NACTO, which released the influential Urban Bikeway Design Guide a few years ago, has now completed a Transit Street Design Guide. It's not out yet, but you can pre-order them.
Developed over the past year through the work of a new peer network of city and transit agency experts, and with the generous support of TransitCenterand the Summit Foundation, the Transit Street Design Guide empowers practitioners to design transit streets as linear public spaces. Sections highlight transit as the centerpiece of transformative street projects, integrating transit-walk-and-bike-friendly design elements like boarding islands with best-practice strategies - like multi-door boarding and transit-friendly signals - that can speed up an entire system.
That would make a nice K Street or Connecticut Avenue.
For more, the Green Lanes Blog has a sneak peak.