Delivering Zero Emissions Bus Infrastructure with MTS
Challenge
The San Diego Metropolitan Transit System (MTS) undertook a multi-facility program to transition toward a zero-emissions bus fleet by 2040, requiring scalable charging capacity, resilient power systems and seamless integration within active transit facilities.
This effort included multiple projects – South Bay Electric Bus Recharging, South Bay Battery Backup Power and Imperial Avenue Division (IAD) Expansion, each with distinct technical requirements but unified by the need to deliver complex infrastructure within fully operational maintenance yards.
Unique conditions included working within a limited footprint, first-of-its-kind charging configurations, underground utility conflicts, long-lead equipment procurement and coordination with San Diego Gas & Electric (SDG&E) for utility upgrades and renewable energy integration. These challenges were compounded by evolving permitting requirements and the need to maintain strict safety, schedule and cost control without disrupting ongoing service, maintenance and administrative operations.
Solution
With these challenges in mind, TRC is delivering comprehensive construction management services across three facilities. The approach is proactive and grounded in technical expertise, structured coordination and strong project controls. One project is complete, while the other two are actively in progress. Together, they show how a coordinated, program-wide strategy can advance large-scale transit electrification.
South Bay Maintenance Facility – Phase 1
At the South Bay Maintenance Facility, one of the first overhead multi-vehicle electric bus charging systems in the United States was installed. The system was designed to charge up to 24 buses at once. The work took place in an active maintenance yard with limited space. Existing infrastructure and a tight urban footprint made expansion difficult, so every decision required careful coordination.
To address these constraints, TRC supported an overhead conductive gantry system. This reduced the need for ground-based equipment and freed up valuable space. A dual verification system using RFID and Wi-Fi was also implemented. It confirmed bus identity and enabled real-time communication with the microgrid controller. TRC worked closely with MTS, the general contractor and SDG&E. The team coordinated utility upgrades, addressed geotechnical challenges and managed complex 3D design coordination. When switchgear delays occurred, temporary power solutions kept construction moving.
TRC also led fabrication inspection and field quality assurance. This included structural welding checks, non-destructive testing, high-strength bolting and coating inspections. The team introduced practical improvements such as charging status indicator lights, improved access to emergency shut-offs and an optimized site layout.
The project demonstrates how strong coordination and thoughtful design can deliver large-scale electrification in a constrained, active environment. The facility remained operational throughout construction while advanced charging infrastructure was successfully deployed. This approach provides a scalable model for transit electrification in urban settings.
South Bay Battery Backup Power Project
The South Bay Battery Backup Power Project is underway as part of a broader resiliency initiative. It is strengthening the South Bay facility with backup power and distributed energy resources. This supports reliable operations today and prepares the site for future microgrid functionality.
TRC is leading the integration of standby gas-powered generation, solar photovoltaic (PV) systems and battery energy storage. The team is coordinating across civil, structural and electrical disciplines to align with existing infrastructure.
To stay on schedule, the team is prioritizing long-lead equipment procurement. It is also working closely with SDG&E to address utility interconnection requirements. In parallel, TRC is managing submittals, stakeholder coordination and risk mitigation to support efficient construction.
As work progresses, the project is improving operational resilience. The facility will be able to maintain service during outages. It also lays the groundwork for future microgrid capabilities and long-term sustainability goals.
Imperial Avenue Division (IAD) Expansion – Phase 1
The Imperial Avenue Division (IAD) Expansion – Phase 1 is underway, expanding charging infrastructure to support up to 40 electric buses. This will more than double the site’s current capacity while helping move zero-emission transit forward.
The scope brings together DC fast chargers, overhead pantographs, conduit systems, structural steel frameworks, electrical switchgear, photovoltaic (PV) systems, battery storage and standby generation into one coordinated system.
TRC is supporting delivery by building on lessons from earlier phases. The team is guiding early electrical coordination, improving procurement sequencing and working closely with SDG&E to keep everything aligned.
Construction management includes submittals, RFIs, change orders, scheduling and field inspections. Along the way, TRC is also supporting design refinements and safety improvements to make the project easier to build and operate over time.
As the project moves forward, it is enabling a larger zero-emission fleet and strengthening readiness for future growth. It reflects a more practical and scalable path for transit electrification.
Results
Through an integrated construction management approach, TRC has supported the successful delivery of the South Bay Maintenance Facility – Phase 1, one of multiple projects within the MTS broader electrification program, which is now operational and actively charging buses. Throughout construction, maintenance, service and administrative functions continued without disruption.
In parallel, TRC continues to support the delivery of additional, distinct projects within the MTS electrification program including the South Bay Battery Backup Power Project and the Imperial Avenue Division (IAD) Expansion. Across these active projects, the same approach is being applied to maintain uninterrupted facility operations while advancing construction.
Together, these projects contribute to the multi-facility electrification program, which is designed to support the transition to a zero-emission bus fleet.
The combined program ensures:
- Establishment of one of the first large-scale overhead bus charging systems in the United States
- Support for scalable charging infrastructure across multiple facilities
- Implementation of advanced technologies including standby generation, solar PV, battery energy storage and future microgrid functionality
- Supports renewable energy integration as part of one of the nation’s leading transit electrification efforts
Work is being completed in compliance with applicable codes, quality standards and performance requirements, within budget and without major claims.
Through our integral role in supporting the MTS electrification efforts, TRC enables the transition to zero-emission transit and commitment to long-term sustainability goals.