New Platform System Used to Rehabilitate Bridges

Bridges Article December 28, 2000
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James Frangos, vice president and general manager of Atlas Painting and Sheeting Corp., Buffalo, N.Y., is a fourth-generation bridge painter and rehabilitator. In his 13 years with Atlas, he often felt that there must be a better way to get his workers underneath long bridges than using cumbersome narrow picks that have to be constantly moved, or building expensive wooden scaffolding.

When considering how to bid some upcoming jobs early in 1995, he got together with his brother-in-law, Lambros Apostolopoulos, who had worked at Atlas before starting his own company, Allied Coatings Inc. Apostolopoulos combined his bridge rehabilitating experience with his civil engineering training and came up with the design for a multi-span platform and shielding system.

Working together with Allied's field foreman, Vasili Kozaris, the two men decided to put their new design into practice in bidding New York State DOT's (NYSDOT's) Robert Moses Bridge. This 25-span structure carries the Robert Moses Parkway across Fire Island Inlet, a popular recreational waterway 23 miles east of New York City. The work included sandblasting, epoxy-base coating and urethane-finish coating, with NYSDOT Class A containment for the entire bridge.

With Allied included as a subcontractor, Frangos successfully won the job based primarily on the labor savings he anticipated from employing Apostolopoulos' breakthrough technology. Atlas came in at $3,969,000, $701,000 under the second lowest bid.

The first project

The two companies began work in June 1995 and worked through November. They began again in April 1996, and finished up the punch list in November 1996. Overall the job took just 13 months to complete. NYSDOT had budgeted 17 months. Frangos estimates that, without the newly designed multi-span platform system, he wouldn't have been able to finish the project until mid-summer 1997.

The Robert Moses Bridge is comprised of two 90-ft approach spans, 14 girder spans of 140 ft each, a 233-ft anchor span, a 460-ft suspended- arch span, another 233-ft anchor span and eight more 140-ft girder spans. Working conditions over the channel can be compromised by strong winds that gust up to 65 knots at times, limiting platform options.

The new platform system employs standard Type B corrugated steel decking, suspended from bridge members using steel cables attached to the proprietary fasteners designed by Apostolopoulos. A patent is pending on his development.

A number of suspension options are available, depending on project requirements and bridge configurations. For the 22 girder spans on this job, the contractor installed I-beam sandwiches held together with threaded steel rods at every second pier, i.e. 280 ft apart. Steel cable sized to provide a 6:1 safety factor was then attached between the opposing I-beams at equal intervals.

Once the cables were securely in place, the contractor installed the corrugated steel decking across them, fastening the parts with the proprietary devices. Three sheets of overlapping decking were used to span the bridge's 30 ft width. Intermediate vertical tie-up cables were installed to meet the job's specific weight requirements. Up to 200 psf may be safely supported by these systems, although this project called for a somewhat lower maximum load.

Four men, eight hours

It took four men just eight hours to deck out the first 140-ft girder span once the cables were in place. Working 70 ft over the channel, they reduced the job to just six hours per span after their initial learning curve. When the decking was complete, the entire area beneath eight girder spans was underlaid at one time, providing a solid 30-ft x 1,120-ft work platform underneath the bridge's beams.

To provide containment, canvas tarpaulins were suspended over the roadway rails down to the work platform. Both ends of the tarp were secured using wooded furring strips.

The platform design was varied to accommodate the bridge's anchor spans. It was widened by 3 ft to permit safe sandblasting and refinishing of the box beam's outside surfaces. Steel outriggers were installed to support the extra platform width.

The western curving anchor span was done first, using a level platform approach. Based on their experience, the designers switched to a platform that followed the span's perimeter down to its pier for the eastern anchor span, providing even greater worker safety and time savings.

For the central 460-ft suspended arch span, cables were hooked to the bridge's 10-ft floor beams. They were suspended across the channel working downward from the bridge's roadway and upward from a contracted work boat.

This scheme allowed the platform to be positioned 5 ft below the steel structure, so that all rehabilitation work, as well as project inspection, could be accomplished without resorting to ladders.

Atlas' crew cleaned and painted the top of the suspended span using power tools and conventional man-lifts. However, the new platform system may be configured to follow along such upper arch members for projects where extended rehabilitation work would make this desirable.

The system allows several crews to work simultaneously on up to eight spans, changing a batch process into an assembly line operation. With the usual approach, a conventional 30-ft x 30-ft platform must be dropped to a barge to get around each pier and then reerected under the bridge for work to continue.

Conventional platforms also need to be constantly redeployed for sandblasting, prime coating and finish coating tasks. On the Moses job, up to 25 workers and their equipment were on the platform doing different tasks at the same time.

Winning bids

While Atlas was undertaking the job at Fire Island, Allied successful bid another job upstate--the N.Y. Route 78 crossing over the New York State Barge Canal at Lockport. Seeking to build upon their acknowledged success with these two prototype projects, Apostolopoulos, Frangos and Kozaris founded a separate company to offer their technological development to bridge contractors and owners throughout North America.

Safeway Platform Systems Inc. was formed in October 1995 to design and manufacture the Safeway Multi-Span Bridge Platform System.

Since that time the system has been used on many projects including the Gowanus Expressway, the Henry Hudson Bridge, the Cazenovia Creek crossing in West Seneca, N.Y., the Spanish River Bridge in Boca Raton, Fla., the harbor Tunnel K-Truss bridge in Baltimore, the Quaboug River Valley Bridge in West Brimfield, Mass., the Mackinac Bridge in Michigan and the Triborough Bridge in New York City.

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