Caldecott Tunnel New Fourth Bore — Oakland, California

The Caldecott Tunnel Improvement Project delivered a fourth bore through Berkeley Hills to bolster capacity on State Route 24 between I-580 and I-680, alleviating reverse-commute congestion for over 166,000 vehicles per day. The new tunnel bore is approximately 3,400 feet long, 41 feet wide, and incorporates a 10-foot-wide shoulder and walkways. The improvements also included retaining and sound walls, modifications to two interchanges and one intersection, and the construction of an operations and maintenance center building. The tunnel is equipped with modern ventilation, air-quality monitoring, traffic monitoring, and life-safety systems, all in a seismically active and environmentally sensitive region.

Our Services And Responsibilities For The Caldecott Tunnel Project

• Led the Project Approval/Environmental Document (PA/ED) phase, including growth-inducement, paleontological, traffic, visual and construction-impact studies, and preparation of portions of the Environmental Impact Report (EIR).
• Provided preliminary engineering and full final design of the tunnel and related facilities: portals, tunnel lining, structural works, ventilation and safety systems, and the O&M building, which were critical for the Caldecott Tunnel expansion.
• Developed and implemented the project QA/QC program, communications plan, risk-management plan (with support from Golder Associates), capital-cost change-control program, scope-change request process, and project controls system.
• Collaborated with Caltrans and CCTA to produce a unified PS&E package: following a 65% submittal, two standalone work packages (Kay Overcrossing improvements and SR 24/13 ramp realignment) were extracted to provide DBE contractor opportunities and were designed under our responsibility as part of the Caldecott Tunnel initiative.
• Conducted advanced geotechnical/seismic modelling: numerical simulation of ground behavior and tunnel lining response under both rare and expected seismic loading, converting stresses/strains into design forces to ensure compliance under challenging conditions.
• Designed the tunnel operations systems: created a comprehensive operations plan, developed the emergency operations plan in coordination with tunnel operations staff and Caltrans, produced the software requirements documentation for control systems, and supported bidding, construction, commissioning, and O&M handover.
• Coordinated permitting and regulatory compliance: engaged early with the fire marshal for mock drill and code compliance, negotiated an amended US Army Corps of Engineers (USACE) permit due to a mitigation failure during construction, crucial for the Caldecott Tunnel project, avoiding schedule delays.
• Provided construction-phase engineering support, including portal building, systems commissioning, and final hand-over. The new bore opened to the public on November 16, 2013.

Caldecott Tunnel Significance And Awards

• The Caldecott Tunnel expansion was named “Project of the Year 2014” by the California Transportation Foundation.
• Recognized as “Top Road Project 2013” by Roads & Bridges magazine.
• Delivered on time and under budget, with no cost or schedule adjustments despite complex seismic, environmental, and stakeholder challenges.

Why This Project Matters

The experience mirrors the scale, complexity, and technical sophistication required for this contract, demonstrating our team’s acumen in managing risk, schedule, budget, and stakeholder coordination while delivering resilient, safe, high-performance infrastructure.