they will not gain any historic value since they offer nothing different from modern bridges. For these reasons, HistoricBridges.org established 1970 as the cutoff date for including bridges in the Bridge Browser. A bridge like the 1969 Francisco Avenue Bridge thus is important to include on HistoricBridges.org because it brings to a conclusion the fascinating story of the historic metal truss bridge. To see one of the best examples of where this story began, take a look at the Reading-Halls Station Bridge which was built in 1846 and is so old it predates the common use of rivets in bridge construction.
Like other Calumet Sag Channel bridges, this fixed truss bridge was designed such that, as indicated in the original plans for the bridge, the structure could be converted to a vertical lift bridge by the addition of towers in the future if increased clearance for boats was ever needed in future years. This need has never presented itself however, so these changes have never taken place. The plans for this bridge also highlight how narrow the Calumet Sag Channel used to be in terms of width, and how much wider the channel is today. Both the original and current dimensions of the channel are shown in the plans. The construction of this bridge most likely was required to accommodate the construction of this much wider channel.
Alfred Benesch was previously an engineer of grade separations for the Illinois Division of Highways.
Main PlaqueFRANCISCO AVENUE BRIDGE
CALUMET SAG CHANNEL
BUILT 1969 BY
COUNTY OF COOK
SEC. 095 - 0101 - M. F. T.
LOADING HS 20 - 44 AND ALT.
Complete Bridge List
Chicago and Cook County are home to one of the largest collections of historic bridges in the country, and no other city in the world has more movable bridges. HistoricBridges.org is proud to offer the most extensive coverage of historic Chicago bridges on the Internet.
General Chicago / Cook County Bridge Resources
Chicago's Bridges - By Nathan Holth, author of HistoricBridges.org, this book provides a discussion of the history of Chicago's movable bridges, and includes a virtual tour discussing all movable bridges remaining in Chicago today. Despite this broad coverage, the book is presented in a compact format that is easy to take with you and carry around for reference on a visit to Chicago. The book includes dozens of full color photos. Only $9.95 U.S! ($11.95 Canadian). Order Now Direct From The Publisher! or order on Amazon.
Chicago River Bridges - By Patrick T. McBriarty, this is a great companion to Holth's book shown above. This much larger book offers an extremely in-depth exploration of Chicago's movable highway bridges, including many crossings that have not existed for many years. Order Now Direct From The Publisher! or order on Amazon.
Chicago Loop Bridges - Chicago Loop Bridges is another website on the Internet that is a great companion to the HistoricBridges.org coverage of the 18 movable bridges within the Chicago Loop. This website includes additional information such as connections to popular culture, overview discussions and essays about Chicago's movable bridges, additional videos, and current news and events relating to the bridges.
Additional Online Articles and Resources - This page is a large gathering of interesting articles and resources that HistoricBridges.org has uncovered during research, but which were not specific to a particular bridge listing.
Coordinates (Latitude, Longitude):
Search For Additional Bridge Listings:
© Copyright 2003-2022, HistoricBridges.org. All Rights Reserved. Disclaimer: HistoricBridges.org is a volunteer group of private citizens. HistoricBridges.org is NOT a government agency, does not represent or work with any governmental agencies, nor is it in any way associated with any government agency or any non-profit organization. While we strive for accuracy in our factual content, HistoricBridges.org offers no guarantee of accuracy. Information is provided "as is" without warranty of any kind, either expressed or implied. Information could include technical inaccuracies or errors of omission. Opinions and commentary are the opinions of the respective HistoricBridges.org member who made them and do not necessarily represent the views of anyone else, including any outside photographers whose images may appear on the page in which the commentary appears. HistoricBridges.org does not bear any responsibility for any consequences resulting from the use of this or any other HistoricBridges.org information. Owners and users of bridges have the responsibility of correctly following all applicable laws, rules, and regulations, regardless of any HistoricBridges.org information.