WASHINGTON -- Sen. Richard Blumenthal, D-Conn., is asking the U.S. Coast Guard to curtail openings of the 100-year-old Walk Bridge, which has disrupted Metro-North rail traffic repeatedly, including twice in the past two weeks.

In a letter to Admiral Paul F. Zukunft, commandant of the Coast Guard, dated Monday, Blumenthal said the frequent malfunctions of the century-old drawbridge in Norwalk have stranded commuters time and again -- as well as snarling highway traffic throughout the New York City metro area.

He said the delays have incurred "huge regional costs. Indeed the economic costs are national in scope."

Blumenthal pointed out that the bridge problems are exacerbated by a larger context of Metro-North accidents and delays.

"I make this request after hearing from hundreds of Connecticut residents whose lives have been disastrously disrupted by unacceptable breakdowns in rail service," he wrote, pointing out that the bridge malfunctions "appear to be chronic and recurring -- 16 times during 2013 alone."

That represents a failure rate of nearly 6 percent of last year's 271 openings, he told Zukunft.

"The probability of the bridge's failing to close is so high -- and the consequences so enormous and unacceptable -- that urgent action is unavoidably essential," the senior senator from Connecticut wrote.

Blumenthal told Zukunft that the bridge has been scheduled for replacement whenever the Department of Transportation provides $349 million in Hurricane Sandy resiliency funding.

"This request has the full backing of Connecticut's congressional delegation," Blumenthal asserted, adding that the delegation is sending a letter to DOT Monday requesting expedited consideration of the funding application "in light of the continuing deterioration of the Walk Bridge."

He said the state of Connecticut has already allocated its 25 percent of the cost of replacement.

Blumenthal requested that Zukunft review the boat traffic that currently results in opening the bridge, particularly during commuting hours.