Palm Desert council weighs keeping Portola interchange in mobility element amid steep cost uncertainty

City staff and outside consultants told the Palm Desert City Council on June 26 that the council must decide whether to keep the Portola Avenue interchange in the city's mobility (circulation) element as part of an ongoing update to the general plan.

Jason Pack, principal with consultant firm Farr and Piers, said the interchange is shown in the city's adopted 2016 mobility element but that a 2024 council resolution had deprioritized the Portola Road project "mostly because of a lack of funding at the state, federal, level." He said key technical steps on the project were completed earlier in the decade but that funding and changing standards complicate moving forward.

Pack said the project reached a PAED (project approval/environmental document) milestone in April 2018 and a PS&E (plans, specifications and estimates) milestone in April 2022, but he told the council the work has been "fairly stalled" since 2022 because funding has not been available. He cited a 2018 construction estimate of about $88,000,000 and said, "If I had to guess, in today's dollars, you're probably looking at maybe somewhere between a 120 to a 140,000,000," noting that potential railroad requirements could change that picture.

The consultant presented pros and cons of leaving the interchange in the mobility element. Benefits include shorter trip lengths, reduced vehicle miles travelled (VMT) under the state's new metrics and related reductions in greenhouse-gas emissions, and improved access for northern development. Trade-offs include substantial construction costs and the potential for increased traffic on Portola south of the interchange if built; leaving Portola out of the plan would shift additional congestion to the Monterey and Cook interchanges.

To give the council better information, staff solicited a civil-engineering scope of work from Mark Thomas and Company to "dust off" prior designs, update them to current highway design standards, produce an updated engineering cost estimate and schedule, and identify potential grant and external funding sources. Pack said the quoted cost for that scope was about $18,000 and that Mark Thomas could complete the work and return to council in roughly two months if authorized.

Council members pressed the consultant on what of the 2022 design could be reused, on whether Union Pacific or other railroad track changes had been accounted for, and on how the Coachella Valley Association of Governments' Transportation Project Prioritization Study (TPPS) would influence funding and regional ranking. Pack said most of the prior design "can still be salvaged" but added the environmental document would likely need revalidation and Caltrans would have to confirm the design meets current standards. He also said Caltrans is typically the lead agency under CEQA for a new interchange.

On funding prospects, Pack described Mark Thomas as having a strong grant-identification practice and gave his impression from past projects that that firm finds some level of funding for roughly 25% to 50% of projects they pursue, though he offered to get more precise success-rate numbers. Council members noted long-term uncertainty in traditional revenue sources such as the gas tax and discussed how replacement mechanisms (for example, registration-based or VMT-linked fees) and Measure A allocations could affect the city's ability to contribute local matches.

After discussion, multiple council members, including Mayor (Speaker 1), expressed support for retaining the Portola interchange in the mobility element so the city can plan for north-side development and future traffic needs. "My feeling is, yes, we put it in there," the mayor said, while also acknowledging that funding "will remain to be seen." The council did not take a formal vote during the study session; staff said the Portola item was the only scheduled topic and that the meeting would recess into closed session at about 4:00 p.m.

Next steps: council members asked staff to consider authorizing the Mark Thomas scope so the city will have updated design assumptions, a current cost estimate and potential funding pathways to inform whether to keep the Portola interchange in the mobility element or remove it.