Since before the turn of the century, devices and methods for escaping emergencies in high-rise buildings have been proposed. The majority of these are directed to single person escape methods, i.e. a system in which each escapee is lowered to the desired destination point before attaching or engaging the next person to the escape system. Very few methods have addressed the problems of multi-person escape systems. Among the problems which must be solved by a multi-person escape system are that deployment of the first evacuee must not interfere with accessibility to the system by the next evacuee and the system must allow for unattended escape of the last evacuee, i.e. the system must not require operation or adjustment by personnel at the top of the system during descent of the last group of evacuees.
Some multi-person escape systems have employed a fixed rope system, i.e. a system in which a single rope is hung in immovable fashion from the escape location and the evacuees slide or ride down the rope using a number of different types of sliding or rolling attachment devices. Typical of such systems are U.S. Pat. No. 3,459,276, issued Aug. 5, 1969 to Fuse and U.S. Pat. No. 1,852,887, issued Apr. 5, 1932 to Lossius. The fixed rope system has certain disadvantages. The rate of descent of each person on a fixed rope system must be controlled in such a manner that a person higher on the system does not descent at a significantly faster rate than a person lower on the system, so as to cause collision between the two evacuees. Prevention of such collision often means that the evacuees must have at least some rudimentary training in the use of the descent system so as to control their own rate of descent. Alternatively, some mechanism or apparatus must be provided to keep the proper spacing between evacuees. Because of these problems, effective fixed rope systems are difficult to design.
Certain single-person evacuation systems have employed a movable rope system, i.e. a system in which the evacuee is attached to the rope in a fixed relationship with respect to the rope and the rope itself is lowered. Examples of such systems include U.S. Pat. No. 3,760,901, issued Sept. 25, 1973 to Hynes and U.S. Pat. No. 3,759,346, issued Sept. 18, 1973 to Brda. Adaption of such movable rope systems to a multiple evacuation situation has presented a number of difficult problems. The system must be provided with a braking device so that after the first evacuee has moved downward, the rope can be stopped for attachment of the next evacuee. This braking system, however, should be of simple design with as few moving parts as possible to minimize the possibility of malfunction which could potentially strand evacuees in mid-air. The system should be usuable by inexperienced or novice persons. Systems such as depicted in U.S. Pat. No. 179,515, issued July 4, 1876 to Bustin when used for multi-person evacuation, require repeated raising of the rope and attached equipment such as a harness which might prove unwieldy to inexperienced or novice persons. This difficulty is even more severe in very high-rise buildings requiring a long length of rope.
A further reason for desiring to minimize the weight and unwieldiness of an escape system relates to the fact that when a fire occurs in a high-rise building, it cannot be predicted from which portion of the building escape by a rope system might be possible. Since it may be economically infeasible to provide permanently attached escape systems at each possible escape location throughout a building, and since such permanent fixtures may be esthetically unpleasing as well as expensive, it is preferable to provide a system which can be positioned and quickly erected at any of a number of locations in the building.
It is also preferable to provide an escape system which can be provided in a form sufficiently portable that it can be carried into a burning building by one or two emergency personnel to provide for escape of, e.g. about 5 evacuees at a time when the building is not provisioned with an escape system, as well as in a form designed for use by about 10 evacuees simultaneously.
Whether the escape system is designed to be carried into a building or is to be provided in a number of locations throughout the building in anticipation of an emergency, it is beneficial if the system is adaptable to a number of different types of buildings. If the system is to be carried into a burning building, the system should be adaptable because the emergency personnel often cannot know the particular characteristics of the building. Even when the system is to be provided as a feature of the building itself, the cost of the escape system is lessened if the system does not have to be individually designed to meet the particular needs of the building. Many escape systems involve some type of attachment or amchorage to a wall or pillar or some weight-bearing function of a wall or pillar of the building. Typical of such systems are U.S. Pat. No. 3,844,377, issued Oct. 29, 1974 to Wilkins, U.S. Pat. No. 4,440,261, issued Apr. 3, 1984. U.S. Pat. No. 4,538,704, issued Sept. 3, 1985 to Forrest discloses horizontal braces that extend from an exit feature to a wall. Use of these systems, however, is at least partly confounded when the exterior of the building is floor to ceiling glass, as is common in many types of high-rise buildings. In such buildings, the structures most capable of bearing weight or stress are typically the floor and ceiling, generally being reinforced concrete or steel structures. Thus, greatest adaptability of the system is obtained when the anchorage for the system does not require that any significant weight or stress be borne by a wall member of the building.
In many emergency situations, it is desirable to raise emergency personnel from the ground to the site of the emergency, as well as to evacuate personnel from the site of the emergency. Previous escape systems were not particularly adaptable to such raising of emergency personnel, because this operation often involve postponing the departure of waiting evacuees and further required some amount of power or some relatively complex mechanism for hauling up personnel, often heavily laden with equipment.
A movable rope system, particularly a system which is to be heavily weighed such as by attachment of a plurality of evacuees, requires somes means to avoid running the movable rope over a sharp edge such as a window ledge or edge of a balcony, etc. One method of accomplishing this objective involves anchoring the rope at the destination point some distance away from the base of the building so that the rope takes on a slanted or angled configuration with respect to the building. As depicted in U.S. Pat. No. 317,704 issued May 12, 1885 to Beale, et al., U.S. Pat. No. 426,540, issued Apr. 29, 1890 to Matthaes and U.S. Pat. No. 293,322, issued Feb. 12, 1884 to Griswold. Such a system, however, puts great stress on the rope and any ground anchors and requires some anchoring mechanism at the ground which ordinarily means that a trained ground crew and often ground based equipment or fixtures must be provided.
Another method for avoiding running the rope over a sharp edge is providing an arm or cantilever beam projecting from the building. Previous beam-type devices such as those depicted in U.S. Pat. No. 3,844,377, issued Oct. 29, 1974 to Wilkins and U.S. Pat. No. 3,459,276, issued Aug. 5, 1969 to Fuse have required heavy support, often necessitating transmittal of force to some portion of a wall, and normally could not be used with more than a few persons, and thus could not be used to evacuate 10 or more persons in a single descent.