The obvious solution for the Newell bridge is to replace it with one that fixes the flood problem, that maintains two lanes of traffic as today (one in each direction, although perhaps a tiny bit wider, so two cars fit side by side) and that add a small lane on each side for pedestrians and people on bikes, who currently have a dangerous time crossing the bridge. This essentially keeps the status quo while implementing the flood management plan and while adding to the safety of people not in cars.
For those concerned about slightly improved automobile lanes, speed humps could be added to the end of the bridge, complementing the stop sign at the other end, in order to calm traffic.
People in nearby neighborhoods who don't like the status quo should have considered buying elsewhere.
Explore trench option
Cars under tracks at Churchill, Meadow and Charleston? No way!
Side streets joining Churchill, Meadow and Charleston within 600 feet of the tracks would be cut off. Numerous private homes would be taken. To maintain connection of cross streets with Alma, cars on Alma would be forced to go through a dipsy-doodle at every intersection.
Worst, school kids on foot or bikes would be forced to cross Alma at the bottom of the pit. Imagine a kid on a bike, rolling down the ramp and losing control, shooting out into Alma traffic.
Compare the cost of trenching with the cost of underpasses. Two stretches of trench are required: one between Adobe and Matadero creeks for the Charleston and Meadow crossings, and one under Churchill. Each trench has 1,000-foot ramps at each end. For comparison, three underpasses would require a total of 600 feet of street at depth plus 12 ramps 600 feet long from depth to the surface.
Cost elements are cubic yards of soil excavated, cubic yards of concrete poured, relocating utilities, taking of private property, and measures to keep the trains rolling during construction. My guess is the cost of trenching would be somewhat more than the underpasses, but not a lot more, so the obvious benefits of tracks-in-trench outweigh the higher cost.
A competent engineer could get a good ballpark number in a week or two, so let's do the math and settle this issue once and for all.
"Big Bill" Cutler