A look back on 2017 as an in-between year 28 Dec 2017

After a record-breaking year in 2016, 2017 has been a low-profile year. After the celebrations of the end of the St Gotthard Baseline Tunnel excavation through the Swiss Alps in 2016 as the leader of the year’s record-breaking landmarks, 2017 by contrast has been a year of heads down and getting on with the job in hand. Even the anticipated highlight events of the year were low-key.

An understated affair for Bertha’s breakthrough

This is exemplified by the understated arrival breakthrough of mega-machine Bertha in Seattle in April. Rather than the razzmatazz of the St Gotthard Baseline end of excavation celebrations in 2016, breakthrough of Bertha, after all its earlier trials and tribulations, was more a sigh of relief that the last 7,000ft (2,100m) of the total 9,270ft (2,850m) long drive had progressed under the streets of Seattle without further ado and after its rebuild repair relaunch in early 2016.

The achievement of Bertha though is important and significant for the tunnelling industry. It provides confirmation that huge diameter tunnels can be excavated with mammoth underground mechanical factories.

During the final part of its journey, crews managed to achieve TBM advance rates of up to 13 rings (27.7m) per day and 46 rings (98m) per week and, while the urge was to push on, it was steady averages of 7m-8m/day that brought the mega 17.48m diameter Hitachi Zosen EPB machine safely to breakthrough. Work now progresses on building the road decks and structures within the 15.54m i.d. tunnel and towards a scheduled opening date by early 2019 of the double-deck highway tunnel. This will be more than three years later than the original design-build contract date of December 2015.

2017 breakthroughs

Drill+blast junction under the sea

• Breakthrough on world’s longest subsea road tunnel (Nov 2017)
• Mega TBM success at Caltanissetta in Sicily (Nov 2017)
• TBM rail drive finish at Ulriken, Norway (Aug 2017)
• Final double breakthrough at Emscher sewer (Aug 2017)
• Laos TBM headrace finishes early despite challenges (Mar 2017)

The event of greatest international attention in 2017 was the collapse of the Rastatt TBM railway tunnel drive in August in Germany. While immediate media reports were about the chaos caused to train services by closure of the international rail route on the surface, it soon became clear that it was collapse of the TBM drive underneath at the root of the chaos.

The circumstances of the collapse raised questions and concerns about almost every aspect of the works starting with the programme of risk analyses undertaken ahead of approval to progress the new tunnel under a combination of:

• Large diameter slurry TBM of 10.97m;
• Shallow overburden of some 4m beneath the surface rail tracks;
• Ground freezing to pre-support loose sand and gravel deposits;
• Horizontal installation of ground freezing from shafts located 100m either side of the surface rail tracks.

An official media briefing by the client, Deutsche Bahn, highlighted a long period of hot summer weather combined with concurrent heavy rainfall during the period as contributory factors.

While investigations are on-going, and toward possible release of an official report in Spring 2018, concerns raised in feedback to the reports published by TunnelTalk have included:

Reported facts of the Rastatt tunnel collapse

• The compatibility of ground freezing with slurry TBM excavation;
• The integrity of the freeze at the ends, and the junction point, of 100m long installations from either side and directly under the surface rail tracks;
• The integrity of the annual grouting behind the segmental lining and in conjunction with ground freezing support;
• The integrity of the segmental lining and in addition to perhaps the common practice of removing the lining bolts at a distance behind the TBM;
• The consequent destruction of the TBM as a result of filling the tunnel with concrete to stabilize the collapsed zone;
• The processes for permitting continuation of the TBM drive through the frozen ground as a contractor alternative to the original design for open face sequential excavation also through ground freezing pre-support.

Contributions in response to Rastatt tunnel collapse reporting by TunnelTalk are published in our Feedback section

Open discussion and thorough investigation report of all the circumstances associated with the collapse will ensure the that industry worldwide learns from the incident and create the safeguards and inspire the improvements in technology and practices required to prevent similar situations in the future.

Conferences provide the perfect forum within which these lessons learned, technological developments and revisions of best practices can be shared and discussed. 2017 was a busy year of regular industry conferences and TunnelTalk attended 10 events across the globe starting in February with the Arabian Tunnelling Conference in Dubai and ahead of hosting the WTC 2018 World Tunnel Congress in April next year; progressing through the Summer and into the Autumn with the WTC in Bergen, the RETC in San Diego, the Salzburg Colloquium in October, the Australian Tunnelling Conference in Sydney and the AFTES conference in Paris, which included the ITA Awards conference day and celebration trophy presentation gala dinner, in November and ending in December with the STUVA congress in Stuttgart and the TurkeyTunnel Symposium in Istanbul.

2017 series of conferences

TunnelTalk attended the Dubai ATC conference in 2017 and is the official media partner for the WTC2018 in Dubai next year

• Germany reviews its underground activity (Dec 2017)
• Turkey examines achievements and aspirations (Dec 2017)
• Australia faces a terrific regional workload (Nov 2017)
• International professionals to gather in Paris (Oct 2017)
• Swiss spotlight refurbishment and upgrades (Jun 2017)
• A family affair at WTC 2017 (Jun 2017)
• RETC2017 a full conference agenda (Jun 2017)
• Malaysia hosts excellent SEACETUS 2017 (Jun 2017)
• Dubai discusses industry concerns for the region (Feb 2017)

Each event presented a wealth of information to ever growing delegations of tunnelling engineers and industry professionals and as reported in the TunnelTalk conference articles and videos. Next year will be an equally busy year of conferences for TunnelTalk and will include the NAT in Washington DC in June and the WTC2018 World Tunnel Congress in Dubai for which TunnelTalk is the Official Media Partner. At all these events, our Annual Review printed yearbook magazine is available for free distribution and to provide a record of the global industry activity every year in a single high-quality printed journal.

Also creating a focus of attention in 2017 was the interest shown by billionaire entrepreneur Elon Musk, advancing, as he did, his Hyperloop One version of supersonic vacuum tube travel in a passenger pod and launching a concept of futuristic car transportation as a suggested solution to chronic highway traffic congestion in mega cities such as Los Angeles.

With underground infrastructure needed for both concepts, Musk turned his attention to improving the performance of TBM excavation. This has injected much needed impetus to shake up the status quo and concentrate on methods to increase productivity and improve sustainability within the industry.

The Musk concept of futuristic underground car travel

While Musk generated much positive Feedback to the reporting of the concepts by TunnelTalk, there are those who have a more realistic response to the ideas. For the labyrinth of multi-layers of automatic car propulsion tunnels accessed by parking lot shafts, discussions at conferences suggested that the idea shifts congestion from one form and platform to another, with long cues for access shafts up and down both on the surface and underground, and the design-capacity of the tunnels themselves becoming overloaded within a short period of time - unless access to the system was reserved for the very wealthy who can afford a prohibitive toll charge.

Innovations and developments in 2017

Alternative to longitudinal ventilation

• An alternative air injection ventilation method (Dec 2017)
• A leap towards smarter engineering (Nov 2017)
• Underground travel at the speed of sound (Oct 2017)
• Training the key to reducing in-tunnel incidents (Oct 2017)
• Effectiveness of sprinklers for fire suppression (Aug 2017)
• TBM equipped for high pressure water control (Aug 2017)
• Pre-excavation grouting – a Nordic focus (Jun 2017)
• Intelligent solutions for drill+blast operations (Mar 2017)
• Musk talks tunnelling concepts (May 2017)

The answer to chronic congestion, it was suggested in discussion groups, is not an elite alternative, but rather a change in social norms. “For all but the most chronic of bottlenecks that need urgent additional capacity, there is ample public transportation road and rail infrastructure, the problem is created because we all want to use it at the same time! The immediate solution is to spread the load more evenly across the hours of the day and the days of the week.”

Another focus of attention and sharing of amazing developments and projects and efforts within the global industry each year is the annual series of ITA Brunel Awards. In 2017, the winners from a shortlist of finalists in nine categories were announced at the gala dinner of the AFTES conference in Paris in November and at the end of a dedicated day-long programme that provided a platform for all the finalists to present the details of their shortlisted entry.

Looking into 2018, the New Year will again host the next in the series of ITA Brunel Awards and will see progress of some major tunnelling projects, including the Brenner Baseline rail link between Austria and Italy, the California WaterFix in the United States, HS2 in the UK and many others. We will take a closing look at the prospects for 2018 in the lead editorial article for next week.

In the meantime, all the members of the TunnelTalk team wish all our readers and advertisement partners continued happy year-end holidays.