Engineers scheduled to begin rappelling down the Washington Monument Tuesday experienced unexpected delays when they had to construct a barrier around the monument's lightning rod system, and the possibility of thunderstorms threatened push their daredevil visual inspection back further.

The monument was damaged last month by a 5.8-magnitude earthquake that shook the nation's capital, and the site has been closed to visitors ever since. Engineers from a private firm retained by the National Park Service have spent the past month inspecting the interior of the 555-foot obelisk, where pieces of stone and other debris rained down during the quake.

Now, a "difficult access team" from engineering firm Wiss, Janney, Elstner Associates is looking for additional cracks and chips on the exterior of the structure, and rappelling will afford them the best up-close look.

On Tuesday morning, team member Dave Megerle emerged from a hatch near the top of the structure and spent about three hours setting up ropes and other equipment. After a break, he came back out for more preparations

Officials said it was the first time the hatch on the monument has been opened in 11 years.

Part of Megerle's time atop the monument was spent constructing a barrier around its lightning rod system, said National Park Service spokeswoman Carol Johnson. The system of gold-plated copper tubes begins at the top of the monument and stretches down the edges of the pyramidion, the uppermost portion of the structure.

The rappelling team was dealing with other logistical issues in the afternoon and was closely monitoring forecasts that indicated a chance of thunderstorms that could force them to wait until Wednesday.

Team member Erik Sohn told The Associated Press Monday that the job was a dream assignment among the relatively small field of architectural engineers certified to hoist themselves up and down the sides of buildings.

"This is definitely a job that everyone would like to get. We have a relatively small group that's certified to our level," said the 33-year-old from Chantilly, Va. "It's such an iconic structure. Everyone wants to be on a monument like this."

The team is being advised by Brandon Latham, a ranger at Denali National Park in Alaska with extensive rappelling experience. He said Monday that working on the monument would be similar to rappelling down the face of a cliff.

While the monument remains structurally sound, the earthquake caused numerous cracks and chips to form in the marble exterior and the granite interior support structure. The longest crack is 4 feet long and about an inch wide, and park service officials said daylight can be seen through some of the cracks.

The exterior inspection is expected to last about 5 days. Afterward, WJE will begin an emergency weatherization of the monument _ essentially filling the holes with caulk or similar substances.

Park service officials hope to establish a timetable for repairing and reopening the monument by mid-October.

On Tuesday, tourists who strolled past the monument gazed at it more intently than usual. George Hoins, 56, of Leavenworth, Kansas, didn't arrive in time to see Megerle atop the obelisk but was impressed by the footage he saw on television.

"Whatever he gets paid, it's not enough," Hoins said.