Updated: A Pain the Bridge

Update:

This weekend’s closure has been postponded due to the weather, and tentatively rescheduled to next weekend

For those of us who just finally got that sense of relief that two years of maintenance on the Broadway Bridge are over (or who suffered through the projects on the Hawthorne or Ross Island bridges before), here we go again. The press release for several years of work on the Burnside Bridge follows.

This raises a couple of questions in my mind:

1) Is the stretched out process of doing the work while keeping some travel lanes open really worth it? I know the County has done good community outreach on this question, but I still have to wonder…

2) The drain on Multnomah County to keep the Willamette bridges in good condition is enormous. Isn’t it time to recognize that these are really regional resources (how many folks from Washington, Clackamas and Clark countries travel them every day) and figure out a way to share the load? Maybe that would let us actually get to replace the Sellwood…

What do people think?

Two years of Burnside Bridge lift span repairs begin with weekend bridge closure

The Burnside Bridge will be closed to road traffic from 8:00 pm on Friday, January 6 until as late as 6:00 am on Monday, January 9 to allow a contractor to set up traffic control and a work zone for a two-year construction project that begins this month. Pedestrians and bicyclists can cross the bridge but may experience brief delays this weekend. TriMet bus routes 12, 19 and 20 will use the Morrison Bridge during the closure. The bridge will reopen before Monday if work is completed early.

The $9 million project will complete two technically challenging repairs to the lift span. The concrete deck of the lift span is worn from 79 years of use and will be completely rebuilt. The Burnside Bridge has one of the largest concrete decks of any bascule drawbridge in the world. At less than five inches thick the deck is also extremely thin for a concrete deck that is stressed and flexed by regular openings.

Rebuilding the deck while keeping the bridge open to road and river traffic is one reason the project will last two years. The contractor, Advanced American Diving Service, will need to keep one leaf of the lift span operable so the bridge can open for river vessels. In order to keep the bridge open to road and river traffic, the new deck will be built in four stages (two per lift span leaf). Each stage will require one month of curing time before the new concrete is hard enough to handle the stress of traffic and bridge openings.

Multnomah County and the City of Portland studied the option of closing the bridge to traffic to shorten the construction schedule. A traffic study determined that other bridges could not absorb the 45,000 vehicles that use the Burnside Bridge each day without creating an unacceptable level of gridlock across a wide area.

The project’s most difficult stage will be the replacement and repair of mechanical parts that help open the bridge. One eighty-year old hinge that attaches the 3.5 million pound counterweight to the lift span has broken and cannot turn freely. Stress from the frozen hinge is causing the eastern leaf of the bridge to open slower than the western leaf. If the hinge were to fail, the leaf would not be able to open and the counterweight could become detached from the lift span.

Replacing the hinge assembly will require the contractor to detach the counterweight without letting the lift span deck tumble into the Willamette River. A complex rigging system will be needed to support the counterweight when it is disconnected from its hinge. Because the bridge was not designed to be repaired, the repair will require the contractor to cut away sections of the concrete counterweight and bridge walls. The repair may be the first of its kind, due to the Burnside’s rare design.

The project will also update electrical wiring, replace lift span motors, install storm water collection and treatment facilities, and replace or repaint corroded steel.

While the project will create inconvenience for bridge users, it will extend the life of the historic bridge. Replacing the Burnside Bridge would cost at least $170 million today.

Federal funds are paying for approximately 70 percent of the project, while Multnomah County is contributing the rest. Construction is scheduled to be completed by the end of 2007.

During most of the project, the bridge will be reduced from five to two traffic lanes, with a single lane in each direction. TriMet bus routes 12, 19 and 20 will continue to use the bridge and both sides of the bridge will be open to pedestrians and bicyclists. The project will require several weekend bridge closures to road traffic, each lasting three to five days, for concrete deck pours.

There will be brief closures to river traffic at off-peak times. During most of the project only one bridge leaf will be operable for bridge openings. A tugboat will be provided for river vessels that need assistance passing the bridge during a single leaf opening. Both lift span leafs will be operable if needed by the Rose Festival fleet. The Rose Festival Grand Floral Parade will also be able to cross the bridge in 2006 and 2007.

OBEC Consulting Engineers of Oregon designed the repairs, with assistance from mechanical engineering consultants Hardesty & Hanover. Multnomah County maintains the Burnside Bridge and more than 300 miles of roads and bridges. For project updates call 503-988-4884.

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