Sounder Ridership By Station

6:46 am Sounder at Lakewood Station (photo by the author)

Since its launch back in 2000, Sounder Commuter Rail has had a split personality, with its South Line widely heralded as a smashing success and its North Line as, at best, a series of disappointments. Except for Tacoma and Lakewood, both lines are considerably faster than their bus counterparts in peak-of-peak, and they scale incredibly well when the demand is there, as the marginal cost of adding railcars is almost nothing as long as platform lengths are sufficient.

But beyond the most commonly reported metrics - riders per train and daily ridership - I thought I'd check in on ridership trends between stations and look at things like average load factor. Who rides from where, and how full are the trains on average, etc? Who rides between intermediate, non-Seattle stations? How many people ride the reverse peak trains? Charts, data, and commentary after the jump.

Appendix D of the 2015 Service Implementation Plan (page 163) has a wealth of data, including boardings by station by time of day, including the two reverse-peak trains between Seattle and Tacoma. The charts below are my own, while the table is from Sound Transit. Looking at the data, several interesting trends stand out:

• Peak load occurs in Kent. On average, each AM northbound train leaves Kent with 645 passengers, a figure that is likely much higher at peak-of-peak. South Sounder's current capacity is 1,038 per train. If the earliest and latest trains are relatively lagging, this supports Sound Transit's goals of adding peak-of-peak frequency instead of increased peak span of service.
• Lakewood and South Tacoma are badly underperforming. Lakewood and South Tacoma board just 34 and 19 passengers per train each morning, respectively, meaning trains are 95% empty upon inbound arrival in Tacoma. But given peak loads in Kent, this may be a blessing in disguise for Sounder capacity. A well-performing Lakewood and South Tacoma would likely mean either standing-room only for Kent and Tukwila passengers or a move to express or skip-stop Sounder schedules.
• Even at 2-car trains, North Sounder isn't quite half full. North Sounder could operate as a 1-car service without capacity issues, but 2 cars are required by safety regulations. The line's current capacity is 290 per train, but trains top out with an average of 134 passengers when leaving Edmonds inbound.
• Reverse peak trains carry approximately 50 people per trip, half of which board in Seattle or Tacoma, and half of which board at intermediate stations. Intermediate stations have roughly an even proportion of boardings and alightings, meaning that the trains maintain approximately 50 passengers throughout the trip.
• 10% of South Sounder boardings are headed for intermediate stations.Every morning, 70% more passengers alight at Tukwila than board, indicating Boeing has a solid number of Sounder riders. Approximately 1,250 daily passengers are headed for intermediate stations, 75% of which at Kent or Tukwila.