The closure next year of the northbound span of the I-5 Interstate Bridge will last for nine days in September 2020, Oregon Department of Transportation (ODOT) announced in a public mailing this week.
The closure is expected to create significant traffic snarls and delays. ODOT is also ramping up its public information campaign advising the public of the project and to plan ahead for the expected congestion and travel impacts.
The 102-year-old northbound span will close while crews replace a cracked trunnion and other mechanical parts in the south tower on the northbound span. The trunnion is the axle at the top of each tower that supports the weight of the bridge and counterweights to help raise and lower the lift span. A similar trunnion repair was carried out in 1997 on the north tower of the southbound span.
Because the work takes place overhead, the northbound bridge must close to keep drivers safe and to provide access for construction crews and heavy equipment.
The project cost is estimated at $13 million. The trunnion crack was first discovered in 1999 during a regular bridge inspection and has been monitored frequently since then.
I-5 Closure Details
During the closure, the southbound span will remain open to traffic in both directions. Northbound and southbound travelers will share the three lanes and the sidewalk on the southbound bridge. Movable concrete barriers will provide two lanes of traffic in the busiest direction. During the morning commute, two southbound lanes and one northbound lane will open for traffic. At midday, crews will move the concrete barriers to provide two northbound lanes and one southbound lane for the evening commute.
In addition, four ramps in the project area will close for traffic control and to ensure a safe work zone. They are:
- Marine Drive on-ramp to I-5 north in Portland.
- Hayden Island on-ramp to I-5 north in Portland.
- I-5 north to SR 14 off-ramp in Vancouver.
- SR 14/Washington Street on-ramp to I-5 south in Vancouver.
The closure reduces the capacity of the bridge by half. Heavy congestion and long delays are expected during the nine-day closure along with heavy traffic on the Glenn Jackson Bridge on Interstate 205 and on local streets in North Portland and Vancouver. Travelers should plan ahead for alternatives that could include, when possible, delaying or changing trips, working from home, carpools or mass transit.
The Interstate Bridge is jointly owned and by Oregon and Washington and maintained and operated by ODOT. The northbound span opened in 1917, the southbound span in 1958.
In 2018, the Interstate Bridge saw an average of 135,700 vehicles each weekday.
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