A downtown MAX tunnel:

Today, the east landing of the Steel Bridge is TriMet's biggest time bomb. Thanks to four crisscrossing MAX lines, it's already at full capacity at rush hour. If TriMet ever wants more frequent trains, some of them will need a different route across the Willamette. Howell's answer: Go underneath. The Blue and Red lines could plunge 200 feet between the Lloyd District and Goose Hollow, with new, underground stations at the Rose Quarter and Pioneer Courthouse Square. Today's crawl through downtown would become a two-stop hop, luring thousands of east-west commuters off the roads.

Cost: $2 billion

Travel time (Lloyd Center to Goose Hollow): 7 minutes, down from 23 today