| Better Bridges
Rehab, Painting Save Oregon Bridge
The northbound structure of the twin Interstate-5
bridge needed new paint and minor structural rehabilitation. The 1917
lift-span bridge was extensively rehabilitated after a new southbound
structure was built in 1958.
Despite several substantial construction and maintenance upgrades since
then, a great deal of maintenance and repair remained.
Three coats of lead-based paint were eroded by the elements and
undermined by rust, compromising the structure’s surface. The bridge’s
structural integrity was at risk in the long run if left unattended.
On site
 The Oregon Department of Transportation’s contractor, Certified
Coatings of Concord, California, began a $17-million project to paint and
rehabilitate the northbound span of the Interstate-5 bridge over the
Columbia River.
The bridge had not been painted since 1966. Three coats of lead-based
paint had to be removed. Work was done by encapsulating the bridge to
prevent environmental contamination during the paint removal and
replacement process.
There were a few new things to learn about the old bridge when it came
to painting the over one-million square feet of steel that makes up the
structure. An initial learning curve, followed by staging complications
and equipment breakdown, contributed to a slower schedule than originally
planned. At press time, the project was nearing completion.
The 13 spans were rehabilitated and painted with lead-free,
corrosion-inhibiting green paint.
Three travel lanes were maintained during most of the project. There
were occasional nighttime/early morning lane closures on I-5 and on the
bridge to move the encapsulation structure as the work progressed on the
bridge’s steel framework.
The encapsulation structure appeared as a tunnel to the motorist. The
entrance of this structure was illuminated to reduce the visual impact and
to clearly identify its perimeter.
Despite a clearly marked construction zone, many motorists drove 10 to
15 miles over the posted 45-miles-per-hour speed limit. This created a
safety issue for both motorists and construction workers.
 Overheight/width vehicles were restricted from using the northbound
span. To avoid striking (contact with) the work-area structure,
transportation officials suggested that in-compliance truck traffic use
the center lane when it was possible.
An audible warning system was used to alert overheight vehicles. Signs
directed errant drivers to take the Jantzen Beach Exit 308.
River traffic was affected as construction crews worked overhead on the
bridge’s long span. The first phase involved 150 feet of the Oregon end
of the 550-foot span.
The contractor’s work area extended below the underside of the bridge
by 6 feet, lessening the clearance from the bridge to the river. This
clearance restriction prevented most river traffic from using the long
span to pass beneath the bridge and increased use of the lift-span.
This article courtesy of the Oregon Department of Transportation.
Reprinted from Better Roads Magazine
May 2002 |
