Interstate 680 Southbound Express Lane

interstate 680 express lane

Interstate 680 Southbound Express Lane

Improving Traffic Operations in Bay Area Through New Managed Express Lanes

Drivers in the Bay Area have long dealt with congestion, bottlenecks and increased travel times on some of the busiest highways in the U.S. I-680 connects the southern San Francisco Bay Area with I-80 and the major north-south freeway is a heavily traveled and key corridor for the region. To maximize highway operations, the Contra Costa Transportation Authority, in cooperation with the Metropolitan Transportation Commission, Caltrans and the Federal Highway Administration, constructed 11 directional miles of express lane on southbound I-680.

HDR provided preliminary engineering, environmental assessment and documentation, public outreach right of way and utilities assistance, final design and design support during construction for the $127 million project, which opened to traffic one year ahead of schedule.

Advanced Design Approach Reduces Changes, Improves Efficiency

Our team made multiple efficiency improvements throughout the project delivery process. As the project began, we proposed an advanced preliminary design approach that undertook activities concurrently for the project approval and environmental documentation process as well as development of the plans, specifications and estimate. This allowed detailed engineering to be developed for critical project components such as overhead sign locations and associated electrical and communications conduits, cabinet locations and service connections.

The advanced design work was performed at the same time as environmental field studies and identification of environmental resources and constraints, but before the environmental technical studies were written. This approach reduced repeated revisions to the environmental technical studies while providing the engineering and environmental resource constraint information needed to guide the project design and minimize environmental impacts.

Early Collaboration, Construction Ahead of Schedule

Originally planned to open in late 2021, an accelerated project schedule was adopted in early 2020, allowing the lane to open in August 2020 as a high occupancy vehicle carpool lane while tolling equipment was still being tested and installed. The lane will be open to tolling in August 2021.

The new segment, from Treat Boulevard to Rudgear Road, creates a 25-mile continuous carpool lane on southbound I-680 between Martinez and San Ramon. The project included the conversion of 8 miles of an existing HOV/carpool lane to an express lane and 3 miles of new lane construction.

Early and engaging workshops with the toll system integrator, civil designer and civil construction manager to develop civil stage sequence and traffic handling plans and associated milestone specifications were critical in allowing the project to be constructed ahead of schedule. With its completion, the new lane closes a gap in the Bay Area’s HOV network and is expected to significantly improve travel time reliability and traffic flow.

interstate 680 express lane
Contra Costa Transportation Authority

Walnut Creek to San Ramon, CA
United States

11 miles


Merit Award (2022)
Engineering Excellence Awards
American Council of Engineering Companies of California
No. 1 Road (2021)
Top 10 Roads
Roads & Bridges Magazine
Project of the Year (2021)
$25-$250M Category
International Partnering Institute