
Larsen & Toubro Limited (Construction) engaged NV Dynamics to conduct detailed noise and vibration assessments for the proposed Mumbai Metro Line-4, extending approximately 19.48 km between Bhakti Park Metro Buffer End and Mulund Fire Station, with 17 elevated stations on a standard gauge double-track alignment.
For the noise assessment, 16 locations were selected considering factors such as lateral distance from the alignment, relative height of the monitoring point with respect to the viaduct bay and surrounding site conditions. Type-1 grade noise data loggers were deployed to evaluate airborne noise within the metro’s zone of influence. The noise data loggers recorded equivalent continuous noise levels (Leq) at 15-minute intervals during daytime (06:00 a.m.–10:00 p.m.) and nighttime (10:00 p.m.–06:00 a.m.) periods. The monitoring program was designed in line with RDSO and FTA guidelines to ensure representative characterization of noise levels.
For the vibration assessment, four locations were identified based on alignment drawings and bore log data. A tripod-based weight drop mechanism was used to generate controlled vibrations, while seismic-grade transducers were installed at 1 m, 10 m, and 20 m distances to analyze vibration attenuation. Additionally, ground transmissibility measurements were performed on the operational Mumbai Metro Line-7 near Gundavali Station using a similar setup. The recorded data were used to assess vibration propagation and validate predicted vibration impacts for Mumbai Metro Line-4.