How to build a highway in the age of climate change

California is moving ahead with a $500 million plan to rebuild part of Highway 37, the flood-prone route linking Solano County to Marin and Sonoma. Over five years, crews would replace one bridge with a version 5 feet taller, raise two one-mile stretches by up to 8 inches, add carpool and bus lanes, and restore surrounding tidal marsh. The road, built on causeways through wetlands near San Pablo Bay, floods regularly and could be permanently underwater in parts by 2050 as sea levels rise. Some researchers and advocates argue the fix doesn't go far enough and want the highway moved miles inland, or want a $10 billion, decades-long rebuild that raises nearly the whole road and adds transit or bike lanes. Regional planners say that bigger version is the eventual goal but is too costly and slow to start now; they've secured $270 million for a bridge replacement as a first step.

This isn't just a California problem. Coastal roads and causeways from Florida's Sanibel Island to Georgia's Tybee Island face similar flooding and closures as seas rise and storms intensify. Some places are testing nature-based fixes like oyster reefs, rain gardens, and living shorelines to absorb wave energy instead of relying only on raising pavement or building seawalls. Researchers also note that rising groundwater can weaken roads from below, shortening their lifespan even without a storm.

For homeowners, the takeaway is less about your own house and more about the roads you depend on. If you live near a coast, a marsh, or a low-lying causeway, expect more debate in your area over how much to spend, and how, to keep those roads passable as flooding becomes routine.