Tunnels renovation programme in Italy
Enrico Mittiga – Anas SpA Gruppo Ferrovie dello Stato Italiane
Summary
Italian road tunnels: an overview
Guidelines for inspection of road tunnels
Tunnel inspection: state-of-the-art and things to do
Lessons learned (so far)
Conclusions
The road network in charge to Anas extends over 32,000 km.
It sums up 25,000 km of ordinary roads and over 8,000 km of highways.
Italian road tunnels: an overview
The highway network in charge to ASPI – Autostrade per l’Italia extends over 2,800 km.
Typical layout of an italian highway with tunnels and viaducts (A2 « del Mediterraneo » highway Salerno-Villa S. Giovanni)
S. Lucia tunnel on A1 highway in the outskirts of Firenze and the TBM used to bore the twin tunnels
Clusters of tunnels
The total number of road tunnels on Anas network is, at present, over 2,000.
Tunnels are not evenly spread across the network: they are mainly present in mountain areas in northern, central and southern Italy.
Classification by age of road tunnels on Anas network permits to highlight a large number (in excess of 25% of total amount) of structures over the age of 50 years. Note that for almost 16-18% of structures there is no information about their age.
Very different features between a tunnel from late XIX century (on the left – Tunnel of Tenda pass, northern Italy, year 1883) and a very recent tunnel (SS 76 Perugia-Ancona, year 2016).
Roads of italian network are affected by heay traffic, both cars and lorries
Italy has a very fragile territory prone to landslides and rockfalls
Flooding inside ‘San Martino’ tunnel (Northern Italy – October 2024)
Tunnels are very sensitive to ageing of materials: interaction between masonry or concrete lining and ground water always leads to alteration and degradation of structures.
When not detected in time, degradation of lining may cause parts to fall onto the road surface, which is the worst event to fear.
Guidelines for inspection of road tunnels
Due to difficulties to cope with each hazard to tunnel safety by using a common “reactive” maintenance approach (act after event), Anas is to adopt a “proactive” maintenance approach (act before event).
With regards to tunnels, the legislative and technical frame of this approach is the Ministry of Infrastructures Decree no. 247/2022 that contains guidelines for inspection and risk assessment (the «LINEE GUIDA PER LA CLASSIFICAZIONE E GESTIONE DEL RISCHIO, LA VALUTAZIONE DELLA SICUREZZA ED IL MONITORAGGIO DELLE GALLERIE ESISTENTI»), a technical specification that, moving from a simplified but consistent risk evaluation, permits to define surveillance and monitoring plan for each structure, by using a multilevel approach, justified by the different kind of recognized potential hazards (structural, geotechnical, geomorphological, seismic, hydraulic).
Thanks to the significant work carried out by the Ministry of Infrastructure with the guidance of the Academia, on 23/08/2022 the Guidelines permit to ensure the homogeneity of risk classification and management, safety assessment and monitoring of existing tunnels; the Guidelines also indicate the scheduling/execution of surveys on the state of conservation, the execution of inspections and scheduling of maintenance and safety interventions.
This is also made possible by the implementation of a tunnel data management system: TMS, short for Tunnel Management System, a digital tool that will manage the very great amount of data coming from inspections.
TMS is being developed in house by Anas and it will be operative by the end of 2024.
2020
2021
2022
2023
2025
Guidelines for bridges
Guidelines for tunnels
Starting of inspection activities for tunnels
End of inspection activities for tunnels (first phase)
Algorythm of application of Tunnel Management System, as is per DM 247/2022
First step: level 0
Documentary check
Second step: level 1
Visual inspection,
investigation and testing
Second step – Visual inspection inside a tunnel
Second step – Health check of lining
Water leakage
Cracks
Second step – Investigation and testing
Georadar survey
Flat jack test
Inspection inside the tunnel means that traffic must be diverted.
Third step: level 2
Risk level assessment
Third step – Risk level assessment – Final sheet for a tunnel
Tunnel inspections: state-of-the-art and things to do
Grand total of tunnels to be inspected
Already done at October 2024
Level 0
Level 1
Level 2
Grand total of tunnels to be inspected
October 2024:
180 tunnels out of 1198
Level 0
Level 1
Level 2
Grand total of tunnels to be inspected
By the end of 2025:
1018+ tunnels
Level 2
Level 0
Level 1
A strong opportunity for italian technical-scientific community to test in true scale theoretical approaches and work techniques for tunnel renovation
Further steps: monitoring and/or intervention to renovate
Further steps – Design and implementation of remediation works
Further steps – Design and implementation of remediation works
BEFORE WORKS
AFTER WORKS
Tunnel ‘Tribito’ (Calabria)
Tunnel ‘Berruiles’ (Sardinia)
Tunnel remediation works: already done
Lesson learned (so far)
Tunnel inspections are a difficult task to cope with.
This is true for many reasons:
Conclusions
NEED TO CAREFULLY PLAN INSPECTIONS WITH DIRECTIVES GIVEN BY A HEAD OFFICE
ACTIVITIES TO BE CARRIED OUT PREFERABLY AT NIGHT
BUDGET FOR DEDICATED STAFF SPECIFIC EDUCATION
and above all remember that:
TIME SPENT FOR INSPECTION IS NOT WASTE TIME BUT A REAL INVESTMENT FOR SAFETY
Thank you for kind attention
e.mittiga@stradeanas.it