ROOFING
or any team owner, weighing up the
decision to install a retractable roof to a
sports stadium or arena, whether it’s a new
build or renovation project, is something
that’s loaded with financial incentive and
necessity. While it’s a costly addition, stadium owners
are continually looking to increase revenue by hosting
events throughout the year, whatever the weather. By
filling the calendar with sporting and non-sporting
events, they look to make a return on not only the
investment for the roof, but also maximize profits from
the venue. Elsewhere, in locations with harsh climate
and weather conditions, which can cause havoc with
the schedule and be too uncomfortable for fans to sit
exposed to the elements, owners opt for a roofing
system to keep fans attending events.
Today’s solutions come in the form of complex
mechanized retractable systems or fixed systems using
modern translucent materials, such as ETFE Ethylene
tetrafluoroethylene that allow natural light in as if
playing in the open air.
These roofing options have evolved greatly over
the past decade, but they all still bring challenges as
the more complex the roof, the more difficult it is
to maintain.
Cowboy builders
Arguably, the venue that kick-started a revolution for
audacious and grand retractable roofs was the AT&T
Stadium in Texas, home to the NFL’s Dallas Cowboys,
which features a roof with 105,000ft2 retractable
section and is still the largest of its kind in the world.
The closed dome roof has two tensile fabric
membrane covered panels that retract revealing a 256ft
by 410ft (78m by 125m) opening.
“Cowboys’ owner Jerry Jones wanted that open air
feel. It feels like an outdoor stadium, and it is nice to
have that especially when it is beautiful weather – I
think we get four or five out of 10 games with the roof
open,” says Scott Woodrow, director of building
engineering at AT&T Stadium.
The 14,000-ton roof panels, which open in just over
ten minutes uses a rack and pinion system that is
powered by 128 electric motors, supplied by Swiss
technology company ABB, that produce more than
1,000bhp to move the roof sections along 325ft (99m)
rails. And all this needs to be serviced.
“We have to grease the rails once a year and give it
a general check,” explains Woodrow. “We check the rail
– that means mean going up in harnesses – to do visual
inspections and perform oil checks.”
But it is not the mechanical aspects of the roof that
are most vulnerable, Woodrow explains.
“There are a lot of extremely complicated
electronics powering the roof,” he says. “There are a lot
of sensors, a lot of safety systems built in, and it is the
worst environment in the building. It is dusty and hot
and dirty up there.”
(Main) The Dallas Cowboy’s
AT&T Stadium was hailed for its
engineering, which included
the largest retractable roof in the
world when it was built in 2009
“There are a lot of extremely complicated electronics
powering the roof. There are a lot of sensors, a lot of
safety systems built in, and it is the worst environment
in the building. It is dusty and hot and dirty up there”
Scott Woodrow, director of building engineering, AT&T Stadium
44 www.stadia-magazine.com September 2019
/www.stadia-magazine.com