Timeline & Current Construction | FAQs
The City of Irvine is advancing the Marine Way extension and undercrossing to improve access and traffic circulation in and around the Great Park. While Marine Way runs along the southern edge of the park, there is currently no direct rail crossing or direct road access into the Great Park from Marine Way and Barranca, where Marine Way currently ends.
The project will create a new rail undercrossing at Marine Way, providing a direct connection between the Great Park and the Spectrum area — the nearest crossings are currently located at Sand Canyon Avenue and Alton Parkway. The Marine Way road extension will connect the two existing termini of Marine Way at the Great Park, and Marine Way and Barranca. These new routes will reduce travel distances, ease congestion, and help save time and fuel for drivers.
Once complete, the project will enhance safety for pedestrians and bicyclists, support walking and biking with new connections, and reduce greenhouse gas emissions by cutting down on vehicle trips.
Construction is underway, with major work continuing through 2026 and full project completion anticipated in 2027.
Watch the Marine Way Undercrossing Visualization.
Timeline
April-May 2026: Construction is underway on the Borrego Channel tunnel structure — a waterway that currently runs north of the train tracks. As Marine Way is extended to create a new rail undercrossing, the channel will be rerouted through this new structure.
May-September 2026: The Marine Way underpass tunnel structure will be constructed, which will serve vehicles, pedestrians, and cyclists.
Current Construction
- In less than 24 hours, crews poured 1,700 cubic yards of concrete to form the bottom of the Marine Way underpass structure. From here, we go up! Work will now transition to forming the walls of the underpass.
- The concrete for the Borrego Channel tunnel structure is continuing to dry and crews are beginning to remove the internal forms used to support the concrete.
- Specialized crews are setting up and receiving materials this week to prep horizontal drilling for pipeline relocation work to lower existing utility lines along the railroad tracks below the new underpass structure. That work is scheduled to start next week!
For more details visit greatparkframework.org.