We stopped building subways cheaply
7 days ago
- #transportation
- #urban infrastructure
- #construction technology
- Historically, subways were built using 'cut and cover' excavation, which was cheaper but highly disruptive to urban areas.
- Tunnel-boring machines (TBMs) have largely replaced cut and cover in urban areas due to their ability to tunnel without disturbing the surface, despite higher initial costs.
- Cut and cover construction faces increasing political and public opposition due to noise, traffic disruption, and property damage, making it less viable in modern cities.
- Technological advancements in TBMs have made them faster and more cost-effective, reducing the relative advantage of cut and cover.
- Environmental laws and public opposition have further increased the challenges and costs associated with cut and cover construction.
- Elevated railways, once common, were largely replaced by subways due to their disruptive nature, though modern elevated systems are quieter and less intrusive.
- The choice between tunneling methods involves not just cost but also political, social, and environmental considerations.