BOH BROS. uses CON FORMS bridge deck spreader again. March 2008

Boh Bros. Construction Co. of New Orleans, one of the country’s leading contractors, especially in the southern US, and a long-time Con Forms customer recently was awarded the contract for major work on the new I-10 Twin Span Bridge in Louisiana. The bridge crosses over Lake Pontchartrain, connecting New Orleans and Slidell, Louisiana. The old bridge was heavily damaged by hurricane Katrina in 2005, and $800 million is being spent to replace it. The project is being funded solely by the Federal Highway Administration.

Boh Brothers has used Con Forms products before in concrete pumping projects, including a previous bridge construction project with the CF Bridge Deck Spreader. Boh Bros. used the spreader for concrete placement in construction of the Peace River Bridge in Punta Gorda, Florida. Managing traffic while constructing the Peace River Bridge was a major priority, so it was essential for Boh Bros. to stay on schedule. Boh Bros. solved the problem by building a middle bridge section and using two CF Bridge Deck Spreaders. The result was a project completed on time and budget, with minimal disruption to commuters.

That experience, and the CF Bridge Deck Spreader‘s history of use on bridges throughout the US, put Boh Bros. in great position for the Twin Span Bridge project.

The new Twin Span Bridge will consist of two parallel structures, each 5.5-miles long. Both bridges will be sixty feet wide and accommodate three 12-foot travel lanes. There will be 12-foot shoulders on either side of the travel lanes.

The new bridge will be 21-feet higher than the existing Twin Span Bridge, and approximately 30-feet above the water level. The bridge will feature an 80-foot high-rise section to provide vertical clearance for marine traffic on Lake Pontchartrain. It will be constructed parallel to the existing Twin Span Bridge. It will be approximately 300-feet east of the existing bridge. Once the new bridge is completed, the current bridge will be demolished.

Plans are to have the westbound span open to traffic within three years of the project start date. Both spans are to be operational in five years of the start.

The Louisiana Department of Transportation and Development is administering the project. Project activities will be coordinated with the Federal Highway Administration. Boh Bros. is building the level portion and the approaches for the new bridge. The 80-foot high-rise section is being constructed by Traylor/Kiewit/Massman Joint Venture.

The CF Bridge Deck Spreader provides a field proven method of distributing concrete on bridge decks that are not accessible by other means of concrete delivery. The Spreader provides a 360o articulating two-stage swivel boom that provides maximum maneuverability for the accurate placement of concrete.

The boom of the spreader is self-contained on an adjustable truss system. The truss assembly is fitted with wheeled bogies that provide it the freedom to travel on a screed rail and not interfere with the steel reinforcement already installed on the bridge deck.

The lightweight structure of the Bridge Deck Spreader, combined with its ability to ride on existing screed rails of multiple widths, creates a huge cost advantage compared to other placement methods. The rail system must already be in-place for screed operation, so the Spreader adds no additional cost for travel.

Boh Bros. used a 38-meter Putzmeister concrete pump to supply concrete to the spreader. The pump delivered concrete at an average rate of 70-cubic yards per hour, with pour sizes running from 500- to 800-cubic yards. This allowed Boh Bros. to comfortably pump, place and finish concrete within the LA-DOTD pre-determined pour schedules.

CF Bridge Deck Spreaders use 5” ID 7 gauge heat-treated pipe and elbows, with Hevi-DutyTM ends and couplings. Standard boom lengths are 32- and 40-feet, with custom boom lengths available depending on the application requirements. Hydraulically powered units are available with manual and remote control. Heights and widths of Bridge Deck Spreaders vary with the application.

Truss sections are modular, in sections of different lengths which allow for custom sizing to each application. The entire spreader unit rides on screed rails or flat bar. Boh Bros. used a Con Forms 40’ Bridge Deck Spreader mounted on an adjustable 65’ truss assembly with hydraulically powered bogies.

The manual two-stage articulating boom provides easy and accurate placement of concrete with as few as two laborers on the end of the boom, as seen above.

Perhaps the Bridge Deck Spreaders greatest advantage is the continued cost savings associated with labor when comparing the number of laborers required to pull the 40-50-foot of 5-inch hose across the deck of a bridge. Con Forms Bridge Deck Spreaders have proven to provide labor savings of $2,000 per pour, which can certainly add up over the duration of project such as the Twin Span Bridge.