One-third of Rockland and Westchester counties' 1,514 bridges need regular maintenance to stay in good working condition or are so old they don't meet current traffic safety standards, according to a report released Tuesday by the American Society of Civil Engineers.
Eighty-six bridges in the two counties are considered structurally deficient, meaning the structures have been damaged or deteriorated and need regular maintenance, according to an analysis of federal highway statistics done by the engineers group.
An additional 431 bridges rank as functionally obsolete, meaning they have narrow lanes, low clearance or lack shoulders to carry the amount of traffic that courses over them every day, the statistics show.
Among those falling into the second category is the Hudson Valley's most famous span, the 57-year-old Tappan Zee Bridge, which state officials are working to replace with a state-of-the art, $3.9 billion structure that comes with a promise to last 100 years.
"We are building a new bridge because the cost to keep the current Tappan Zee Bridge safe for the foreseeable future is almost as much as the cost of the new bridge, without any of the benefits for drivers offered by the new bridge," said State Thruway Authority spokesman Dan Weiller.
Thruway Authority officials said the lack of shoulders and breakdown lanes make the bridge a safety hazard and have plans to replace it with a dual span that will have eight lanes for traffic and four breakdown lanes.
The Tappan Zee Bridge has "had a good life, but it's time to replace it," said Andrew Herrmann, a bridge engineer whose company has worked on the bridge and is a past president of the American Society of Civil Engineers.
The bridge report comes out of the group's assessment of the nation's infrastructure, which was last updated in 2009. Aside from bridges, the report looked at trends in aviation, levees and wastewater systems, to name a few.
The group gave the nation a D+ overall grade, up from a D four years ago, based largely on the amount of money that the government has spent in recent years to remedy its infrastructure ailments.
Bridges improved to a C+ grade after earning a C in 2009.
AGING SPANS TYPICAL IN NY
The Rockland and Westchester bridges included in the group's study form a hodgepodge of structures big and small, from Interstate 287 exit ramps to spans that cross brooks and streams in the two counties.
Some, like one in Stony Point that carries Tiorati Brook Road over the brook from which it takes its name, was built in 1910. It's considered structurally deficient, according to state Department of Transportation records. So is another span that carries Beaver Dam Road over Beaver Dam Creek in Bedford. It was built in 1928 and is classified as structurally deficient, state reports show.
Herrmann, who until recently lived in Ossining, said such aging structures are typical of the bridge stock in northeastern states.
As a result, they may have posted weight restrictions or prohibit truck traffic. "It doesn't mean they're not safe," Herrmann said.
Structurally deficient bridges may require more inspections -- as frequently as once a month -- in addition to the annual or biennial checks done by the state, Herrmann said.
GROUP URGES INVESTMENT
Nationally, some 11 percent of the nation's bridges were considered structurally deficient; an additional 25 percent ranked as functionally obsolete.
New York State figures closely track the national numbers.
Statewide, some 2,169 of 17,420 bridges -- 12.5 percent -- are considered structurally deficient, and an additional 4,718 -- 27.1 percent -- are classified as functionally obsolete.
The study estimated that 200 million trips are taken every day over deficient bridges in 102 metropolitan areas across the country.
It calls on all levels of government to increase annual spending for bridge repair and reconstruction by $8 billion annually to a total funding level of $20.5 billion.
And it called for a national strategy to address the nation's structurally deficient and functionally obsolete bridges, a strategy that would include research on how to develop "more resilient bridges."
The goal of the American Society of Civil Engineers is to decrease the percentage of the population driving over all deficient bridges by 75 percent in 2020.
The organization's study on the nation's infrastructure can be found at http://www.infrastructurereportcard.org/.