Of Long Island?s 688 highway bridges, transportation authorities say 17 are structurally deficient and 426 are functionally obsolete.

The New York State Department of Transportation suggests that neither classification means the bridges are unsafe for the public, however they do say the structurally deficient bridges are in need of repair in the future.

"Bridges that are open to traffic are safe," DOT Public Information Officer Eileen Peters said. "If a bridge is not safe, it will be closed immediately."

See alsoExplore the inspection ratings

The DOT is required to inspect every highway bridge at least once every two years in New York State, except toll bridges -- which are inspected by the agency collecting the toll.

The bridges are scored on a scale of one to seven, seven being the bridge is new and in good condition. If a bridge receives a score of less than five, they are considered deficient and can be classified as either structurally deficient or functionally obsolete.

Bridges that are classified as structurally deficient often require a weight limit in order to remain open. Bridges that are classified as functionally obsolete bridges are unable to accommodate the current traffic flow either because they are too narrow, too low, or lack a shoulder.

advertisement | advertise on newsday

Overall, New York State has 2,016 structurally deficient and 4,735 functionally obsolete bridges, according to the DOT. Senator Kirsten Gillibrand announced June 2 that she plans to amend a highway bill that will allow more federal funding to be spent by local governments to repair bridges in need.

"My amendment will finally give states the flexibility to spend federal transportation dollars where they?re needed most, including thousands of locally-owned bridges across the state," Gillibrand said in a statement. "This is among my priorities for the federal transportation spending bill we'll pass this year, and I will continue to fight to ensure that New York receives the resources it needs to maintain and improve our critical infrastructure."

"We have worked closely with Senator Gillibrand on this bill and fully support her efforts to make federal funding available for local bridges," Peters said. "This bill does not attempt to address the level of transportation infrastructure funding, which is something Congress has been working on for several years."

@Newsday

Dr. Manuel Miranda, a civil engineering associate professor at Hofstra University who studies structural design and mechanics, said the funding problems are the main reasons for the existence of outdated bridges.

"Long Island's bridges suffer from similar issues affecting the state's and the nation's infrastructure," Miranda said. "The root cause of this is insufficient funding for maintenance, repair, rehabilitation, and replacement when necessary. This is not just a one-time thing but needs to be a sustained investment over long periods of time."

Out of the 323 bridges in Nassau County, 10 are structurally deficient and 224 are functionally obsolete. Nassau County Executive Ed Mangano expressed support of Gillibrand?s proposed amendment.

"We welcome Senator Gillibrand's advocacy as such an investment will strengthen our critical transportation infrastructure," Mangano said.

Suffolk County, with 365 bridges, has seven that are structurally deficient and 202 that are functionally obsolete. Vanessa B. Streeter, with Suffolk County Executive Steve Bellone?s office, said the bridges that are monitored by the county have either been replaced or are scheduled to be repaired.

advertisement | advertise on newsday

"Of the eight structurally deficient bridges in the geographical boundaries of Suffolk County only two are under the jurisdiction of Suffolk County," Streeter said. "And one structure was completely replaced in 2014 to 2015 and then the other is included in a project that will go out to bid this fall and constructions and repairs will begin the following spring or summer."