Obituary 06 May 2021

When introduced, there were few who understood, and knew how to design, apply and control the excavation method called at the time NATM. One of them was Freidrich Blindow, a civil engineer of underground space construction who appreciated the concept of the method from the engineering, construction, contractual and site supervision perspectives.

Dipl.-Ing. Friedrich Blindow Sep 1933-Apr 2021

He had a foot in each camp – as a design engineer and a contractor – and he knew that the concept would not work without the one working in direct and seamless collaboration with the other. The international adoption of what was, and continues to be known, as NATM, the new Austrian tunnelling method (as opposed to the old Austrian tunnelling method), and went on to morph into the SCL, sprayed concrete lining, method in the UK and the SEM, sequential excavation method, in the USA, was thanks to those with the ability to convey the advantages of the concept, often communicated in English as the one common language around an international table of engineers or through non-technical interpreters. Freidrich Blindow was one of them.

After a long and dedicated career, applying and promoting and the advantages of NATM, both in Europe and internationally, Friedrich died on 20 April after a short battle with a rare and aggressive cancer, aged 87.

After studying at the Mining University Clausthal in Harz, Germany, graduating with an engineer mining degree in 1960 and a mining degree in 1963, Blindow began his career and his a long association with construction company Beton- und Monierbau in 1965. He was first with the company’s Düsseldorf Overseas Department in the estimating and site management department. He then moved to the company’s Austrian subsidiary in Innsbruck from 1969 to 1993, becoming Managing Director in 1971 and developing the company to specialise in all kinds of underground works with central departments for planning, estimating, work preparations, cost controlling, plant and equipment procurement and with construction projects in Austria, Germany, elsewhere in Europe and internationally.

Metro underpass of live railway in Bonn with only 4m cover

In a conference presentation, Blindow listed the main advantages of NATM as he appreciated them:

• The rock pressure, so feared before, is avoided by a suitable support, including shotcrete, established in close contact to the ground
• The rock is handled gently with stability preserved to increase the security of the excavation.
• Rock deformations and surface settlements can be minimised by the easily controllable and flexible excavation method.
• The excavation area remains free of bracings.
• Excavation cross sections and profiles can be readily changed for transitions, junctions and enlargements.
• Excavation is applicable under shallow cover, where in former times a minimum cover of one tunnel diameter was assumed as a practical limit.
• Costs were reduced by 50% in comparison with other tunnelling methods.

There is only one significant disadvantage of the method, he admitted, and that is its dependence on experienced engineers, who are willing to accept responsibility, and of a skilled crew. The founders of the method, Professors Rabcewicz, Müller and Pacher, were well aware of these facts, he said, and made it a condition of their consulting activities to employ only contractors with experienced personnel, with qualifications down to the foreman having to be proven. Any one who wants to apply the NATM and to make full use of its advantages, he added, has to consider these facts in the earliest planning stages.

NATM was applied expertly with Beton- und Monierbau on the North Downs tunnel on the Channel Tunnel rail link in UK in 1998

Having worked in the 1960s on the first NATM project in Germany with Beton- und Monierbau, the Schwaikheimer railway tunnel, Blindow compiled a portfolio of design and construction contracts, consultancy contracts and expert panel and expert witness services, all in support of the concept of the NATM and its proper application around the world, all in the effort to bring the engineering and cost saving advantages of the concept to owners and contractors alike. Among them include many perceived high risk but highly successful soft ground, low cover, highly sensitive urban applications for metros (more than 30km), railways and roads (more than 60km) and many station, parking and other purpose caverns.

The portfolio highlights include the Karawanken railway tunnel, Austria; Pallaresa highway tunnel in Barcelona, Spain; Hanaging Lake highway tunnel Colorado, USA; Tauern highway tunnel, Austria; and contracts for the Munich, Bonn, Nurnberg, Dortmund, Frankfurt, Bochum and Vienna Metros.

Also as part of Beton- und Monierbau Innsbruck, Blindow took the company into international joint ventures as the expert NATM partner including in the UK with Thyssen GB for an unsuccessful bid for the Dinorwig pumped storage hydro project in Wales and for the successful JV with Miller Construction on the Heathrow baggage tunnel project in the early 1990s and as a JV partner with Morgan EST (previously Miller Construction) and Vinci of France on the North Downs twin-track single tube railway tunnel on the Channel Tunnel rail link to London in 1998.

Since 1994, Blindow ran his own company with partner Martin Fedorcio (left) and son Axel (right)

Blindow was also called and gave evidence to the ICE inquiry chaired by Colin Kirkland following the collapse of NATM excavation of station caverns on the Heathrow Airport rail link project in the UK in 1994. It was as a consequence of the collapse and the ICE inquiry that NATM in the UK was redefined and renamed as the SCL sprayed concrete lining method and stripping away the flexibility and on-site engineering decision-making to cost-effectively suit the prevailing conditions, much to his disappointment as it was from the flexibility in processes that the core advantages and cost savings were are accrued. The inquiry turn the method into a pre-designed prescriptive excavation method to high design factors of safety and not changes permitted once into construction on site. While the means of excavation of NATM and SCL are the same, the processes of application in design, in construction and in management of the contract are different.

When Beton-und Monierbau was taken over as a fully-owned subsidiary of Alpine Bau GmbH and eventually sold on again to Metrostav of the Czech Republic, Blindow left and established his own project management consulting company with partners Martin Fedorcio and his son Axel. In addition to consulting on planning, design, estimating, construction management, and site supervision of NATM projects, the company assists with training, information and documentation, operational site control systems and claims development and management.

Blindow, as a well respected colleague, business partner, fellow engineer, and international collaborator, will be missed and personal friends and supporters send condolences to Mrs Ute Blindow and to the family and to son Axel who will continue the work of his father for the professional and successful application of the NATM concept for construction of underground public infrastructure worldwide.