Project Overview
Pizzi Terra, an Italian engineering and monitoring specialist, was engaged to support a major road infrastructure upgrade in Tuscany. The works involved the construction of a new tunnel alongside an existing one, effectively doubling road capacity while maintaining the structural safety of the original tunnel during ongoing construction.
Due to the proximity of the new excavation, deformation was observed in the existing tunnel structure. This required a comprehensive and reliable monitoring system to track structural behaviour throughout excavation, reinforcement, and concrete works.
Ackcio was selected to support the structural monitoring system inside the tunnel under restoration, operating alongside an integrated monitoring approach that also included automatic topographic measurements.
Monitoring Challenges
Tunnel enlargement and restoration present a number of practical monitoring challenges:
- Monitoring had to be carried out in parallel with excavation and reinforcement activities
- Sensors needed to be installed early and protected during concrete casting
- Wireless communication was difficult due to tunnel length, curvature, and dense steel reinforcement
- Cabling had to be minimized to avoid clashes with construction operations
- Monitoring equipment needed to be temporarily relocated as works progressed
Ensuring reliable data transmission in a confined underground environment was critical.
Monitoring Setup
The tunnel section under restoration spans approximately 1,500 metres, with 15 monitoring sections installed at regular intervals of 100 metres.
Each monitored cross section includes:
- 8 pairs of vibrating wire strain gauges per section
- Sensors installed on both intrados and extrados of reinforced tunnel ribs
- Additional control sensors to monitor structural behaviour during concrete curing
All strain gauges were tied directly to reinforcement steel prior to concrete placement.
Ackcio Solution
Ackcio’s Vibrating Wire Nodes, including both 1-channel and 8-channel variants, were deployed together with wireless gateways to collect and transmit structural data.
Deployment methodology:
- Reverse arch sensors were installed immediately after jackhammer excavation
- Nodes were temporarily mounted on upper reinforcement bars during early construction stages
- Nodes were removed and reinstalled as upper arch sensors were added
- Sensor cables were routed through conduits embedded within the concrete lining
- Final node positions were fixed once the upper arch concrete had fully cured
Ackcio’s wireless mesh network ensured reliable data transmission despite steel congestion and frequent obstructions along the tunnel.
Outcomes and Benefits
The monitoring system delivered several key benefits for Pizzi Terra and the project team:
- Stable wireless communication in a challenging underground environment
- Reduced cabling, simplifying installation and minimizing interference with site works
- Consistent data quality across all monitored sections
- Flexible installation, allowing nodes to be temporarily repositioned as construction progressed
- Strong quality-to-price ratio, supporting long-term monitoring requirements
The ability to maintain data continuity despite evolving site conditions was a major advantage.
Client Experience
Pizzi Terra highlighted Ackcio’s technical support and responsiveness throughout the project.
“Ackcio makes tunnel monitoring easier.”
Support was described as precise, fast, and dependable, particularly during installation planning and early deployment phases.
Looking Ahead
Following the successful deployment, Pizzi Terra looks forward to using Ackcio devices again on future tunnel and infrastructure monitoring projects.
