State Route 99/120 Interchange Connector Project

Project Facts

Project Description

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

Purpose and Need

The purpose of the project is to provide traffic congestion relief and improve operations of the SR 99/120 connectors and the Austin Road Interchange.  The need is to increase the capacity of connectors and improve the weaving, merge and diverge movements between the SR 99/120 connectors and SR 99 Austin Road Interchange.


Funding Source

The current Plans Specifications & Estimate phase is being funded by San Joaquin Council of Governments (SJCOG) with Federal/State and Local funds. Caltrans District 10 will provide $28.7 million in Construction Capital funds.  SJCOG will provide Statewide Transportation Improvement Program (STIP) and Senate Bill 1 (SB1) fund to cover the remaining needs for Right of Way (R/W) and Construction phases.

Project Cost/Programmed

Phase 1A Capital $$ Support $$
Project Approval & Environmental $1,800,000
Plans, Specifications, & Estimates $4,511,000
Right of Way $5,116,000 $1,700,000
Construction $36,907,000 $5,200,000
 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 September 1, 2021: Planned $  Expended $
 Project Approval & Environmental  $1,800,000  $1,359,000*
 Plans, Specifications, & Estimates  $4,511,000  $1,500,000*
 Right of Way  $5,116,000  $53,000*
 Right of Way Support  $1,542,000  $502,000*
 Construction Support  $10,272,000  
 Construction Capital $ 45,373,000  

*Confirm actual expenditures with SJCOG (consultant contracts)


Current Schedule

Project Study Report (M010) 12/21/2015
Project Approval & Environmental Document (M200) 9/30/2019
Right of Way Certification (M410) 4/20/2022
Ready – to – List (M460) 4/22/2022
Approve Construction Contract (M500) Fall 2022
Project Completion (M600) Spring 2025


Project Status

The project is currently in the design phase, with the work on the railroad agreement, R/W  acquisition, and utilities in the process. SJCOG is the implementing agency for Project Approval & Environmental Document (PA&ED), Plans, Specifications, and Estimates (PS&E) and construction. Caltrans will lead the R/W phases of work.


Contact Information

Caltrans District 10 - Public Information Office

Phone: (209) 948-7977


Address:  P.O. Box 2048, Stockton, CA 95201-2048