Print this page Touching the Earth Lightly: The U.S. 20 Iowa River Bridge
J.M. Syken
Course Outline
In this course, we will examine the creation of the U.S. 20 Iowa River Bridge in central Iowa. Located in an environmentally sensitive area on a ten-acre site along the Iowa Rive Greenbelt, the extreme precautions taken to protect the site, river and native species during the construction of the bridge will be the focus of the presentation.
This will include; site selection, bridge type selection (I-girder deck), construction method (via incremental launch), erosion control, foundation types, species monitoring, site restoration etc. As well, the successful use of the incremental launching method for a steel I-girder bridge for the first time will be highlighted/discussed as will be the minimal environmental impact of the bridge to the Greenbelt.
This course includes a multiple-choice quiz at the end, which is designed to enhance the understanding of the course materials.
Learning Objective
At the conclusion of this course, the student will:
- Understand/appreciate the history of the 1920s-era U.S. 20, its planned improvement (including a highway bridge across the Iowa River) beginning in the late 1960s;
- Understand/appreciate the environmental sensitive issues involved with building a highway bridge across a protected ten-acre site within the Iowa River Greenbelt;
- Understand/appreciate the selection of a long-span I-girder deck-type bridge using the incremental launch method as least disturbing to the river valley;
- Understand/appreciate the use of drill shaft footings at bridge piers located near the river banks as least disturbing and measures taken to protect the river from fluid contamination;
- Understand/appreciate the measures taken to prevent soil erosion from the steeply sloping sides of the river valley;
- Understand/appreciate the measures taken to control storm water runoff via a sealed drainage system;
- Understand/appreciate measures taken to protect native species from harm/disturbance;
- Understand/appreciate the measures taken to restore the construction site to its pristine condition prior to the construction of the bridge and its approaches; and
- Understand/appreciate the precedent set by the creation of the environmentally sensitive, multiple award-winning Iowa River Bridge and its ongoing legacy.
Intended Audience
This course is intended for architects, engineers and other design professionals.
Benefit to Attendees
The attendee/s will gain an intimate knowledge and insight into the design, construction and legacy of the environmentally conscious U.S. 20 Iowa River Bridge
Course Introduction
The course includes an in-depth PowerPoint presentation and a documentary film
Course Content
In this course, you are required to view/study the following slideshow and the materials contained in the web pages:
Touching the Earth Lightly: The U.S. 20 Iowa River Bridge (printable handout in PDF, 1 MB, see Note A below for downloading instruction)'
Touching the Earth Lightly: The U.S. 20 Iowa River Bridge (non-printable slideshow for screen-viewing only, 4 MB, see Note A below for downloading instruction)
Archival/Documentary Film:
TITLE: The Iowa River Bridge
LINK: http://www.youtube.com/watch?v=FH_HK1Plggk
DURATION: 32:06
Note A: Please click on the above underlined hypertext to view, download or print the document for your study. Because of the large file size, we recommend that you first save the file to your computer by right-clicking the mouse and choosing "Save Target As ...", and then open the file in Adobe Acrobat Reader from your computer.
Course Summary
Why did it take twenty-five years to build a highway bridge over a river valley in central Iowa? The answer is as complicated as the design/construction of the bridge itself. Open since the summer of 2003, the average motorist passes over the +1,600-foot span in less than a minute, perhaps noticing the beautiful river valley from a sideways glance. That was the “big idea” behind the bridge: maintain the beauty and fragile ecosystem of the river and its valley for posterity by “touching the earth lightly.” That meant selecting a bridge type/method of construction, pier foundation/type/s, soil erosion/water contamination control measures and site monitoring/restoration during all phases – before, during and after – construction to make sure the ten acres the bridge and its approaches occupy in the Iowa River Greenbelt testify to the care and concern for its well-being that the men and women who designed and built it at the beginning of the twenty-first century took to keep it that way for the generations of Americans yet to be born.
Related Links
For additional technical information related to this subject, please visit the following websites:
http://en.wikipedia.org/wiki/U.S._Route_20_in_Iowa
http://iowarivergreenbelt.org/www.iowarivergreenbelt.org/Welcome.html
https://www.youtube.com/watch?v=190eH_AJeWQ
(Film: Bridge Girder Erection Machine - 10:18)
https://www.youtube.com/watch?v=5M3WnaZ9YPw
(Film: Heavy-Duty Largr Bridge Building Machines - 14:22)
Quiz
Once you finish studying the above course content, you need to take a quiz to obtain the PDH credits.
DISCLAIMER: The materials contained in the online course are not intended as a representation or warranty on the part of PDH Center or any other person/organization named herein. The materials are for general information only. They are not a substitute for competent professional advice. Application of this information to a specific project should be reviewed by a registered architect and/or professional engineer/surveyor. Anyone making use of the information set forth herein does so at their own risk and assumes any and all resulting liability arising therefrom.
