# California's Longest Tunnel Project Set for $3.5B Development by 2031

> Design, land purchase and permits for the $3.5 billion tunnel will proceed from 2026 to 2031.

- Publisher: Briefzora (https://briefzora.com)
- URL: https://briefzora.com/californias-longest-tunnel-project-set-for-35b-development-by-2031
- Published: 2026-10-29T00:24:00+05:00
- Author: Briefzora Desk (https://briefzora.com/author/briefzora-desk)
- Section: Technology
- Image: https://briefzora.com/uploads/2026/10/dramatic-plans-for-californias-longest-ever-tunnel-revealed-as-35-m9blxm.webp

## Key points

- The tunnel is billed as California's longest ever.
- The project cost is $3.5 billion.
- Final design work will run from 2026 to 2031.
- Property acquisition is included in the 2026-2031 timeline.
- Environmental permitting will also continue through 2031.

## Why it matters

The extensive construction schedule will affect landowners, regulatory agencies and communities along the tunnel's route.

## Article

The $3.5 billion tunnel, touted as California's longest ever, will see its final design, property acquisition and environmental permitting carried out between 2026 and 2031.

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