Saturday, October 24, 2020
Oct. 24, 2020

Linkedin Pinterest

Interstate Bridge closure: Plan for life without the span

9-day closure of I-5 Bridge northbound side is 6 days away; being prepared will help ease expected traffic backups

By , Columbian business reporter
4 Photos
The Interstate Bridge is seen looking north from the Oregon side in 2017.
The Interstate Bridge is seen looking north from the Oregon side in 2017. Photo Gallery

If anyone out there doesn’t yet know about the upcoming nine-day closure of the northbound Interstate 5 Bridge, consider this your official warning.

In six days, the northbound span of the twin drawbridges will close to all traffic while crews undertake a $13 million maintenance project to replace parts of its century-old lift system. All freeway traffic will use the southbound span from Sept. 12 to 20.

Halving the capacity of one of the Portland region’s only two Columbia River crossing points has the potential to create some spectacularly unpleasant traffic congestion.

The Oregon Department of Transportation, which manages the bridge, and the Washington State Department of Transportation have spent months urging commuters to plan ahead to save themselves from spending hours stuck in traffic. And if enough drivers take the advice to heart, a trafficocalypse might be averted altogether.

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.

The other components are being replaced as a precaution due to their advanced age. The two I-5 Bridge spans may look identical, but the northbound sibling is the older one by several decades — it opened in 1917 and was the Portland region’s sole crossing until the southbound span was added in 1958.

“These are parts that go back to the opening of the bridge,” Hamilton said.

The northbound bridge closed for a similar operation in 1997 after a trunnion crack was found on the span’s northern tower, but the project didn’t replace the south tower components because, in a case of unfortunate timing, the south tower crack wasn’t discovered until two years later.

How will traffic patterns change?


Both directions of I-5 will share the three-lane southbound span, with the middle lane taking southbound traffic in the mornings and northbound traffic in the evenings to match the direction of rush hour traffic. A temporary jersey barrier will be installed between the northbound and southbound lanes.

Twice per day — once starting at 2 a.m. and again at noon — a “zipper” machine will drive across the bridge and move the barrier from one side of the central lane to the other.

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.

By the numbers

40 mph: Speed limit on the bridge during the work.

6.5 miles: The length of the pulley cables in both spans that need oiling and greasing each year.

12 feet: The diameter of the sheaves, the big wheels in the pulley system that wind up the cable during a bridge lift. Crews will install two new sheaves to the south tower.

20 inches: The diameter of the trunnion.

103 years: Age of the northbound span.

760 tons: The weight of counterweights at the top of the bridge used to balance the weight of the road deck during lifts.

2,425 miles: The distance replacement parts traveled from fabrication at G&G Steel in Russellville, Ala., to the Interstate 5 Bridge.

Source: Oregon Department of Transportation

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.

There are also alternatives to driving. C-Tran’s commuter bus lines will continue their usual service during the closure, and the agency has been working with WSDOT for the past two months to create a hybrid bus-on-shoulder lane on the final 5 miles of southbound I-5 leading up to the bridge, which will allow buses to skip past most of the jam-ups if freeway traffic drops below 35 mph.

Buses will also be allowed to use the shoulders on the I-205 Bridge to skip past congestion. Amtrak service between the Vancouver and Portland stations will continue.

Clark County residents did a pretty good job last time. A headline in The Columbian after the first day of work in 1997 proclaimed “C ommuters sail through bridge work,” and the story reported that traffic volumes had dropped to possibly as low as a quarter of their usual levels.

That said, Clark County has grown since 1997. When the bridge last closed, there were about 50,000 daily Vancouver-to-Portland commuters, based on the number of Clark County residents who paid Oregon income taxes. Today, that number stands at about 72,000, Hamilton said.

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.

Trunnion replacement

Read more about the Interstate 5 trunnion replacement project at

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.