SMART participated in the first ever Caltrans Planning and Environmental Linkages (PEL) study for SR 37 and is now part of the MOUs amongst the North Bay transportation authorities, MTC, and Caltrans. But a PEL is a FHWA process and SMART was a bit of an after thought since the focus was on selecting a preferred alignment for the long-term highway and a type (on fill vs causeway structure).

However, other than making a big deal about the need to do something about the existing flooding near the Ignacio Wye, they really haven't done much studies other than some renderings of a tail causeway next to the future SR 37 causeway.

The entire SMART mainline needs to elevated on fill between the US 101 Franklin Overhead and the Bel Marin Keys Overhead. That would also provide flood protection for US 101 and the shopping center and hospital in Novato. But that will also require replacing all of the 37/101 connector ramps at a higher elevation to maintain vertical clearance above the tracks and to tie into the SR 37 Novato Creek bridge replacement that's in the PS&E phase now as the first phase of the long-term Resilient SR 37 Program. Still short a lot of funds for the bridge replacement since Caltrans has competing interests in the SHOPP, not to mention getting the causeway all the way to Atherton Drive.

All SMART has right now is their East-West feasibility study done in 2019 (that didn't look at SLR). Caltrans HQ Planning is working on a bare bones PSR for SMART right now before they start working on the $500k Corridor ID funds awarded by FRA. No funds identified for environmental or design though, and getting to Healdsburg and Cloverdale remains SMART's priority.

The big question is whether SMART will stay on their existing alignment past Sears Point up to Schellville, or switch to parallel the SR 37 alignment to Mare Island and possibly tie into the existing California Northern tracks at the SR 29/37 interchange (as envisioned by Caltrana HQ). Another option could be to use the existing Mare Island causeway bridge and the existing City of Vallejo owned spur line, which could provide some possibilities like a new wye with a connection down Mare Island Way to the Vallejo ferry terminal close to downtown, and a second Vallejo station platform at the Sereno Transfer Center bus station close to the Vallejo Kaiser Medical Center.

But getting UPRR approval to use the California Northern to Suisun/Fairfield (or even all the way to Sacramento in DRMT's pipedreams) will be hard sell without a lot of capacity improvements.