Upgrading the Center Street Bridge to withstand a major earthquake may cost $100 million, exceeding the $60 million budgeted by state lawmakers barely two years ago.

Retrofitting the span that carries upwards of 47,000 drivers a day from West Salem into downtown includes several steps to safeguard the bridge and ramps from earthquake damage, such as reconstructing in-water piers and strengthening columns and foundations. The project will not widen the bridge or add lanes to increase traffic capacity.

Construction for the seismic retrofitting could start as early as 2024, according to records obtained Wednesday by the Statesman Journal through a public records request.

"The Center Street Bridge wouldn't close during construction, but there may be traffic control at times," said ODOT spokeswoman Angela Beers Seydel.

In a 172-page advanced investigation report dated April 10, officials pegged the retrofit for the main bridge area at about $88 million, the west approach on-ramp from Highway 22 at about $9 million, the east approach off-ramp to southbound Front Street NE at about $2 million and the east approach off-ramp to northbound Front Street NE at about $1 million. The estimates account for an inflation rate of 3% per year.

'There are a variety of options'

House Bill 2017 allocated $60 million for the retrofit. "We're reviewing our options for reducing project costs and covering the estimated funding gaps," said Beers Seydel.

Still, she said the $100 million figure was an estimate. "There are a variety of options for what can be done — including what ramps are included, how the bridge will look when completed, how the work is staged, and other specific design elements," Beers Seydel said.

At the heart of the project is developing and maintaining a passable route, she said.

The Cascadia Subduction Zone earthquake could hit 9.0 in magnitude and trigger a tsunami, according to the Oregon Office of Emergency Management. The catastrophe could lead to as many as 25,000 fatalities, with tens of thousands of structures and buildings either damaged or destroyed.

ODOT spokesman Lou Torres told the Statesman Journal in 2017 the Marion and Center street bridges wouldn't survive an earthquake as big as the Subduction Zone earthquake. The Marion Street Bridge is too old to retrofit.

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The Marion Street Bridge was built in the 1950s, while the current version of the Center Street Bridge was constructed in the 1980s, according to ODOT. Crews have worked on the bridges over the years, including a $2.5 million repair and repaving project for the Center Street Bridge in 2017.

While the Center Street Bridge is approximately 30 years younger than the Marion Street Bridge, it was built before modern seismic bridge designs became standard during the 1990s. More than 75% of Oregon bridges had been built before then, according to Torres.

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ODOT has classified the Center Street Bridge as functionally obsolete, which can happen when a bridge's design is compared to current standards. For example, bridges can be called functionally obsolete if they have substandard bridge widths or low vertical clearance, according to ODOT.

Meanwhile, the Marion Street Bridge has been categorized as structurally deficient, which typically means an important part of the bridge — such as the deck — is considered to be in poor condition, according to ODOT. Bridges also can be categorized as such if, for instance, their load carrying capacity is far below present-day standards.

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To get the retrofit estimate, the Oregon Department of Transportation, City of Salem and Salem-Keizer Area Transportation Study agreed to split a $200,000 bill.

SKATS contributed the most at $179,460, while Salem contributed $5,135 and ODOT contributed $15,405, according to ODOT.

Salem City Manager Steve Powers disclosed the $100 million cost estimate in a recent memo to city councilors and the mayor.

Mayor Chuck Bennett said in an interview the estimate didn't surprise him, but stressed Salem doesn't have $40 million to make up the deficit. The city is facing an estimated $9.2 million budget gap of its own in the upcoming budget year.

He said the best Salem can do is hope Oregon lawmakers can make up the difference.

Bennett said: "It is a state bridge."

Bennett also said he thought the news should remind city councilors and community members of why there was more than a decade of planning to get a third bridge that's up to seismic standards across the Willamette River. In a 6-3 vote, the Salem City Council axed an approximately $425 million proposal for a third bridge in February.

Jonathan Bach has been the Statesman Journal's business and City Hall reporter since 2016. To support his work, Subscribe to the Statesman Journal. Contact him by email at jbach@statesmanjournal.com, call (503) 399-6714 or follow him on Twitter @jonathanmbach.