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July 2, 2008

Local Bridge Expert leads Innovative work

Suspension bridge cables hold up the roadway, so fighting corrosion and keeping them in the best shape possible is an obvious priority. 

Now, thanks to a seven-year trial run and a product developed with the guidance of State Bridge Authority Chief Engineer Bill Moreau, the Bear Mountain and Mid-Hudson bridges can expect an even longer life.

“People may not realize it, but we have a true expert in bridge maintenance and safety right here in the Hudson Valley,” Bridge Authority Chairman James P. Sproat said. “Bill Moreau is one of the best in the business and we’re proud that he’s making sure our bridges are in great shape.”

The project has earned recognition across the Atlantic as well since Moreau’s work was recently cited in the UK based Bridge Design & Engineering Magazine.  The publication is considered a leading journal for bridge engineers around the world.

“Suspension Bridge cables are made up of thousands of individual strands of steel wire that are bound together,” Moreau explained, “and keeping moisture out of those strands to prevent corrosion is one of the biggest hurdles faced by bridge engineers.”

The traditional method to protecting cables was to pack them in lead based red paste.  The cables were smeared with the paste to provide a protective seal, but red lead paste is highly toxic, dries out and can crack, leading to water infiltration.

The non-toxic polymer-based product, Grikote Z, was developed by the Grignard Company who worked with Moreau to meet the tough specifications he demanded.  Moreau then put the product through a multi-year series of tests on the Bear Mountain Bridge.

Last year, while undergoing annual safety and cable reviews, the cables on the Bear Mountain Bridge were opened and inspected.  “The product looked as good as the day it was applied in 2000 and is providing a great moisture barrier,” Moreau said.

Moreau added that this will cut maintenance costs, add life to the spans and remove an environmental toxin from the bridges all at the same time.  The new coating requires no special warnings, is non-flammable and requires no safety precautions for handling, application or removal.

Next year, the Mid-Hudson Bridge is due for a major cable inspection project and Moreau has already decided that any parts that are unwrapped will be put back together with the new product.  “I don’t see any reason to ever use red lead paste again,” Moreau added.

Preserving the suspension cables is a big-ticket item for bridges.  The replacement cost for new cables on either Hudson River bridge would run well over $100 million.

The Bear Mountain Bridge was opened in 1924 and is the oldest of the Bridge Authority’s five river crossings.  At the time it was built, it was also the longest suspension bridge in the world and the first suspended bridge to have a concrete deck.

Quick Facts about the New York State Bridge Authority

  • The NYS Bridge Authority operates the Bear Mountain, Newburgh-Beacon, Mid-Hudson, Kingston-Rhinecliff and Rip Van Winkle bridges.          
  • The Authority is funded from bridge tolls and receives no tax monies for bridge maintenance and operation.
  • The Authority holds the highest bond rating given any public toll-transportation entity in the United States, reducing bond and annual costs.
  • The $1 passenger vehicle toll for east-bound passage on all Authority bridges is among the lowest nationwide for self-supporting transportation agencies (there is no toll for west-bound passage).
  • Tolls today are actually lower, in real dollars, than they were in 1933 when the Authority began operations.
  • Accidents on Authority bridges in 2007 were among the lowest in recent history, resulting in one accident for every 383,000 crossings.