State Route 99/120 Interchange Connector Project

Project Description

The California Department of Transportation (Caltrans) District 10, with the cooperation of the City of Manteca and the San Joaquin Council of Governments (SJCOG), proposes to reconstruct the existing State Route (SR) 99/120 Interchange. Due to funding constraints, the Project will be constructed in three phases:

  • Phase 1A will widen the State Route 120 (SR 120) eastbound to southbound SR 99 connector, build the Austin Road and Union Pacific separation structure, realign the at grade crossing and construct local roads for access.
  • Phase 1B will widen the SR 99 northbound to westbound connector.
  • Phase 1C will complete the Austin Road Interchange and complete the local road improvements.
Phase 1A Location Map



Project Benefits


The purpose of the project is to relieve traffic congestion and improve operations of SR 99 with the SR 120 and Austin Road Interchanges.


The project need has identified deficiencies between SR 99 and SR 120 and Austin Road Interchanges that facilitate improvements meant to increase the traffic capacity and improve the operation of weaving, merge, and diverge traffic movements between SR 99 and the SR 120 and Austin Road Interchanges.


Funding Source

Phase 1A is funded through a combination of Regional Improvement Program (RIP), State Highway Operations and Protection Program, Regional Surface Transportation Program, State SB1 Local Partnership Program, local funds - San Joaquin County Measure K and local funds - developer fees.


Project Cost/Programmed

Phase 1A Capital $$ Support $$
Project Approval & Environmental $0 $2,474,000
Plans, Specifications, & Estimates $0 $2,226,000
Right of Way $5,116,000 $1,700,000
Construction $36,907,000 $0
 Phase 1B: (open to traffic on 2033)  $28,089,000  (Total cost)
 Phase 1C: (open to traffic on 2042)  $62,014,000  (Total cost)
 Costs current as of July 6, 2022: Planned $  Expended $
 Project Approval & Environmental  $2,274,000  $1,359,000
 Plans, Specifications, & Estimates  $2,870,000  $841,000
 Right of Way  $5,116,000  $1,184,000*
 Right of Way Support  $1,700,000  $716,000
 Construction Support  $0  $0
 Construction Capital $ 36,907,000  $0

*Confirm actual expenditures with SJCOG (consultant contracts)


Current Schedule

Process Date
Ready – to – List (M460) Spring 2023
Approve Construction Contract (M500) Fall 2023
Project Completion (M600) Winter 2025


Project Status

The project is currently in the design and Right of Way Phases, with the work on the railroad agreement, right of way acquisition, and utility agreements in the process. San Joaquin Council of Government (SJCOG) is the implementing agency for Project Approval & Environmental Document (PA&ED), Plans, Specifications, and Estimates (PS&E) and Construction Phases and Caltrans is the implementing agency for the Right of Way Phase.


Project Contact

Caltrans District 10 - Public Information Office
Phone: (209) 948-7977


Title VI Information

The California Department of Transportation (Caltrans) assures that no person shall, on the basis of race, color, or national origin, be excluded from participation in, be denied the benefits of, or be otherwise subjected to discrimination under any program or activity receiving Federal financial assistance, as required by Title VI of the Civil Rights Act of 1964, as amended, the Civil Rights Restoration Act of 1987, and Federal Executive Order 12898 (Federal Actions to Address Environmental Justice in Minority Populations and Low-Income Populations).

Caltrans will make every effort to ensure nondiscrimination in all of its programs and activities, whether they are federally funded or not, and that services and benefits are fairly distributed to all people, regardless of race, color, or national origin. In addition, Caltrans will facilitate meaningful participation in the transportation planning process in a nondiscriminatory manner.