Web application layer (or web tier) is a Java based application server which manages communication between 4-tier client and server manager. So neither TC Data nor TC Root are in web app layer.
As far as I understood the architecture concepts: TC_ROOT is in client layer and TC_DATA should be in resource tier.
NX 11 | SW 2016 | Creo 4 | TcUA 11.4
Evaluating: AW 3.4