Automate Ballard Link

Sound Transit is currently in the planning phase of building the Ballard Link Extension (BLE). These plans currently include a second downtown Seattle transit tunnel parallel to the one currently used by the 1 Line. By 2026, trains will run Lynnwood - Federal Way and Lynnwood - Redmond using this tunnel. Once all planned link extensions are completed (est. 2041), the plan is for trains to run Mariner-Redmond and Everett-West Seattle via the existing downtown tunnel (DSTT1). The new tunnel (DSTT2) will be underused, with only Ballard-Tacoma trains. The alignment options for DSTT2 between Westlake and International District bypass dense neighborhoods east of I-5 while failing to meaningfully improve transit options within Downtown Seattle. Instead, Sound Transit should build an independent, automated Ballard - Westlake line.

First, it is important to acknowledge that the BLE will probably be one of the most successful rail expansions in the Puget Sound region, even if the project is built as planned. The project connects some of the densest neighborhoods in Seattle (Downtown, SLU, Uptown, and Ballard) with a completely grade-separated alignment. This is projected to reduce travel times to around 11 minutes between Ballard and Westlake (WSBLE Draft EIS), which is faster than driving at all times of day. This is largely because there is no freeway between these neighborhoods, unlike suburban extensions of the 1 Line. This also means that the stations along the BLE will not have to contend with large amounts of the station walkshed being consumed by a freeway that leaves the rest of the developable land with unhealthy levels of air and noise pollution. The usefulness of this new rail alignment is clear, and we should strive to get it built as soon as possible.

While a new rail alignment between Ballard and Westlake Station has clear benefits, the same is not true for the portion of the planned alignment south of Westlake. Estimated at $2-3 billion, this section would likely be one of the most expensive project sections of any Link expansion. Planned service patterns would make the system worse than it currently is for many riders, since riders traveling between southeast Seattle or the airport and northeast Seattle would have to transfer. This would remove one of Link's biggest advantages over other transit options: downtown Seattle through-running. These new transfers would not be quick either because of long access times to extremely deep planned stations. The latest preferred alternative doesn't even include a stop in International District, further worsening the transfer experience.

To avoid spending billions of dollars on a new tunnel that results in worse transit service for existing riders, Sound Transit should build Ballard Link as an independent, automated line with a medium-term terminus at Westlake Station. This would nicely complement a revised service pattern with three lines using DSTT1: Lynnwood - Federal Way, Northgate -Redmond, and Lynnwood - West Seattle, combining for very high frequency service between Northgate and International District (see appendix A below). Using automation to reduce operating costs, the Ballard - Westlake line could independently operate at frequencies rivaling the other three lines combined, minimizing transfer time. The Vancouver SkyTrain is a good example of what is possible, with trains arriving as quickly as every two minutes. Sound Transit believes that achieving better than 3-minute frequencies will require upgrades to DSTT1, including egress improvements (stairs/elevators/escalators) and better signaling. Even if these upgrades cost several times more than the 2015 estimate of $20 million, it would still be far cheaper than a new $2+ billion tunnel.

Ballard Link should be built as an independent line rather than connecting to the existing transit tunnel. The track geometry makes connecting difficult, since the current and planned alignments are perpendicular at Westlake. The existing tunnel was also not built with any future branches in mind, so breaking through the tunnel wall would be difficult and cause significant disruption to current operations. Furthermore, this would limit the maximum number of trains between Westlake and UW, the most crowded segment. Unfortunately, this means the new line would not be connected to existing maintenance facilities, so a small maintenance facility would need to be constructed in Interbay. However, the size could be minimized by parking some of the trains at stations overnight like Sound Transit is currently doing to mitigate the delayed opening of East Link.

Perhaps the most exciting aspect of truncating BLE at Westlake is the possibilities for better transit that could follow. Initially, any leftover funds should be used to improve the speed, safety, and reliability of the rest of the Link system, which would allow for trains to run more frequently throughout the system and maximize use of the existing downtown transit tunnel. This could be accomplished by fully grade-separating the tracks in Rainier Valley, SODO, and BelRed, allowing for full automation of the system. Otherwise, Sound Transit should at least reduce crossing distances and add four quadrant gates to all at grade crossings and improve the signalling system. Unfortunately, there may not be much funding left over since cost estimates for ST3 projects (and infrastructure projects nationwide) have increased significantly.

Once funding becomes available, the Ballard - Westlake line should be extended to Mount Baker via First Hill, Yesler Terrace, the Central District, and Judkins Park. This would provide fast, frequent transit service to these already-dense and growing neighborhoods while still providing redundancy for many trips. The new station at Westlake should be designed as shallow as possible with fast, convenient transfers to the other lines. The line would then continue on a tunnelled alignment, with the potential for cut-and-cover or elevated sections (see appendix B below). Importantly, the alignment would connect neighborhoods with potential for dense development that would be away from noisy, polluted freeways. Connections could be made to the existing station at Mount Baker or the soon-to-open station at Judkins Park. This would greatly improve the resiliency and efficiency of the transit network, since many trips would no longer require riders to travel out of their way to downtown Seattle to make a transfer. If funding allows and Sound Transit can justify including it as part of ST3, another option would be to build the initial line to First Hill. This would serve what would likely be the highest-ridership station on the extension sooner.

Proposed Westlake - Mount Baker Alignment (Purple) with Existing (Black), Under Construction (Blue), and Planned (Green) Alignments

Sound Transit should move quickly to focus their efforts on building Ballard Link to Westlake sooner with plans for an extension via First Hill in the future. First Hill has been passed over for rapid transit for too long, and serving it would give Sound Transit the opportunity to serve several other growing urban neighborhoods away from polluted freeway corridors.

Appendix A: Proposed Service Pattern

• 1 Line (Green): Lynnwood - Federal Way (Tacoma)
• 2 Line (Blue): Northgate - Redmond
• 3 Line (Red): Lynnwood (Everett) - West Seattle
• 4 Line (Purple): Ballard - Mount Baker

Proposed service pattern with a Ballard - Mount Baker line. Solid lines indicate existing track, dashed sections are under construction, and dotted sections are planned/proposed.

With an independent Ballard - Westlake 4 Line", a service pattern with trains running from Ballard to Federal Way would not be possible. Frequent service of 2-3 minutes on this new line would nicely complement a revised service pattern where the 1 Line continues to run the full length of the existing/under construction light rail spine" from Lynnwood to Federal Way (or Tacoma if/when that extension is built). Since the 2 Line is primarily an east-west route, it makes the most sense for this line to turn around early and run from Northgate to Redmond. The Stride S2 BRT route will also serve Lynnwood - Bellevue trips. This would maintain the highest frequency service in the most congested parts of the network, and Northgate already has crossover and pocket tracks. Riders from north of Seattle destined for the Eastside are already better served by buses from UW station, so this should not introduce new transfers in most scenarios. The 3 Line would then run from Lynnwood (or Everett if/when that extension is built) to West Seattle as planned. In the past, plans called for 3 minute combined frequencies in DSTT1. However, Sound Transit currently plans to run trains every 4 minutes downtown, so these 3 lines could each run every 12 minutes assuming that is the limit. This would constitute a downgrade from current peak headways of 8 minutes on the lowest ridership sections. However, it seems plausible that Sound Transit could maintain existing service by making improvements to at-grade crossings. With full grade separation (and therefore the possibility of automation), 6 minute headways on all lines combining for 2 minute headways downtown would likely be attainable.

Appendix B: Westlake - Mount Baker Alignment and Stations

Potential station locations are shown below to illustrate what a Westlake - Mount Baker extension might look like. Station boxes shown are approximately 100 ft by 300 ft, which would only accommodate the equivalent of 3 car Link light rail trains. This seems reasonable, as the Vancouver SkyTrain uses 250 ft platforms. This was done to reduce station construction costs throughout the line and especially in First Hill, where blocks are about that long. In addition to the lower cost and impact of construction, this reduction in theoretical maximum capacity could be justified by running more frequent service using automated trains. Such trains can fit more people at a given length since they don't need operator cabs (Each 4-car link train currently has 8 operator cabs, which takes up a significant amount of space). It would certainly be possible to accommodate longer trains, but it may not be necessary with automation.

First Hill StationYesler Terrace StationCentral District StationJudkins Park StationMount Baker Station

After leaving Westlake Station, the proposed Ballard-Mount Baker line would continue to First Hill with a station near Boren Ave and Madison St. The station could potentially be located on the site of the O'Dea High School parking lot one block from Madison. The train would then continue along Boren Ave to Yesler Terrace, with a station near Yesler Way and 12th Ave. This alignment leaves open the possibility for a cut-and-cover tunnel beneath Boren Ave. The Yesler Terrace Station could potentially permanently close the section of 12th Ave S between Yesler Way and Boren Ave as part of a project to simplify and improve safety at the intersections in the area. The Central District station would be built near 23rd Ave S and S Jackson St, a low-pollution area that has been significantly upzoned. The station could be built on Washington Middle School property or as part of a redevelopment of the Autozone/Walgreens and their parking lots. To reach Judkins Park station, the line could potentially be built cut-and-cover or even elevated along the edge of the middle school property and Judkins Park. If not already above ground, the tracks would emerge before I-90 and cross the freeway on a bridge. The station could be located partially over I-90 eastbound and the Benvenuto viewpoint. A direct connection to the 2 Line median station would make for easy transfers. The remainder of the alignment could be constructed elevated or cut-and-cover along 23rd Ave S and Rainier Ave S with an elevated station adjacent to the existing 1 Line station. The new terminus should be designed such that the line could be extended south along either Martin Luther King Jr Way S or Rainier Ave S in the future, perhaps to Renton.

Further ReadingSeattle Transit Blog

A single downtown tunnel is completely possible and provides the best outcomes
Put First Hill back on the table?
Focus on SLU and Ballard
Implications of the West Seattle Link Cost

The Urbanist

Build Ballard Link Faster and Better By Skipping Second Downtown Tunnel
Will First Hill Ever Get the Rapid Transit It Deserves?
New South Lake Union Station Alternative Could Delay Ballard Link Opening Several Years

Seattle Subway

Vision Map

Sound Transit

WSBLE Draft EIS
Transit Tunnel improvements enabling increases in system frequency
Sound Transit System Expansion