Express Lane Completion


In-Person Public Meeting
June 5, 2024 | 6-8 p.m.
CCTA Office
2999 Oak Road, Suite 110
Walnut Creek, 94597

Comment on Draft EIR/EA

Submit your comments anytime from May 8, 2024 through June 24, 2024 using any of the following methods:

Caltrans, District 4
Office of Environmental Analysis
Attn: Lily Mu, Environmental Scientist
P.O. Box 23660, Mail Station 8B
Oakland, CA 94623-0660

(925) 278-5978



icon blue part time transit lanes 2Caltrans, in partnership with CCTA, is proposing to complete the Interstate 680 (I-680) Northbound Express Lane Completion Project to address the existing express lanes gap, relieve congestion, reduce travel delays, and improve operations. The proposed project would construct a northbound express lane from Livorna Road to State Route 242 (SR-242) and convert the existing northbound High-Occupancy Vehicle (HOV) Lane from SR-242 to north of Arthur Road near Martinez to an express lane – which means both HOV and single-occupancy drivers who pay a toll can use the lane. The proposed project has four build alternatives (1C, 2, 3 and 5) and one no-build alternative.

Why Do We Need This Project?

  • Congestion Relief: The general-purpose lanes on northbound I-680 can have a long delay during peak hours.
  • System Continuity: The lack of continuous express lanes leads to increased travel times for users.
  • Operational Improvements: The way the on and off-ramps between North Main Street/Lawrence Way and Treat Boulevard are designed creates a lot of merging and traffic back up to the SR-24 interchange.

Project Map

Map of the four build alternatives.


Estimated construction costs range from $102.3 to $327.4 million in current dollars. Right-of-way costs will range from $7.1 to $11.5 million. These are preliminary estimates that will be adjusted as the Project is further defined. This Project is eligible for a variety of funding source types, including:

  • Federal
  • State
  • Regional
  • Local
Express lane highway traffic graphic


By constructing a northbound express lane and converting an existing HOV lane to an express lane (which means both HOV and single occupancy drivers who pay a toll can use the lane), the Project will:

Project Schedule

planned milestones

Environmental Phase

The proposed I-680 Northbound Express Lane Completion Project is subject to State and Federal environmental requirements. A Draft Environmental Impact Report and Environmental Analysis (Draft EIR/EA) has been prepared in compliance with California Environmental Quality Act (CEQA) and National Environmental Protection Act (NEPA). The Draft EIR/EA includes an analysis of the proposed build alternatives.

Design Elements Included In The Proposed Build Alternatives

A combination of these design elements appears in the four proposed build alternatives.

  • Braided Ramps: Braided ramps would separate the Treat Boulevard off-ramp traffic from the North Main Street/Lawrence Way on-ramp. The Treat Boulevard off-ramp would be elevated over the Lawrence Way on-ramp to make merging onto the freeway safer and more efficient.
  • Southbound I-680 Realignment: Realign lanes on southbound I-680 between South Main Street and North Main Street in Walnut Creek to make room for a new northbound express lane, which provides a continuous express lane through the SR-24 interchange.
  • Lane Addition: Add an express lane by widening northbound I-680.
  • High-Occupancy Vehicle (HOV) Lane Conversion: Convert the existing HOV lane to an express lane between SR-242 and north of Arthur Road near Martinez, providing access to high occupancy vehicles and toll-paying drivers.
  • General-Purpose (GP) Lane Conversion: Convert the existing inside lane to an express lane without widening.

All four of the build alternatives convert the existing HOV Lane to an express lane from SR-242 to north of Arthur Road.

Three of the four alternatives also address merging conflicts between the North Main Street/Lawrence Way on-ramp and the Treat Boulevard off-ramp by constructing braided ramps.

The alternatives are proposed as follows:

  • Alternative 1C: Closes the northbound express lane gap through lane addition and southbound I-680 realignment.
  • Alternative 2: Reduces the northbound express lane gap through lane addition and construction of braided ramps.
  • Alternative 3: Closes the northbound express lane gap through lane addition, southbound I-680 realignment, and construction of braided ramps.
  • Alternative 5: Reduces the northbound express lane gap by GP lane conversion and constructing braided ramps.
  • No-Build Alternative: Leaves northbound I-680 in its current configuration without any improvements.
Learn more about the proposed project alternatives:
Proposed project fact sheet:
A wide variety of environmental issues were evaluated for impacts as part of the Draft EIR/EA including:

Air Quality

Biological Resources

(habitats, threatened & endangered species, wetlands)

Climate Change / Greenhouse Gases

Community Impacts

Cultural Resources

(archaeology, historic buildings & structures, tribal cultural resources)

Cumulative Impacts

Environmental Justice


Geology, Soils & Seismicity


Hazardous Materials & Waste

Land Use



Sea Level Rise



Visual Resources

Water Quality, Hydrology & Stormwater

Vehicle Miles Traveled (VMT)

A California law, Senate Bill 743, changes how public agencies, like CCTA, measure transportation project impacts and how agencies decide what projects to build. The law requires using Vehicle Miles Travelled (VMT). VMT measures how many new vehicle miles of travel residents, visitors, shoppers, and employees will produce within the project area.

Public Scoping Meeting Archive

Public and agency scoping was conducted from June 15 through July 9, 2020. The scoping process provides an opportunity for the public and agencies to provide input on a project prior to the preparation of the environmental document. Below are materials from the public scoping process.

Stay Informed

We welcome and encourage your participation in this important project. If you are interested in the Project presenting to your organization or association, please contact us at or leave a message at (925) 278-5978.