The Washington Monument elevator briefly broke down again over Memorial Day weekend, leaving visitors to wait at the top for about half an hour, as questions remain about the elevator's reliability.
National Park Service spokesperson Carol Johnson said the elevator stopped working for about 32 minutes Saturday, starting around 1 p.m. Visitors at the top waited until the elevator began running again instead of walking down the nearly 900 steps.
Johnson said the elevator worked well for the remainder of the weekend.
However, the monument's elevator has been plagued by problems since the site reopened May 12 following a nearly three-year closure. In one case, human error -- an improperly turned key -- was to blame. In another, a sensor reading led the NPS to halt elevator service.
Johnson acknowledged that there is no single source to which the NPS can point as the cause of the problems.
"Obviously there are issues that we're looking into, and we're trying to remedy all of them," she said.
The shutdowns have at times forced visitors to walk down the monument's 897 steps, and in at least one case, stranded visitors inside the elevator.
Not every case can be attributed to an actual breakdown, however. A shutdown on the night of May 21 was caused by an elevator key that was turned halfway between operating mode and inspector mode.
Johnson said someone inside the elevator may have bumped up against the key.
About 50 visitors were on the monument's observation deck when that happened -- and because no one realized the cause of the problem, they were forced to walk down the hundreds of stairs when a thunderstorm mandated an evacuation.
"[A]ll of us up top got to walk down the 860+ stairs!" visitor Kelly Baker told News4 in an email. "Hats off to the pregnant gal who... also had to trek down to the bottom."
The monument -- and its elevator -- reopened about half an hour later.
Johnson emphasized that the May 21 incident was an anomaly. "We're certainly not saying [the elevator shutdowns] were all human error," she said.
However, an NPS memo obtained by NBC Washington said a turned key may have caused a shutdown in another case about a week earlier.
In another incident, on May 19, a computer indicated that the elevator needed repair. A crew arrived on site at 6 a.m. the following day, but the work postponed the morning's opening by about an hour, frustrating some people with timed tickets.
Johnson said that the NPS works to let in ticket holders who may be delayed because of the elevator problems, without extending the delays throughout the rest of the day.
"We just try to fit them in, and the groups that come in, we try to accommodate them," she said.
According to the NPS memo, another shutdown occurred when construction materials were blocking the elevator's sensors. Simply moving the materials solved that problem.
The closures come at a time of increased focus on the Washington Monument, which celebrated its reopening May 12 with a ceremony on the National Mall. The monument had been closed for nearly three years after a 5.8-magnitude earthquake rattled the region, leaving hundreds of cracks in the monument's façade and damaging its elevator.
The elevator was the first thing to be repaired at the site, and it was used throughout the reconstruction process at the monument.
However, the NPS memo said the elevator had occasionally shut down during that time as well -- and that includes the weekend before reopening.
Before the monument reopened, the elevator was inspected by the monument's contractor, Quality Elevator, and by the General Services Administration. It was certified May 9.
"Based on those inspections and the certification, I was confident that the elevator was back to full and safe operating condition," wrote National Mall Superintendent Robert A. Vogel in the memo.
But the first breakdown for the public came just two days after the monument reopened. In that case, the elevator doors malfunctioned about 20 feet above the ground floor, stranding 18 people inside. About 60 people were on the observation level 500 feet up, and walked down the hundreds of stairs.
D.C. Del. Eleanor Holmes Norton suggested recently that simple wear and tear may be the culprit for an elevator that runs about 13 hours a day.
"Too many glitches should warn us we need a new elevator altogether," she said.
The NPS has said it doesn't think needs the elevator to be replaced.
Vogel said that after problems occurred the weekend before the reopening, he ordered the elevator contractor to stay onsite during operating hours to make on-the-spot repairs and to diagnose problems as they occur.
The contractor has also brought in additional experts and has extra replacement parts on-hand if they're needed, Vogel said.
The NPS has denied reports that the elevator's failures have been dangerous. Vogel said last week a rumor that the elevator had gone into a freefall at one point is "categorically not correct."
"I have been assured by experts we have called in to diagnose why the elevator has experienced stoppages that the elevator is safe to operate," Vogel wrote in the NPS memo.