Dr. Martin Herrenknecht celebrated his 70th birthday in June. He’s able to look back on a practically unparalleled career and could rest on his laurels. But far from it: he still finds it a privilege to forge ahead with projects, come up with solutions and enjoy that particular atmosphere on site together with tunnellers that fascinates us all. At the beginning of June 2012, Dr. Herrenknecht took time out for an interview with tunnel to respond to the following questions.
This interview will be published in the September issue of tunnel so that you will have already celebrated your 70th birthday. Do you know a tunnel as old as or even older than you are?
I don’t know a tunnel that’s exactly 70. As far as I’m aware the first shield driven tunnel is in Britain and considerably older, built about 150 years ago.
Can you still recall the 70th Herrenknecht TBM?
The 70th machine was one for a project in Paris, a collector VRL 3. An EPB machine for Bouyges. An interesting project, which we developed jointly at the time.
I can still remember a lot about the machine as we conducted many discussions on whether the cutting wheel should be closed or open. The Germans favoured the open cutting wheel: the Mixshields possessed an open stem, no rim and nothing else. The French for their part always applied a closed cutting wheel as they didn’t want an articulated shield at the rear. In the end we decided to build an articulated shield and a closed cutting wheel for the VRL system. This still applies today. The open cutting wheel, the stem or star, which we had e.g. for Hera, did not prove itself. It needed a rim built around it. The cutting wheel became locked in the cloying material and couldn’t move because the torque was inadequate here. This is why today’s cutting wheels all have rims.
I don’t know if you’re already targeting the 70 m diameter as the next record diameter. But what do you regard the limit to be as far as the diameter is concerned?
I believe we can still reach 20 m and will also do so. We’re involved in a project with 19.20 m. If the geology is right, I can imagine both a Mixshield and a hard rock shield with 20 m diameter.
But in future, even more will be possible. It depends on the bearing technology and the geology. Indeed this will be called for in future for multi-tunnels with more than one application. It’s a sure thing where everything is combined, road and rail transport for instance.
Developments take their course and you also learn from your experiences?
Yes, often temporary solutions evolve, as e.g. extending the face liner plates in Germany. The cutting wheel had to be pushed into a certain position to extend the face liner plates. During the retraction process the face was harmed and for this reason a closed cutting wheel is applied increasingly today.
You have supplied a tunnel boring machine to practically every country or helped produce a tunnel. Is there a country which you would still like to be involved in or supply something to?
Yes, Vietnam or Myanmar, which are becoming of ever greater interest. We have supplied micro-machines to Indonesia but
large machines are still very much needed there.
As from 1971 you acquired your first experiences in tunnelling with the Seelisberg Tunnel and since then you have tackled numerous projects with your staff and seen them accomplished. If you look back on these 4 decades of tunnelling: what were the most evident changes, what impressed you most regarding technology or the project procedure?
If I think of 1970, then it was excavators with tear-out forces of 3,000 t, which tackled the rock with brutal force. The hydraulic system was nothing like as far advanced then as it is today. A great deal has changed during these last few decades. At the time we were initially faced with standstills of up to 4 months. No one was bothered as we attained a positive result in the end. If a machine stops for 1 or 2 days nowadays, then the telephone rings – no matter how late it is. You’ve got to pull on your pants at once and get to the construction site. These are the sort of changes that have developed during the course of time.
When you say “you’ve got to pull on your pants at once…” I believe that’s one of your strong points. If a project is held up, you get a call and intervene personally.
Yes that’s counseling guidance if you like, which is also enormously important in tunnelling. We did it then and tried to do everything as well as possible. For me it’s clear that that’s also the decisive factor for PPP projects, for time and money play an important role there. You can only take part by providing proper service. I believe that preassembling the machines at the factory belongs to the service. I find it irresponsible when competitors lure the customer with a seemingly low-cost concept, which ultimately leads to an extension of 4 to 6 months on the construction site. This results in enormous problems. This happened at the Great Belt, when it emerged that the hydraulic system was faulty thus resulting in almost a year being lost. In my view preassembly at the factory is absolutely essential for the customer, the project and the client. As long as I call the shots I won’t agree to initial assembly taking place on site. I find it irresponsible from the commercial viewpoint to offer and supply a product cheaply and then have to solve the technical problem on site. It is my conviction that mechanised tunnelling is being ruined through claiming that TBMs can be “assembled directly on the construction site”.
You said “as long as I call the shots”. Based on your life experience and seen from how things stand at present: would you want to do anything in a different way?
I don’t think so. Since 1970 mechanised tunnelling has developed in leaps and bounds. There are many examples of projects showing how we used the experiences we gathered to benefit new developments and at the same time having to find new, unorthodox solutions. If anything the degrees of difficulty in mechanised tunnelling have increased and nowadays tunnels are produced, which we would never have contemplated 30 years ago. If you look at the Weinberg Tunnel or the Zimmerberg Tunnel in Switzerland, they could not have been accomplished 30 years ago. 30 years ago you had hard rock machines, then along came Mixshields for stable soft ground with central axis and low torque, as e.g. in Antwerp or Hamburg. Today more power is required for the machines and as a result the trend is towards the Mixshield with subsequent enlargement.
I’ve frequently heard you presenting papers during which your infectious enthusiasm for tunnelling was evident. What are you particularly proud of?
I’d say that are these also genuine keystones in my life. Developing the Mixshield with Wayss & Freytag for instance. And there in particular involving the late Claus Becker and the then chairman of the board Erich Jacob, who was very farsighted. At the time we realised that tricky geologies needed substantially higher torques and that a peripheral drive was required for higher torques. That functioned with the EPB shield as well as later too in hard rock. Today we are able to combine practically all methods in a convertible type of shield when the route bored for the tunnel calls for it and thus accomplish extremely complex projects technically.
You just mentioned the outstanding engineer Claus Becker of Wayss & Freytag, incidentally another STUVA prize winner. Above all in Germany as well as in other European countries, the shortfall of engineers is a hot topic. Is that also evident in tunnelling?
We are able to attract people and if you look at the ITA today, it is certainly on the right path namely by interesting young engineers in tunnelling, furthering their training and holding courses. For there is no doubt that mechanised tunnelling is becoming highly attractive again. You get more people interested as opposed to the conventional blasting method because mechanised tunnelling involves and applies a great deal more high-tech. And that affects all diameters and types of shield, whether it’s a micro-machine, a Mixshield or a hard rock machine. When you see how they are equipped nowadays, then it is essential that we can deploy young, well trained engineers for this purpose.
The German-speaking countries, i.e. Germany, Austria and Switzerland (D-A-CH) or the West Europeans have been the technical experts and trailblazers in tunnelling. Does this apply, are many impulses being provided? How do you see the position of China or Japan in international competition?
If I look at Switzerland for example, that’s where the most difficult geology is: moraine, hard rock, it’s all found there. There the geology is difficult to master but a clear political line prevails. It’s quite the opposite in some countries.
If you look at Austria, how the Austrians have also veered in tunnelling from pure conventional driving to mechanised driving. The Austrians are aware that they no longer have a chance of becoming engaged abroad without resorting to mechanised driving.
Let us take e.g. the Metro in Vienna, the Wienerwald Tunnel and above all the access to the Inntal Valley with truly tricky geological formations, which we accomplished brilliantly. However, I must add that Swiss, German and Austrian construction companies jointly tackled the project there involving great tunnellers. You can really forge ahead with developments given such experts.
If I now turn to China: in most cases relatively straightforward geology has to be bored here. 30 years ago we traipsed to Japan as well and looked at the technology there and came away with ideas. That’s all long gone today. In other words Japan has become slower, considerably slower in developing and has difficulties worldwide in being able to sell machines. And that often only succeeds because they finance complete projects and of course also sell Japanese machines in the process. In the meantime we even have Japanese customers, who buy machines for use abroad. But Japan is no open market for us, we can’t sell anything there.
How do you regard collaboration among those involved in the project? Has anything changed compared to the past?
Formerly you stood by your word. If you look at the projects in Switzerland, we didn’t draw up contracts; we sealed a contract by shaking hands. The banks were always bothered by this approach: the money came in on the 4th of each month, that was a 12th part, and we signed the contract after we had installed the first segment. This method belongs to the past. Today lawyers tend to do the talking and when you receive a contract you have to check 10 times to make sure it contains the nitty-gritty. I believe it’s all got a bit out of hand. I am sure that we could build better and cheaper tunnels if lawyers weren’t always getting thrown into the mix. In the end, if there´s a dispute in court, clients and contractors land up paying more.
In the interim you also provide solutions for geothermics, mining and furnishing the construction site with equipment and services in addition to tunnel boring machines. Where do you see the greatest opportunities for development?
When observing developments in tunnelling we must on no account neglect the micro-machines. The development of small diameters is extremely interesting when you consider that we began in Berlin 25 years ago and have now more or less sold in excess of 1,000 machines. You’ve no chance of doing anything manually in the case of small diameters. This market has grown very strongly, there was and still is enormous competition.
All in all the development is truly impressive: if you look at the situation in Sochi it becomes evident: tricky, young geology prevails in the Caucasus and you can’t get far with a conventional shield machine, a hard rock machine with belt conveyor. You need a screw in the lower section, which removes the material and supports the face more adequately operating with a high torque so that soft ground zones can also be mastered well. Hard rock machines with integrated screw represent one of the trends.
A somewhat more personal question: What do you enjoy more, office work or working at the face?
Both. I’m certainly not desk-bound but someone who loves being on the move with customers with a preference for resolving tricky situations. In other words if something goes wrong and I’m able to be there to put things right, that’s what I really find fascinating about tunnelling. On the one hand you make progress, and on the other hand, you can apply relatively good ideas and adjust the machine to the geology. This often results in disputes, where no punches are pulled. Like when I advocated applying mechanised tunnelling for the Katzenberg Tunnel, where I threatened to take the company abroad with all political implications to underline just how serious I was. And ultimately it also turned out that mechanised driving at the Katzenberg represented the better solution. This was also confirmed by those, who wanted to drive the Katzenberg by conventional means. We exceeded the costs by 10 % - if we had driven it by conventional means the costs would have overrun by 100 % like at the Engelberg or 150 % like on the new Ingolstadt and Nuremberg route. For this reason I advocate mechanised driving, also for Stuttgart 21, as I’m convinced that you can work far better here in terms of cost. If you are restricted by budgets from the very outset and no grand experiments are possible later on, you should at least look at the time you need to complete the project. The costs can be controlled by dint of a feasible schedule. Then of course, I find it much more elegant to produce tunnels by mechanised driving.
Anyone who knows you is aware you are a genuine “man of action” and that tunnelling is your “elixir of life”. Is there an era after Dr. M. Herrenknecht, and if so what does it look like?
What should I get up at home, get on my wife’s nerves for instance? I can’t cook and I’m a hopeless gardener. For as long as I can take part and help
shape things I’m rather in the office to see that we clinch a project, advance mechanised tunnelling worldwide and actively lend a push to mechanised driving at congresses for instance.
Is there a successor, an arrangement for the time after Dr. M. Herrenknecht?
We have successors on the board, who we are grooming to secure the next generation. My son for example is studying mechanical engineering and I want to give him the chance to join the company. This year he’ll wind up his mechanical engineering studies at the Uni Munich graduating as an engineer (Dipl.-Ing.). I’m proud that he’s not aiming for a Bachelor or a Master but is pursuing his studies to become a graduate engineer at the Uni in Munich. I feel it’s the right thing to do and I believe it’s the right way for him to slowly become acquainted with the company.
Thank you for the interview!