Project
The project for the rehabilitation of the tunnel between Piola and Lambrate stations on Milan Metro Line MM2 included interventions to waterproof the upper part of the tunnel, focusing on the roadbed of Via Pacini, and waterproofing of the lower part of the tunnel, involving the tunnel’s base slab. The entire section between the two stations was divided into two subsections: one leading to Lambrate station and the other to Piola station. The overall intervention led to a significant reduction in water within the tunnel and the waterproofing of the cavity.
Intervention
Field was tasked with the supply, installation and data management of the entire monitoring system using the AIDA IoT platform. In detail, the extensive monitoring system implemented consisted of the following components:
Surface Monitoring:
- Levelling rods for topographical monitoring of the facades of buildings along Via Pacini (44 for both directions).
- Wireless biaxial clinometers to measure changes in the verticality of building facades along two orthogonal axes. Clinometer monitoring was carried out only in the first subsection (14 clinometers were installed along with a data collection and transmission gateway).
Groundwater Level Monitoring:
- 4 piezometric pipes equipped with wired pressure transducers connected to automated data loggers.
Tunnel Track Monitoring:
- Dozens of digital RDS (Rail Deflection Sensors) placed on sleepers to monitor key track geometry parameters during work in the first subsection from Lambrate station to the ventilation shaft.
Tunnel Crack Monitoring:
- Numerous crackmeters with a measurement range of ± 25 mm were installed to monitor the tunnel’s cracks status. After the intervention in the first subsection, the crackmeters were dismantled and reinstalled in the second subsection.
Tunnel Convergence Monitoring:
- Tunnel sections were equipped with digital biaxial clinometers to monitor convergences. A total of 35 convergence sections were installed in the first subsection and 37 in the second subsection, with an average spacing among them of 9 meters.
Flow Monitoring:
- Monitoring of the water collection channel’s gate beneath the walkway. A flow meter was installed near the drainage well.
All the instrumentation installed in the tunnel was wired to two data loggers located inside the drainage well.
Finally, the construction and installation of two specular panels were required, one inside the construction site shacks and the other in the ATM (Azienda Trasporti Milanesi) operational center at Piola station.
Results
The fully automated monitoring system, managed through the AIDA IoT web platform, allowed the client, designers and the MM (Milan Metro) construction management team to monitor the measured parameters in real-time during the execution of the works. This ensured the safety of subway Line 2 train circulation in the section during the most critical operations. Access to data and direct, immediate alerting in case of issues thanks to the AIDA IoT web platform enabled a faster and more secure response from the technical staff involved.
Furthermore, the two specular panels installed at the construction site and in the ATM operational center, which could be activated/deactivated through a dedicated section of the AIDA IoT web platform, provided direct, continuous and timely visual feedback to ensure the safety of train circulation.
