Sound Transit’s ridership numbers in their various reports have always been rather “curious”. For example their 2014-year-end quarterly reports “average weekday ridership” as 32,924 and total yearly ridership as 10,950,276. However, if you multiply the “weekday” ridership by the number of weekdays (260) you get 8,560,240 or 78% of total. The other 2,390,036 yearly riders must have used light rail on the 104 weekend days for an average of 22,981 riders. That seems rather “high” for Saturdays and Sundays.
The Sound Transit projection their “University Link will add 71,000 riders to the system by 2030, "bringing the system-wide total to 114,000” is also “curious”. It “suggests” that Central Link will only have 43,000 daily riders in 2030. Not exactly optimistic since their 2018 projection for their Angle Lake Station adds “5,400 daily riders coming and going”. ST makes up for that lack of “optimism” with their 71,000-rider claim for the UW extension.
The 71,000-claim raises two questions. First, one would have thought an extension that tripled the ridership would have a high priority. Why wait until 2016 to begin operating the UW extension? Second, where will all the riders come from? It’s difficult to believe those commuting between Seattle and UW will be more than a fraction of that number.
The UW Link could have added thousands of riders if ST had included a T/C near the UW station. The T/C would have provided an interface between 520 BRT and Central Link for thousands of riders from both sides of the lake. (The UW T/C would have twice the capacity of what ST can achieve with their plans to use South Bellevue and Mercer Island T/C's to transfer all I-90 cross-lake bus riders to East Link). It would have generated more ridership than what ST will get from the billions they'll spend on Central Link extensions to Northgate and beyond.
Other ridership numbers are even more “curious”. For example the ST Table 1 “Sound Transit Ridership” from the 2015 Financial Plan (June 2015) predicts that Link Light Rail ridership will increase from 10.9 million in 2014 to 84.1 million in 2030. Assuming 78% of the yearly ridership is on weekdays, 78% of the 84.1 million riders during 260 weekdays in 2030 would require 252,300 riders daily, 90,000 more than the combination of the 114,000 Central Link and 50,000 (also "curious") East Link predictions.
As “curious” as their June 2015 financial plan ridership predictions are, the Aug 5 Green bond announcement prediction is even “curiouser”. That announcement, which presumably reflected what ST told investors, predicted daily ridership would be 350,000 by 2030. It’s “likely” those buying the bonds will not be “pleased” with the 186,000-rider discrepancy and the potential loss in “fare box revenue”.
It’s not clear whether Sytemalytics evaluated the financial as well as the environmental details. Like everything else about Sound Transit, somebody should have.