Where will riders use the ST3 Link system in 2040? Longtime readers will be familiar with project ridership estimates, but most riders on Link are not going to the ends of the line. Along any line, ridership can be much higher on some segments than others. The suburban lines have weak ridership at the tails. Even the Seattle ST3 extensions have lower ridership outside of downtown than is widely understood.
The busiest part of the system is, of course, downtown Seattle with about 200,000 daily riders expected across both tunnels. Near downtown, the largest number of riders will traverse the North Line (about 108,000 daily riders near Northgate), the South Line (72,000 riders near Tukwila), and the east (65,000 riders crossing Lake Washington).*
Ridership to downtown Seattle from the ends of the Ballard and West Seattle extensions are smaller. West Seattle Link will carry 32,000 over the West Seattle bridge. Ballard Link has 34,000 riders on the segment west of Seattle Center. Taken together, this is scarcely more than the East Link ridership across Lake Washington.
Project ridership estimates obscure how many Ballard line riders aren’t going near Ballard. Depending on how one defines the endpoints of the project, some ridership estimates ran into six digits. But those are mostly in downtown. Even defining the Ballard Line to include the South Lake Union station, 52 thousand are expected. More than twice that number will use the second downtown rail tunnel.
Outside core Seattle, ridership gradually thins out in every direction. In East King County, the large majority of 2040 riders will be only on the segments built in ST2. Even East Link ridership tails off sharply beyond Microsoft. The more productive of the new extensions is the segment of the Kirkland-Issaquah line within Bellevue. 12,000 riders are anticipated between downtown Bellevue and Factoria. Ridership is lower on the Eastside BRT lines, though the resources invested are correspondingly small.
To the north, Everett Link ridership drops off sharply beyond Mariner. Even the projected low ridership tail to Everett may be overstated because it is based on regional growth projections that anticipate Everett growing 2 ½ times faster than Seattle through 2040. If you think that’s unlikely, you should have a yet lower estimate for Link ridership into Everett.
Ridership into Tacoma is about one-third of the rider counts on the train passing Seatac. Again, most riders are to Seattle, with fewer commuters on Link to Tacoma.
Link, measured in track miles or capital dollars, is a mostly suburban system. Two of every three ST3 capital dollars are invested in the suburban extensions. A close analogue is the BART system in the Bay Area. BART has comparable track miles to the fully built-out ST3 network, and a continuing program of suburban expansions. But just nine stations between San Francisco and Berkeley account for half of all rider on/offs.
The vital contribution of ST3 is core capacity in Downtown and South Lake Union. This explains, perhaps, official Seattle’s preference for a Downtown-Ballard line over Ballard-UW. It’s not about the ridership expected from Ballard because that’s not where so many of the riders on the Ballard line will be.
Another lesson is that the models do not anticipate much ridership between suburban centers. Regional growth centers outside of Seattle and Bellevue mostly have low current transit shares, and the growth in regional transit ridership is to and within the major cities, not between minor centers.
The weak intra-suburban estimates bely the hope that ST3 would serve travel within the Eastside after ST2 had connected it to Seattle. Nor is Everett Link carrying many Everett residents to jobs at Paine Field. Snohomish County riders are mostly starting their morning trips south of Paine Field, and commuting to Seattle. Perhaps Snohomish County should have prioritized an early extension serving commuters from Ash Way and Mariner, rather than waiting to open those stations along with lower demand markets at Paine Field and Everett.
What of concerns about future overcrowding? The busiest individual segments on each line are generally around the Seattle core:
- North line between Westlake and Capitol Hill stations: 148,000
- North line between UW and University District stations: 132,000
- East line between International District and Judkins Park stations: 70,000
- South line between SoDo and Beacon Hill stations: 86,000
- Tacoma Link through downtown Tacoma: 20,000
- Sounder between Tukwila and Kent: 27,000
Sound Transit anticipates trains at six minute headways on each line will be sufficient to manage demand through 2040. The Kirkland-Issaquah line, where crowding is not a concern, will also run at six minute headways to interline with East Link in Bellevue. Of the segments with the most riders, the SoDo-Beacon Hill may be the most congested because it would be served only every six minutes and the balance of people travelling in one direction at peak may be more skewed than on the North Line in Seattle.
* Weekday daily ridership is about 1/307 annual ridership, with the ratio reflecting the typical balance of weekday/weekend riders in the annual numbers. This author finds daily counts more intuitive than annual totals, so I have converted all numbers to weekday counts. All estimates are midpoints of a range.