Abstract
Incineration expansion changes the composition and scale of municipal waste treatment systems. Using original China Urban Construction Statistical Yearbook records for 2012–2024, we examine 376 city-year expansion events in 212 cities and compare post-2018 expansion cohorts with eligible comparison cities. Capacity offsets are reductions in reported non-incineration capacity accompanying incineration additions. During collection declines, offsets absorbed 43.7% of additions, although the median event offset was zero and most events increased total capacity. Two years later, 36 of 70 decline events combined capacity more than 5% above and collection more than 5% below their respective pre-expansion levels. The five decline events with the largest reductions in other capacity did not meet this criterion, although other offset events did. The configuration remained observable after excluding later expansions and using complete capacity fields. In the main comparisons, doubly robust and synthetic difference-in-differences estimators yield positive total capacity contrasts under their identifying assumptions; collection confidence intervals include zero. These findings distinguish aggregate offsets from the typical expansion event and connect initial adjustments to later capacity and collection, informing reviews of replacement schedules, service areas and residual waste forecasts.