When ST3 is complete in 2041, the residents of King, Snohomish, and Pierce Counties will be connected by rail, tram, and bus rapid transit from Everett to Tacoma out to Bellevue, Redmond, and Issaquah. By then there will be more than 4 million people squeezed into those three counties, and the pressure to fit in more will no doubt spill across Puget Sound into Kitsap County.
Ferries make for a pleasant commute, but not a fast method of travel. Unlike a light rail train, it takes up to 10 minutes to load and unload the Bainbridge-Seattle ferry, which turns a 35 minute rush-hour ride into a 50-60 minute journey, not counting the time to get to and from the ferry terminal.
The Bainbridge Island ferry terminal is only 8 miles from Colman Dock in downtown Seattle (as the seagull flies), and the Bremerton ferry terminal is just another 6.3 for that same seagull. By car, those two terminals are 32 miles and 55 minutes apart. By transit, Google suggests the fastest path is 90 minutes, hopping the ferry from Bainbridge to Seattle and switching to the new, fast ferry to Bremerton.
Meanwhile, when ST3’s East Link is done, the 6.3 miles (as the crow flies) between Downtown Bellevue and International District/Chinatown will take just 10 minutes. Similarly, when ST3 finally reaches Ballard in 2035, the 7.3 mile trip from Ballard to Westlake center will take just 15 minutes, including stops in Interbay, Smith Cove, Seattle Center, and South Lake Union.
We can fix this commute time and open up Kitsap County to the inevitable population growth by adding Kitsap County to Sound Transit’s service, designing and digging a transit tunnel under Puget Sound.
Puget Sound is deep, more than 650 feet deep in the channel between Eagle Harbor and Elliot Bay. But deep, underwater transit tunnels have been built in Japan, Norway, and most famously, under the English Channel.
It is only 6.3 miles from the Bainbridge Ferry Terminal to the future ST3 station at Smith Cove. An ST3.5 line from there to Bainbridge Island and continuing underground to Bremerton would be a total of 12.6 miles long.
These are two communities that already have large number of public transit riders. 3.3 million foot passengers between Bainbridge Island an Seattle in 2017, plus another 1.7 million foot passengers between Bremerton and Seattle. Because of that ridership, Kitsap County is well covered by Kitsap Transit’s bus system.
Connecting Kitsap County to Sound Transit is inevitable. The question is not if, but when. The key question is the cost of 12.6 miles of deep tunnels and two deep, underground stations. But the alternative isn’t free. The alternative is the cost of expanding and operating the ferry system to support the next 240,000 Kitsap County residents who want to reach King, Snohomish, and Pierce Counties including SeaTac Airport and whatever high speed rail makes it to Seattle.