What's Ahead for Tunneling Machines

Ten yr of tunnel construction data from 1955 to 1965 are reviewed to establish particular characteristics of the past-tunneling market. These characteristics include: (1) Total footage of tunnel construction completed each year; (2) a breakdown of these tunnels according to use (water transportation, vehicle tunnels, railroad and subway tunnels and mining tunnels); and (3) a profile of the 1955-1965 tunneling according to unlined-tunnel diameter and tunnel length. This data provided a history of tunneling activity and growth rates which were used in conjunction with expert opinions and announced future tunneling expectations to develop a forecast of 3,000 miles of worldwide-tunneling activity from 1966 to 1976. To estimate the impact of tunneling machines on the total market, a detailed cost analysis is outlined for Drill and Blast versus Mechanical Boring. The economic comparison showed tunneling machines to be an effective economic alternative in a significant portion of the future tunneling. It is estimated that tunneling machines will complete 1,000 miles of the total 3,000 miles forecasted between 1966 and 1976.