The International Federation of Consulting Engineers and the International Tunneling and Underground Space Association (ITA-AITES) launched a new set of contract documents specifically tailored to the challenges of underground works that involve geologic uncertainty, including tunneling and foundations. 

The groups released the documents, known as The Emerald Book, at the World Tunneling Congress, held in Naples, Italy, May 3-9. The book specifies allocating risk for underground conditions and groundwater to the project owner, while the contractor owns performance-related risk. It also includes an unforeseeable physical conditions clause as well as a contractual geotechnical baseline and alternative dispute avoidance and resolution, said Matthias Neuenschwander, chair of the book’s workgroup.

“Despite all the technological developments of equipment and techniques in the field, many underground construction projects end up unsuccessful because of contractual disputes,” said Tarcisio Celestino, outgoing president of ITA-AITES. The book “will have positive benefits for both owners and contractors.”

Several other working groups presented studies, including new guidelines on rebuilding tunnel boring machines. Refurbishment has become a common practice as tunneling projects have ramped up around the world. “The new guidelines reduce risk for safety and economic losses,” according to the authors.

Keynote speaker Martin Herrenknecht, chairman of the TBM manufacturing company that bears his name, expounded on how technology will impact tunneling. “Digitalization is quite important, training the TBM with fuzzy logic so it is adaptive to the geologic profile and can do much more automatization,” he says. He also sees improvements in shaft construction, engine design, conveyor systems and high voltage cabling, which will help machines approach 20 meters in diameter in the next five to 10 years. 

Another keynote speaker, Pietro Salini, CEO of Salini Impregilo, told ENR that it’s a good time to be in the tunneling business. “Infrastructure needs around the world are booming,” he says. But to deliver these projects on budget and on time, the industry needs to adopt AI, lean practices and attract the next generation of workers and innovators, he added.