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SR-57/SR-60 Interchange Improvements Project

Metro, in partnership with the City of Diamond Bar, the City of Industry, and the San Gabriel Valley Council of Governments (SGVCOG) and in cooperation with Caltrans District 7, is revalidating a portion of the environmental process and design for the SR-57/SR-60 Confluence at Grand Avenue Project’s (57/60 Confluence) Final Environmental Impact Report (FEIR; 2013). Built in the 1970’s, the two-mile long stretch of SR-57/SR-60 confluence is the third worst congested freeway segment in California , and sixth worst in the U.S., serving more than 100 million vehicles per year and transporting nearly $4 billion dollars of goods. For these reasons, completing improvements to the SR-57/60 confluence is important for regional mobility and for the economic vitality for the region.

The SR-57/SR-60 Interchange Improvements is the next and final step in completing improvements to the 57/60 Confluence. Project improvements will stretch from just south of the northbound SR-57/SR-60 merge to eastbound SR-60 and south of the Golden Springs Drive overpass and along a portion of Grand Avenue from the City of Industry to the City of Diamond Bar. Before construction may begin, the project will ensure previous environmental work is updated to accurately consider current state and federal standards, identify and update assessments for existing project area conditions, and determine the need for minor design alterations that best serve the goals of the project.

Project Goals :

  • Increase freeway capacity while reducing traffic congestion
  • Improve traffic flow and community connections
  • Increase freight travel efficiency
  • Improve freeway operations and safety
  • Enhance quality of l ife


Current Measure M funds and efforts to obtain grant funding are currently being conducted to fully fund the project.

Both, SR-57 and SR-60 are major travel routes that are critical to Southern California’s regional traffic flow and serve as important links in the movement of goods from coastal ports to inland counties and other states. SR-57 is one of few north-south freeways in the region, serving as a key link between Orange County and East Los Angeles County. In contrast, SR-60 is an essential east-west corridor connecting employees and freight between Los Angeles County and the most populous parts of the Inland Empire.  It is also one of the most highly utilized truck routes moving 43% of freight goods in-and-out of the Greater Los Angeles Basin.

The need and travel demand at the confluence of the SR-57 and SR-60 are at growing risk due to increased pressure from increased population and economic demands. This stretch of freeway has been ranked the sixth worst freight bottleneck in the nation and number one in California for delays and truck related accidents. In 2013, the Federal Highway Administration identified it as one of the 25 most “Congested Freight-Significant Locations” in the nation. Ranked as the second highest truck accident location in Southern California, this significantly impacts travel and goods movement as well as further congesting the Cities of Diamond Bar and Industry streets. Diamond Bar commuter habits reflect this, since they are among the highest San Gabriel Valley commute times to work, averaging 35.9 minutes.

The project is broken-up into the following construction elements to complete the SR-57/SR-60 confluence improvements .

  • Construct an eastbound on-ramp bypass lane from SR-60
  • Construct a new eastbound general-purpose lane
  • Reconfigure the Grand Av eastbound on- and off-ramps and complete improvements to the westbound on-ramp
  • Widen Grand Av and reconstruct the Grand Av bridge overcrossing
  • Construct an eastbound SR-60 off-ramp bypass from the northbound SR-57 split
  • Reconstruct the eastbound SR-60 Diamond Bar Bl on-ramp

In addition to the se improvements, two related improvement projects are active in the project area: the City of Industry’s Grand/Golden Springs improvement project and the Diamond Bar Golf Course Renovation. Construction is anticipated to complete in mid-2021 for Grand/Golden Springs and in mid-2022 for the golf course.

This project is in the Plan, Specification and Estimate (PS&E) phase, which includes final design updates and Environmental Revalidation, and is anticipated to end in late summer 2021. As part of this process, a PS&E report will be developed to account for refinements to elements of the SR-57/SR-60 Confluence Project FEIR, to quantify the cost implications for the current updates, and to guide construction for improvements.

Construction, led by the San Gabriel Valley Council of Governments (SGVCOG), is anticipated to begin the middle of 2022. Environmental Revalidation began in late 2018 construction to start in middle of 2022 and complete in late 2026. Project website and collateral information will be updated through construction.


Environmental Revalidation began in late 2018 construction to start in middle of 2022 and complete in late 2026. Project website and collateral information will be updated through construction.

Milestone Date
Initiate Environmental Revalidation Late 2018
Conclude Environmental Revalidation Mid 2021
Construction Mid 2022 – Late 2026
Other related active projects within the area
Diamond Bar Golf Course Renovation Construction Early 2021 – Mid 2022
Grand/Golden Springs (Grand/GSD) Construction Early 2020 – Mid 2021

A first round of informational meetings are planned for summer 2020. However due to COVID-19 conditions, these meetings may b ecome virtual online meetings. Both options will provide an opportunity for participants to:

  • Meet the project t eam

  • Learn more about the overall project (s)

  • Get details on the progress of each project

  • Ask questions

  • Share your thoughts