The $174 million RapidRide I Line between Renton, Kent, and Auburn is poised to start construction soon after Metro's receipt of a FTA grant in the final days of the Biden Administration. (HBB Landscape Architecture)

King County leaders Wednesday celebrated the receipt of a $79.7 million grant from the Federal Transit Administration for the RapidRide I Line. The 17-mile enhanced bus route will run between Renton, Kent, and Auburn and replace the existing Route 160. In the works since 2019, construction along the corridor is set to start in the coming months, with a grand opening planned for 2027.

The I Line will be King County Metro’s tenth RapidRide line to start construction and the first to open fully outside Seattle city limits since the F Line in 2014. RapidRide is Metro’s enhanced bus brand that includes some bus rapid transit (BRT) features, such as off-board payment, dedicated bus lanes, and real-time arrival displays at enhanced bus shelters.

Metro secured the federal allocation just days before the Trump administration prepares to take office, with future federal funding for transit very much at risk in a second Trump term. Several transit projects in the Seattle metropolitan area experienced delays getting grants during the last Trump presidency.

Along with its sizable direct federal contribution, the I Line is being funded by $19 million in federal dollars allocated via the Puget Sound Regional Council (PSRC) and $27 million from the State of Washington. The project’s total estimated cost is $174 million.

The RapidRide I stretches from Renton to Auburn, providing connections to transit hubs like South Renton Transit Center, Kent Station and Auburn Station. (King County Metro)

In contrast with other recent RapidRide projects, like the G Line along Seattle’s Madison Street or the H Line between Downtown Seattle and Burien, the I Line will include less reconstruction of full corridors where Metro’s buses operate and more spot improvements. Lighter-touch transit upgrades, including transit signal priority (TSP) and redesigned intersections will be combined with just under two miles of business access and transit (BAT) lanes to provide quicker, more reliable trips. BAT lanes are curbside lanes that drivers are allowed to use to turn right, but are otherwise for dedicated bus use.

By 2040, RapidRide I upgrades are projected to provide travel time savings exceeding eight minutes during the PM peak period from one end of the corridor to the other — substantial time savings, but less dramatic than other recent RapidRide projects. More frequent buses will also be a boon for riders, meaning less time waiting at stops.

“We’re launching a transformative opportunity in some of the most critical parts of our county: Renton, Kent and Auburn,” said Chris O’Claire, Metro’s mobility division director. “If you think about Sound Transit and where they’re expanding — north, east and south — there’s an opportunity for us to make a real connection with RapidRide through Renton, Kent and Auburn. It’s an area that isn’t connected well by fast, frequent, reliable service that has the capital investments that are represented in RapidRide.”

The RapidRide I Line includes light-touch transit upgrades like BAT lanes that get coaches through intersections faster, rather than full-corridor priority. (HBB Landscape Architecture)

The I Line has the potential to build on land use changes that are already happening in the cities where it runs. In Renton, the I Line will connect with the F Line at South Renton’s transit center, turning the area into a transit hub with the launch of Sound Transit’s Stride BRT service to Burien, Bellevue, and points beyond. Renton has been paving the way for increased development in that area, though some of the choices around how that development is intended to take shape may hold back the area’s full potential, maintaining wide, high-speed state highways through areas that are intended to become more transit-oriented.

Meanwhile Kent’s newly adopted Comprehensive Plan is set to encourage more mixed-use development along 104th Avenue SE, also known as the Benson Corridor, where the I Line will run. That plan “reimagines Benson Corridor and Kent-Kangley with active centers of mixed-use development supported by commercial and retail uses that provide opportunities for local businesses.”

“Benson Corridor is also currently the location of many culturally significant retail and restaurant uses, which is envisioned to continue to grow as a destination,” the Kent Comprehensive Plan states. “New housing options along the corridor will leverage public transit investments and support local businesses.”

The newly adopted Comprehensive Plan in Kent envisions the RapidRide I corridor, along Benson Corridor in addition to Downtown Kent, as being a focus of development that will create a positive feedback loop for transit ridership. (City of Kent)

South King County saw fewer ridership losses during the pandemic and many of its bus routes recovered quickly, which indicates an area with more transit-dependent riders and service workers that cannot work remotely. Metro acknowledged the need is great in South King, while major transit investments have been sparser than in other parts of the county.

“For far too long, South King County has been underserved in its transit options, and it’s also where a lot of growth in the county and where a lot of affordability in the county is, so it’s our responsibility to connect these communities through these investments,” said Metro General Manager Michelle Allison.

Along with the direct transit upgrades, the I Line includes pedestrian upgrades, including over 50 improved crosswalks and 11 street crossings that don’t currently exist, connections that fill in gaps in the network that prevent people from being able to access transit and other amenities. And upgraded stations up and down the corridor will provide real-time information for bus riders. And of course, ADA upgrades that make it easier for people with disabilities to access the RapidRide stations.

“The new RapidRide I Line is a big investment, and it is going to make a big difference. It offers a seamless, efficient travel experience for all people of all abilities: young, and old, and those in between,” Allison said. “We also know that investments like these help us live up to our commitment of a safe, clean and reliable community where transit connections have the infrastructure that helps support people’s choices to use mobility, instead of single occupancy vehicles. The infrastructure of lighting, technology, sidewalks, frequency, all of those lead to a vibrant transit network, and we’re going to build that in the I Line.”

While no additional RapidRide lines are currently in the pipeline for South King County, a new prioritization report highly ranked the Route 150, between Kent and Downtown Seattle via Tukwila, on a list of potential future RapidRide Lines. That report found that an upgrade to RapidRide would roughly double ridership, bringing in 4,000 daily riders simply on its own, a staggering number that illustrates the missing potential of not moving faster on RapidRide network expansion. With growth in South King County not expected to slow down anytime soon, projects like the RapidRide I Line can’t come fast enough.

Article Author

Ryan Packer has been writing for The Urbanist since 2015, and currently reports full-time as Contributing Editor. Their beats are transportation, land use, public space, traffic safety, and obscure community meetings. Packer has also reported for other regional outlets including Capitol Hill Seattle, BikePortland, Seattle Met, and PubliCola. They live in the Capitol Hill neighborhood of Seattle.