Recent Trends in Conventional Tunneling (SEM/NATM) in the US

Synopsis:

Conventional tunneling as defined by ITA WG19 is also known as the New Austrian Tunneling Method (NATM) or Sequential Excavation Method (SEM) was transformed in the US to deal with challenging tunneling conditions as an alternative to the more traditional tunneling methods. It is being used more often in urban areas, under difficult ground and ground water conditions, and with limited cover. Often the tunnel is of a large and non-uniform cross section in soft soils or weak rocks. The intent of using this tunneling method is to minimize impact on traffic and utilities and reduce disruption of everyday life of people and businesses.
To meet these challenges, the industry developed technical approaches and implementation techniques and established sophisticated contractual relationships and collaboration in the field among various parties for successful implementation.

This paper examines the development of conventional tunneling (NATM/SEM) in the US to deal with these challenges using recent examples such as Russia Wharf in Boston, Northern Boulevard Crossing, in New York, and Chinatown Station in San Francisco.

2016 World Tunnel Congress and 42nd ITA General Assembly Proceedings
April 22-28, 2016, San Francisco, CA (Nitschke, A. G., Dolsak, W., Gall, V., & Ossenbühl, I.)
Copyright holds the International Tunnelling and Underground Space Association (ITA).