Examination of space/volume requirements for US underground coal mine refuge alternatives
ABSTRACT The Mine Safety and Health Administration requires that 1.4 m2 (15 ft2) of floor space is to be provided for each person inside a refuge alternative (RA). However, the amount of floor space needed for a person to reside inside an RA and perform basic tasks is unknown. During testing, participants entered into an RA or a simulated RA of various space/volume configurations and performed several simulated tasks that are representative of the survivability tasks performed within an RA. The results indicate that the floor space requirements were generally adequate for the tasks studied. Certain tasks such as changing scrubber cartridges, using toilets, and moving about the RA were impacted by the minimum height tested (0.6 m). As such, RAs of this height will require critical design consideration as a whole and the supplies provided for use inside of the RA to ensure the ability to use an RA.
Appropriate ingress/egress dimensions for mobile underground mining equipment
Sixteen male and sixteen female subjects were tested to determine appropriate ingress and egress opening dimensions for mobile underground mining equipment. Opening dimensions were determined for seating configurations used in five different seam heights: 81, 95, 123, 135, and 160 cm. A modified psychophysical methodology was used whereby each subject entered and exited a mock-up of a cab and adjusted the width of a sliding door to the minimum width that allowed for safe and comfortable ingress and egress. Each subject was given two trials for each seam height, for a total of ten trials per subject. Finally, the mean and 95th percentile opening widths were determined for each seam height. The mean opening widths, from lowest to highest seam height, are 132, 122, 112, 98, and 78 cm. The 95th percentile opening widths, from lowest to highest seam height, are 162, 149, 140, 122, and 101 cm. These values can be used by design engineers to provide adequate ingress and egress opening for mobile underground mining equipment.
Effect of seat cushions on human response to +Gz impact.
Human response to vertical (+Gz) impact acceleration was evaluated as a function of various seat cushions, including current operational cushions used in such aircraft as the A-10, F-15, and F-111 and proposed alternative cushions comprised of rate-dependent, slow-recovery polyurethane foams. There were 133 tests conducted of volunteer subjects in seven different experimental conditions, using a vertical deceleration tower facility. The mean peak acceleration of the impact carriage for these tests was 9.85 G (S.D. = 0.07) and the mean carriage velocity change was 8.01 m X s-1 (S.D. = 0.05). Resultant seat loads and head and chest accelerations were significantly higher for the F-111 cushion than for the rate-dependent foam cushions, which included cushions comprised of Confor foam or Temper foam. Resultant head and chest accelerations were also significantly higher for the ACES II cushion than for the rate-dependent foam cushions. Therefore, from an impact protection standpoint, the operational cushions were inferior to the proposed alternative cushions. Operational use of rate-dependent foam cushions is recommended to improve the impact protection performance of escape systems. Flight tests conducted by the USAF Strategic Air Command have shown that these cushions enhance crewmember sitting comfort during long-duration missions.