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State Route 60 (SR-60) is an interregional freeway, freight corridor, and a primary link between Los Angeles and Riverside Counties. SR-60 is also part of the National Highway System (NHS), and a vital east-west link in the multi-modal transportation network in Southern California.

State Route 57 (SR-57) is a major north-south freeway that links Orange County with the two counties in the Inland Empire (Riverside and San Bernardino). The two freeways merge into a shared alignment for approximately 2-mile stretch, otherwise known as the 57/60 Confluence.

The traffic model by the Southern California Associated Government (SCAG) estimated about 356,000 vehicles, 26,000 are trucks carrying goods to warehouses, travel on the 57/60 Confluence every day. During the morning and the afternoon rush hours, peak traffic generally last for 3 to 4 hours on a typical weekday with hourly volume of approximately 8,900 and 9,400 vehicles traveling on six lanes of freeway in the westbound and eastbound direction, respectively.

Grand Avenue Interchange is located at about the midpoint in the 57/60 Confluence. With the weaving conflicts between the traffic to-and-from Grand Avenue Interchange and the two freeways, commuters experience long delays with the Level of Service (LOS) approaching B and D for both the morning and afternoon commutes. The 57/60 Confluence is one of the most severe freeway bottlenecks in Southern California.

Caltrans has identified the 57/60 Confluence as one of the five (5) most congested segments within Caltrans District 07, which encompasses Los Angeles County and Ventura County. In January 2017, the American Transportation Research Institute ranked this freight bottleneck as No.7 in the Nation and No.1 for freight delays and truck accidents in California.

The 2037 traffic forecast indicates a 16% increase in traffic volumes on the two freeways in the 57/60 Confluence. Without this Project, operations on both SR-57 and SR-60 freeways will be at LOS of “F” with severe congestion lasting for several hours daily.

The 57/60 Confluence also carries heavy freight traffic. A 2009 survey of the heavy-duty trucks (trucks originated from the LA Ports) indicated an average truck volume between 8% and 10% during the peak hours, or about 750 and 500 trucks per hour in the morning and the afternoon, respectively. As observed, along this SR-60 Freight Corridor, trucks mixed with general-purpose traffic contribute to the freeway operational problems on the 57/60 Confluence. Freeway weaving becomes more complex with a high volume of trucks trapped in the middle lanes of the two freeways in the 57/60 Confluence.

The proposed 57/60 Confluence improvements will:
  • Construct an eastbound on-ramp bypass lane from SR-60

  • Construct a new eastbound general-purpose lane

  • Reconfigure the Grand Avenue westbound on-ramp and
    the eastbound on- and off-ramps

  • Widen Grand Avenue and reconstruct the Grand Avenue
    bridge overcrossing

  • Construct an eastbound SR-60 off-ramp bypass from the
    northbound SR-57 split

  • Reconstruct eastbound SR-60 Diamond Bar Boulevard on-ramp

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