Troy

The Route 4 bridge over the Hudson River linking Troy and Waterford has been closed indefinitely, city officials said Friday.

A crack in a major I-beam was discovered by state engineers during the bridge's routine biannual inspection this week, leading to the order to close the bridge, Deputy Mayor Peter Ryan and state Department of Transportation officials said.

The DOT is evaluating the condition of the bridge to determine what must be done to fix it.

The bridge, known as the Union Bridge, connects 126th Street in Troy's Lansingburgh section to Broad Street in Waterford.

Motorists are advised to use the 112th Street Bridge, which carries Route 470 over the Hudson River between Cohoes and Troy, as an alternate route.

"No one has used the term fracture critical, but with this type of tension member and the fact that we have to close the bridge, it's most likely a fractured critical element, which means if it does fail, you could have a localized failure of the bridge," Troy City Engineer Russ Reeves said Friday evening. "It's not apparent if that would catastrophic. At the present time we don't know how bad this is. That's being communicated to us very shortly. But as a precautionary measure we are shutting this down."

The Waterford-Troy Bridge succeeds a span built in 1804 as a toll bridge by business leaders from Waterford and Lansingburgh, which has been called the first bridge to cross the Hudson River north of New York Harbor. Today it is one of six bridges that link Troy to communities on the Hudson River's western shore.

Waterford Village Mayor J. Bert Mahoney said the original covered bridge burned in 1909. The current crossing was rebuilt in the mid-1980s, he said, though it still sits on the original piers from 1804. This year the spans were named National Historic Civil Engineering Landmarks.

DOT's online traffic data map shows an average of 12,836 vehicles cross the bridge each day.

Mahoney said several major steel I-beams support the bridge. Only one had been identified as having a crack Friday evening.

"I agree that they've got to make sure that bridge is safe," Mahoney said. "If it takes a day, a week, a month, whatever it takes to fix the bridge, that's what we've got to do."

The closing comes one week after the Troy ordered the Spring Avenue Bridge to be closed for a year after city and state engineers determined it was no longer safe for vehicles. About 3,000 automobiles crossed that 129-year-old bridge every day. Traffic is being detoured along Canal Street to Fourth Street during the closure, expected to last about a year, when a new bridge will be built to replace it at a cost of $3 million.

Not far away, plans were detailed this summer to replace an 81-year-old deteriorating bridge over the Mohawk River between Cohoes and Waterford.

The $20 million state project would result in a new span to carry Saratoga Avenue, also known as Route 32, across the Mohawk. An average of 6,800 vehicles use the bridge daily. A replacement is expected to be completed in 2020, with construction set to start in late 2018, DOT officials have said.

In March 1977, the Green Island Bridge collapsed into the Hudson. Both the old and new are lift bridges that vertically raise the road to let ships pass.

Kenneth C. Crowe II contributed to this story.