One of the main reasons I support the surface/transit/I-5 option is because it actually reduces capacity for cars and increases capacity for people (because it improves access to downtown and increases the availability of alternatives to driving alone, such as transit, avoiding or rescheduling trips, and finding alternative routes).

The state Department of Transportation has argued that car use will continue to increase indefinitely, making surface/transit impractical. Surface/transit proponents have retorted that single-occupancy car use will continue to decline, and that WSDOT's basic assumption is wrong.

So it's pretty ironic to see  tunnel opponents like Sightline and Slog now taking at face value a study concluding that the tunnel---which would be four lanes wide, compared to the current six-lane viaduct---will reduce car capacity through downtown and lamenting that it will carry "fewer cars than the Ballard Bridge" and force tens of thousands more cars onto city streets.

There are plenty of environmental arguments against the tunnel, but "it's too narrow and won't carry enough cars" isn't one of them.