What would Sound Transit do in East King County if it were trying to maximize the effectiveness of the ST3 package? How many transit riders could be served within the constraints of a likely ST3 package?
I’ve borrowed Martin Duke’s calculation of a $2.6 billion “budget” for East King. Martin estimates this from the $15 billion request to the Legislature, converted to $10 billion in 2014 dollars (to align with the corridor study cost methodology). With $800 million committed to completing East Link to Redmond, that leaves $1.8 billion for other projects.
The approach is to calculate cost per rider (using the mid-range of estimates from the corridor studies). The options are ranked and the best are selected, unless they duplicate an already selected option. Many of the options are close substitutes, so it makes sense to select only one. For instance, 405 BRT occupies three of the top six slots, but only the highest ranked of these is selected. I ignore other options which were not reviewed in the corridor studies (such as the bridge to Sand Point).
Cost per rider is a somewhat problematic metric, in that it fails to acknowledge existing ridership. The studies don’t break out incremental ridership estimates. But it won’t affect our ordering of projects unless one project has much more incremental ridership than another. (More ambitious projects may have greater incremental ridership because they represent a larger change versus the status quo, so a total ridership approach does bias the analysis toward smaller projects somewhat).
I’ve also broken out the incremental costs and ridership of 405 “full” options against “phased” options. Viewed separately, the incremental investments for the full build-out do not perform well (highlighted in green in the table).
Within those constraints, it’s possible to get quite a lot of service on the Eastside. About 50,000 riders would be served on four BRT routes (in bold red in table). Kirkland, Bellevue, Redmond, Issaquah, Renton and the 405 corridor would all see local benefits.
The winners are:
- BRT University District to Redmond via 520. At only $55 million, it’s by far the cheapest option on the table. On the other hand, with so little investment, it’s only modestly superior to today’s express bus service between Redmond and downtown Seattle.
- BRT University District to Kirkland via 520 and the Eastside Rail Corridor. At only 8,000 riders, it’s still a relative bargain because it costs only $210 million.
- BRT 405 Phased Build-out with trunk and branch service. The phased build-out is much more cost-effective, and realistic, than the full build-out which assumes a large unfunded investment by WSDOT. The trunk-and-branch service enjoys 20% better ridership than the single-route service with no additional capital costs. However, there are about $20 million per year in increased operating costs to consider, so the single-route phased build-out remains in play.
- BRT Kirkland to Issaquah via the Eastside Rail Corridor, Bellevue Way, I-90 and via mixed traffic from central Issaquah to the Highlands. This is lower in the rank ordering, but makes the cut because we’re not selecting duplicate services on the same corridors. Service to the Highlands is in mixed traffic. But that is relatively inexpensive for 2,000 additional riders, so it improves the overall cost-effectiveness of this service.
That adds up to $1.95 billion, slightly over the “budget”. I’ve assumed no double-counting of costs between the two selected alignments that use the Eastside Rail Corridor. If there is overlap, then total costs are reduced.
Snohomish County should contribute something towards the $800 million cost of 405 BRT, which serves a lot of commuters from Snohomish cities into Bellevue. A contribution proportionate to ridership could be up to $200 million. Snohomish would surely resist such a large contribution as they seek to conserve funds for a Link extension to Everett, but the trunk-and-branch service reaches all the way into Lynnwood and Everett.
Cost per rider isn’t the only consideration, of course. But this looks like a coherent package of transportation improvements tying together all of the Eastside communities. The development potential and environmental impacts wouldn’t appear to warrant a major revision to the list. LRT systems might be more “future-proofed”, but the studied options run $2.2 to $2.9 billion each. In other words, none of them are affordable, although a truncated version of the Kirkland-Issaquah line would fit. The four BRT routes suggested by this analysis are collectively less expensive than any one rail project on the Eastside.
The best options leverage existing or planned investments. These include HOT lanes on 405, new transit infrastructure on SR 520, and the purchase of a portion of the rail corridor by the City of Kirkland. Adding BRT infrastructure on the rail corridor would improve Metro service in the area also.
The exercise also suggests we are near the limits of further investment on the Eastside unless there is a willingness to make much larger investments in rail that are not supported by Sound Transit’s ridership estimates. These four options have an average cost per daily rider of $39,000. These buy service in every corridor studied except the Bellevue-Renton segment of the Eastside Rail Corridor which is better served via I-405. Rail options in East King start at $111,000 per daily rider, so additional future funding may be better invested in smoothing out the compromises inherent in some of the BRT options.
A few additional caveats and notes follow the table.
|BRT U-District to Redmond via SR 520||$55||12||$5|
|BRT U-District-Kirkland via ERC, SR 520||$210||8||$26|
|BRT 405 Phased Build-out Trunk & Branch||$800||19||$43|
|BRT U-District-Kirkland via I-405, SR 520||$400||8||$50|
|BRT 405 Phased Build-out Single Route||$800||16||$52|
|BRT 405 Full Build-out Trunk & Branch||$1,475||23||$66|
|BRT Kirkland-Issaquah Highlands via ERC, Bellevue Way, I-90, mixed traffic to Highlands||$885||12||$74|
|BRT 405 Full Build-out Single Route||$1,475||19||$78|
|BRT Kirkland-Issaquah via I-90, Bellevue Way, and ERC||$850||10||$85|
|BRT Kirkland-Issaquah via I-90, Bellevue Way, and I-405||$625||7||$89|
|BRT Totem Lake-Issaquah via I-405, I-90||$625||7||$96|
|LRT U-District-Redmond via 520 and East Link||$2,210||20||$111|
|BRT Eastside Rail Corridor, Renton-Woodinville||$1,255||10||$126|
|BRT 405 Incremental Trunk & Branch (Full-Phased)||$675||4||$169|
|BRT Kirkland-Issaquah via I-90, Richards Rd, and ERC||$1,370||8||$183|
|BRT 405 Incremental Single Route (Full-Phased)||$675||4||$193|
|LRT U-District-Redmond via 520 with transfer to East Link||$2,270||10||$227|
|LRT Kirkland-Issaquah via I-90, I-405, and ERC||$2,280||10||$228|
|LRT Eastside Rail Corridor, Renton-Woodinville||$2,310||10||$231|
|LRT Issaquah-Totem Lake via I-90, Richards Rd, and ERC||$2,315||10||$232|
|LRT Kirkland-Issaquah with Tunnel to Issaquah Highlands||$2,845||12||$237|
|LRT U-District-Kirkland via ERC, SR 520||$2,485||8||$311|
|CR Eastside Rail Corridor, Renton-Woodinville||$1,385||4||$326|
A few notes to accompany the data:
* All ridership and cost numbers are mid-points between high and low estimates. Using high or low wouldn’t have changed the rank ordering in any important way, but the highest cost estimates for the four suggested projects would be $280 million more than the mid-point. At that level, we’d need to carefully consider pruning this list.
* All costs are from the corridor studies. In the case of 405 BRT, the full buildout costs excludes infrastructure to be built by WSDOT even though WSDOT has not prioritized some of those elements. In the case of the Eastside rail corridor, it includes costs for a trail beside the rail/bus ROW even though Sound Transit has not agreed to shoulder those expenses.
* Only the representative options studied by Sound Transit are included. Other commenters have speculated that truncating Issaquah service at Eastgate might make that corridor more cost-effective. We don’t have data to verify that. The much shorter distance to Eastgate might be offset by the complexity of the nearby interchange.
* 405 BRT spans the East subarea and a portion of Snohomish County. About 28% of projected ridership is on the segment north of Totem Lake, so I’ve inferred this might translate to a 25% Snohomish share of ridership.
* I borrowed Chris Stefan’s idea of ranking options by cost per rider, although I prefer to use mid-point estimates.