A Trial run of city`s first underground Metro line 3 was done on sunday. The Metro line 3, will be a 33.5 km underground route which will connect south Mumbai with the western suburbs and is expected to reduce the burden on the suburban locals.Length of the corridor is marked with 27 key stations out of which 26 will be underground.The Mumbai Metro Rail Corporation Limited intends to complete the work and begin operations between Aarey and Bandra Kurla Complex for the phase I corridor by June 2023. The remaining will be completed after that.