The Sepulveda Transit Corridor is designed to cut congestion on Interstate 405, where 400,000 vehicles travel daily, and reshape mobility ahead of the 2028 Olympics.
Los Angeles Metro, a $24 billion answer to chronic traffic
Anyone who has spent time in Los Angeles knows that moving across the city often requires a car and considerable patience. Interstate 405, which connects major suburbs and employment hubs, carries about 400,000 vehicles a day. Traffic frequently slows to a crawl, both day and night.
While many global cities have long relied on underground rail systems as a backbone of urban mobility, Los Angeles is now accelerating its investment in transit. The Los Angeles County Metropolitan Transportation Authority, known as Los Angeles Metro, has approved the Sepulveda Transit Corridor, a $24 billion megaproject aimed at linking the San Fernando Valley with the Westside and Santa Monica.
Tunneling beneath the Santa Monica Mountains
The project calls for drilling through the Santa Monica Mountains to create a new heavy rail corridor. The tunnel will be excavated using advanced tunnel boring machines and engineered to withstand the region’s high seismic risk, with flexible segments and joints designed to absorb earthquake stress.
The scale of the undertaking makes it one of the most ambitious infrastructure projects in California’s recent history. For Los Angeles Metro, the strategy is clear, address structural congestion rather than continue expanding highway capacity.
Speed, automation and network integration
The plan is built around a fully automated heavy rail system. Although an elevated monorail option was considered, heavy rail was selected for its higher passenger capacity and operational efficiency.
The future line is expected to carry more than 120,000 passengers per day. The 21-kilometer route would be completed in less than 20 minutes, compared with 40 to 80 minutes by car today. Trains are projected to arrive every two and a half minutes during peak periods.
Beyond easing pressure on the 405, the new corridor will integrate with bus services, the Metro D Line and the regional Metrolink rail network, offering a cohesive alternative to road dependence.
Funding hurdles and neighborhood concerns
The road to completion remains complex. With a projected cost of $24 billion, the project is poised to become one of the most expensive urban transit investments in U.S. history.
Current local funding covers only a fraction of the total, pushing Los Angeles Metro to pursue a mix of public-private partnerships, federal support and alternative financing tools. Options under discussion include leveraging pension funds and exploring urban tolling mechanisms.
Community resistance has also surfaced, particularly in neighborhoods such as Bel Air, where residents have raised concerns about vibration and noise. However, trains are expected to run at depths of up to 150 meters, limiting surface disruption.
Toward the 2028 Olympics and a cultural shift
As Los Angeles prepares for the 2028 Olympic Games, the Sepulveda project carries symbolic weight. The city is attempting to demonstrate that even a metropolis long defined by car culture can transition toward a more sustainable mobility model.
Construction will likely require at least a decade, meaning the Olympics may showcase only the early stages of development. Still, the investment represents more than infrastructure. It signals a cultural transformation for a region that can no longer rely solely on widening highways to support growth.
