Ridership Patterns for RapidRide A Line

King County Metro's RapidRide A Line travels inbound from the Federal Way Transit Center to Tukwila International Boulevard Station, primarily along State Route 99. Outbound trips travel in the reverse direction. In November 2024, the A Line was the third busiest bus route in King County with 9,407 average weekday boardings.

As noted in a 2023 STB article by Andrew Bowen, the A Line is one of the most efficient Metro routes in terms of Rides per Platform Hour. This metric tracks how many people use the route for every hour a bus is operating it. Given the ridership data below, this is not too surprising. The A Line is heavily used for shorter trips and almost every stop has a few passengers boarding or alighting per trip.

A Line MapAverage Ridership Per Trip

For the first time in this series, the data shown in the graphs were collected during the Spring 2024 service change, from March 30, 2024 to September 14, 2024. The plots below show the average weekday ridership by stop in each direction, color-coded by time of day. For a more detailed breakdown of how the plots are set up, please refer to the How to Read the Plots section of the article discussing Route 70.

Average Weekday Ridership per A Line Trip: March 2024 to September 2024. Inbound" is toward Tukwila International Blvd Station; Outbound" is toward Federal Way Transit Center. Click the plot to view at full-resolution in a new tab.

The ridership patterns for the A Line show a route with strong all-day ridership between the many commercial and residential areas it serves. Some observations:

• Similar to several other RapidRide routes, the A Line's outbound terminus in Federal Way is located at a transit center surrounded by low density retail and a few apartment buildings. This stop is busy all day, with almost 10 passengers boarding or alighting each A Line trip. The Federal Way Transit Center is a Park & Ride facility with 1,190 spaces and also serves Metro routes 177, 179, 181, 182, 183, 187, 193, 197, DART 901, DART 903, Sound Transit routes 574, 577, 578, and Pierce Transit routes 402, 500, 501.
• North of the transit center, the next two stops at Pacific Hwy S & S 316th St and Pacific Hwy S & S 312th St have decent ridership. Inbound trips primarily pick up passengers while outbound trips primarily drop off passengers. These stops serve the north end of the Federal Way commercial area.
• The stop at Pacific Hwy & 308th St is next to Federal Way High School. Both inbound and outbound morning trips have more passengers alight here than at adjacent stops, suggesting some students use the A Line to get to school.
• Outbound morning trips have an overall increase in ridership south of 272nd St. This suggests some riders who live between 272nd St and the Federal Way Transit Center use the A Line to get to their job in Federal Way, or as a connection to the many other routes that serve the Federal Way Transit Center. A similar pattern was observed with the H Line in Burien.
• Between 272nd St and 252nd St, the A Line stops adjacent to several big box retail and grocery stores. These stops have decent ridership churn throughout the day, with the exception of the stop at 268th St. The stop at 268th St serves the Woodmont Library, Woodmont K-8 School, and part of the Woodmont residential neighborhood. It has minimal inbound ridership and less outbound ridership than the other three stops in this section.
• Highline College is located walking distance from the A Line stop at Pacific Hwy & 240th St. Inbound morning trips primarily drop off passengers, while inbound trips later in the day and all outbound trips have more even ridership churn. Riders can easily transfer to Route 165 at this stop.
• In Des Moines, the A Line has good all-day ridership at International Blvd (inbound)/ Pacific Hwy (outbound) & 216th St. This stop is adjacent to a few apartment buildings and a Safeway grocery store. Note: International Blvd and Pacific Hwy are the same physical road, only the name changes at 216th St.
• The Link 1 Line's current southern terminus, Angle Lake Station, is one block west of the A Line stop at 200th St. Inbound trips primarily see passengers disembark at this stop, likely to transfer to the 1 Line. Likewise, outbound trips have quite a few passengers board at all times of the day. Late night/early morning inbound trips have a spike in passengers boarding at this stop. One possible explanation for this pattern is these riders parked in the Angle Lake Station Park & Ride before the 1 Line starts service for an early morning shift and will use Link for their return trip later in the day.
• Just one stop north at 195th St, the A Line serves Angle Lake Park, the Alaska Airlines Headquarters, and various hotels. Morning trips in both directions primarily drop off passengers, while trips at other times in the day have more even boarding and alighting counts. This suggests some Alaska Airlines employees use the A Line to get to work, or as a last mile connection from Link.
• Seattle-Tacoma International Airport is served by two A Line stop pairs, at 180th St (inbound)/ 182nd St (outbound) and at 176th St. These stops also provide access to numerous hotels and the nearby residential neighborhood. Passengers can transfer to Metro routes 156, 161 and Sound Transit routes 560, 574. A full breakdown of the A Line's ridership at these stops is in the section below.
• The A Line's northern terminus at Tukwila International Blvd Station is consistently busy. Over 10 people board or alight each A Line trip. This station is a Park & Ride with 600 spaces and also serves routes 124, 128, F Line, and Link 1 Line.

Seattle-Tacoma International Airport

The A Line has two stop pairs that serve the airport: International Blvd & S 176th St and International Blvd & S 180th St (inbound)/ S 182nd St (outbound). The 176th St stop is adjacent to the SeaTac/Airport Link Station. To travel between the airport terminal and this stop, passengers use the parking garage corridor, pass through the Link station, and cross International Blvd via an overpass (red path on the map). Passengers traveling to or from an outbound A Line trip will also need to cross back over International Blvd at street level (yellow path).

The 180th St/182nd St stop pair is located near the southern end of the airport terminal. To access these stops from the terminal, passengers exit baggage claim and use a sidewalk next to Arrivals Drive (blue path). At the intersection with International Blvd, passengers traveling outbound need to continue about 200ft to the south to reach the A Line stop. Passengers traveling inbound will need to cross International Blvd and continue about 750ft north to reach the stop at 180th St (purple path).

Given the stop locations, the ridership between these two stops is unsurprising. For inbound A Line trips, the stop at 176th St has significantly more riders alighting than the stop at 180th St. The stop location for 180th St discourages ridership from airport-bound passengers. Late-night (10pm-5am) inbound trips are an exception, as more passengers alight at 180th St than at 176th St. For outbound trips, ridership is more evenly distributed between the two stops. The stop at 182nd St is arguably more convenient than the outbound stop at 176th St as it does not require taking the overpass over International Blvd, then crossing back to the stop at street level. The stop at 182nd St has much higher late-night ridership than the stop at 176th St.

Map of SeaTac Airport from OpenStreetMap, edited by the authorDaily Totals per Stop

The average daily total boarding and alighting counts show a similar pattern to the per trip data. The A Line stop at Tukwila International Blvd Station likely has the highest single-route ridership for a stop pair in the entire King County Metro network.

Average A Line Weekday Boarding and Alighting Counts: March 2024 to September 2024. Inbound" is toward Tukwila International Blvd Station; Outbound" is toward Federal Way Transit Center. Click the plot to view at full-resolution in a new tab.Looking Ahead

The Federal Way Link Extension (FWLE) is an eight mile extension of the Link 1 Line from Angle Lake to Federal Way with stops at Kent Des Moines and Star Lake. Sound Transit estimates it will open in Spring 2026. To better align bus service with this extension, King County Metro has released an initial restructure proposal, previously covered on the Blog by Wesley Lin. In the proposal, the A Line is only mentioned as getting improved service. From a ridership perspective, the FWLE will likely cause two significant changes to the A Line. First, riders who use the A Line to connect from the Federal Way Transit Center to the Link 1 Line will now just use Link directly. Second, the new direct connection between the A Line and Link at Kent Des Moines may encourage more transit trips in the immediate area, as riders can use the A Line as a quick last-mile connection to Link.

Comments are limited to south King County transit. Comments about the new federal administration starting today belong in yesterday's open thread.