The Tioga Bridge is on a heavily traveled route between industrial areas of Pennsylvania and the Five Finger Lakes area of New York. The area experiences heavy snowfall, exposing the bridge to corrosive, chloride-containing road salts used to keep the bridge free from ice and snow accumulation. Thus, the hot-dip galvanized reinforcing steel was chosen to protect the bridge deck from corrosion to ensure durability and longevity.

The Tioga Bridge has been in place since 1974 and was originally constructed as a 48-ft wide, 8-span, continuous composite steel multi-girder bridge incorporating a single lane of traffic in each direction (one northbound lane and one southbound lane). The bridge was subsequently widened, and the original structure now incorporates two northbound lanes.

An inspection of the galvanized rebar (coring samples) conducted by the International Lead & Zinc Research Organization (ILZRO) and the American Galvanizers Association (AGA) in 2001 measured an average of over 7 mils of zinc coating remained on the cored samples. The zinc coating was enough to meet the specification for newly galvanized rebar (ASTM A767). The chloride levels measured at the galvanized bar surface were at least two times the level that would initiate corrosion on untreated reinforcing steel.

An additional inspection conducted by the AGA Rebar Focus Group and International Zinc Association (IZA) in 2020 revealed similar performance where cored samples measured an average of 9 mils. The chloride levels measured at the galvanized bar surface had doubled since the inspection in 2001; however, significant consumption of the zinc coating via corrosion had not yet occurred during the bridge deck's 46 years of service.

Because the galvanizing continues to provide unsurpassed corrosion resistance to the reinforcing steel, the bridge and Penn DOT can expect to benefit from a maintenance-free deck for an additional 20-30 years.

Coating Thickness