Frequently Asked Questions about the Sellwood Bridge Move and Detour Bridge
Table of Contents
How long will it take to move the bridge?
The contractor estimates it will take 12 to 16 hours to move the truss span. It is hard to predict the time because the move will not be continuous. The bridge will be pushed a few inches at a time and then checked, a process that will be repeated many times.
How long did it take to construct the entire detour bridge, including the land approaches?
A little more than one year.
When will the bridge be closed?
Beginning Thursday, January 17 at 5 a.m.
When will the bridge reopen?
By Thursday, January 24 at 7 a.m., weather permitting.
UPDATE: After a successful move, the detour bridge opened early - at 3:30 pm on Wednesday, January 23.
What type of weather could delay the move?
Strong winds or ice could postpone the move. Those conditions could put workers at risk.
How long will the detour bridge be in place?
The detour bridge will be in place until summer 2015, when the new Sellwood Bridge will open to traffic.
Which part of the bridge is the “truss span”?
The truss span is the continuous green steel span that is connected to five main piers across the river. It is almost 1100 feet long. The road deck and sidewalk sit above the truss. The span is one continuous structure rather than a series of connected spans, which is unusual. This design requires the contractor to move the entire span in one piece.
How will the bridge be moved?
Once the existing bridge is closed, crews will remove short spans at the east and west ends of the truss span that will not be part of the new “Shoofly” detour bridge. Hydraulic jacks will lift the truss span several inches off the old concrete piers, then horizontal jacks will push the span on rails along steel translation beams linking the old piers with the detour bridge piers. Once the span is secured on the new piers, crews will connect the Shoofly to new east and west approaches. (Read the Bridge Move article - coming soon - for a more detailed description of the move.)
How far will the bridge be moved?
The truss span will be moved 33 feet north at its east end and 66 feet north at the west end.
Why will the bridge be moved twice as far at the west than at the east end?
The new permanent bridge will be wider at its west end, where it will flare out from two to four lanes to add traffic capacity at a new signal at Hwy 43. Therefore, the detour bridge at the west end must be outside the new intersection construction area. The truss span will be moved at a skew, along a curving path, to accomplish this. The span’s west end will need to move twice as far (66 feet) as the east end (33 feet).
How heavy is the truss span that will be moved?
About 3400 tons or 6.8 million pounds.
Is this one of the longest bridges to ever be moved?
Yes, although direct comparisons with the Sellwood move are hard to find. Heavier bridges have been moved before. But the Sellwood is one of the longest, oldest structures to be moved this way.
Why is the detour bridge sometimes called a “shoofly?”
“Shoofly” is a construction term for a detour around a work zone. In this case, the detour bridge will route traffic north of where the new bridge will be built. The term comes from railroads. A shoofly is a track that bypasses a portion of the main track and is used for emergencies, or to allow a train to move off the main track to allow other trains to pass.
Why is a detour bridge needed?
To minimize negative impacts to businesses and bridge users, Multnomah County committed to keeping a bridge open at Sellwood as much as possible during construction. The original concept was to construct the new bridge in two phases, while keeping the old bridge open in the first phase. The detour bridge eliminates the need for phased construction of the new bridge. With the old bridge moved north, the contractor can build the new span in one phase. This will save up to one year of time, reduces costs by $5 to $10 million, improves safety by separating traffic from construction, and reduces environmental impacts. By eliminating structural parts that would be only needed for phased-construction, the new bridge will also have a sleeker look.
How do we know the detour bridge will be safe?
After its move, the detour bridge will be extensively inspected by independent and county engineers and the contractor. The bridge will not open to the public until a long list of items has been inspected. The detour bridge will not include the old west approach, which was the most damaged section of the old bridge, due to a landslide. The landslide that damaged the west end of the old bridge is being held in place by a new underground system of anchors and beams that tie into bedrock. The detour bridge was also built to modern construction codes, unlike the 1925 bridge. For these reasons, engineers believe the detour bridge is actually stronger than the old bridge.
What is the vehicle weight limit on the detour bridge?
10 tons, gross vehicle weight (loaded). This is the same weight limit as the old bridge.
What are some major risks involved in moving the bridge?
The truss span will be raised vertically several inches and then pushed north 33 to 66 feet by hydraulic jacks. The contractor will use several methods to ensure that the truss span is not bent or twisted during the move. One challenge is that the entire truss span must be moved in one piece, and the west end will move twice as fast as the east end. Dropping the bridge is less of a risk than bending it, since it will be fully supported by heavy duty translation beams during its journey.
What measures will be taken to ensure the bridge is not damaged during the move?
Lasers and Global Position System (GPS) monitoring will be used to determine if the span is in the correct position during the move. Strain gauges attached to the steel truss will monitor the structure for stress. The span will be moved a few inches then measured to confirm its position, a process that will be repeated many times during the move.
What will it be like to watch the bridge move?
The bridge will be moved very slowly to ensure it is not damaged during the move. The contractor will move it a few inches, then take measurements to ensure it is properly positioned before moving it a few more inches. The movement will be too slow for the human eye to detect in real time from a distance.
Where’s the best place to view the move?
On the Internet. It won't be possible to see the bridge "move" in real time, because it will move so slowly over a period of several hours. Multnomah County encourages you to view the bridge throughout the move on the project’s web camera or watch a time-lapse video of the bridge that will be posted to the website the day after the move. Twitter users can receive real time updates on the day of the bridge move by following @sellwoodbridge.
Are there places near the bridge to watch in person?
The Sellwood-Moreland Business Alliance will host a viewing event Saturday from 11 a.m. to 3 p.m. at Oaks Pioneer Church at 455 SE Spokane Street and SE Grand Avenue. Refreshments will be served.
Sellwood Riverfront Park on the northeast side of the bridge (SE Spokane Street and SE Oaks Park Way) is a public space where the bridge move can be viewed, although no sponsored viewing events will be held. The park has very limited space for public parking, the parking lot is likely to fill up, and visitors may need to park several blocks away and walk to the park.
- Street Closure: SE Spokane Street will be closed west of SE Oaks Park Way the day of the bridge move, except to local traffic. No parking is permitted on SE Oaks Park Way and No Parking signs are posted.
- Parking: The owner of the adjoining office building parking lot south of the park and the manager of Oaks Park Amusement Park north of the park have notified Multnomah County that park visitors can park in their parking lots on Saturday, January 19th. Signs will be posted to direct visitors to the overflow parking sites.
- Trails: The Springwater Corridor Trail and the Westside Regional Trail will remain open at all times during the bridge move.
Can I watch from a boat on the river?
For safety, the river under the bridge will be closed to boats the day of the bridge move. Unauthorized boats will need to remain 500 feet from the bridge operation. The Sheriff’s River Patrol will enforce the river closure.
Will the bridge be closed to all traffic, including bicyclists and pedestrians?
Yes, because the truss span will not be connected to the bridge approaches during the move.
Will Highway 43 on the west side of the bridge remain open during the bridge closure?
Yes. Brief lane closures near the bridge will be needed at times to move crews and equipment. Flaggers will direct traffic, so use caution when traveling in this area. The speed limit on Highway 43 near the bridge has been reduced to 25 miles per hour until the project is completed in 2016.
What are the detour routes while the bridge is closed?
The posted westbound detour routes during the closure are:
- Northbound: Hwy. 99E to Ross Island Bridge to Hwy. 43
- Southbound: Hwy. 99E to Interstate 205 (Abernethy Bridge) to Hwy. 43
Eastbound routes are the reverse. Bridge users have multiple destinations, so the best alternate route may vary. Advance warning signs will be posted on the detour and other key routes to the bridge. Congestion is expected on the north side detour route during weekday commute hours. Travelers should plan their alternate route in advance and expect longer trips during the closure, especially on weekdays.
How will the new Sellwood Bridge intersection at Hwy 43 work after the detour bridge opens?
For 2013, the intersection will function much like the old one has. In later years of construction, traffic patterns in the intersection will change as the contractor builds a new split-level interchange and a half-mile section of Highway 43.
What is the vehicle speed limit on the detour bridge?
25 miles per hour. The speed limit on the old bridge was 30 miles per hour. The bridge speed limit was reduced because of the curve at the east end of the detour bridge and the nearby construction zone.
What about access to the bridge or trail system for bikes and pedestrians?
The Sellwood Bridge will be closed to all vehicles, including bikes and pedestrians, January 17 to 24. Popular trails on both sides of the river (Springwater on the east, Willamette Greenway on the west) will remain open. The Hawthorne Bridge to the north is one of the closest river crossings with good connections to both trails. The Hawthorne is about 3.5 miles north of the Sellwood Bridge.
What facilities will the detour bridge have for bicyclists and pedestrians?
Like the old Sellwood Bridge, the approach spans of the detour bridge will have a raised sidewalk that is about four feet wide. On the west approach the sidewalk will be separated from traffic by a crash barrier. Most of the old east approach will remain in use on the detour bridge. The narrow sidewalk on the 1100-foot long truss span remains.
Can boats travel under the detour bridge?
River traffic will be able to pass the bridge before and after the bridge move, which should be completed in one day. For safety, the river under the bridge will be closed to boats the day of the bridge move.