The second axis of market taxonomy is application, which partitions demand by train category and directly drives capacity planning for washing facilities. Passenger services dominate usage patterns, representing approximately 60 % of installed plant capacity; high turnover and stringent cleanliness standards compel operators to invest in larger, often automatic, stations to sustain punctuality. Freight locomotives, accounting for roughly 30 % of the market, operate on longer cycles and tolerate lower cleaning frequencies, allowing semi‑automatic or manual solutions to meet cost constraints while still protecting cargo integrity. High‑speed rail, though a niche segment at about 10 % of total revenue, requires specialized high‑pressure nozzles and precision timing to avoid service disruption, prompting premium‑priced, fully automatic installations. This application‑focused Train Washing Plants segmentation aligns capital allocation with service intensity: higher‑frequency passenger corridors justify higher‑throughput plants, whereas freight and high‑speed lines justify tailored configurations. Consequently, the proportional split of application segments underpins the aggregate market size, with each share reflecting distinct operational imperatives and investment rationales.