This Bureau of Mines report presents two phases of a research program to evaluate a single-entry system for longwall development. Organizations participating in the program, which began in July 1971, include the Bureau of Mines, the Mining Enforcement and Safety Administration, and the University of Utah, working under a cooperative agreement with Kaiser Steel Corp. at its Sunnyside mine in Utah. Part 1 of this report desribes the present longwall mining practice, including a brief history, and discusses the advantages and disadvantages of a single-entry development system and its introduction in the United States. Part 2 of the report presents the research program, test design, instrumentation for ground and support evaluation, and the test results from the No. 2 mine. Subsequent reports will describe the research conducted in the No. 1 mine.

Coal will continue to provide a major portion of energy requirements in the United States for at least the next several decades. It is imperative that accurate information describing the amount, location, and quality of the coal resources and reserves be available to fulfill energy needs. It is also important that the United States extract its coal resources efficiently, safely, and in an environmentally responsible manner. A renewed focus on federal support for coal-related research, coordinated across agencies and with the active participation of the states and industrial sector, is a critical element for each of these requirements. Coal focuses on the research and development needs and priorities in the areas of coal resource and reserve assessments, coal mining and processing, transportation of coal and coal products, and coal utilization.