CIVIC-FA Track B: Revitalizing Legacy Infrastructure Using Rapidly Deployable Pop-Up Metro

About This Grant

The objective of this NSF Civic Innovation Challenge (CIVIC) Stage 2 project is to explore and demonstrate an alternative model of rail transit development that revitalizes underutilized—or “legacy”—rail through partnerships. Rail transit in the United States faces several challenges that drive up costs and delay implementation: technical complexity requiring expensive signaling and inspection systems, complex regulatory hurdles, rigid funding structures that limit financial innovation, and reliance on costly feasibility studies to justify demand. These barriers reinforce high-cost, consultant-driven development models that discourage scalable, community-responsive transit. Rather than relying on billion-dollar rail projects, the project team asks: What if transit could start small, grow with demand, and be shaped by the people it serves? The project centers on how legacy rail can overcome barriers that inflate revitalization costs by combining modular rail technology, onboard sensing for safety and maintenance, new regulatory pathways, and grassroots planning. To achieve this, it brings together a partnership of eight organizations, led by Carnegie Mellon University, Pop-Up Metro, and the Delaware River Waterfront Corporation. Through this partnership, the project deploys and operates a full-scale metro along 1.61 miles of legacy rail along Philadelphia’s Delaware River. The demonstration showcases a scalable, cost-effective transit model, with replication in other communities supported through workshops for municipal leaders and transit agencies interested in revitalizing rail infrastructure. The outcome includes a public-facing blueprint outlining regulatory, technical, and financial strategies for replication, and a dedicated Pop-Up Metro division to guide implementation across the country’s thousands of miles of legacy rail. This project advances knowledge through an empirically rigorous, interdisciplinary approach to transform underutilized infrastructure into viable transit systems by combining engineering innovation, public engagement, and regulatory adaptation. It examines four key questions with significant knowledge contributions: (1) how onboard defect detection technology improves maintenance strategies and reduces costs; (2) how modular train units impact financial sustainability compared to fixed-infrastructure systems; (3) what regulatory pathways enable effective and scalable legacy rail reactivation; and (4) how grassroots engagement can replace traditional feasibility studies to inform needs, demand, and rail service justification. The research methodology combines rigorous technical validation, quantitative economic analysis, regulatory blueprint development, and mixed-methods community engagement analysis. A new paradigm is established for implementing transit by combining technical innovation with civic participation, creating empirically validated frameworks that can be applied across diverse urban and rural settings while deepening the fundamental understanding of infrastructure management. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.