What’s Going On with the 57/60 Confluence Project Construction?

Metro and Caltrans’ re-tool of the 57 and 60 Freeways’ confluence in Diamond Bar and City of Industry recently encountered some potential construction delays. As of late July construction was about a year behind schedule, but the agencies in charge were taking steps to eliminate some or all of that delay. 

The project – which will add an extra lane to the 57 and 60’s shared two-mile trunk, in addition to new on-/off-ramps and a rebuilt Grand Avenue Bridge – has enjoyed popular support from the member cities of the San Gabriel Valley Council of Governments. The SGVCOG is managing the project, which has an expected price tag of $444 million (not including the westbound expansion completed earlier).

Construction began late 2023, and has made relatively swift progress. The project is around 33 percent complete. However, some of that progress has stalled due to necessary utility relocations for Southern California Edison infrastructure. Per a July Caltrans presentation, the ball was dropped when the contractor missed notifying Edison in a timely manner.

This snag was estimated to delay completion by up to 13 months, but the SGVCOG is working to mitigate this.

SGVCOG spokesperson Ricky Choi explained to Streetsblog that one way the COG is getting the project back on track is to re-stage various construction phases. The main change would be that two of the project’s bridges would be built at the same time: the widened/replaced Grand Avenue Bridge and the new eastbound SR-60 flyover viaduct.

The demolition of the Grand Ave Bridge will be done in two sections, one side at a time, so people can continue to use the bridge during construction. Partial demolition is scheduled to begin March 2026 with a temporary weekend freeway closure. From there that side will be rebuilt, traffic will be redirected onto the new half, and then the process will be repeated for the other side.

Other than the temporary closures needed for demolition, there should be minimal construction impacts on drivers. The current traffic flow is expected to be maintained on the 57/60 confluence, according to Choi.

In July, SGVCOG Director of Capital Projects Kevin Lai stated that he still expects the project to complete just in time for the 2028 Olympic games.

Choi told SBLA that in future COG-managed projects, construction contractors may be asked to perform utility relocations themselves, or if possible, advance utility work would be a separate phase as a precursor to construction.

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