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Caltrans Secures $73 Million Grant to Widen Flood-Vulnerable Highway 37

The grant approval paves the way for December 2026 work on a $500 million expansion deemed inadequate to withstand mid-century sea level rise.

Overview

  • On June 26, the California Transportation Commission approved a $73 million grant for the first phase of Caltrans’ planned $500 million widening of Highway 37 between Sears Point and Mare Island.
  • The interim project will add one tolled lane in each direction and raise key flood-prone sections by up to five feet or eight inches to ease chronic bottlenecks.
  • Caltrans estimates the expansion will cut eastbound evening commutes from 100 minutes to 26 minutes and westbound morning trips from 60 minutes to 30 minutes.
  • Environmental and climate advocates warn that rising tides are projected to submerge much of the corridor by 2050 and call the grant an irresponsible investment without a fully funded long-term solution.
  • Caltrans’ ultimate plan remains a $10 billion elevated causeway to replace the at-grade highway, but that project currently lacks funding and a firm timeline.