Our Team

GZ is assembled of a team including 30+ international experts across various disciplines including tunnel engineers, geotechnical engineers, geologists, tunnel inspectors, CAD technicians, and administrative staff.  Ranging from junior level to well-experienced, our team members represent GZ worldwide.

Axel Nitschke, Ph.D., P.E.

Vice President

Axel Nitschke, Ph.D., P.E. - Senior Tunnel EngineerExperience Summary
Axel Nitschke received his Ph.D. in civil engineering in 1998 and has since gained fourteen years of in-depth, on-the-job experience in all aspects of tunneling, including feasibility and constructability studies, tunnel design, and tunnel construction management. He has headed the engineering and construction of a large number of tunnel projects in both Europe and the United States and specializes in the application of the New Austrian Tunneling Method (NATM), often referred to as the Sequential Excavation Method (SEM). He is well experienced in all ground conditions ranging from soft ground to hard rock and the associated implications for design and construction methods. Dr. Nitschke has held key positions such as Senior NATM Manager, Contract / Claims Manager, Risk Manager, and Project Manager.

John Rudolf, P.E.

Chief Structural Engineer

Experience Summary
John Rudolf’s experience with the design and construction management of underground and above ground structures spans a career lasting over 5o years. Mr. Rudolf has been directly involved with the design and construction of the 106 miles of the Washington Metrorail system on multiple major infrastructure projects for over 30 years, including his contribution of approximately 15 miles of aerial structures and over 40 miles of subsurface structures for the system. Mr. Rudolf’s experience involves design and construction of various types of bridges and viaducts, including post-tensioned CIP and post-tensioned pre-cast Concrete Segmental Guideways. John’s tunneling experience includes the design and construction of various tunnels using conventional tunneling methods, including NATM, cut-and-cover, and TBMs, both in soft ground and rock with CIP as well as pre-cast concrete linings.

Julius Hirscher

Senior Tunnel Engineer

Experience Summary
Julius Hirscher has over 27 years of experience in wide-ranging aspects of tunneling, including design, management, and construction. During his career, he has gained particular experience in the New Austrian Tunneling Method (NATM), also referred to as the Sprayed Concrete Method (SCL). He has applied NATM in ground conditions ranging from soft ground to hard rock. Mr. Hirscher has held key positions throughout his tunneling career, including Senior SCL Construction Engineer, Claim Manager, and Project Manager, as well as Project and SCL Heading Engineer on various tunneling projects throughout both the United States and Europe.

Günter Pohn

Senior Tunnel Engineer

Experience Summary
Günter Pohn has more than 20 years of experience in the planning, design, and supervision of underground public transit and highway projects. He specializes in NATM / SCL and cut-and-cover design in both soft ground and hard rock, as well as construction supervision, foundations, and rock mechanics. He is well-versed in cost and program estimates for various design stages of major tunnel projects. Mr. Pohn has managed the design efforts of multi-disciplinary teams on numerous large infrastructure projects integrating mechanical, electrical and ventilation systems with the overall design. He has a proven track record of delivering designs that adhere strictly to all budget and time constraints.

Ermin Stehlik

Senior Tunnel Engineer

Experience Summary
Ermin Stehlik has over 39 years of extensive experience in the design and construction supervision of major international tunneling schemes. During his career, Mr. Stehlik has gained specific knowledge and expertise in the design of underground structures, construction methods, and management of tunnel construction.

Walter Klary

Senior Tunnel – Geotechnical Engineer

Experience Summary
Walter Klary has more than fifteen years of extensive experience in geotechnical engineering and tunnel construction using various construction methods, including NATM / SEM and Tunnel boring Machine (TBM). He has worked on high profile international projects in Europe, Asia and USA in all ground conditions ranging from soft to hard rock. He is well experienced in difficult ground conditions and all aspects of tunneling, such as caverns, shafts and pressure tunnels.

Robert Wallner

Senior Tunnel – Geotechnical Engineer

Robert Wallner - Senior Tunnel Geotechnical EngineerExperience Summary
Robert Wallner has more than seventeen years of practical geotechnical experience in tunneling and civil engineering consulting for underground construction, foundations, and rock mechanics. He has been in charge of quality assurance and quality control, control of compliance with various standards and specifications, materials testing, and verification and validation of systems for a wide variety of complex international tunnel projects. As Senior Tunnel Engineer and Project Manager, he has fulfilled organizing, planning, and scheduling functions, and has gained a detailed understanding of both contract administration and project control.

Andrés Giraldo

Senior Project Engineer

Experience Summary
Mr. Andrés Giraldo has over seven years of experience in civil engineering, ranging from basic technical duties to the responsibilities of Senior Bids and Commercial Coordinator. Andrés possesses valuable project management skills, experience in the preparation of construction projects (including planning and budgeting), and commercial experience in processes for new projects in both the public and private domains, as well as knowledge in public-private partnership (PPP) planning and structuring with Capex analysis for concession projects. Additionally, Mr. Giraldo’s status as a native Spanish speaker with fluency in English and proficiency in Portuguese have enabled him to work in various international markets around the globe.

Anthony Bauer

Tunnel Engineer

Experience Summary Anthony Bauer - Tunnel Engineer
Anthony Bauer graduated from the Virginia Polytechnic Institute & State University with a B.S. in Civil Engineering concentrating in structural engineering.  He has since been involved in the design, analysis, and project management of numerous tunneling and underground construction projects all over the globe, including the United States, Europe, South America, and Asia. He has extensive experience performing analysis for underground structures in both two- and three-dimensional numerical modeling (finite element) programs. Anthony specializes in the design of SEM / NATM / SCL underground structures, including initial support, final support and waterproofing.

Thomas Schultheis

Tunnel Engineer

Thomas Schultheis - Tunnel EngineerExperience Summary
Thomas Schultheis has worked on geotechnical engineering, tunnel construction, and consultancy projects in Sweden, Austria, Germany, the United Kingdom, and Switzerland. After receiving his engineering degree, he has spent the last twelve years working in geotechnical and materials engineering. He has worked on prestigious international projects, including the CTRL in the United Kingdom, the Gotthard Base Tunnel in Switzerland, Kings Cross Redevelopment Phase II project, and the CrossRail. His responsibilities usually range from assessment of ground conditions and support measures, development, coordination, and implementation of contract documents to recording of construction progress, geotechnical data, and compensation events.

Raimund Noisternig

Tunnel Engineer

Experience Summary
Raimund Noisternig has more than 13 years of extensive, international experience in all aspects of tunneling, including construction management, quality control, and tunnel rehabilitation, as well as modernization, waterproofing and the inspection of tunnels and other underground structures. During his career, Mr. Noisternig has gained hands-on knowledge and experience in the implementation of design and application of NATM/SEM. His experience further encompasses shaft construction, TBM tunneling, drill-and-blast methods and application of ground improvement and pre-support techniques.

Sandeep Pyakurel, Ph.D.

Tunnel Engineer

Sandeep Pyakurel – Tunnel EngineerExperience Summary
Sandeep Pyakurel has a Ph.D. in Civil Engineering from West Virginia University with emphasis on structural and geotechnical design. He has experience in both small and large scale projects pertaining to tunnel and underground engineering. He has been involved in the design of tunnel structural support systems and numerical analyses involving soil-structure interaction, and also has experience in developing design specifications and contract drawings, project scheduling, and construction cost estimation. Dr. Pyakurel has performed several site visits including tunnels for structural inspection and assessment. He is familiar with both United States and international design standards, and has good hands-on experience in design and analysis programs.

Nikolaos Syrtariotis

Tunnel Engineer

Experience Summary
Nikoloas Syrtariotis is a highly-experienced tunnel engineer with expertise in NATM tunneling methods, including SEM and SCL, with a strong background in face mapping and rock mass classification (RMR, Q, GSI), geotechnical monitoring, ground investigations, implementation of tunnel support measures and tunnel construction in conditions ranging from drill-and-blast to squeezing ground.

Dominic Reda

Tunnel Engineer

Dominic Reda - Tunnel EngineerExperience Summary
Dominic Reda graduated from the Polytechnic Institute of New York University with a B.S. and M.S. in Civil Engineering with a focus in Geotechnical Engineering. He has experience in a number of tunneling projects ranging from design, drawing development, independent design checks, tunnel excavation and support inspection, as well as waterproofing inspection. Mr. Reda has also been involved in the development of standards and specifications for small and large scale projects. Mr. Reda is familiar with analysis of underground structures in both two- and three-dimensional numerical modeling programs.

Andreas Gerstgrasser

Tunnel Engineer

Experience Summary Andreas Gerstgrasser - Tunnel Engineer
Andreas Gerstgrasser has gained hands-on experience in generating structural design and as-built drawings utilizing a number of common tunnel design software applications. Mr. Gerstgrasser has gained six years of profound engineering and site supervision experience in underground schemes. His primary duties usually involve developing overall tunnel layouts, cross sections, and excavation and support sequences, as well as the design application of various construction methods.


William Loughney

Tunnel Engineer

Experience Summary
William Loughney has experience in the construction engineering, inspection and engineering design fields. His professional activities range from design, permitting and site inspection. Additionally, he has experience in AutoCad drafting including the development of shop drawings and design drawings for various national and international projects. Mr. Loughney has also been involved in the development of project standards and specifications.

Thomas Martin

Tunnel Engineer

Experience Summary
Thomas Martin has been involved in a number of tunneling projects, performing design services and several independent checks. In addition, Mr. Martin has experience in AutoCad drafting shop drawings and design drawings for various national and international projects. He has also been involved in the development of standards and specifications for small and large scale projects.

Steve Wakefield

Safety Manager

Steve Wakefield - Safety ManagerExperience Summary
Steve Wakefield has over twenty-five years of extensive experience with the supervision of time critical remedial and general construction projects. During the course of his career, he has been responsible for all aspects of operations and schedule management for a number of high profile projects, with scopes ranging from underground construction and tunneling, general construction, coordination of piping efforts, hazardous material remediation, plant and building closures, tank closures and installation, asbestos abatement and emergency responses. Mr. Wakefield is a technically diverse safety and project supervisor with a strong environmental, underground construction and tunneling background. Some of Steve’s major strengths include health and safety, compliance, and project management related to health and safety. Mr. Wakefield possesses skills related to hazardous materials response, fire prevention, fire protection, fire investigation, construction supervision, administrative management, and sub contract coordination.

Jorge Carretero Rodriguez

Regional Representative – South America

Experience SummaryJorge Carretero, Regional Representative - South America
During his career as an architect that spans over more than fifteen years, Jorge Carretero has gained extensive international experience in the construction industry on projects in South America, South Africa, and Europe. He specializes in architecture planning, engineering, civil work projects, tunneling (NATM / SEM and TBM), and other underground projects. He is well-versed in managing the design and construction efforts of multi-disciplinary teams for large infrastructure projects, from initial inception stage to construction quality assurance and final delivery. Mr. Carretero is GZ’s representative in Chile and in charge of the business development effort in South America.

John Douglas

Advisor – Business Development – United Kingdom

Experience SummaryJohn Douglas, Advisor, Business Development
John Douglas has over fourty years experience in the civil engineering industry. His experience ranges from giving lectures in the collegiate setting to senior management in business development at a major civil engineering company which specializes in public transportation (including the rail sector). He has been a consultant for GZ for the past 3 years as an advisor on business development matters within the United Kingdom.


Thomas Sonntag

Senior Project Controls Manager

Thomas Sonntag - Senior Project Controls ManagerExperience Summary
Thomas Sonntag has over eighteen years of experience related to project control, coordination, accounting, and procurement. He is well-versed in financial project management and analysis. Mr. Sonntag is responsible for accounting, invoicing, payroll, financial analysis, and human resource related financial tasks for all GZ locations and entities worldwide. He graduated with a B.S. in Accounting from Strayer University, Summa Cum Laude and he recently received his Master of Science in Business Management at the University of Maryland with a focus on Accounting. Mr. Sonntag is the direct advisor to the GZ management in all financially-related business activities.

Linda Kelly

Office Manager and Notary Public

Experience Summary
Linda Kelly provides daily supervision of the administrative staff and is responsible for organizing and coordinating office operations and procedures to ensure organizational effectiveness and efficiency. Before joining the company, she spent over 20 years in the telephony industry, most recently at Verizon. A large portion of her career was working in the government business sector. Mrs. Kelly’s responsibilities included fulfilling government contract requirements, working closely with sales and other telecoms, researching and developing processes, and troubleshooting and implementing the solutions required to fulfill the needs of the customer.