Tag: East Link

Cascading Construction Errors Add New Delays to Light Rail Expansion

Inspectors found gaps between rails and pre-cast concrete plinths on both sides of the I-90 water crossing. They addressed the problem by installing mortar, which subsequently failed. Image: Sound Transit presentation

By Erica C. Barnett

Shoddy workmanship, the concrete workers’ strike, and the collapse of an embankment in Kent will delay the opening of the regional light rail expansion by a year or more, Sound Transit staff told agency board members on Thursday. The board already knew that a light rail extension linking Seattle to the Eastside across Lake Washington was behind schedule because of issues with concrete plinths, or track supports, installed by contractor Kiewit-Hoffman, but learned more details last week about both that construction snafu and other issues that will contribute to delays throughout the project.

The biggest potential delay involves the light-rail extension across I-90, where Sound Transit inspectors discovered problems with the concrete plinths that directly support the rails leading up to the water crossing, pre-cast concrete blocks on the bridge deck, and the nylon inserts that hold bolts in place where the rail is attached to the floating bridge itself.

“I want to be clear that as we talk about challenges and risks, we’re speaking to the ability to meet current schedules and not the ability to deliver light rail across the I-90 floating bridge,” Sound Transit’s interim CEO, Brooke Belman, said during last week’s meeting. “We are 100 percent confident in the design and operability of the segment across the floating bridge and [that we will] complete the entire alignment.”

“It was a very strange working situation for absolutely everybody, including folks who would have been on the ground looking at the work and now were required to work from home. So there were a variety of issues that led to this place where we find ourselves.”—Sound Transit deputy director Kimberly Farley

Sound Transit started unearthing problems with its I-90 crossing in 2019, when inspectors discovered that the top surface of some plinths did not connect with the rails they were supposed to be supporting. To close these gaps, Sound Transit’s Kiewit-Hoffman installed mortar between the blocks and the rails, a solution Sound Transit deputy director Kimberly Farley said the agency believed would fix the problem. Subsequently, though, that mortar failed, and Sound Transit discovered another set of problems, “including concrete placements that were too low, too high, constructed to the wrong geometry, or resulting in voids under rail fasteners,” according to a staff report.

During work to fix those construction problems, the team discovered additional issues, “such that the overall scope of the challenges has increased rather than decreased”; for example, many of the blocks had improperly installed or missing rebar, which strengthens concrete and prevents it from cracking. During this time, Sound Transit also discovered that the nylon bolt holders were stripped and decided to replace all of them. They also noticed that some of the pre-cast concrete blocks that support the rails across the bridge were cracking.

Asked why Sound Transit’s inspectors didn’t discover these problems sooner, Farley noted that much of the construction took place at the height of the pandemic, when “it was just a struggle to get everybody on site, keep the work going, and keep the protocols in place.”

“It was a very strange working situation for absolutely everybody, including folks who would have been on the ground looking at the work and now were required to work from home,” Farley continued. “So there were a variety of issues that led to this place where we find ourselves.” Earlier this year, Sound Transit hired a forensic engineer to evaluate Kiewit-Hoffman’s repairs and keep tabs on construction.

Board member Claudia Balducci told PubliCola  she was glad Sound Transit staff revealed the latest issues to the board at this stage, rather than waiting until they had come up with fixes, noting that the agency has historically had issues with transparency. Former director Peter Rogoff could reportedly be tight-fisted with information, preferring to address issues internally rather than bringing them to the board or discussing them in public. “I want that kind of transparency,” Balducci said. “I don’t want staff to be like, ‘We won’t report to the board or to the public until months later, when we have identified a problem and fully engineered a solution.'”

It could be months before the agency identifies a solution to unstable soil conditions along the alignment between Kent and Federal Way, where a 200-foot section of embankment slid nine feet earlier this year, forcing a partial closure of I-5. Originally, Farley said at last week’s meeting, Sound Transit had hoped to use timber pilings to shore up the slope, but after the slide, they went back to the drawing board. “The reason that you didn’t hear the solution [at the meeting] is because, frankly, we don’t have one yet,” Farley told PubliCola. Continue reading “Cascading Construction Errors Add New Delays to Light Rail Expansion”

Light Rail Riders Will Have to Switch Trains to Get Through Downtown Tunnel During East Link Construction

Sound Transit light rail riders traveling through the downtown Seattle transit tunnel will have to switch trains on a new, temporary center platform at the Pioneer Square station for ten weeks in early 2020 to accommodate construction to move tracks and install switches for the new East Link train line, which opens in 2023, into the existing rail system. During those ten weeks, people traveling through the tunnel in either direction will stop at Pioneer Square, deboard on a 14-foot-wide platform in the middle of the tunnel, and switch to the train that has just arrived from the opposite direction. After two minutes—an amount of time Sound Transit planners say is necessary to allow passengers on each train to get across the platform and reboard, and for train drivers to get from one end of the train to the other—the trains will continue in the same direction from which they came.

Sound Transit staffers said train doors will not open until another train has arrived from the opposite direction, to prevent riders from succumbing to the “temptation” to rush across the open trackway to the opposite station platform. The temporary center platform will be staffed with security and Sound Transit wayfinding staff during all hours when trains are running.

“This is a necessary inconvenience so we can enjoy the massive convenience of having access to 10 stations on the Eastside in 2023.” – Sound Transit CEO Peter Rogoff

If you have trouble visualizing how this would work, Sound Transit has created a couple of animations that I found extremely helpful. Essentially, trains that go to the University District station will be traveling to Pioneer Square and turning back, and trains coming from Angle Lake and the airport will be doing the same thing from the south. Four stations will operate with only one platform at a time during construction—Stadium, Chinatown/ID, University, and Westlake.

Additionally, the tunnel will be shut down altogether for three weekends during the construction period; during that time, riders will have to transfer to street-level buses between the Westlake and SoDo stations.

While construction is going on, four-car trains will operate at 12-minute frequencies all day (currently, Sound Transit runs three-car trains more frequently during rush hour and less often when demand is lower.) The result will be more crowding during busy periods—trains will have about 23 percent less capacity during the weekday peak—and less crowding during off hours, when there will be 11 percent more room for riders to spread out. Sound Transit staffers say they’re working on a plan to accommodate bikes and luggage when trains are more crowded than usual.

At a meeting of Sound Transit’s newly christened Rider Experience and Operations Committee meeting Thursday, Sound Transit CEO Peter Rogoff called the 10-week partial closure “a necessary inconvenience so we can enjoy the massive convenience of having access to 10 stations on the Eastside in 2023,” and predicted that riders would “scarcely remember the inconvenience of the 10 weeks in 2020, given the benefits that the whole region will get when East Link is done.”

Support