CogKnoSys

Knowledge you can walk. Read the idea below, then step up to the general, across to peers or down to the specific.

Physical

Glenn L. Jackson Memorial Bridge

The Glenn L. Jackson Memorial Bridge carries Interstate 205 across the Columbia River between Portland, Oregon, and Vancouver, Washington.

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The idea

The Glenn L. Jackson Memorial Bridge, also called the I-205 Bridge, crosses the Columbia River between Portland, Oregon, and Vancouver, Washington. It carries Interstate 205, a freeway that lets traffic bypass Portland. It is one of only two public bridges linking the two cities, along with the Interstate Bridge.

It is a segmental bridge, built one piece at a time to avoid disrupting river traffic. Workers cast each concrete segment downstream, and barges floated the heavy pieces into place so ships could keep using the river. The bridge is actually a pair of side-by-side structures with four lanes in each direction and a path for bicycles and walkers in the middle. It crosses Government Island on the way, but there is no access to the island from the bridge.

The bridge is named for Glenn Jackson, who led the Oregon State Highway Commission. The Oregon Department of Transportation maintains it. In 2019, an average of 166,152 vehicles crossed it each weekday.

Check yourself

Question 1 of 2

Why was the bridge built one segment at a time?

Pick one. The first pick counts.

Composition

what it's made of

  • Twin spans — Two side-by-side structures, each with four lanes of traffic.
  • Concrete segments — Pieces weighing upwards of 200 tons, cast downstream and floated into place by barge.
  • Bicycle and pedestrian path — A path about 9 feet wide running between the two traffic decks.
  • Main span — The longest opening, near the Washington side, 600 feet long with 144 feet of clearance at low water.

Connection

how it relates

Under Lower Columbia Bridges and Transportation

In place

  1. Columbia Riverstrength 90 of 100

    The bridge spans the Columbia River.

  2. Portland, Oregonstrength 80 of 100

    The bridge links Portland to Vancouver and carries a freeway that bypasses Portland.

  3. Vancouver, Washingtonstrength 80 of 100

    The bridge's northern end is in Vancouver, Washington.

Change

how and why it evolves

Past
Planning began in earnest in 1964, construction started in August 1977, and the bridge opened on December 15, 1982. It cost $169.6 million, and three men died during its construction.
Now
In 2020, the two state transportation departments began a pilot that let C-Tran buses use the bridge's shoulders to get around traffic jams.
Next
Traffic on the bridge is expected to rise significantly once tolls begin on the Interstate Bridge under the Interstate Bridge Replacement Program.

Knowledge you can walk. Read the idea, then step up, across or down.

Glenn L. Jackson Memorial Bridge

The Glenn L. Jackson Memorial Bridge carries Interstate 205 across the Columbia River between Portland, Oregon, and Vancouver, Washington.

See it on the map

Learn, discuss, create, buy or invest

The idea

The Glenn L. Jackson Memorial Bridge, also called the I-205 Bridge, crosses the Columbia River between Portland, Oregon, and Vancouver, Washington. It carries Interstate 205, a freeway that lets traffic bypass Portland. It is one of only two public bridges linking the two cities, along with the Interstate Bridge.

It is a segmental bridge, built one piece at a time to avoid disrupting river traffic. Workers cast each concrete segment downstream, and barges floated the heavy pieces into place so ships could keep using the river. The bridge is actually a pair of side-by-side structures with four lanes in each direction and a path for bicycles and walkers in the middle. It crosses Government Island on the way, but there is no access to the island from the bridge.

The bridge is named for Glenn Jackson, who led the Oregon State Highway Commission. The Oregon Department of Transportation maintains it. In 2019, an average of 166,152 vehicles crossed it each weekday.

Check yourself

2 quick questions, instant feedback.