How the MBTA Gets New Subway Cars Into Boston’s Tunnels

Because the MBTA’s century‑old tunnels have tight clearances, new railcars cannot be shipped whole. Instead, they’re delivered as modular sub‑assemblies (shells, trucks, equipment boxes) via flatbed truck, lowered through street‑level portals or shaft openings, and assembled underground in maintenance yards. This “kit‑of‑parts” approach avoids disruptive tunnel enlargement.