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With two Burnside Bridge construction efforts set to kick off in 2017, much scrutiny is headed for the 90-year-old span. Planners have identified it as a 鈥渓ifeline鈥� 鈥� a vital access route to hold the community together after a large-scale seismic disaster.

But right now, the bridge itself is kind of a seismic disaster.

鈥淚t has an array of big issues that would probably manifest themselves in a big earthquake,鈥� said Ian Cannon, transportation director for Multnomah County. 鈥淭he approaches have issues. The foundations have issues. The river piers are a concern. The structure that supports the lift span is a concern. It also has large counterweights underneath the deck that are going to want to swing around in an earthquake.鈥�

For these reasons the county’s transportation department is focusing its resources and attention on the Burnside Bridge. The goal for a two-year project is to help make the Burnside street and bridge a resilient corridor. The end result might be drastically different 鈥� a new Burnside Bridge might even be built.

Preservation of a vital connector

Maintaining the six Willamette River crossings managed by Multnomah County is a constant process, Cannon said. Drains must be cleared, and lightbulbs replaced without delay. The decks are swept often, and the steel itself must be kept clear of debris so it doesn’t collect and accelerate corrosion.

鈥淭hey’re all complicated structures, particularly the older ones,鈥� Cannon said. 鈥淎nd four of them are movable, which adds another layer of complexity to all of that.鈥�

Those daily costs are about to be compounded with a major capital effort on the Burnside.

About two years ago the county reworked its 20-year bridge capital improvement plan to provide a road map for preservation. One major change since the previous plan was formed, in the 1980s, is the acceptance of seismic realities facing the city. There’s now a common understanding that Portland may well see a devastating earthquake in our lifetimes.

According to the Oregon Department of Geology and Mineral Industries, the likelihood of a magnitude 8 earthquake occurring here in the next 50 years is one in three. Thousands of people in the Portland area may die, and the reason, according to the Oregon Resilience Plan, is that emergency routes will become blocked or unusable.

The cost to upgrade all Multnomah County-managed bridges‘ seismic strength to ideal levels would total more than $2 billion. But in the 1990s, Metro designated Burnside Street a 鈥渞egional lifeline route,鈥� due to its 19-mile length and relatively low number of overhead hazards; also, the Burnside Bridge’s machinery is simpler and better protected than other county bridges’ machinery.

Because the Burnside Bridge is a designated lifeline, the county is focusing on it first. Officials want to ensure it can withstand a major Cascadia subduction zone earthquake and remain operable afterward.

Multiple options 鈥� including full bridge replacement 鈥� are on the table, according to Cannon.

鈥淐ertainly, we’re keeping an open mind as to what the right answer is, and that will include looking at replacement options,鈥� he said.

For now, the plan is to take care of the Burnside Bridge, and perform minor seismic improvements on the other bridges. But among the six, the Burnside requires the most repairs, according to the capital plan. Some of its immediate needs are concrete replacement, electrical system upgrades and work to address rusting steel framework.

The Burnside has already gained a few seismic fixes, but the larger, $18 million to $20 million repair project will begin next month and is scheduled to last through fall 2019. Those repairs are expected to make the bridge safe through 2035 鈥� absent an earthquake. But perhaps the most important aspect of the repair project will be providing analysis for a .

Three elements will be addressed 鈥� the road surface, the bridge structure and mechanical systems. The drawbridge span locks and motor will be replaced, and the power supply and drawbridge controls will be upgraded. A number of structural issues will be also addressed, including aged concrete columns that hold up the bridge and cracks in the piers.

Improvements beyond Portland

A major bridge project takes time. Replacing the 90-year-old Sellwood Bridge has taken Multnomah County more than a decade (the new bridge opened to traffic in February, though minor work is ongoing). That’s why a push is being made now to secure money for the rehabilitation and maintenance of the county’s bridges 鈥� especially the Burnside.

Financing infrastructure projects with less federal money and more state and local money is becoming a trend, said Charles Riley, professor of civil engineering at Oregon Institute of Technology. Another for such projects is making structures more resistant, because it’s understood that events like a Cascadia quake cannot be avoided.

Riley said anxiety around earthquakes in the Pacific Northwest could lead to a revival in civil engineering.

鈥淐ascadia might usher in a new dot-com era of bridge building,鈥� he said during a panel discussion after a local screening of 鈥淏ridging Urban America鈥� 鈥� a documentary profiling the life and works of Ralph Modjeski, a Polish immigrant civil engineer whose catalog of immense industrial-era projects includes Portland’s Broadway Bridge.

Oregon of course has many more bridges than those in Portland. There are 2,700 in the maintained by the Oregon Department of Transportation. Only about a third were built during the 鈥淚nterstate era,鈥� aka the 1950s, and are sturdy enough that they’re expected to fare reasonably well in a Cascadia quake. But risks are much greater for older bridges.

鈥淢ost of our bridges were designed prior to the modern seismic standards, before we really even knew about the Cascadia fault line,鈥� said Bert Hartman, managing engineer for . 鈥淪o most of our older bridges probably wouldn’t fare that well.鈥�

Due to technological advancement, it’s unlikely that Portland’s century-old spans would be constructed the same way if they had to be rebuilt today.

鈥淚t used to be that there were separate cities on both sides of the river, and the bridges have enabled it to become one city,鈥� Cannon said.

Rolling through Broadway Bridge repairs

Century-old workings within the Broadway Bridge will be addressed in an upcoming project.

Massive steel wheels eight feet in diameter and tracks they run on to raise and lower the bridge will be replaced.

The was designed by pioneering civil engineer Thomas Rall and is a major element in the 103-year-old bridge’s historic character. Essentially, the mechanism allows for a wider channel opening without a long bridge span.

Designs for the project are nearly complete, according to Ian Cannon, transportation director for Multnomah County. The goal will be to complete it with minimal impacts to traffic. The bridge is used by 30,000 drivers and 2,000 bicyclists per day.

鈥淗ow do you replace the wheels and keep the traffic flowing and the streetcar going?鈥� Cannon said. 鈥淲ell, we’re going to be doing that.鈥�