Salerno – Reggio Calabria high speed railway line, Lots 1a, 1b, 1c. Tunnelling with traditional technique and EPB – TBM through gassy rock masses and soils. Technical – scientific advisory support during design phase

Client: Italferr S.p.A.
Project: Salerno – Reggio Calabria new railway line. Lots 1a, 1b and 1c
Date: February 2022 – March 2024

The Salerno – Reggio Calabria new railway line detailed design (Lots 1a, 1b e 1c, Figure 1) includes the excavation of about 124 km of line and service tunnels (access and pedestrian tunnels) in potentially gassy rock masses and soils.
SERENGEO provided technical – scientific assistance, during detailed design, on safety against air–methane mixtures detonation / deflagration during tunnels’ construction works.

Figure 1. Route of Lot 1b of the new Salerno-Reggio Calabria. The green line identifies the tunnel route

Project goals

• Risk assessment associated with potential methane emissions during tunnels’ construction and technical classification of the line and service tunnels (access and pedestrian tunnels);
• Specific guidance for safe design and construction of tunnels (with traditional excavation technique and EPB – TBM) in gassy rock masses and soils.

Activities performed

1. Bibliographic and hystorical documentation’s analysis on:
   a. geo-structural framework of the area surrounding the new railway line route;
   b. evidences of methane presence in the investigated area and geological formations that will be involved in tunnelling works of the new railway line route:
   • surface methane emissions (Figure 2);
   • lignite, asphalt and bitumen mines;
   • methane detected during construction of tunnels excavated in the same geological formations;
   • mining licenses, issued by the Ministry of the Environment and Energy Security (MASE, UNMIG), for the exploration and extraction of hydrocarbons (oil and/or gas) and stratigraphy of exploratory and production wells close to the route (Figure 3);
2. Analysis and interpretation of geognostic and methane investigations’ results;
3. Critical analysis of excavation methods and techniques, section and technical data of the line and service tunnels;
4. Definition of the hypothetical methane emission model and technical classification of the line and service tunnels in relation to methane risk, according to “Grisù” Guideline;
5. Definition of the criteria and technical specifications for the EPB – TBM design and construction for tunnelling in gassy formations, according to “Grisù – TBM” Guideline;
6. Development of the safety measures and procedures to be adopted against air – methane mixtures’ detonation / explosion hazard, during line and service tunnels construction to ensure the highest safety level.

Figure 2. Lot 1b route (solid blue line), superimposed on the map of gas emissions catalogued by Minissale et al. (2016), classified according to the measured methane concentrations (reported next to each emission point)

Figure 3. Expired exploration permits issued in the area including the Lot 1c route (UNMIG data, ViDEPI project): Monte Rossino (a), Sapri (b), Lagonegro (c), Montesano sulla Marcellana, and Torraca (d)