The east ramps of the Morrison Bridge, which connect downtown Portland with the inner east side, Interstate 5 and Interstate 84, are getting a new concrete overlay in 2001. While the new surface will provide a smooth ride for the next 25 years, the project will require bridge users to make detours during construction, which began Monday, February 19 and ends in October 2001.
Every lane of the ramps from SE Grand Avenue to the east end of the bridge lift span will be ground and overlaid with a one and a half-inch layer of microsilica concrete. This dense material takes three weeks to cure but has a service life two to three times longer than asphalt. The ramp surface is worn and rutted and metal rebar has been exposed in areas. The project will cost roughly $3.1 million, including federal and local funds.
Construction is taking place in six stages that will last up to eight weeks each. During most of the project, one lane will be closed in each direction. Two lanes will remain open in both directions during commute hours. However, the work will require up to eight-week closures of ramps leading to and from I-5 and I-84, and to Water Avenue and Martin Luther King, Jr. Blvd. The contractor, Wildish Standard Paving of Eugene, has completed two stages before the Rose Festival and will begin stages 3 and 4 on June 19th.
Work began on Monday, February 19 when crews closed a section of the right westbound lane on the Morrison ramp to replace a section of deck that was deteriorated. The existing concrete deck was removed, exposing the supporting steel stringers. New reinforced concrete was placed for the deck, sidewalk and handrail wall. Once the deck work was completed, work began to remove damaged concrete around the expansion joints. New concrete was placed and the joints sealed with watertight material. The on-ramp to I-5 north and the off-ramp from I-5 to city center were kept open until crews closed the right lane for overlay work in early April.
The deck overlay work begins when workers place lane markers, concrete barriers and temporary traffic signs on the ramps to separate the work zone from the traffic lanes. Crews test and adjust the machinery to be used to prepare the concrete decks for the new microsilica overlay. Shotblasting machines, using tiny ball bearings, remove a thin layer of the existing concrete to provide a rough surface for the new microsilica to bond. After the prep work is complete, the microsilica concrete overlay is placed using large paving machines which distribute the concrete evenly across the bridge deck, compact it and seal the surface. Burlap and plastic sheets are used to cover the fresh concrete to keep it moist during the curing period.
The county will use posted and variable message signs and work with the news media to keep travelers informed of construction progress and changes to traffic patterns. Motorists, buses, and pedestrians will be able to cross the bridge in both directions at all times. Currently, bicycles are not permitted on the bridge. The sidewalks on the south side of the bridge and on the Water Avenue ramp will be closed to pedestrians while the Belmont eastbound lanes are being repaired.
Multnomah County owns and maintains more than 300 miles of roads and bridges, including the Morrison Bridge.
For the most current information on traffic changes for this project, check the Transportation Division's news release page for the Willamette River Bridges. For information on other projects in the Portland area, check out Keep Portland Moving.