Data and Code for Delineating grey-green substitution thresholds for climate-resilient highway drainage

This study defines a substitution index, the share of required grey drainage upsizing that a feasible green footprint can displace, and derives grey-mandatory, hybrid and green-only regimes from hydraulic reliability and life-cycle cost. A weighted 15-model CMIP6 ensemble with non-stationary extreme value fits, station-corrected satellite design rainfall, curve-number runoff and Green-Ampt infiltration were applied to 433 one-kilometer segments of two Chinese expressways. Existing drainage exceeded its reliability target on every segment under all three emissions scenarios.