Sound Transit previews NE 130th options

Preliminary design for the NE 130th Link station (image: Sound Transit)

At Thursday's System Expansion Committee meeting, staff shared options for opening the NE 130th Link station ahead of the currently scheduled 2031 date. An early opening will be less expensive in capital dollars and avoid rider disruptions later. But the earlier expenditure has some modest impacts for Sound Transit's indebtedness at an arguably sensitive time for other projects.

Three options are now on the table. The default is to proceed with the ST3 plan to build an infill station in 2031 after Lynnwood Link has opened in 2024. Seattle would prefer to build the station concurrently with the Lynnwood line and have the station open by 2025. Staff offered a third partial build option which would build just enough of the station to avoid the worst construction impacts, but defer other construction until later so the station opens years after Lynnwood Link.

Three construction options

If the ST3 schedule is followed, work on the station would commence only after Lynnwood Link has opened. The station platforms would then be built alongside the active rail line. That would mean single-tracking of trains through the area while each platform is built, with construction on one side and trains running on the other. 61,000 daily riders through this area would face delays and reliability could be impacted throughout the system. Construction impacts to the neighborhood would be lengthy as station construction begins after 2024. Because the station platforms would be separate structures with their own foundations, they would move independently and require expansion joints at the platform edge making the station permanently less friendly to wheeled riders. The separate platform structures also need extra support pillars below.

The ST3 plan envisioned the station being built around the active guideway as a separate structure (image: Sound Transit)

Either the early full build or partial build option constructs the guideway and platforms on a single foundation at the same time as other construction on Lynnwood Link. The difference is with the non-structural elements within the station and the plaza below. The partial build option defers construction on the 'plaza and finishes' package until after 2024. Either full- or partial build avoids single-tracking of trains after Lynnwood Link has opened. But the partial build option draws out construction, denies riders the use of the station, and burdens neighbors with a partially constructed station for years.

The partial build option would construct the foundation and platform packages with Lynnwood Link, and defer the plaza and finishes within the station until later. (image: Sound Transit)An earlier opening reduces capital costs

The early full build significantly reduces capital cost versus either of the other options. On any timeline, however, the latest project cost estimate is more than twice the $72 million (2018 dollars) in ST3 planning. Expenditures for the Lynnwood line generally have come in high, and the tightly constrained NE 130th site is entirely on a slope adding more costs than anticipated in the preliminary estimates in 2016. If the original timetable is followed, the full project cost is now expected to reach $174 million. With fully accelerated construction and a 2025 opening, that is reduced by $30 million to $144 million. The partial build option is almost as expensive as the ST3 schedule at $167 million. An early opening also very slightly increases operating costs.

Suburbs are watching the debt cap

So far, an early station opening seems a "no-brainer" to borrow Jenny Durkan's characterization at the meeting. The wrinkle is that earlier spending is financed by borrowing. That adds more debt service expense and very slightly increases the odds that other projects would be delayed if Sound Transit hits the debt cap.

Sound Transit's borrowing is limited by statute and coverage requirements. On current projections, agency debt will be $3 billion shy of the debt cap in 2032, and the largest risks to coverage ratios are in the 2030s. The cost of this station is too low to impact those projections much. Nevertheless, forecasts so far into the future are highly uncertain, so it's possible the financial position in the early 2030s will be more constrained. Snohomish County is particularly sensitive about this because the timing of their projects mean they are more likely to be delayed if debt is not well-managed.

Capital costs favor the earliest opening, but there are offsetting debt and operating costs (image: Sound Transit)

The staff presentation cited $51 million in added debt service costs from an early full build, vs $11 million from an early partial build. But servicing costs are secondary to debt cap constraints. It's unlikely the ST3 schedule of late 2020s construction has any advantage in avoiding the debt cap vs a less expensive construction in the early 2020s. Either schedule places the outlays before the most critical window for the debt cap, and the early opening schedule reduces the total capital outlays.

Where next?

Thursday's meeting was a briefing only. Committee and Board action is expected at the February meetings. Sentiment at Thursday's meeting seemed overwhelmingly in favor of some sort of accelerated schedule, with Seattle representatives particularly favoring the early full build. The Board must make a decision on whether to proceed with some sort of early build soon if work is to proceed concurrent with Lynnwood Link, but could punt a choice between the partial- and full- build options into next year. Because design is so far only at 30%, formal approval with baselined costs must wait until next year in any case.

Thursday's presentation indicated updated station ridership estimates of 2,200, though estimates from 2016 suggested fewer than 1,000 incremental system riders (the balance would divert from Northgate). Local advocates are more optimistic, believing there would be more riders to the station from Lake City and Bitter Lake. To further boost ridership, Seattle officials are interested in denser land use along the east-west corridor near the station.