When SR 99 closed for three weeks, we knew people were relying on Metro, Seattle and the Washington State Department of Transportation to keep them moving.
Review of the West Seattle Water Taxi showed ridership tripled to 30,915 compared to 9,826 in 2018, thanks in part to more frequency and reliability of an added boat, twice as many shuttles and free parking in West Seattle.
Ridership samples also show that after an apparent dip during Week 2 (likely due to lower ridership demand on the Martin Luther King Jr. holiday), Metro finished with higher estimated bus ridership on the 41 routes that were directly affected by the closure, compared to January 2018 baselines. Transit use was up according to Sound Transit also: During the viaduct closure Link light rail ridership was up 14 percent and Sounder ridership was up 4 percent. Between those two services they had more than 15,000 new people using transit.
Clearly, travelers changed their habits – avoiding optional trips, shifting from driving to transit, flexing work schedules or telecommuting, carpooling and taking time off. Metro had 20 buses on standby for when traffic backed up on critical routes and doubled the West Seattle water taxi sailing frequency, adding shuttles and parking at Pier 2 in West Seattle.
Across the 41 routes, Metro collected ridership samples on weekday trips Jan. 14-18, Jan. 21-25 and Jan. 28-Feb. 1. The SR 99 tunnel opened Feb. 4 (but we are still collecting ridership as the travel patterns will evolve for several more months.)
What did we find?
Based on samples and extrapolations, we’ve produced an unofficial ridership tally that helps us understand how ridership might have shifted during the SR 99 closure period. Metro typically provides more than 400,000 bus rides to the region each day across more than 200 bus routes, upwards of 122 million rides per year.
King County Metro bus service on 41 selected affected routes |
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Timeframe | Average Weekday Daily Ridership | Change from Baseline |
Baseline 2018 | 129,918 | |
SR 99 closure Week 1 | 131,422 | +1.2% |
SR 99 closure Week 2 | 121,556 | -6.4% |
SR 99 closure Week 3 | 134,844 | +3.8% |
King County Metro bus service |
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Timeframe | Average Weekday Daily Ridership | Change from Baseline |
Baseline January 2018 | 131,675 | |
SR 99 closure Week 1 | 134,842 | +2.4% |
SR 99 closure Week 2 | 124,426 | -5.5% |
SR 99 closure Week 3 | 137,915 | +4.7% |
It’s too early to say how overall annual ridership will be affected. The recent snowstorm reduced ridership for about two weeks. We’re pleased to see that, based on these extrapolations and smooth traffic overall, transit played a major role in keeping people moving during the biggest closure of a highway in Puget Sound history.
How did we estimate ridership?
Metro has automatic passenger counters on about 50 percent of its fleet. To calculate ridership estimates, it usually takes months of observations and rotating the fleet around King County in order to produce a reliable estimate of ridership – both for totals and daily averages by route.
But during the SR 99 closure Metro collected samples on the 41 most affected routes and compiled sampling data weekly.
Math part: We tallied trips and riders to establish a “January 2018 average” for each of the 41 routes. We then observed as many trips as we were able to using buses with passenger counters. We calculated an average (sometimes plugging in data on an unobserved trip by using a data from the previous month) and multiplied it by the number of scheduled trips and extrapolated an unofficial average daily total. We also calculated average “standby” bus ridership for the extra buses that were temporarily added to the schedule to compensate for traffic congestion.
January 2018 | Week 1 | Week 2 | Week 3 | |||||||
Route | Corridor | Sched. Trips | Summary of Ridership | Sched. Trips | Summary of Ridership | Sched. Trips | Summary of Ridership | Sched. Trips | Summary of Ridership | |
15 | 15th/Elliott | 22 | 1,509 | 22 | 1,448 | 22 | 1,193 | 23 | 1,517 | |
17 | 15th/Elliott | 17 | 1,159 | 19 | 1,227 | 19 | 1,025 | 19 | 1,250 | |
18 | 15th/Elliott | 16 | 1,120 | 17 | 1,187 | 17 | 865 | 17 | 1,142 | |
19 | 15th/Elliott | 11 | 347 | 11 | 370 | 11 | 317 | 11 | 341 | |
24 | 15th/Elliott | 81 | 2,310 | 82 | 2,338 | 82 | 2,118 | 82 | 2,287 | |
33 | 15th/Elliott | 79 | 2,177 | 79 | 2,122 | 79 | 1,871 | 79 | 2,119 | |
D Line | 15th/Elliott | 230 | 14,465 | 234 | 14,371 | 240 | 13,495 | 234 | 14,521 | |
5 | Aurora | 176 | 8,419 | 186 | 8,573 | 186 | 7,857 | 187 | 8,421 | |
26 | Aurora | 87 | 3,005 | 87 | 2,984 | 87 | 2,599 | 87 | 3,185 | |
28 | Aurora | 98 | 3,316 | 101 | 3,436 | 101 | 3,070 | 101 | 3,514 | |
E Line | Aurora | 230 | 17,472 | 259 | 16,816 | 259 | 16,257 | 258 | 17,667 | |
62 | Dexter | 162 | 7,629 | 163 | 8,431 | 163 | 7,884 | 163 | 8,412 | |
101 | I-5 south of downtown | 97 | 4,766 | 122 | 4,689 | 121 | 4,488 | 121 | 5,023 | |
102 | I-5 south of downtown | 14 | 1,013 | 22 | 1,454 | 22 | 1,292 | 22 | 1,479 | |
143 | I-5 south of downtown | 14 | 583 | 14 | 543 | 14 | 486 | 14 | 543 | |
150 | I-5 south of downtown | 130 | 6,068 | 132 | 6,163 | 132 | 5,728 | 133 | 6,578 | |
157 | I-5 south of downtown | 7 | 209 | 7 | 242 | 7 | 194 | 7 | 217 | |
158 | I-5 south of downtown | 12 | 564 | 12 | 540 | 12 | 540 | 12 | 566 | |
159 | I-5 south of downtown | 9 | 367 | 9 | 337 | 9 | 251 | 9 | 351 | |
177 | I-5 south of downtown | 18 | 566 | 18 | 489 | 18 | 360 | 18 | 513 | |
178 | I-5 south of downtown | 15 | 454 | 15 | 417 | 15 | 345 | 15 | 461 | |
179 | I-5 south of downtown | 19 | 811 | 19 | 692 | 19 | 599 | 19 | 746 | |
190 | I-5 south of downtown | 15 | 405 | 15 | 391 | 15 | 344 | 15 | 380 | |
192 | I-5 south of downtown | 8 | 134 | 8 | 120 | 8 | 121 | 8 | 148 | |
193 | I-5 south of downtown | 14 | 487 | 14 | 453 | 14 | 427 | 14 | 466 | |
21 | Viaduct/1st/ 4th |
157 | 4,885 | 162 | 5,040 | 162 | 4,722 | 164 | 5,142 | |
37 | Viaduct/1st/ 4th |
7 | 183 | 8 | 171 | 8 | 162 | 8 | 180 | |
55 | Viaduct/1st/ 4th |
22 | 1,081 | 23 | 844 | 23 | 678 | 23 | 903 | |
56 | Viaduct/1st/ 4th |
17 | 821 | 19 | 666 | 19 | 727 | 19 | 822 | |
57 | Viaduct/1st/ 4th |
8 | 424 | 10 | 409 | 10 | 423 | 10 | 472 | |
113 | Viaduct/1st/ 4th |
11 | 242 | 11 | 227 | 11 | 213 | 11 | 241 | |
116 | Viaduct/1st/ 4th |
17 | 635 | 17 | 530 | 17 | 466 | 17 | 624 | |
120 | Viaduct/1st/ 4th |
164 | 8,430 | 186 | 8,442 | 187 | 7,989 | 185 | 8,832 | |
121 | Viaduct/1st/ 4th |
37 | 992 | 37 | 802 | 37 | 745 | 37 | 927 | |
122 | Viaduct/1st/ 4th |
14 | 508 | 14 | 411 | 14 | 365 | 14 | 431 | |
123 | Viaduct/1st/ 4th |
9 | 355 | 9 | 273 | 9 | 262 | 9 | 282 | |
125 | Viaduct/1st/ 4th |
78 | 1,694 | 78 | 1,479 | 78 | 1,433 | 78 | 1,457 | |
131 | Viaduct/1st/ 4th |
81 | 3,125 | 82 | 3,443 | 83 | 3,044 | 81 | 3,333 | |
132 | Viaduct/1st/ 4th |
80 | 2,793 | 80 | 2,965 | 81 | 2,762 | 81 | 2,941 | |
C Line | Viaduct/1st/ 4th |
238 | 12,214 | 255 | 12,694 | 255 | 12,069 | 254 | 13,434 | |
WT – Vashon | Water Taxi | 12 | 1,003 | 12 | 1,128 | 12 | 964 | 12 | 1,088 | |
WT – West Seattle | Water Taxi | 24 | 754 | 58 | 2,291 | 58 | 1,906 | 58 | 1,983 | |
40 | Westlake | 177 | 12,180 | 192 | 13,191 | 192 | 11,773 | 193 | 12,974 | |
*Total estimates (average figures were rounded to the nearest whole number) |
2,734 | 131,674 | 2,920 | 134,839 | 2,928 | 124,429 | 2,922 | 137,913 |