Ridership Patterns for King County Metro Route 70

A few months ago, I was waiting for a Route 7 bus and was frustrated by the far too common bus bunching along Rainier Ave. When the bus arrived at my stop, it was followed immediately by two other Route 7 buses. I spent some time thinking about simple changes King County Metro (KCM) could implement to reduce bunching in Rainier Valley. One idea seemed to make sense: turn some northbound buses around at the Mount Baker Transit Center. To further back up my idea, I requested stop-level ridership data (boardings, de-boardings, and bus passenger load) by time of day for Route 7 and numerous other routes from King County. While the actual ridership patterns invalidated my turn-back idea, plotting the data showed some interesting stories hidden in the numbers.

Fortunately, I can share this detailed ridership data with the Seattle Transit Blog community. Through a series of posts, I'll share the results for various routes in the KCM network. Like the data shared in Bruce Nourish's excellent series of posts on 2010 ridership patterns, these numbers are gathered by the Automated Passenger Counters (APCs) present on almost all KCM buses. Metro reports these totals per service change, with each service change lasting approximately three months. Although there is potential for error with APC data, the large number of trips over the course of a service change absorbs the impact of one-off errors or missing values. To smooth out potential outliers and errors, I calculated an annual average across three service change periods spanning March 2023 to March 2024: March 18, 2023 to June 10, 2023; June 10, 2023 to September 2, 2023; and September 2, 2023 to March 30, 2024.

I'll get to Route 7 soon, but let's start the series with the results from Route 70, soon to be converted into RapidRide J. The plot below shows average weekday ridership by stop in each direction, color-coded by time of day.

Average Weekday Ridership per Route 70 Trip: March 2023 to March 2024. Inbound" is toward Downtown; Outbound" is toward University District. Click the plot to view at full-resolution in a new tab.How to Read the Plots

Stops are listed on the left axis; passenger counts along the bottom. For each color-coded time period, the bars represent how many people got on or off the bus at each stop. Centered on zero, the right-hand bar shows boardings as positive passenger count and the left-hand bar shows de-boardings as negative passenger count. The dots represent how people were on the bus when it departed the stop. From this data, we can see where along the route the bus is busiest, where riders are mostly getting on or off, and where most riders are simply passing through.

Each plot will have up to 5 values per stop, one per time of day: morning (AM"; 5am to 9am), midday (MID"; 9am to 3pm), evening (PM", 3pm to 7pm), late evening (XEV"; 7pm to 10pm), and overnight (XNT"; 10pm to 5am). The stops are listed in the order returned by the OneBusAway stops-for-route API. Some stops will not have data for all time periods, this is most often due to slightly modified route paths based on time of day (for example: Routes 7 and 49 through-run each other in the evening and early morning).

Finally, the data is split into inbound" and outbound" trips. This is a direction value determined by KCM. For most routes, inbound trips travel towards downtown Seattle. If a route does not travel to downtown Seattle, the direction towards a transit center or other trip generator is assigned the inbound" direction. In the plots shared for each route, inbound trips travel from top to bottom, while outbound trips travel from bottom to top.

Looking at Route 70

King County Metro's Route 70 travels inbound from University District to downtown Seattle, primarily on Eastlake Ave. It passes through Portage Bay, Eastlake, South Lake Union (SLU), and Denny Triangle. Outbound trips travel in the reverse direction. In August 2024, Route 70 had 4,819 average weekday boardings.

The overall ridership patterns for Route 70 show strong all day ridership, further boosted by several distinct commute trips.Some observations:

• University District is a significant population center with strong inbound boardings throughout the day. Some of these riders may be transferring from the U District Link Station, but most are boarding at stops near dense residential development.
• Outbound morning data show there are some reverse commute trips from Eastlake to the University of Washington (UW). However, the majority of Eastlake residents commuting on Route 70 travel inbound, towards south SLU and downtown.
• Outside of commute trips, the Eastlake commercial area (Eastlake Ave & E Lynn St) has some use, primarily with riders traveling outbound to Eastlake in the morning and returning in the midday or afternoon.
• South Lake Union is a significant job center. Several biomedical companies and the Fred Hutch Cancer Center are located at the northern end of the neighborhood (Fairview Ave N & Yale Ave N). Both inbound and outbound trips have many alighting passengers in the morning and many boarding passengers in the afternoon.
• Passengers can transfer between Route 70, the C Line, and the SLU Streetcar at Fairview Ave & Aloha St (Inbound)/Valley St (Outbound). While these stops do have some ridership churn, the low ridership of the streetcar and C Line in this area suggest transfers are not common.
• Further south, Route 70 serves offices for Amazon and Google, as well as the many retail and service jobs in SLU. Additionally, lots of high density housing has been built in the area (Fairview & Mercer/Harrison and Fairview & Thomas/Denny). Both inbound and outbound trips experience significant ridership churn in this part of SLU. Inbound morning trips drop off passengers from Eastlake and UW, while picking up new passengers heading downtown. Outbound morning trips drop off riders from downtown and pick up passengers headed to Eastlake and UW.
• The high inbound afternoon ridership suggests Route 70 is also used for recreational trips from UW to SLU.
• Ridership between SLU and downtown Seattle is decent throughout the day.As there are a few frequent bus routes (particularly RapidRide C Line and Route 40) traveling between downtown and SLU, the total ridership between these neighborhoods is likely split between these routes.

Daily Ridership per Stop

While the per-trip data is great for understanding ridership patterns across the route, it does not tell the full story for stop utilization. Like many KCM routes, Route 70 runs more frequently during peak hours than during midday or evening hours (every 10 minutes vs 15 minutes). As a result, the per-trip boarding/alighting data does not indicate total ridership for a given stop, as riders in the morning and afternoon are spread across more trips. The plot below shows the average boarding and alighting data for each stop over the course of an entire weekday. Similar to the plot above, the negative bars are passengers getting off the bus and the positive bars are passengers getting on the bus.

Average Route 70 Weekday Boarding and Alighting Counts: March 2023 to March 2024. Inbound" is toward Downtown; Outbound" is toward University District. Click the plot to view at full-resolution in a new tab.

The daily ridership data clearly shows the unbalanced inbound trip boardings and outbound trip departures at U District Station. One scenario that could explain this pattern is someone from north of University District who takes Link downtown in the morning, stops in SLU for dinner or errands after work, then takes Route 70 back to U District Station in the afternoon or evening.

Looking Ahead

King County Metro is planning to replace Route 70 with the RapidRide J Line in 2027. To prepare for the new route, the Seattle Department of Transportation is expected to begin construction along the corridor in October 2024. Planned improvements include new transit lanes, transit signal priority, updated curb ramps and sidewalks, new protected bike lanes, and utility upgrades. Wesley Lin discussed the full details of the project in a recent Blog post.