PATCHWORK: Fixing the Burnside Bridge's crumbling underbelly
Two lanes closed on the 91-year-old Burnside Bridge this January, as they will be for the next two years.
Construction on the bridge has been underway since Spring 2017, for the $19 million Burnside Bridge Maintenance Project, which includes structural, mechanical, electrical and surface repairs designed to extend the life of the bridge for 15 to 20 years.
Although Multnomah County maintains the Burnside Bridge — and five others that cross the Willamette River — Hamilton Construction is doing the work as part of the county's plan for the regional lifeline route.
However, the 2017-2019 repairs are for maintenance, and will not improve the bridge's performance in an earthquake.
Because of a separate upcoming seismic strengthening project, debates surrounding whether or not the Burnside Bridge will be repaired or replaced will occur in the next two to three years: the bridge is a major east-west emergency thoroughfare and in case of a quake, it's vital to have this bridge standing (see sidebar).
When the project started in spring 2017, most of the work took place underneath it — where they had to install black nets over the Saturday Market to catch crumbling concrete that was falling down on parking lots. Now that the Saturday Market is closed, the County and Hamilton can get to fixing the bridge's concrete underbelly above the waterfront park and Naito Parkway.
"I think for the community perspective, it was really appreciated that we didn't work up on top of the bridge until after New Year's," Mike Pullen, communications coordinator with Multnomah County, told the Business Tribune. "We had the contractor focus on areas underneath the bridge that didn't require lane closures of traffic impacts."
The Business Tribune spoke with Will Muller, engineering tech three with Multnomah County, one of the lead inspectors for the bridge department, along with Megan Neill engineering services manager at Multnomah County and Emily Miletich, an engineer two with Multnomah County.
"The contractor will sound the area (with a hammer) for anything loose," Muller told the Tribune on site. "If we do a thorough sounding, we assess for anything in imminent danger of breaking loose. We remove it, then patch it. Ones damaged are in need of replacement and repair to keep water from getting in there and expanding cracks."
After sand blasting and excavating anything that needs to be repaired, they'll seal the deck with microsilica high-performance concrete to keep water from dripping below, where the electrical maintenance access to the counterweights is.
"In the huge chunk of concrete, lots of smaller cracks are coming down," Pullen said. "The problem is when businesses tell you your bridge is dropping concrete bits on their car in employee parking lots."
"There's a 13-foot long crack that faces the Willamette River that we intend to repair during this project," Miletich said. "The contractor will probably bandage the pier with additional concrete, and connect it with an anchor. There are a variety of ways the contractor can go about doing that."
Miletich told the Tribune the work on the south side of the bridge installing traffic control plans went really well. On site they have electricians, general laborers, carpenters, painters, ironworkers and concrete workers.
"Going forward, they started to work in the Saturday Market area underneath the bridge, a continuation of the same kind of work we've been doing the last two months: concrete repairs, repairing shallow rebar, doing crack injection, that kind of work," Miletich said. "Above deck, they are probably starting (this) week on doing some baluster repair — the bridge railing will be the first thing on their docket."
Hamilton and subcontractors will paint the trusses and rehabilitate the operator houses as well — there's original lead paint in both — and repair the concrete on the sidewalk and deck.
The potholes in some of the concrete are flaking so badly from numerous patch jobs that when a boot steps down near one, water puddles up — and everyone knows what happens when water gets in concrete cracks over the freezing winter.
Eight years ago, the deck was resurfaced with concrete (not asphalt). Burnside also had a partial minor seismic upgrade about 12 years ago.
"This contractor (Hamilton) is patching areas from that project that have opened up with all the hard winter weather we had," said Pullen. "Sidewalks and railings have not been (completely) done in decades."
According to Miletich, there are two main crews of five to 10 people, but the subs will likely add to the headcount.
"The contractor (Hamilton) anticipates a pretty sizeable increase in crew size to cover all the work in the allotted time," Miletich said.
The project is open shop, so anybody, union or not, can work on it.
Obstacles and crushed bearings
One of the challenges of this project is to fit in $19 million worth of work into three years: to fit in with the schedule of the Saturday Market, the work is being done from January to March in that area, while the market is closed. It also allowed flexibility while the Morrison and Broadway bridges limited traffic for their construction.
"This project, the theme is such a long timeline that we're really able to avoid impacting closures for the most part," Pullen said. "We have the luxury on this project: it's not an emergency repair so it has this longer schedule."
As for the bearings in the bascule bridge, the existing ones were concrete, but the new replacements are steel.
"We ended up having to replace some bearings that we didn't initially anticipate," Miletich said. "We had to jack up the bridge a little bit, and when we did that they crumbled out of there. They were old, deteriorating, and when we got there up close we could see they were really damaged. As soon as we lifted up the bridge to remove them, they basically crumbled."
They had last been touched on a project during the 1990s.
"Some work was done in that area of the bridge, and for whatever reason, the people doing the work removed a critical piece of the structural concrete, increasing the load on these concrete bearings," Neill said. "That really should not have been done, and fast forward to 2018 when those bearing were enshrouded by a metal mesh that prevents pigeons from roosting, when we removed the metal mesh that's when we realized there was a problem and some of these bearings were crushed."
Piecing together a new job over patchwork on a 91-year-old bridge, they came across some work that should not have been done, but corrected the damage.
"Working on a 100-year-old structure, there isn't always a record of the work," Miletich said. "It just so happens these crushed bearings coincided with when a couple folks recently retired were hired with the county and we're able to talk to people who work here about what happened 25 years ago — which is a lot of times not the best route to getting information you need — it's like being a detective and you have to track down multiple leads in order to figure out what happened."
Replacing the bearings was one of the successes of this project so far.
"We did a really great job mitigating that issue and responding quickly," Miletich said. "The contractor did a great job replacing those."
There's another funky spot beneath the bridge out by the seawall, where there's a sanitary needle drop-off box. It was installed because people were throwing trash out to the river, but directly below there's a standing pool inside concrete supports that doesn't wash out, and was collecting debris.
"The crack on the river side is the most serious and hard to fix," Pullen said.
They'll be working on that soon, but underneath the bridge on the west side already looks better: straps reinforce the beams above the parking lot at the White Stag building.
"During the design phase, we were very thoughtful about only spending money on things we felt could last for the next 20 years ... such as only painting the lower area even though the entire thing needs paint," Neill said. "We've really tried to only spend the minimum amount of money required, to get this bridge to the next investment phase slowly."
Coming up on Burnside
The county is also planning a feasibility study for a project that could possibly replace the Burnside Bridge or alternately, do a huge seismic upgrade.
"By the end of this year, we hope to have three or four of the best options for making the bridge earthquake ready. Then those options will be studied in greater depth, a federally required process that leads to one preferred alternative. We design it and find the best options," Pullen said.
But the Burnside Bridge is the county's only bridge where nearby buildings actually connect to it, at the Yard on the east side and underneath the west side at the MAX station.
"When you build hundreds of thousands of dollars' worth of buildings around a bridge, it effects the decision-making whether to repair or replace it," Pullen said. "Fixing it would be expensive, but a comparable cost (to replacement). If the community wants to save the old bridge, it's got to be looked at, but to make it earthquake-ready would make it look significantly different anyway."
The county has already replaced two bridges — Sauvie Island and Sellwood, which aren't downtown — in the past 10 years. It expects to make the repair-or-replace decision about Burnside within the next two to three years.
"One way to answer it, if the earthquake is going to happen here and it's someday going to happen, the bridge is nowhere near ready to be the bridge we rely on after the earthquake," Pullen said. "To be fair, we can say that about
every other old bridge as well, and 91 years is an old bridge."
The maintenance project is scheduled for completion Nov. 2019.
Burnside Bridge maintenance project
Total budget: $19 million
Owner: Multnomah County
Contractor: Hamilton Construction
Listen to the BizTribCast podcast to hear an exclusive interview with Megan Neill at: biztrib.com