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Irvine-Corona Expressway

Project Background

State Route 91 (SR-91) is a transportation corridor with strategic value and local, regional and national significance. Every day, the SR-91 connects hundreds of thousands of commuters living in Riverside County with employment centers in Orange County, and vice-versa. The SR-91 is also the corridor of choice for commercial truckers transporting goods from the Ports of Los Angeles and Long Beach to store shelves in Orange County, Riverside County and the rest of the nation. On the weekends, locals use the SR-91 to reach essential shopping and recreational destinations, while visitors use it to visit entertainment and tourist attractions, from Disneyland, to the ballpark, to the beach. In short, commuters drive the SR-91 and the SR-91 helps drive our economy and our quality of life.And things aren’t likely to change. Projected travel demand requires that transportation capacity on the SR-91 and other viable options be studied and developed. As a result, the Riverside County Transportation Commission (RCTC), in cooperation with OCTA and the Foothill-Eastern Transportation Corridor Agency (FE/TCA), commissioned a feasibility evaluation of the Irvine-Corona Expressway (ICE) tunnels.The purpose of the study was to further define and evaluate site conditions that affect the feasibility of constructing transportation tunnels beneath the Cleveland National Forest and connect Orange and Riverside Counties.

What Was Studied?

The transportation tunnel concepts evaluated assumed 11.5-mile long tunnels accommodating both highway and rail traffic. Specifically, the following three (3) tunnel concept alternatives were studied:

  • Two large (52.5’) vehicular tunnels carrying two one-way lanes of traffic connected by cross passages (cross passages are for emergency access and for maintenance purposes)
  • Three smaller (38’) tunnels with one lane each, connected by cross passages
  • Two large (52.5’) vehicular tunnels carrying two lanes of one-way traffic each, and one small (26.5’) rail tunnel all connected by cross passages

Eight (8) Primary Feasibility Issues Were Considered

As part of the study, eight (8) primary and pivotal issues were examined, including:

  • Geologic, Hydrogeologic/Hydrologic, and Geotechnical Conditions
  • Corridor Concepts (Full Tunnel and Partial Tunnel/ Partial Surface Road)
  • Tunnel Configuration (Cross Section)
  • Tunnel Excavation and Support Methods
  • Tunnel Systems (e.g. Ventilation, Emergency Fire Systems, Operation Building, Toll Systems, etc.)
  • Construction Considerations (e.g. Staging Areas, Access Roads, Muck Disposal, etc)
  • Construction Costs
  • Operation & Maintenance (O&M) Costs

Project Phasing

The feasibility study focused on a phased construction approach. Constructing one large reversible vehicular tunnel and a smaller rail tunnel as part of a first phase would potentially allow generation of toll revenues to support construction of a second large vehicular tunnel in a later phase. The design assumes current California Department of Transportation Standards.
Phase 1 - Vehicular Tunnel and Rail Tunnel (Not To Scale)

Phase 1 - Vehicular Tunnel and Rail Tunnel (Not To Scale)

The Study Considered Three (3) Profile Grades for Tunnels 

  • 5% grade to avoid high ground water pressures (Riverside County- Orange County Major Investment Study profile)
  • 3% grade to accommodate a transit/rail facility
  • Central Pool Augmentation (CPA)/gravity grade to accommodate the potential of co-locating future MWD pipeline potentially connecting Lake Mathews to Orange County
3 Profile Grades for Tunnels image

Project Schedule and Estimated Costs

The project approval and environmental document (PA/ED) and the final design phases are estimated to take 7 to 11 years. Once the project is approved and permitted, construction of the initial phase of the project (single bore plus rail tunnel) is estimated to take up to 10.5 years, but construction could be expedited by strategically and effectively overlapping of activities. The second phase of construction timing (third bore) was not evaluated as part of this study.

Estimated Cost
Contingency (included in cost)
Construction $8.6 Billion 25%
Operations & Maintenance $51.7 Million annual 35%

Financial Analysis – What would it cost to build ICE?

A financial analysis of the ICE tunnels project was conducted by RCTC and OCTA assuming the following project conditions:
  • Construction schedule of 10.5 years
  • Bond amount fully funded at the beginning of construction (BBB)
  • No federal, state, or private seed money
  • Debt payment from toll revenues only
  • Construction cost of $13.4 billion (escalated)

The financial analysis results in a need for $28.3 billion in bond proceeds. Estimated tolls are not sufficient to cover debt service and operating costs. The high financing costs are attributed to the long construction schedule, capitalized interest, and inflation.

Additional study of the Irvine Corona Expressway tunnel project has been deferred until such time as financial considerations improve and/or technological advancements warrant reexamination. Future tunnel discussions will be evaluated annually by the State Route 91 Advisory Committee as part of its State Route 91 Implementation Plan update. The annual review will determine if any of the major assumptions with regard to financial considerations, private sector interest, or technological advancements have changed to make the tunnel financially viable.

Traffic Demand

Demand will continue to increase. Given its location, the SR-91 is used by a wide array of commuters, and that’s not likely to change. Here’s a snap-shot of traffic demand:
  • SR-91 is the only direct commuter facility connecting Riverside County to Orange County.
  • The existing ADT at the county line is 280,000 vehicles and is expected to grow to roughly 450,000 ADT by 2030.
  • Existing SR-91 accommodates 12-14 traffic lanes. By 2030, the number of lanes will need to be increased to 22 lanes to accommodate the anticipated growth. Various constraints preclude accommodating the 22 lanes needed along SR-91.
  • Commuter rail services within the SR-91 corridor are constrained with little room for growth.
  • A two-lane reversible tunnel would accommodate a maximum capacity of 72,000 average daily traffic, with a daily average forecast from 55,000 to 65,000 vehicles per day (vpd).


Based on the limited studies conducted to date, it is determined that a tunnel system is technically feasible. While there are no fatal flaws identified that would prevent the project from being designed, constructed and operated, there are however, significant challenges. The most critical challenges determined to date are the following:
  • Protection of groundwater resources
  • Large tunnel diameter construction technology
  • Tunnel ventilation
  • Tunnel configuration and tunnel grade considerations
  • Schedule implementation
  • Construction and operating costs