Imagine driving along a four-lane elevated causeway above the brackish San Pablo Bay, shaving more than an hour off the normal Highway 37 commute. Transportation planners have for years envisioned remaking the 20-mile route from Novato to Vallejo into the North Bay’s most important east-west corridor. Now, they are ready to act. Officials in Marin, Sonoma, Napa and Solano counties have been meeting for several years, pondering solutions to Highway 37’s notorious bottlenecks, where 45,000 cars per day stretch the normal 20-minute commute to as much as 100 minutes. They have also acknowledged that traffic improvements will be irrelevant without...