Could Link to Mariner open early?

Near the Ash Way P&R on I-5 (image: SounderBruce)

The draft ST3 plan in March 2016 extended rail beyond Lynnwood in two steps. The first, in 2036, would bring service to North Lynnwood, serving stations at West Alderwood Mall, Ash Way, and Mariner. The second, in 2041, extended around the SW Everett Industrial Center (Paine Field) and north to Everett Station.

When the plan was finalized two months later, the extensions were combined so the Paine Field and Everett stations would open served five years earlier. It was a telling decision that all the extra financial resources of the final plan were put into the northern segment. This looks like an error. While all parts of Everett Link have their value, the immediate rider needs are mostly between Lynnwood and Mariner.

Rearranging the Snohomish subarea resources could still open those stations by about 2030. The trade-off is that accelerating some capital spending generally means delays elsewhere. This may mean a later opening of service to Paine Field and Everett where the need for light rail is less urgent.

Famously, Snohomish County has bad traffic, the worst in the nation by some measures. A significant part of this stems from the booming bedroom communities from which thousands commute daily to Seattle. Almost as many Snohomish residents work in King County (145,000) as in Snohomish (158,000). For those who use transit, Lynnwood Link will deliver faster and more reliable travel times. It could serve these riders even more efficiently with more stations a little further north to intercept buses from across the County.

The Ash Way and Mariner areas are fast growing communities with healthy concentrations of local riders commuting to King County. Link would also connect to Swift BRT service at Mariner.

Snohomish County leaders do not, however, wax lyrical about one of the nation's large bedroom communities. They envision Paine Field as the urbanized hub of future employment growth in the county with commuters arriving by rail from Everett and Seattle. Such a long-term vision will develop over decades. It is less pressing than responding to the needs of the commuters already stuck on I-5.

An earlier Link extension to Mariner wouldn't affect the capital cost of the ST3 program much; it's the same line constructed in two steps rather than one. It may affect the delicate debt management problem Sound Transit faces after 2030. And it would add some operations cost if the trains started service earlier to North Lynnwood. Let's take these in turn.

Sound Transit debt is limited to 1.5% of the assessed value of property in the RTA (unless 60% of voters approve more debt). The agency adds debt as the ST3 program is built out, and then the debt burden declines as projects are completed. The 'pinch year', when the debt load is closest to the maximum allowed, is currently projected as 2032.

Projections that far into the future are uncertain and sensitive to small changes in assumptions. Sound Transit may comfortably stay under the limit if interest rates remain low and costs are well-managed. With a recession, Sound Transit could hit the limit and needing to delay planned projects. It's important to acknowledge how debt dynamics figure large in Snohomish County leaders' thinking about ST3. The debt limit is projected to constrain most just as construction along the Everett alignment is scheduled to ramp up.

Prudently, an early opening of the line to Mariner means a balanced slowing of outlays on Mariner-Everett rail so cash flows are balanced until the "pinch year" is passed. That may mean construction beyond Mariner would not commence until after 2032 when the spare debt capacity expands again. But it would be worth it to have earlier service to the busiest stops north of Lynnwood.

An accelerated opening means operating costs start earlier. But they're not so large. The Sound Transit Financial plan projects that Link to Everett will add $77 million of operations expense beginning in 2036. It is 6.8 miles from Lynnwood TC to Mariner P&R. That's 42% of the 16.3 miles to Everett. We can ballpark the operations costs of the shorter segment by multiplying these numbers. The added operating cost of an early opening to North Lynnwood comes to about $32 million per year (or $21 million per year in current dollars). That's not very large, and it would be even less with an offsetting delay to the opening of the Mariner-Everett segment.

Money is not the only challenge to an early opening, of course. But it's probably technically feasible to open about the same time as the more complex alignment to West Seattle, scheduled for 2030. That would be six years earlier than the current plan for Everett Link. Snohomish County and Sound Transit should accelerate planning to make this early opening possible.

Even with optimistic growth targets for Everett, ridership on Link is projected to tail off precipitously beyond Mariner (image original: Sound Transit)