Metro skated through Hurricane Sandy without any significant damage, but the storm has left an impact of another kind on the transit agency.

Transit agency officials have to reconcile the cost of not running service for a day and a half while workers logged overtime hours monitoring the storm and protecting the system.

They also have the specter of New York City's flooded subway as a cautionary tale of how rising waters in Washington could devastate their own rail system. The central core of Metrorail is among the most vulnerable spots for flooding at the transit agency, noted board member Mortimer Downey.

Cost of no service
Not running trains can have unexpected costs -- for systems and riders. MARC blamed some of its service problems last week on having trains not running along local tracks for three days, causing leaves to build up. That in turn, caused leaf oil to accumulate on the tracks when passing trains crush the acumulated leaves, which ultimately lead to flat spots on the train wheels. "This coating decreases the friction of a train's wheels, creating slippery rails and causing the brakes to stick and wheels to slide along the tracks -- causing the flat spots," the Maryland Transit Administration told riders in a newsletter. "Cars must be removed from service when this occurs to have the wheels repaired."

The National Mall's flood system can reportedly withstand crests of 17 feet or higher. But a 2009 Army Corps of Engineers study for the Federal Emergency Management Agency suggests that portions of the Green, Yellow, Blue and Orange lines all could be flooded should rising water spill onto the National Mall. Board members cited 1972's Hurricane Agnes and another storm in the 1920s when the Mall flooded, all well before Metro had underground tunnels there.

Metro has vent shafts at the sidewalk level on Seventh Street along the Mall, for example. If the storm drains became blocked during a storm and water levels rose to curb levels, it would flood into the system. "We have had conversations with the National Park Service and others about possible engineering solutions," said Metro spokesman Philip Stewart. "There is no project, timeline, etc., as yet."

But it's not clear how the overall system would be affected and what Metro should do to protect itself. Metro General Manager Richard Sarles pledged to look into the issue.

It's also not clear how much Sandy cost Metro in expenses and lost revenue, but it could be in the millions.

Metro did not run service Monday and much of Tuesday, a total 28 hours of service time. And even when it did reopen, it had far few riders than usual. Riders logged 54,366 trips on Metrorail Tuesday, compared with a typical weekday average of about 745,000. Metrobus had a ridership of about 30,000, down from the usual 438,000 average.

That means minimal fare revenue coming in to the agency for two days. Metro has previously estimated it costs the system about $2 million per day in lost fares when the federal government shuts down. Since federal workers make up about 40 percent of the morning rush, the revenue lost by having no riders would likely be far higher.

The agency saved on fuel costs by not running trains and buses and about $300,000 by not running MetroAccess, Metro spokesman Dan Stessel said. But when it was shuttered, Metro paid all its bus drivers, train operators and non-essential workers to stay at home, yet had scores of workers on duty monitoring the system throughout the storm, many of them working overtime shifts. Workers' salaries and benefits are the agency's biggest costs.

The agency is still tallying the costs as timecards come in, Stessel said. Sarles noted that if emergency funds become available, Metro will seek them.