(photos by Timothy Smith) The first of three cranes is erected Sunday at Building A’s construction site. Inset: Safety workers climb the newly erected crane.

According to Robert Bowers, who oversees all of Clark’s tower crane erections and dismantling, this is the 21st crane erected by Clark in 2008. The tower crane stands nearly 168 feet above ground level and will be used primarily, to haul and place concrete and to move items around the site.

Work on the tower crane began in early September, with the pouring of a concrete slab to support the crane and coordination⁄ safety meetings held between the Navy Crane Center, Naval Facilities Engineering Command and Clark⁄Balfour Beatty. NCC also provided a comprehensive safety presentation to NAVFAC staff. Safety was the greatest concern of all coming into the erection, especially following a recent spate of crane catastrophes in New York and Miami.

In major metropolitan areas, where space is tight, cranes are anchored to buildings by girders and struts. In March 2008, an 18 story high, New York tower crane collapsed while the crew was placing the last of three girders, when the straps holding it up snapped. The girder plummeted down the tower, smashing into the second one, snapping it loose. The two plummeting girders stacked on top of the bottom girder. Once the girders gave way the crane fell, shearing off a segment of a neighboring building and crushing a townhouse. It was a rigging failure. We’ve increased the emphasis on the rigging equipment to make sure it’s in good shape,” said Dennis Brown, OICC Bethesda’s safety manager. ‘‘The rigging itself is supposed to be inspected by the guys doing the rigging every time they put that stuff up.”

In Miami, 10 days later a 20 foot segment from a crane fell. The crane was jacking itself up, a process where the crane extends its own height. According to an NCC PowerPoint presentation, ‘‘the Miami incident was caused by improper handling or procedures used when climbing the crane.” Two workers died.

Fewer than three months later, a second New York crane collapsed. This time, the turntable came loose, the jib and cabin fell, shearing off balconies from a nearby apartment. Two workers died.

In early September, a New York crane worker fell 400 feet to his death, after losing his footing, when the platform he was standing on tilted. The victim had on a harness, but had not tied off.

Despite the recent disasters NCC’s crane safety presentation stated ‘‘tower cranes are the safest crane to have on your job site.”

‘‘They’re at their most dangerous during erection and dismantling. The tower cranes are as good or have a better record than your standard cranes, while their in operation,” Brown said. ‘‘The problem with tower cranes is that they have a tendency to fall down when they’re being erected or coming back down again.”

As part of CBB’s policy, construction workers must wear fall protection. According to Bill Bready, CBB’s safety manager, if a worker falls and the fall protection catches him, CBB requires the equipment immediately removed for inspection and replaced with another set.

Crane operators must pass a health physical and be certified either by their union, or the National Commission for the Certification of Crane Operators. The state can issue certifications, but Maryland, however; has no such certification program.

To better ensure the crane’s safe erection, OICC Bethesda asked the Naval Crane Center to help monitor the work. NCC representatives reviewed the rigging plans and stayed on site during the entirety of the work.

NCC has extensive experience in container cranes, bridge cranes, floating cranes and hoist cranes, but this was their first tower crane. Given that a tower crane will be erected at a NAVFAC construction project in Italy, NCC had two videographers on site to film the process. The film will be turned into a NAVFAC training video.

Work began early on Oct. 9 with the arrival and assembly of a mobile boom crane used to lift segments of the crane into place. On Friday, the day the tower crane arrived; NCC, NAVFAC and Clark had a meeting to review a 21 item check list of safety and construction concerns. Just before work began Saturday morning, CBB, NAVFAC and NCC staff huddled again, to go over last minute safety matters.

The tower crane was assembled in four 40-foot sections and one eight-foot section, plus the turn table, cabin and jib.

After the first segment was put in place, a four man crew, moved in to fasten the segment to the slab. Four massive bolts were then inserted into the base, slug wrenches were slid over them and they were thwacked with sledge hammers, until the bolts were fastened. As the structure climbed higher, men anchored by harnesses, fastened each additional section by hand.

On Saturday, with the placement of the entire tower, turn table, cabin and a large part of the jib, most of the work was nearly complete, as evening approached. Early the next day, work resumed and was completed when the last section of the jib and the counterweights were placed.

The crane’s jib extends 200 feet and can hoist between 13,000 and 22,000 pounds. Two additional cranes are scheduled to be erected on the site later in October.

After the project, Chuck Cotton, NCC’s design director, said tower cranes are similar to the other cranes he’s familiar with.

‘‘The effort’s the same; the crew effort is the same, just different pieces. The company obviously knows what they’re doing,” Cotton said.

Doug Blakley, who offered rigging quality assurance called the experience ‘‘very educational.”