ABSTRACT
Between 1972 and 1975 the U.S. Department of the Interior, Bureau of Mines planned a three-year, $6.6 million dollar program seeking to find more effective ways for improving rock excavation. This sum was, at the time, some 18% of the entire Federal budget for research into rapid excavation. The program was sponsored by the Advanced Research Projects Agency of the Department of Defense and in may ways underwrote the initial development of many of the programs which have been described in this chapter. A review of those programs [9.1] describes some of the earliest experiments and concepts developed for the use of high pressure waterjets, and also describes some of the initial negative results which led to the termination of some of those creative ideas. Regrettably the U.S. Congress deleted funds for this program after the first year of funding, thus, many of the potentially promising new programs were not initiated, and many of those funded did not reach the levels of field experimentation initially planned to demonstrate their potential commercial value. This may be one reason it has taken this technology so long to reach its current level of maturity, and why, as yet, some of the ideas first developed many years ago have not yet become a commercial reality.
