The SMART Windsor Extension delivers complex FRA-jurisdiction mainline railroad infrastructure, expanding passenger rail service 3.6 miles from the Sonoma County Airport Station to the Town of Windsor while integrating freight compatibility, active transportation, and advanced safety systems into SMART's regional rail network.
Need
The Windsor Extension addresses long-standing mobility and connectivity challenges in the northern San Francisco Bay Area by expanding accessible transportation options, strengthening community connections, and supporting economic development along the corridor. It advances sustainable growth by enabling transit-oriented and affordable housing development, preserving freight rail service and workforce transport, and boosting regional tourism. By improving access in a region historically underserved by public transit, the extension advances SMART's goal of making rail a viable option for both residents and visitors alike.
Work
The extension includes just over three miles of mainline track, five railroad bridges, four pedestrian bridges, and a pedestrian undercrossing. The project features three miles of paved bicycle-pedestrian pathway, gauntlet tracks to accommodate freight train passage, five at-grade crossings including one within a roundabout, federally mandated positive train control, and a new downtown Windsor station with dedicated parking.
The project also replaced five aging timber railroad bridges with modern concrete structures spanning creeks and streambeds. Work includes reconstructing 3.2 miles of track, constructing 2.6 miles of SMART multi-use pathway as part of the larger 307-mile Great Redwood Trail, upgrading grade crossings with modern safety technology, and installing signaling and communications infrastructure. Extensive utility relocations were coordinated throughout construction to support phased delivery and protect adjacent operations.
Impact
The Windsor Extension expands commuter and visitor access across one of the Bay Area's most transit-underserved corridors. The project advances mode shift from single-occupancy vehicles to transit and active transportation, reducing congestion and greenhouse gas emissions in support of California's climate goals. It also supports transit-oriented development, freight rail continuity, and regional tourism along the corridor.
Collaboration
Stacy Witbeck, SMART, and the design team collaborated with the Town of Windsor to successfully phase construction of the adjacent roundabout, ensuring uninterrupted train operations throughout construction and completing all work in the shared area without damage or rework. The same collaborative approach guided construction of the multi-use pathway and undercrossing, providing pedestrians safe passage beneath the tracks and improving access to the adjacent high school without at-grade conflicts.
Stacy Witbeck's longstanding relationships with subcontractors across Sonoma and Marin Counties carried directly into the Windsor project. Of the 34% of work subcontracted, 71% was performed by 50 local contractors, which is a result of sustained investment in regional workforce partnerships built over years of work throughout the area.
Innovations
Advanced simulation modeling, pre-testing of enforcement zones, and system implementation scenarios
Awards
2026
2025
2024
Windsor, CA
Commuter Rail
Design-Build
2025
Sonoma-Marin Area Rail Transit (SMART)
West
“After two years of collaboration with Stacy Witbeck on SMART’s extensive fencing scope from Petaluma to Windsor, I’m proud to have built more than just secured boundaries. Together we built a strong, respectful partnership with strong commitment to quality and mutual success.”
Johnny Fruiht, Operations Manager, Ahlborn Fence & Steel, Inc.