Innovative safety engineering solutions for compressed air tunneling in urban areas

Client: Salini Impregilo SpA & Astaldi SpA
Project: Naples – Bari high speed railway project, Naples – Cancello Lot, PA1266
Date: 2016

The Naples – Bari High speed railway project includes the construction of the Casalnuovo artificial tunnel in urban area. Part of the tunnel will be excavated under the water table. The Client expects to adopt the “cut and cover” excavation method in hyperbaric conditions as an alternative to jet-grouting.
During tender phase, SERENGEO reviewed the technical and technological solutions to ensure the highest workers’ safety level during tunneling works.


Casalnuovo tunnel track


Geological profile and piezometric level. The red rectangle borders the Casalnuovo tunnel’s section under the water table

Project Goals

  • Assess the adequacy of the technical and technological solutions proposed by the Client;

  • Provide specific guidance for safe tunnelling under hyperbaric conditions..

Excavation under hyperbaric conditions

Activities performed

  1. Review of tender and Client’s bid technical documentation;
  2. Review of the current national and international regulatory framework and of the guidelines for tunnelling under hyperbaric conditions;
  3. Identification of the hazards for workers operating under hyperbaric conditions and analysis of the mitigation and preventive measures proposed by the Client;
  4. Definition of the best practices to be adopted in tunnel design and construction to ensure the most appropriate health and safety conditions for workers.

Innovative aspects

  • Innovative tunnelling technique never applied in Italy;
  • Introduced innovative organizational, technological and technical solutions that improve workers’ safety;
  • Defined brand new good practices for safe compressed air tunneling with the “cut and cover” method.