The publishing of the Central Tacoma Link Extension (CTLE) proposal within this blog has stirred a large debate regarding how Link should properly serve the City of Tacoma over a decade from now. There was broad agreement that terminating services at Tacoma Dome Station was deeply unsatisfactory, with most commenters agreeing that a natural terminus for the regional metro system is, indeed, Downtown Tacoma.
However, among the many proponents of such an extension, there were legitimate concerns of how it would be accomplished. Where CTLE came under routine fire was on two fronts: its interaction with the existing streetcar system, and the location of the Central Tacoma Station. Although these points are addressed extensively on these pages and on other websites, they are real concerns that warrant further investigation. The CTLE surface option remains the cheapest and most cost effective manner of delivering trains into Central Tacoma. That station, even without extensive bus connections, has independent utility as a rail station in an urban core. Still, it is worthy to consider alternative alignments into Tacoma that: one, have no impacts on the existing streetcar system; two, more finely integrate Link with the existing Downtown transit corridor along Commerce Street, and; three, furthers the conversation of getting trains into the city center.
A preliminary review of alternative alignments into Downtown Tacoma produced three distinct alignments, whose components could be mixed to produce a larger variety of routing options. Of course, the first option is the original surface alignment. The three new alignments include substantial tunneling or aerial segments. Costs have not (yet) been considered and are highly variable depending upon the construction method and ultimate scope-of-work. Worthy of note, the impacted areas are predominately surface parking lots, a wide avenue, or the margins of a freeway, all of which should dramatically reduce construction costs relative to other large rail projects through a developed urban quarter.
TUNNEL: Pacific Avenue is a wide thoroughfare and should be a prime candidate for cut-and-cover tunneling. This manner of tunneling is disruptive, but it can be substantially less expensive than deep bore tunneling and quicker to construct. Of course, TBMs should remain on the table if it is determined that their method of construction could deliver a better product for the city.
- A surface and tunneling mixture. This proposal preserves the Union Station-area track sharing arrangement of the CTLE surface alignment, but then sends trains into a tunnel under Pacific Avenue. Directly under Pacific Avenue, a new station could be constructed just south of the intersection of 9th and Pacific, or trains could be sent westerly into the large property now hosting the multi-story parking garage owned by Commencement Plaza, LLC. This property would be purchased by Sound Transit and would accommodate a seamless bus/Link transfer facility, along with affordable and market-rate housing and commercial businesses. The City Center Station would be a gamechanger for the City of Tacoma and the regional transit system.
- An aerial and tunneling mixture. This proposals abandons in its entirety the surface alignment of the CTLE and has no track sharing with the existing streetcar system. Instead, an easterly and largely aerial alignment hugs the west side of I-705, curving around freeway facilities both horizontally and vertically, to provide a new approach into Downtown. Union Station / UWT would be served by a new side-platform rail station to the east of the History Museum, requiring a rebuild of the Bridge of Glass that fully integrates into the platform system. At 109 South 15th Street, presently a lone building surrounded by a sunken surface parking lot, the track would eventually rest underneath future development as it begins a true tunnel alignment that curves toward Pacific Avenue. With only surface parking lots and a wide avenue above, the construction method again favors cut-and-cover tunneling. Once under Pacific Avenue, the line again either terminates directly under Pacific Avenue, or it shifts west under the parking garage property for a larger regional transportation facility (City Center Station). The latter is preferred.
Note: both tunneling alignments feature a pocket track in lieu of tail tracks that would otherwise extend a train length beyond the platform. This dramatically reduces the size and scale of the scope-of-work underground. Additional analysis should be performed to determine if pocket tracks located beyond Tacoma’s urban core would eliminate the need for a third track in the Pacific Avenue tunnel.
AERIAL: An aerial alternative exists that is not represented within the plans. They were removed from consideration as being too complex, too visually obstructive, and for making only marginal improvements to local transit system integration over the proposed Central Tacoma Station of the surface alignment.
- A largely aerial alignment. This proposals abandons in its entirety the surface alignment of the CTLE and has no track sharing with the existing streetcar system. Instead, an easterly and largely aerial alignment hugs the west side of I-705, curving around freeway facilities both horizontally and vertically, to provide a new approach into Downtown. Union Station / UWT would be served by a new side-platform rail station to the east of the History Museum, requiring a rebuild of the Bridge of Glass that fully integrates into the platform system. Near the I-705 offramps at East 15th Street, both the at-grade and aerial approach to access A Street would require presently unknown impacts to the offramps. The offramp to A Street, in particular, may need to be destroyed to accommodate a northerly extension onto A Street. Given the great number of I-705 connections to and from Downtown Tacoma, this would seem to be a modest impact to the area highway system. Still, such a project would require complicated engagement with the State and the federal government. Once on the A Street viaduct, trains would either terminate on A Street somewhere between East 10th and 12th Street, or the trains could swing sharply via a reverse curve on 12th Street into the alley. There, a station could be sited at 110 South 10th Street. This building, now a multi-story parking garage, would be replaced by an aerial station facility along with affordable and market-rate housing.
Note: for the aerial option, it is presently unclear where a pocket track might be located. One conceivably could be sited to the east of the Tacoma Art Museum, but the location is constricted. Regardless, the unappealing nature of this alignment alternative does not warrant any further investigation at this time.
Any of the four CTLE alignments would directly serve Downtown Tacoma and properly interface with the local transit system, if not at Union Station then at City Center Station via the tunnel alignments. As Pierce Transit advances plans to redirect bus services toward Tacoma Dome Station, mandating transfers there at the expense of quality services to the urban core of the city, the CTLE promises to restore the proper dominance of Central Tacoma. This is the logical path forward for the South Sound and the Link spine, and the first step to ensuring its realization is securing a TDLE Puyallup Avenue alignment.
Central Tacoma Link Extension (CTLE) Alternative Alignments Map
ArcGIS Interactive Map, detailing the CTLE alternative alignments on a viewer-friendly map.
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