SYSTEMATIC REVIEW ON THE IMPACT OF LARGE-SCALE RAILWAY INFRASTRUCTURE ON REGIONAL CONNECTIVITY AND RESILIENCE IN THE U.S.

This systematic review synthesized quantitative evidence on how large-scale railway infrastructure influenced regional connectivity and resilience in the United States. After comprehensive database and grey-literature searches and two-stage screening, 68 studies met eligibility criteria and produced 214 extractable effect sizes. Connectivity outcomes dominated the evidence base with 143 effects (66.8%), while resilience outcomes contributed 71 effects (33.2%). Random-effects pooling showed positive impacts across every outcome family. Average connectivity gains were moderate in magnitude, led by accessibility expansion (pooled g = 0.41), followed by interaction‐intensity change (g = 0.35) and network‐performance improvement (g = 0.29). Resilience gains were also positive, with redundancy/robustness improvement (g = 0.33) and recovery‐performance change (g = 0.30) exceeding continuity-of-flow stabilization (g = 0.25). Heterogeneity was substantial (I² roughly 65–73% across families), supporting moderator testing. Meta-regression indicated that baseline accessibility systematically shaped effect size: low-baseline regions displayed larger proportional accessibility gains (g = 0.49) than high-baseline regions (g = 0.31), whereas high-baseline megaregion corridors showed larger absolute interaction increases. Metro scale strengthened passenger connectivity, with large metros outperforming small metros (difference ≈ 0.17 g). Freight-intensive regions registered higher freight continuity and resilience gains (g = 0.37 vs 0.21). Shared passenger–freight corridors produced stronger passenger reliability and recovery effects, while freight-exclusive corridors yielded larger freight throughput gains. Hazard context moderated resilience, as flood-exposed and coastal corridors showed the largest resilience effects (g ≈ 0.38). Sensitivity analyses excluding higher-bias or short-horizon studies preserved positive direction and significance. Overall, the evidence portrayed U.S. large-scale railway infrastructure as a dual regional intervention that strengthened everyday functional linkage and improved shock tolerance through measurable gains in access, flows, reliability, redundancy, and recovery.