Stride S1 Line Updates: TIBS Reroute, Renton Station Swap, and More

Edit, September 10, 7pm: the original article has been updated to correct errors and clarify statements with input from Sound Transit. We regret the errors.

Sound Transit's Stride S1 Line, the bus rapid transit (BRT) project approved under ST3 to connect Bellevue to Burien via South Renton in 2028, has been updated over the last year to include support for full electrification, temporary route changes around the Tukwila International Boulevard Station due to issues with fish water culvert requirements, and consideration of potential station location swap in South Renton.

While some of these changes are being spun to imply better connectivity for future riders, the real impact is in making the line slower and likely less useful for future riders, compromising the S1 Line's original goals of prioritizing speed as a compromise for skipping major destinations in South King County. For the S1 Line to represent a real improvement in transit service worth the capital investment, Sound Transit must find ways to make up for these potential degradations in future service.

South Renton Station and Electrification

Originally, Sound Transit's proposed South Renton Transit Center project focused on building lots of parking with the centerpiece being a new 700-stall multi-story parking garage next to transit-oriented development. However, construction of the parking garage was delayed to at least 2034 during the Sound Transit Board's Realignment of its major capital projects.

Final design of the Renton Transit Center, from Sound Transit's SEPA Checklist Addendum.

Changes to the transit center are reflected in Sound Transit's SEPA checklist addendum published in June 2024, showing a near-complete redesign of the station area. As part of Sound Transit's 2023 updates to Stride to support all-electric battery-bus service, the now-deferred parking garage has been replaced by a larger layover facility with chargers, and the TOD plot has been replaced by a large interim surface parking lot. Rachelle Cunningham, a Sound Transit Public Information Officer, told the Seattle Transit Blog the layovers and electrification are for King County Metro's use, as the transit center will be a major hub for KCM and ST service".

Meanwhile, ST's design documents indicate the parking area could eventually be redeveloped with TOD. Rachelle Cunningham stated that surface parking is interim, rather than leaving the site fenced off and unusable until the garage is built" but affirmed that transfer of that land to a TOD developer would follow completion of the parking garage in 2034, or later.

South Renton Land Swap?Red Lion with P circle and across South Grady Way from proposed Transit Center (Google Maps).

As Sound Transit has been moving forward with remediation and design of the planned Transit Center on the north side of Grady Way, the City of Renton seems to have other plans in mind. As revealed in a May 14, 2024 Sound Transit Memo obtained by The Urbanist, Renton has proposed swapping the South Renton Transit Center and the Red Lion property owned by King county.

The supposed benefits of this location include placing the station closer to the S1 Line's route on I-405, but travel time benefits are unquantified. Conversely, this would place the transit center even farther from downtown Renton and force most transit riders to cross the busy, 6-lane South Grady Way.

Rachelle Cunningham affirmed that Sound Transit is committed to the original station location, telling the Blog construction at the original station location is expected to begin in 2025".

Salmon Problems

As reviewed in a January 25th 2024 board meeting, WSDOT unfortunately found that the construction of the planned S1 Line station in SR-518 next to the Tukwila International Boulevard Station, or TIBS, would trigger rebuilding a major water culvert to be fish-passable. This would greatly increase the station project costs to an unaffordable level. Based on this determination, Sound Transit has decided to move forward with a new route using the existing freeway ramps to reach TIBS instead. This project isn't the only facing cost issues associated with fish passage requirements; earlier this year, the Seattle Times ($) dove into the expectedly high costs associated with meeting the decade-old landmark ruling requiring rehabilitation of culverts and other barriers between critical salmon habitats.

TIBS S1 Re-Route: WestboundThe likely westbound route of Stride S1 to TIBS without an in-line freeway station (Google Maps)TIBS S1 Re-Route: EastboundGoogle maps refuses to route using the eastbound freeway ramps next to international boulevard given the 3 lane change to continue traveling east on SR-518, but it's possible the Stride bus might still use it (Google Maps)

Although sending the S1 Line to the existing Tukwila International Boulevard Station would save on culvert replacement and slightly shorten transfer times between the BRT line and Link, the new route would add roughly six minutes of travel time to the line. For a line meant to cut travel time between Bellevue and Burien from 55 minutes to 38-42 minutes, a 6-minute travel time increase is a serious hit to the expected time savings.

Although it appears an in-line station is out of the cards for now, Sound Transit will continue design of the in-line station in case funding to pay for the fish passage project becomes available in the future.

Update, 9/10: Rachelle Cunningham informed the Blog the culvert failed in June and emergency repairs are underway by WSDOT, but ST remains committed to the in-line station" and the route deviation to serve TIBS directly is an interim solution until the in-line station is built". The Blog has asked for clarification on the potential schedule for construction of the in-line station, and will provide readers with any updates.

Bellevue to Renton Express Lane Construction

WSDOT also recently presented an update on its construction of new express lanes as part of its I-405 Renton to Bellevue Toll Lanes project. The project is adding one new express lane and converting the existing HOV lanes for a total of two express lanes in both directions from Renton to Bellevue. The Stride S1 Line is expecting to utilize these new lanes to bypass traffic on the congested interstate.

Sound Transit is also working with WSDOT on a few major in-line station construction projects for its Stride lines. Between Renton and Bellevue, WSDOT recently highlighted a pair of direct access ramps which are under way: one at Northeast 44th street in May Creek which will be served by Stride with a bus station, and the other at 112th Ave Southeast serving the Newport Hills Park and Ride, which will not be served by Stride.

Rendering of the 44th Street interchange (WSDOT)

The new 44th Street interchange will feature direct bus access ramps and a transit station as shown in WSDOT's rendering, above. The transit stop is near the Seahawks training facility, but besides that the only nearby destinations are single family homes.

Conceptual design of the reconstructed 112th Avenue Southeast/Lake Washington Boulevard interchange direct access ramp, next to the Newport Hills Park & Ride (WSDOT)

The Newport Hills Park and Ride is currently served by Sound Transit's Route 560, which is expected to be replaced by the Stride S1 Line. Although WSDOT is designing a whole new interchange featuring direct access ramp, space for a potential transit stop, and expanded parking, Sound Transit perplexingly has no plans to have the S1 make use this new infrastructure.

S1 Losing Speed and Still Weak on Service

While the Stride S2 Line (Lynnwood to Bellevue) is being enhanced with more center-running freeway stations, the S1 Line is on a slippery slope to being no faster than the 560 it plans to replace while serving far fewer destinations. The route of the S1 Line originally skipped Renton Landing, downtown Renton, the Tukwila Sounder Station, and Southcenter to provide much faster travel times between Bellevue and Burien by serving only a few freeway stations. With the temporary" loss of the freeway station in Tukwila, an undecided station location in Renton, and still-poor network connectivity elsewhere, the S1 Line is losing speed and still missing many important destinations.

Unless Sound Transit can find a way to get the S1 to serve more (or better) destinations or recover some of these loses in speed, it seem that it might need to go back to the drawing board to deliver useful BRT service between the South King and East King subareas. They might consider additional enhancements to Metro's RapidRide F and the existing Route 560, which currently cover the S1 Line's service area. If the S1 Line can't deliver on its promise of faster travel at the cost of very few stations, the best use of transit dollars might be toward less-flashy but more reliable projects such as more BRT-like improvements for these existing lines.

What do you think Sound Transit could do to make up for these potential impacts to the S1 Line's service?