Interstate Bridge closure: Plan for life without the span

Here’s everything you need to know about what’s on the way:

What are the exact closure times?

The northbound span will close to all traffic for a period that officially runs from 12:01 a.m. Sept. 12 until 11:59 p.m., Sept. 20, according to ODOT spokesman Don Hamilton.

“That’s one Monday-to-Friday work week with two weekends on either side of it,” ODOT spokeswoman Erica Sweeney said during a recent webinar. That gives the contractor crews nine days to get the job done, with all the weekday disruptions falling within a single calendar week.

It will take several hours to transition the northbound traffic over to the southbound bridge once work starts on the morning of Sept. 12. The transition is expected to be completed by the afternoon, according to a press release from ODOT.

What will the crews be doing?

They’ll be replacing several key parts of the northbound bridge’s lift system, including the trunnions and sheaves at the top of its southern tower, along with the cables and some peripheral components.

The bridge uses the same lift design on both spans. Steel cables run from the corners of the lift span to the top of the towers, where they pass over the sheaves – pairs of 12-foot-diameter wheels that function like pulleys – and then down to the 760-ton counterweights inside each tower.

The sheaves are mounted on 20-inch-diameter axles called trunnions. During bridge lifts, a motor rotates the sheaves to feed the cables through toward the counterweights, causing them to descend and pull the lift span upward, and then reverses to lower the bridge back into place.

Crews have spent the past several weeks building temporary falsework that will support the counterweights and lift span, allowing them to be disconnected so that the sheaves, trunnions and cables can all be swapped out.

Why do the components need to be replaced?

One of the trunnions on the south tower has developed a crack, and the crack is spreading. A small crack isn’t enough to compromise the system, according to Hamilton, but routine inspections have revealed that the crack has begun to spread more quickly in the past few years.

Four nearby freeway ramps will be closed during the project: the ramp from state Highway 14 and downtown Vancouver to southbound I-5, the ramp from northbound I-5 to Highway 14, the ramp from Hayden Island to northbound I-5 and the ramp from Marine Drive in Portland to northbound I-5.

Drivers trying to get onto southbound I-5 from Vancouver will need to use the Mill Plain interchange. ODOT recommends that drivers on Highway 14 detour onto I-5 north and then use the Fourth Plain interchange to reach I-5 south.

On the Oregon side, drivers trying to get onto northbound I-5 from Marine Drive or Hayden Island will need to get on southbound I-5 and double back to exit 306 onto Victory Boulevard, where they’ll be able to cross under the freeway and use the onramp to get to northbound I-5.

All bike and pedestrian traffic will need to use the sidewalk on the southbound span. Northbound travelers should exit at Hayden Island and follow the path by North Hayden Island Drive to cross under the freeway and reach the south sidewalk.

How bad is the congestion going to get?

If traffic volumes were at normal levels and nobody changed their behavior, Sweeney said during the webinar, ODOT would expect to see four miles of backups — double the usual length — and 16 hours of congestion per day.

The backups would cause a chain reaction on nearby roads and other area freeways. The Interstate 205 Bridge is already at capacity, according to ODOT, and won’t be able to absorb the excess traffic if everyone simply detours.

Normal traffic for the I-5 Bridge is about 125,000 to 149,000 crossings per day — that was the weekday range for 2020 until the COVID-19 pandemic hit, according to ODOT data.

Daily I-5 crossings bottomed out at about 80,000 in late March, but the number has risen steadily since then. As of mid-August, WSDOT spokeswoman Tamara Greenwell said traffic on I-5 in Vancouver was only about 8 to 17 percent below normal.

In other words: the pandemic won’t save us. The amount of congestion is going to depend heavily on how many commuters decide to be proactive.

How do I survive?

The best advice to beat the traffic is to not fight it in the first place.

ODOT and WSDOT recommend that commuters and their employers find ways to work from home and avoid crossing the river at all during the closure.

If that’s not possible, commuters should adjust their schedules to avoid the usual rush hour periods, such as by coming in at midday and returning later in the evening.

Could the crews finish the job early?

It’s possible, but don’t count on it.

The contract includes incentives if the crews are able to wrap up and reopen the bridge ahead of schedule, Hamilton said, but nine days is ODOT’s best estimate of the time needed to complete the required work.

The 1997 project wrapped up after six days, which was well ahead of schedule. According to reports in The Columbian, ODOT had estimated that the work would take 10 days and had allowed up to three weeks for what was at the time a first-of-its-kind repair project for the bridge.

The crews did encounter some difficulties in 1997, including windy weather and corroded steel pins, according to The Columbian’s daily coverage at the time. Some unexpected issues are inevitable on projects of this scale, Hamilton said, and the current project timeline was designed to account for those delays.

Will there be any further closures?

Partial closures, yes. Immediately after the full closure ends, ODOT will need to close the eastern lane of the southbound span for seven days, from Sept. 21 to 27, as a safety precaution while crews finish up the project and take down equipment.

There were periodic nighttime lane closures on the bridge throughout August as crews prepared for the project. Some of those small-scale disruptions may continue into October, according to ODOT.

Washington and Oregon are talking about a potential replacement bridge. Couldn’t we just wait for that project?

In a way, ODOT tried that approach already.

About 10 years ago, the previous attempt at a replacement bridge — the Columbia River Crossing — was in full swing. If the project had moved forward on its envisioned timeline, at this point we’d probably be talking about where to sell the old bridge for scrap rather than how to replace its trunnion.

But it didn’t work out. Washington’s Legislature didn’t supply the state’s share of the funding in 2013, and the whole project collapsed before any shovels could hit the dirt.

The current round of renewed talks have been promising so far, but ODOT isn’t taking anything for granted. And even if this attempt does get off the ground, a new bridge wouldn’t open for the better part of a decade — and the old bridge’s trunnion crack is still spreading.

“Right now, there’s a study underway of the bridge, but there’s no funding, no design,” Hamilton said. “It’s important to take care of this. We’re not going to make presumptions about what may or may not happen.”

The trunnion replacement probably won’t be the last big project, either. The northbound span is going to need a resurfaced deck sometime in the next decade, Hamilton said, and the southbound span will need repainting. The northbound span was repainted in 2000, but its younger sibling is still wearing its original 62-year-old coat.

How much does this all cost?

The price tag is about $13 million, split evenly between Oregon and Washington. The two states co-own the bridge and share its costs, although ODOT alone manages the bridge’s operations, including this project. ODOT’s half of the funding came out of its regular budget, Hamilton said; this project has been in the works for years, so the money was allocated long ago.

In terms of bigger maintenance projects, $13 million is at the lower end of the cost scale. Hamilton said early estimates suggest that the deck replacement could run about $33 million and a new coat of paint could be about $75 million.

For comparison, it costs about $1 million per year to operate the bridge with its 10-person crew, and about $1.2 million for routine subcontracted repairs, Hamilton said.

Why now? Why couldn’t this all have been done back in April, when everyone was working from home anyway?

From a commuter standpoint, it certainly would’ve been nice to get the project out of the way during the early weeks of the pandemic when traffic was at a low point. But there’s a pretty straightforward reason why that wouldn’t have worked: The new trunnion and sheaves weren’t ready.

The replacement parts had to be custom-fabricated by a company in Alabama, and the process was timed to coincide with the September closure schedule. The new parts only arrived last month after being trucked to Portland and then delivered to the bridge via barge.

But even if the parts had been on hand in the spring, Hamilton said, ODOT still would have stuck with the September closure dates because of the impact on river traffic. The central raised “hump” of the I-5 Bridge only offers about 72 feet of clearance. For any vessels taller than that, taking the lift system offline will turn the bridge into an impassable barrier.

That’s part of why this closure and the 1997 one were both scheduled for September, when the Columbia River is at its natural seasonal low point, creating more clearance for vessels to slip through under the hump. But the Columbia River’s regular marine traffic includes some vessels that are simply too tall to fit without the lift span, at any time of year.

ODOT has spent two years conducting outreach about the project and coordinating with the owners of those vessels to give them time to plan around the closure, Hamilton said — and it’s all been done with an ironclad set of dates on the calendar. Moving the project to the spring would have undermined all that planning and left river shipping companies in the lurch.