Making Headway on Bridge Repair and Maintenance

by Eileen Houlihan

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More than 61,000 U.S. bridges—nearly one of every nine—is structurally deficient and in need of significant repair, according to the Federal Highway Administration National Bridge Inventory. But while the numbers are staggering, some 2,000 bridges on earlier lists have been repaired or replaced over the last year or so.

Bridge repair and maintenance is big business, as well as a key component in keeping drivers safe. Many companies involved in transportation infrastructure are working to incorporate the latest innovations and techniques into the manufacture and distribution of materials for the maintenance, rehabilitation and preservation of bridges.

For example, New Rochelle, New York-based Transpo Industries, Inc. focuses on saving concrete and steel of bridge decks. The company says its T-18 Methyl Methacrylate Thin Slurry, a thin, polymer concrete overlay, helps to prevent deck cracks, protects and waterproofs grout areas and provides an anti-skid surface. It was used on the Welcome Center Bridge in Ocean City, New Jersey, which opened in 2013.

Transpo says the overlay will preserve the bridge deck and assure its safe function to the full extent of its design life of 15-25 years, while the impervious overlay will also help extend the service life of the bridge deck. “Polymer concrete overlays can enable bridge decks to maintain a like new condition that can make it possible to obtain a 75-100 year service life,” said company President and Chief Operating Officer Michael Stenko.

Dave Meggers, a research development engineer at the Kansas Department of Transportation, said the state has been using multi-coat polymer overlays for bridge preservation for 15 years, helping to extend the life of the structures without the need to mill off the existing wearing surface. He said that over 200 bridges in Kansas have polymer concrete overlays.

Congress Parkway Bridge. Photo courtesy of Parsons Brinckerhoff

Congress Parkway Bridge. Photo courtesy of Parsons Brinckerhoff

Placing an orthotropic deck on an existing bridge is another preservation technique, used recently by global consulting firm Parsons Brinckerhoff on the Congress Parkway Bascule Bridge in Chicago. The existing bascule deck with an open steel grid design leaves the bridge components vulnerable to the effects of mechanical wear and weather.

Parsons Brinckerhoff said various deck options were analyzed, based on their ability to protect the structural elements below as well as for the weight of the movable spans, including necessary rebalancing of the bridge and increased stresses on the existing machinery elements. Many of the options considered partially addressed the wear and weather issues, but lacked attributes that would provide complete protection from the elements while enhancing ride, traction, and lane delineation/visibility for motorists, the company said.

To address those issues and provide the most cost-effective long-term solution within the constraints of budget and schedule, an orthotropic bridge deck was selected. It consists of a steel plate deck topped by a polyurethane wearing surface. As an added benefit, the company said, orthotropic deck panels assembled in the shop can help expedite deck replacement and minimize construction time and traffic disruption.

Parsons Brinckerhoff said it was the first time an orthotropic deck has been placed on a movable bridge in Illinois, and one of the first such efforts in the U.S.

Castleton, Indiana bridge. Photo courtesy of AZZ Galvanizing Services.

Castleton, Indiana bridge. Photo courtesy of AZZ Galvanizing Services.

Another company working on the repair and upkeep of the nation’s bridges is Forth Worth, Texas-based AZZ Galvanizing. It uses a hot-dip galvanizing process to apply molten zinc to fabricated steel, rendering corrosion protection for up to 50 years, the company said.

AZZ said it recently tested a structural steel highway bridge in Castleton, Indiana after 44 years of service. A 188-foot-long steel beam bridge section that was hot-dip galvanized steel remains in very good condition and does not require any additional coating, reducing long-term maintenance costs, the company said.

Bridge inspector Jim Mickler of the Indiana Department of Transportation said galvanizing was a very effective method for corrosion protection in areas like Castleton. The added corrosion protection reduces the impact of road de-icing salts, which build up due to frequent use in the winter months.

In Nebraska, the Department of Roads is helping to find a way to more easily identify which parts of a bridge need fixing. The agency recently issued a grant to the University of Nebraska Lincoln (UNL) to build a 3-D computer model of an area bridge. The model allows engineers, with the click of a mouse, to identify which parts need fixing.

The data management tool is based on Building Information Modeling, software used to draft three-dimensional, detailed architectural plans for buildings and their various structural systems, according to Zhigang Shen, the UNL associate professor that developed it.

State bridge engineers have been quoted as saying road officials across the country could find the system useful, particularly those with multiple large or complicated bridges to manage.

The implementation of bridge preservation strategies that prevent, delay, or reduce deterioration is vital for the future of our nation’s aging infrastructure. ARTBA member companies remain fully active in this important work.

Eileen Houlihan is ARTBA senior writer/editor.

Featured photo: Welcome Center Bridge. Photo courtesy of Transpo Industries.

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