Civil Engineering | NEWS
THE ROBERT C. BYRD Green Bank Telescope, in Green Bank, West Vir- ginia, the world’s largest fully movable radio telescope, features a 328.4 ft diameter collecting area and about 8,488 tons of
moving weight. It is used by the National Radio
Astronomy Observatory (NRAO) to collect radio waves from outer space, and it routinely discovers celestial bodies and obtains information
about phenomena thousands of light-years away.
The telescope took more than a decade to build and began
operations in 2000, replacing a telescope that had a diameter
of 300 ft and collapsed in 1988 because of the failure of a single gusset plate. That telescope had stood for 26 years until
the plate, which was attached to a box girder that formed the
antenna’s main support, suddenly fractured, transforming the
structure into a heap of unusable metal.
To avoid a similar occurrence, the new telescope undergoes an exhaustive inspection every three years, and engineers examine nearly 8,000 members and joints on the
485 ft tall structure. The process not only requires careful planning and execution but also
places extreme physical demands on the engineers as they work 10-hour days traversing the
massive structure in search of the earliest signs
of wear and tear.
“You are documenting and detailing each
and every member and joint while you’re ei-
ther hanging on ropes and slings or climbing
the structure,” says Michael Januszkiewicz,
P.E., the senior associate in the field servic-
es group for the engineering firm Modjeski
and Masters, of Mechanicsburg, Pennsylvania,
which conducted inspections this summer.
“You’re going to use every trick in the book
for inspecting this thing.”
Januszkiewicz, who also serves as a rope access and climb-
ing instructor for the firm, led the inspection. His team com-
prised nearly 20 engineers, 4 or 5 of them in action at any one
time. Over a period of 10 weeks they compiled detailed notes
on the condition of about 7,800 members and joints, more
than half of the 13,269 that make up the structure.
Modjeski and Masters first inspected the telescope in
2003 and 2004, and it has performed inspections every three
years since 2006. The inspections focus on critical elements of
the telescope, including its rotating base structure, box structure, elevation shaft, and vertical and horizontal feeding arms. Engineers also inspect half of
the backup support structure during each visit. The right half was examined this year, and
the left half is scheduled for 2018.
“They get to bring a lot of their inspectors
To Inspection of
Engineers who had under-
gone special training com-
piled detailed notes on each
member and joint, often while
suspended high in the air.