Geosynthetics and the new I-35W Bridge

Examples of the geosynthetic materials used on the I-35W project.

By Ron Bygness, and courtesy of Flatiron Corp., Maccaferri Inc., and MnDOT

Construction of the Interstate-35W Bridge, which collapsed in catastrophic fashion on Aug. 1, 2007, was completed ahead of schedule, and reopened on Sept. 18, 2008. Geosynthetic materials of all types were used in this project, and several examples are highlighted here.

A panel discussion about the Interstate-35W Bridge will be held during the Geosynthetics-2009 conference and exhibit Feb. 25-27, 2009, in Salt Lake City (www.geoshow.info).

For the construction of the retaining walls at the I-35W Bridge, the Kasota stone placed in the wire gabion baskets came from the same quarry that supplied the stone for the nearby historic Stone Arch Bridge across the Mississippi River in Minneapolis (built by James J. Hill in 1883, see also www.ci.minneapolis.mn.us/about/stonearch.asp). The stone for these gabion walls was supplied by a third-generation company based in Mankato, Minn., (about an hour south of Minneapolis-St. Paul).

Here is a link to an article that explains how local citizens were involved in choosing the style of retaining walls for the new I-35W Bridge and why they chose what they did:

www.startribune.com/local/11552951.html.

The wall design that was selected consisted of wire mesh baskets—gabions—filled with stones. This design was similar in style and construction to a retaining wall built previously at the I-35E crossing of the Mississippi in St. Paul.

Maccaferri was among numerous manufacturers that supplied geosynthetic materials, in particular custom-made gabion baskets for the mechanically-stabilized earth (MSE) walls for the approach ramps to the new bridge. There are 7 walls that total approximately 30,000ft² of facing.

The walls included the wire/mesh baskets, plu sgeogrids, geotextiles, and geomembranes.

“This is probably the highest profile project Maccaferri has supplied, and the product is completely different than anything we’ve produced, due to aesthetic requirements,” said Anamarie Stralla, a regional sales and customer service manager for Maccaferri Inc. who was on-site many times during construction.

Ron Bygness is the editor of Geosynthetics magazine. Flatiron was the general contractor on the I-35W Bridge construction. Maccaferri was one of the manufacturers and suppliers of geosynthetic materials for this project. The Minnesota Department of Transportation oversaw the construction and is responsible for bridge maintenance.