King County Metro’s Most Productive Routes

King County Metro recently completed the 2025 System Evaluation, which is expected to be published later this month. This report is a review of Metro's service in 2024 and highlights where additional service is needed. This article will focus on the Route Productivity data shared in Appendix H. Upcoming articles will discuss other sections of the report.

Northbound A Line bus on International Blvd (Andy Tucker)

King County Metro measures route productivity using two metrics:

• Rides per platform hour (RPPH): how many people are using a route relative to how many hours it is in operation
• Passenger miles per platform mile (PMPPM): how far people are traveling on a route relative to how many miles the route serves.

Both are important measures for how well a route is serving communities in King County. Routes with a high number of rides per platform hour are serving a lot of trips. Routes with more passenger miles per platform mile are used by passengers for longer trips.

Most Productive Routes By Rides Per Platform Hour

The System Evaluation reports each route's RPPH by weekday peak, weekday off-peak, weekday night, Saturday, and Sunday. To simplify this analysis, we've calculated the weighted average RPPH for each route. The top ten routes are listed below, along with the RapidRide routes that did not make the top ten. Click/tap on a route to see its schedule and map. Note: Only routes that run during all time periods were considered.

Rank	Route	Weighted Average Rides per Platform Hour
1	A Line	39.73
2	E Line	39.71
3	8	39.27
4	D Line	36.75
5	7	35.51
6	44	33.01
7	45	32.82
8	67	32.06
9	G Line	30.23
10	2	29.73
11	H Line	29.63
15	B Line	27.44
21	F Line	25.53
30	C Line	23.47

The A Line continues to be one of the most efficient routes in King County. The route's direct path and use of HOV lanes make it a fast and reliable option for many trips along Pacific Highway. Andrew Bowen discussed the surprising efficiency of the route in a 2023 article. The E Line is the highest ridership route in King County. Similar to the A Line, it follows a direct path on a state highway. Unlike the A Line, the E Line travels to downtown Seattle. Route 8 rounds out the top 3 most productive routes. As discussed in the post about the Route 8's ridership patterns, the east-west section has significantly more ridership than the north-south section. The route is also prone to significant delays due to traffic on Denny Way. These delays have caused some would-be passengers to use other travel modes, suggesting the route is not operating at it's full ridership potential.

The D Line, Route 7, and Route 44 rank fourth, fifth, and sixth, respectively. Each of these routes serve a primary corridor in Seattle. Routes 45 and 67 rank seventh and eight. Both of these routes connect UW with several north Seattle neighborhoods. Metro's newest RapidRide route, the G Line, is the 9th most productive route. After a rocky launch, the route has seen a ridership increase in 11 of the past 12 months. Given the 50% year over year ridership increase, expect the G Line to rank higher next year.

Average Weekday G Line Boardings in 2024 and 2025.

Route 2 is Metro's 10th most productive route. The route connects several dense close-in neighborhoods with downtown Seattle. RapidRide lines B, C, F, and H did not make it in the top ten, but they are all still high performing routes. As one would expect, routes with high number of riders per platform hour serve corridors with lots of destinations. This results in a given bus trip serving more people as passengers get on and off throughout the route.

Most Productive Routes By Passenger Miles Per Platform Mile

Passenger miles per platform mile (PMPPM) is another key metric used by Metro to evaluate route productivity. This metric focuses on how far people travel on each route. Routes with a high PMPPM may benefit from dedicated transit lanes, stop consolidation, and off-board payment as these treatments speed up travel times. Reducing dwell times by 10 seconds per stop adds up for passengers traveling a longer distance. The ten routes with the highest PMPPM during peak hours (M-F, 5am-9am, 3pm-7pm) are listed below.

Rank	Route	Peak Passenger Miles per Platform Mile
1	H Line	13.7
2	A Line	13.6
3	E Line	13.4
4	44	12.2
5	D Line	12.2
6	101	12.2
7	150	12.1
8	131	11.8
9	5	11.5
10	311	11.4
14	C Line	10.9
21	B Line	8.8
39	F Line	7.5
58	G Line	6

Longer routes that connect downtown Seattle with neighborhoods farther from downtown dominate the top of this list. Many of these routes are already RapidRide routes (D, E, H) or have a highway/express component (5, 101, 150, 311) to speed up longer trips. Route 131 serves downtown but does not have the RapidRide treatment or an express component. It's high PMPPM is likely due to the lack of faster alternative routes for most passengers. Ridership patterns for Route 131 show many passengers travel between White Center Heights or Highland Park and downtown Seattle. Two routes in the top ten do not travel downtown: the A Line and Route 44. The A Line connects the Pacific Highway corridor with the Link 1 Line, F Line, and Sea-Tac airport. Route 44 is an essential east-west route that connects Ballard, Fremont, and Wallingford with the University of Washington.

Metro's Most Productive Route

With the most rides per platform hour and the second most peak passenger miles per platform mile in Metro's network, the A Line was the most productive route in 2024. It may not serve the densest part of the county, but it does what good transit should do: gets a lot of people to their destinations, quickly and reliably. With the Federal Way Link Extension opening next month, the A Line's ridership and productivity are about to change. Will its productivity decrease as some passengers switch to Link? Will its productivity increase as it now acts a feeder route to several new Link stations? Only time (and Metro's future System Evaluations) will tell.