When Sound Transit makes the tie-in of East Link to Central Link in Seattle next year, service on the Central Link light rail line will be temporarily disrupted over a 10-week period, possibly longer. Sound Transit plans to use a single-track approach in the Downtown Seattle Transit Tunnel, which will force passengers to transfer at Pioneer Square Station. It will be a delicate dance to keep trains running with minimal delays and passengers happy.

“We had two options: close the line for several weeks during construction, or continue to serve our 80,000 daily riders over a slightly longer construction period,” said Peter Rogoff, Chief Executive Officer of Sound Transit. “We choose to keep service running at the highest level conditions will allow.”

“We’ve devised a plan that will keep riders moving,” Rogoff said. “This unavoidably disruptive period is the inconvenience we all must face so we can enjoy the extraordinary convenience of traveling to ten new light rail stations across the Eastside in 2023. By scheduling this construction during our slowest weeks for light rail ridership, we aim to inconvenience the fewest number of riders possible.”

Rendering of East Link light rail trains operating on the I-90 floating bridge. (Sound Transit)
Rendering of East Link light rail trains operating on the I-90 floating bridge. (Sound Transit)

Sound Transit says that construction on the tie-in will begin next January and continue into mid-March. During this timeframe, passengers can expect lower-than-normal frequencies every 12 minutes. That frequency will apply to service in both directions. To compensate for the crowding this will create at peak times, Sound Transit plans to put four-car trains into service. At some hours of the day, this actually could be considered a service improvement, but it will be a challenge at peak hours and still mean longer travel times.

The timing of construction is intentional. Rogoff told the Rider Experience and Operations Committee yesterday that there were three primary reasons for the chosen construction period:

  • Buses will no longer be in the Downtown Seattle Transit Tunnel;
  • The early part of the year is the lightest travel period for light rail passengers; and
  • It will be the last season where it will be slow in system operations as test of the Northgate Link extension is likely to occur in early 2021.
Diagram of the full closure weekends. (Sound Transit)
Diagram of the full closure weekends. (Sound Transit)

For three weekends of the construction period, Sound Transit will have to fully close International District/Chinatown Station and several other stations in the Downtown Seattle Tansit Tunnel. During this period, trains will still operate, they just will not operate through the closed stations. Instead, trains will run from University of Washington Station to Westlake Station and Stadium Station to Angle Lake Station. Sound Transit will put a special shuttle bus in place to bridge the service gap between stations.

The delicate dance that trains will have to make changes over the construction period. There will be two phases as construction progresses. The reason for this is that there needs to be enough a work zone space to build the tie-in tracks for East Link. The first phase will focus on the eastern main track tie-in while the second phase will focus on the western main track tie-in.

Where the temporary center exchange platform will go at Pioneer Square Station. (Sound Transit)
Where the temporary center exchange platform will go at Pioneer Square Station. (Sound Transit)

During the first phase (January through February), trains heading southbound from University of Washington Station will operate as normal until they reach the Downtown Seattle Transit Tunnel at which point they will switch tracks that typically serve northbound trains. They will then proceed as normal in the southbound direction but drop off and pick up passengers on the eastern platforms as the western ones, except for the one at Pioneer Square Station, will be closed. The latter station will be the last station served and a special center exchange platform will be deployed allowing passengers to connect to trains on the other track that will then head southbound. Trains will then reverse to head back northbound and operate as they normally do.

Diagram of the Phase 1 operations, closures, and work zones. (Sound Transit)
Diagram of the Phase 1 operations, closures, and work zones. (Sound Transit)

For passengers heading northbound from stations south of Stadium Station, trains will switch tracks after SoDo Station, which typically serve southbound trains. The trains will then proceed northbound on the track dropping off and picking up passengers center platform at Stadium Station, western platform of International District/Chinatown Station, and the western and temporary center exchange platform at Pioneer Square Station. Again, passengers will be able to change trains at Pioneer Square Staton to continue northbound. Trains will then reverse direction and operate as normal.

During the second phase (February through March), trains heading southbound from University of Washington Station will operate as normal as far as Pioneer Square Station. A special center exchange platform will be deployed at the station allowing passengers to connect to trains on the other track that will then head southbound. Trains will then reverse to head back northbound picking up and dropping off passengers on the western platforms at other stations in the Downtown Seattle Transit Tunnel, as the eastern platforms will be closed. After Westlake Station, trains will switch tracks to operate as they normally do.

Diagram of the Phase 2 operations, closures, and work zones. (Sound Transit)
Diagram of the Phase 2 operations, closures, and work zones. (Sound Transit)

For passengers heading southbound Pioneer Square Station, trains will be departing from the eastern platform. Trains will then serve the eastern platform at International District/Chinatown Station in the southbound direction and center platform at Stadium Station. After this station, trains will switch to the regular southbound track and operate as normal. In the northbound direction, trains will operate as they normally do as far as Pioneer Square Station. Again, passengers will be able to change trains at Pioneer Square Staton to continue northbound.

Sound Transit also has put out some helpful simulation videos that better visualize how this all works:

The center exchange platform will be fully staffed, Sound Transit said. When trains meet, staff will make sure that the transfer of passengers is orderly and complete, ensuring that no passengers remain on the platform once trains depart. Sound Transit plans to have “gap” trains on the ready in cases where connecting trains do not meet on or near the 12-minute headway.

To help manage the chaos and confusion that the temporary service changes may make, Sound Transit will have ambassadors on platforms to help passengers in the shuffle. Temporary signage will also be put into to place to help direct passengers. In advance of this all, Sound Transit will also work on public information campaigns so passengers will not be surprised at the changes.

Sound Transit staff said the plan should be able to accommodate 3,000 passengers per hour per direction, based upon their modeling. That is in line with what ridership forecasts show for demand. Managing the safety aspect of getting people in and out the stations will be a high priority with operational management.

Sound Transit will also make several changes to facilitate the work next year. The transit agency will construct a center turn-back track at International District/Chinatown Station to facilitate future work, beginning some time this summer. Sound Transit will alsi construction a temporary center exchange platform at Pioneer Square Station, which is slated to occur in October. ORCA card readers may be consolidated to the mezzanine level at stations and remove the ones at platforms, but that is no decision has yet been made yet. Once buses come out of the Downtown Seattle Transit Tunnel, the platforms will always be a proof of payment zone.

The temporary service disruptions next year will no doubt be a challenge for passengers, but they are better than the alternative of a full shutdown that would debilitate the entire transit network with passenger overload. It will be worth the interim pain when East Link opens in 2023 and frees transit users from cross-lake traffic congestion.

Correction: At the time of publishing, The Urbanist had relied upon outdated information supplied by Sound Transit on when the turn-back track would be constructed and modification of ORCA readers. This article has been updated to reflect the new plans for these construction items.

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