Work on the Oregon Department of Transportation's project to replace the twin Interstate 5 viaducts, crossing a ravine that leads to SW Iowa Street, started in August 2010. Click here for a general project summary. Wildish Standard Paving Company of Eugene, Oregon, is the prime contractor on the project.
The Interstate 5: Iowa St. Viaduct Replacement project is located at milepost 298, just north of the Terwilliger Curves. The viaduct – technically two viaducts side-by-side – was completed in 1957, with three lanes in each direction and substandard three-foot shoulders. The new viaduct will include standard shoulder widths, a wider median and maintain three lanes in each direction.
Project Benefits
** The existing decks of the I-5 Iowa viaducts are in poor condition and the viaducts do not meet the current “life line” seismic standards. ODOT’s bridge maintenance unit had done several patching projects on the deck. These patches were failing while new cracks continued to appear. The new viaducts will meet current roadway and seismic standards.
**The replacement viaducts will maintain three travel lanes in each direction. Safety will be improved with wider shoulders, wider center medians and higher concrete barrier. The new viaducts will be wide enough to accommodate a future truck-climbing lane for southbound I-5 traffic.
**The trail passing under the viaducts will be rebuilt to City of Portland trail standards. Maintenance of the trail will be handed over to the City following project completion.
I-5 Traffic Impacts In order to accommodate traffic mobility during construction, a temporary three-lane detour structure was built to the west of the existing viaducts. During construction, motorists should expect lane closures on northbound and southbound I-5 during nighttime hours and on some weekend days. Also, the contractor may need to temporarily close lanes on Barbur Boulevard for access in and out of the western side of the project area.
Noise Impacts
Much of the project work is expected to take place during daytime hours (pile driving, for example, will only take place during the day. However, work that requires lane closures on I-5 will take place during nightime and weekend hours. ODOT has received permission (a noise variance) from the City of Portland for nighttime and weekend work during construction.
Click here for a newsletter (Spring 2012) with the latest project information, bridge demolition, traffic shifts and more.
  Wildish Standard Paving Co. of Eugene, Oregon started work on this four-year bridge replacement project in summer 2010. Following is a projected schedule of work, subject to change due to contractor activity, unforeseen delays and weather conditions:
Summer 2010 - Summer 2011
During this period the contractor excavated and constructed the west side retaining walls and built the temporary detour bridge and roadway.
Summer 2011 - Fall 2012
During this period the contractor shifted northbound traffic to the southbound bridge. I-5 southbound traffic shifted to the temporary roadway on the west side. The existing I-5 northbound bridge was demolished. Work was completed on the new northbound bridge supports. The contractor completed the east side retaining walls and finished the new I-5 northbound bridge. Once the northbound bridge barrier is finished, northbound I-5 traffic will be shifted to the new northbound bridge. Also, trees were planted on the west side in areas not impacted by construction.
Fall 2012 – Summer 2013
The contractor is expected to demolish the existing I-5 southbound bridge, construct the new I-5 southbound bridge and shift I-5 southbound traffic from the west side detour bridge to the new permanent southbound bridge.
Summer 2013 – Summer 2014
During this period work will be done to remove the detour bridge (the western most lanes), install the Oregon Basalt fascia, complete the embankment in front of the west side retaining walls, build the pedestrian trail under the bridge and complete final landscaping.
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