"The contract for the procurement of two Tunnel Boring Machines (TBM) for the construction of the first phase of the Belgrade Metro, i.e. the excavation of the tunnel section of Line 1, was signed today by the project manager of Metro Line 1 on behalf of the company "PowerChina" Han Zhiping and the representative of the company CRCHI Cao Jianfeng, which was attended by the director of the Public Utility Company "Belgrade Metro and Train" Andreja Mladenović."

Tunnel Boring Machines have a diameter of almost 10 meters.

https://www.beograd.rs/cir/beoinfo-vesti/a108018/Potpisan-ugovor-za-nabavku-dve-TBM-masine-za-beogradski-metro.html