In its Capital Committee meeting on Thursday, Sound Transit announced its intent to exercise a contract option for an additional 30 light rail vehicles (LRVs) to be purchased from Siemens. This option comes on top of the 122 vehicles Sound Transit ordered last September. The 30 new vehicles will arrive no later than 18 months after the original order has been fulfilled, and the total order will more than triple Link’s fleet to nearly 220 vehicles. Ordering now locks in a lower unit price from Siemens, with price escalation if the Board waits to order beyond May 2017.

Once Northgate is open in 2021, Link will move to all 4-car train operations. The 122 vehicles originally ordered are required to operate the Lynnwood and Overlake extensions opening in 2023, and the additional 30 are required for the Downtown Redmond and Federal Way extensions opening in 2024. The current operating plan calls for 8 minute peak headways on each line and 10 minutes off peak, with combined 4 minute peak and 5 minute off peak headways between Lynnwood and International District Station. Current riders from International District to Angle Lake will see their peak headways decline a bit, from 6 minutes to 8, but will also see capacity boosted by 25%, from 24 LRVs/peak hour to 30.

The Siemens S70 vehicles will be roomier, quieter, and have more bike storage than the current fleet. The aisles will be wider, especially in the center articulated section, improving passenger flow. Otherwise they will function much like the current Kinkisharyo vehicles, with 4-car trains and 8 cab cars running in fully interchangeable push-pull trainsets. This maximizes operational flexibility but also diminishes capacity slightly.

Sound Transit anticipates the new vehicles will begin arriving in mid-2019, with a steady but slow drip of 1-3 vehicle deliveries per month between 2019-2024. This delivery schedule means that though ST will be able to boost capacity on current operations between 2019-2021, they will also not be able to fully backfill the loss of tunnel buses within the One Center City timeframe. The vehicles take roughly 100 days for commissioning and testing, some of which can be done in revenue service, somewhat minimizing the need to do overnight testing. By purchasing off-the-shelf, the S70 LRVs are a known quantity and should be able to expedite burn-in processes. This model already successfully runs in places such as Portland, Minneapolis, San Diego, Salt Lake City, and suburban Paris.

As new vehicles arrive and are certified, the current Forest Street Operations and Maintenance Facility (OMF) will max out its capacity. Once the new East Link OMF is complete in 2020, a mix of old and new vehicles will be trucked there for storage, where ST promises to “keep the trains warm and move them around.”

Once fully operational, Link will have two nearly-maxed out OMF facilities, and additional cars will be stored on the lines overnight. Lynnwood and Redmond will be able to store two trainsets overnight, much like Angle Lake and UW can today. But in the south, Sound Transit is planning much more substantial storage. An extended tail track south of Federal Way will hold additional vehicles, and ST is also planning a pocket track between Federal Way and Star Lake that can hold 1-2 additional trainsets. Having vehicle storage at all 3 termini will allow quicker start of service each day, and minimize vehicle deadheading.

The full Board will likely approve the $132m option at its regular meeting on April 27.