Featured Span: Sauvie Island Bridge
Sauvie
Island Float-In and
Bridge Lift
See also: photo
essay.
On December 28, 2007 the Sauvie Island Bridge’s
arch span was barged eight miles from Terminal 2 along Front Avenue
down the main channel and Multnomah Channel of the Willamette
River. Four tugs pushed it into place between new concrete piers
located south of the old 1950 bridge and the only entrance and
exit to and from Sauvie Island. This is the first new big river
bridge built by Multnomah County in fifty years.* Funding for
the new bridge was secured mainly through the efforts of Multnomah
County Commissioner Maria Rojo de Steffey.
These
are my photos documenting the arch’s journey.
The arch, 365 feet long, 77 feet tall, 1,600 tons,
and held together by 80,000 high-strength bolts, needed to be
jacked up high enough to be set down on the pier tops 70 feet
above zero water. The flags you see in the photo above are waving
185 feet above the Willamette River.
The float-in was delayed several times. Ed Wortman,
engineering advisor for Multnomah County for the construction,
float-in, and lift of the Sauvie Island Bridge, was scheduled
to retire from the County the end of November 2007, but stayed
an extra month to help with the lift and float-in—delayed
due to weather, getting the right barge (the one used, arriving
here from Alaska, was 84 wide and 300 feet long), and other unforeseen
events.
There were additional delays in December and we
wondered if Ed was going to be around—his last day of paid
work for Multnomah County was to be December 28, 2007. The four
Foss tugboats turned the arch and moved it in place at about 11
a.m. that same day, a perfect ending for this engineer who’s
been sliding his rule for 47 years now at some very exciting elevations.
Ed came to Portland in 1971 and helped with the construction of
the Fremont Bridge, also an arch like the new Sauvie Island Bridge
— the latter job bringing Ed’s career in Portland
full circle.
Scott Bronson, the Webmaster for <www.bridgestories.com>,
recently asked why the bridge wasn’t jacked up to its final
height at the new site rather than at Terminal 2, and was there
ever a worry about the arch tipping because of the high center
of gravity?
Ed Wortman responds:
Jacking the span up at the Terminal 2 dock was
much easier than jacking it at the site. Skidding the arch out
onto the barge was the hardest part of the job. The crew was out
there from 11 a.m. Saturday until 12:30 p.m. on Sunday—24
hours in the worst, wet, most awful weather.
After the arch was
in the air, the back end of the skid units on land—pushed
with jacks. The front end, on the barge, was on rollers. This
proved to be way more complicated that floating the bridge up
the river.
In each of the four jacking towers is a stack of hardwood, 4”x4”
and 48" long. The span was jacked up eight inches at a time.
The contractor used a clever system where they put the pieces
of wood in two layers at a time at the bottom of the stack, then
jacked those layers, gradually lifting the arch up.
NORSAR, an engineering transport
and lifting company that specializes in moving barges and other
large industrial objects, developed this jacking system in Chicago
to lower a 700-ton German submarine into an underground gallery
in the Chicago Museum of Science and Industry in 2005.
The Sauvie Island Bridge could have been even heavier,
and it wouldn’t have been a problem.
*Multnomah County owns and
maintains the Sauvie Island, Hawthorne, Morrison, Burnside, Broadway,
and Sellwood bridges across the Willamette River and more than
20 smaller bridges in East Multnomah County
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