Orphan Road

For a variety of reasons, I think the 6-lane option is best for a new 520 bridge, as I've said before.

But the simple fact is this: Sound Transit, the only agency that would build such a light rail line, has no interest in a 520 rail link. Heck, they still don't have the funds or a mandate for an I-90 link (as Mike @ CIS notes). And the Husky Stadium station, as currently designed, would not be able to handle the incoming connection from 520. More expensive excavating would be required, perhaps directly underneath the Stadium or Arboretum. it would be a mess.

That said, I'm somewhat sympathetic to the idea, pushed by Eastside pols, that using the only two HOV lanes for light rail at a later date would be somewhat problematic. Running light rail to, say, Redmond, would mean that carpoolers heading to Kirkland would be stuck in general purpose traffic, and we'd be back to our current problem. But trying to predict the technology, demographics, or business climate 50 years out is a fool's game. There's no guarantee that we'll still be using light rail then, or that Microsoft will even exist.

I'd be more interested in seeing money invested in good HOV connections from 520 to I-5 and I-405 so that buses can use the full HOV network to get around.