A Popular Rail Corridor

Serving Metrolink, Amtrak, Union Pacific, and BNSF freight trains, the Los Angeles-San Diego-San Luis Obispo (LOSSAN) rail corridor is the second most heavily traveled intercity passenger rail corridor in the nation. With more than seven million passengers and countless tons of cargo, maintaining and operating this corridor is a key element in the region’s overall transit system.  Keeping this corridor open and operational is critical to the region’s mobility and economy. However, some segments of the track along the corridor were at risk of obstruction and collapse from eroding slopes and sub-grades adjacent to the corridor. To ensure continued operation and protect critical regional infrastructure, the LOSSAN Slope Stabilization project repaired previous erosion damage and prevented future issues via a combination of enhanced drainage facilities and slope armoring.

Reinforcing Strong Slopes and Modifying Facilities

The project assessed previously eroded slopes and protected them by installing modern geosynthetic face armor. Additionally, in areas where historically concentrated flows had occurred near the track, a combination of underdrains, channels, and energy dissipation facilities were installed. Construction was completed in live track conditions and without substantially modifying existing utility facilities within the corridor, reducing impacts and costs.

Based on site conditions and past issues, a variety of improvements were completed at several locations including:

• Selective slope grading
• Installing geosynthetic armor
• Installing shotcrete along slopes close to tracks
• Utility protection
• Underdrain Construction
• Gunite Channel Construction
• Rip-Rap Energy Dissipation Installations

Additionally, at each site, our team performed coordination, overall management, and other support including:

• Railway coordination
• Utility Coordination
• Site management per SCRRA requirements
• Storm Water Pollution Prevention Planning (SWPPP) and implementation
• Federal Transit Administration fund administration and compliance

Responsive and Adaptive Oversight

Ghirardelli Associates (Ghirardelli) supported OCTA by providing construction management and inspection services for the project. Because the project required working within an active rail corridor it presented a unique set of challenges that required a combination of both methodical planning and the ability to adapt to the types of unforeseen conflicts typical with underground construction.