CFR 30, Part 57 requires, in addition to the two ways out, that egress must be possible within one hour using the normal mode of travel in the tunnel. The normal mode of travel in the tunnel was specified to be motorized transport with a speed up to ten miles per hour, which would allow for a ten mile separation of exits, twice the distance between the primary connection points for the technical systems and four times the distance between the primary and secondary connection points. It was recognized that provision of emergency exit capability at the secondary connection points, 2.7 miles from the primary connection points, would make the tunnel compliant even for travel on foot. Special sections of the lattice along the seven mile straight sections joining the two arcs of the facility would result in blind stubs off the main tunnel, particularly in the areas of the beam abort lines. The Working Group examined the design of these sections in the light of relevant codes as part of their charge to determine whether addition provision would be needed for personnel safety.
Most codes are concerned with time of travel to an exit.
CFR 30, Part 57 requires that an internal refuge, within 30 minutes by the normal mode of transportation, be provided where two ways out are not available and exit is not possible within one hour as specified for the normal tunnel section. A distance specification is contained in CalOSHA for nonmetal mines which requires that a refuge be provided when the distance is more than a mile from a blind heading to a place where two ways out are provided. Everything between the upstream and downstream shafts has two ways out and maximum travel times are less than one hour, so this portion of the facility is conformable to the CFR requirements for a facility of this type. The NuMI design in this regard is more benign than the design accepted by DOE and under construction for the SSC facilities. The region from the downstream shaft through the experimental cavities can be considered as a blind stub with a length of approximately a quarter of a mile, somewhat greater than a fourth of the allowed distance without a refuge in CFR 30, Part 57.