Street-running railway goes underground
https://www.railwaygazette.com/infrastructure/street-running-railway-goes-underground/61668.article
Premetro system is common among European cities. If tram runs underground, it's called "Premetro system"
On the other hand, in Japan, there is no premetro system. Tram is basically running on road, while subway basically runs underground, and never runs on road. I guess this is because people in the country don't understand necessity of tram, and subway system is believed to be appropriate only for mass transportation.
