Inflatable Roadway

A variety of techniques are currently in use for permitting passage across sand, swamps, water, thin ice, snow, or other areas where the terrain is of unfirm or hazardous nature. A well-known approach is to place steel or aluminum interlocking planks over the soft terrain to distribute the bearing pressure over a wide area and thereby allow the traverse of men and equipment. Bridging water usually calls for innerconnecting sections of a pontoon bridge and pushing them out across the water obstacle. Both of these approaches present a formidable logistical effort and are time consuming. In a situation where the bridging crews are exposed to hostile fire, the necessary exposure of personnel often results in unacceptable casualties. Assault groups cannot take the time nor have the logistics capability in a rapidly moving combat operation. There is a continuing need in the state of the art for a rapidly erectable, lightweight device for allowing the transport of men and equipment across water, swamps, thin ice or similar natural obstacles. In a more friendly atmosphere there is also a continuing need for a rapidly deployable roadway permitting the off-loading of cargo across an irregular surface such as a dock or a sandy soft beach which does not itself create a formidable logistics problem.

The present invention is directed to providing an inflatable roadway for bridging an unfirm foundation. A first elongate panel and a second elongate panel are bonded together around their peripheries and are flexible enough to be stored in a laterally rolled configuration. A gas fitting is coupled to a source of pressurized gas and the roadway is unrolled as pressurized gas fills at least one longitudinal envelope defined between the two panels. A multitude of strands extend between the two panels to ensure the creation of a smooth, exposed surface for pneumatically cooperating with a cargo laden air bearing.

It is a prime object of the invention to provide a rapidly deployable roadway.

Another object is to provide a rapidly deployable roadway which is lightweight.

Yet another object is to provide an inflatable roadway suitable for deployment under combat conditions.

Still another object is to provide an inflatable roadway which neutralizes the adverse effects of unfirm terrain.

Still another object is to provide an inflatable roadway that is deployed as it unrolls across an area of unfirm terrain.

Still another object is to provide an inflatable roadway which ensures the creation of an even exposed surface.

Yet another object is to provide a method for deploying an inflatable roadway to ensure the transfer of heavy cargo loads.

Still another object is to provide a method for ensuring the creation of a smooth exposed surface for pneumatic cooperation with a cargo laden air bearing.

These and other objects of the invention will become more readily apparent from the ensuing description when taken together with the drawings.

FIG. 1 is an isometric depiction of one embodiment of the invention being deployed.

FIG. 2 is a cross-sectional view of the inflatable roadway taken generally along lines 2--2 in FIG. 1.

FIG. 3 is an isometric depiction of the invention used as a bearing surface for an air bearing.

FIG. 4 shows another use of the inflatable roadway providing the bearing surface for an air bearing.

FIG. 5 schematically depicts the method of the invention.

Referring now to the drawings, a representative embodiment of an inflatable roadway 10 is depicted as it is bridging an area of unfirm terrain 11. In this particular demonstration the generically referred to area of unfirm terrain is water. Swamps, ice, snow, slush, sand, aggregate and other similar areas in the topography are equally bridged with ease by the present invention. Beaches which are a combination of being soft and irregular also present no obstacles for personnel, equipment and cargo as will be explained below. The only applications where the invention has been found to be somewhat lacking are in bridging volcanoes, lion cages, and racially troubled areas, for example.

The main constituent parts of the invention are an elongate upper panel 12 and an elongate lower panel 13. Both of the panels are fashioned from a heavy duty flexible material such as a rubber impregnated canvas having a flexibility which allows their being stored and transported in a laterally rolled configuration. The panels are secured to one another around their peripheries by a variety of techniques well known in the art. In one preferred embodiment the peripheries were bonded with a commercial adhesive and sewn together create a tough enough joint to contain pressurized gas in a longitudinal envelope or chamber 14.

The longitudinal chamber is distended to its full dimension when a pressurized gas source 15 is coupled to a fitting 16 which communicates with the envelope. Although a tank of compressed air is shown in the drawings, it is understood that an air compressor or chemical gas generator optionally is substituted.

As more and more of the gas is fed to the chamber, the rolled-up upper and lower panels 12 and 13 automatically unroll in a direction away from the pressurized gas source. The unrolling deploys the roadway across water, sand, thin ice or other unfirm area. It should be noted that the automatic deployment of the roadway does not call for the undue exposure of personnel. This feature, along with the portability of the roadway, makes it highly suitable for use by assault teams under combat conditions.

After the panels are unrolled completely, an additional volume of gas is fed into the longitudinal envelope. A multitude of strands 17 are connected at their opposite ends to the upper and lower panels and ensure that the longitudinal envelope has a uniform rectangular, cross-sectional shape. Optionally, several equidistantly spaced partitioning walls 18 run the length of the inflatable roadway and to aid in restricting the width of the chamber. The walls are fabricated from a flexible fabriclike material so as not to interfere with the rolling and unrolling of the roadway. A combination of strands and walls also can be used, their main function is to hold elongate upper panel 12 so that it defines a smooth outer surface 19. This smooth upper surface is essential for pneumatic cooperation with an air bearing 22 as will be explained below.

When the inflatable roadway is used by a mobil assault group, decking panels 20 usually are provided to protect the upper surface. These decking panels preferably are some lightweight rugged material such as plastic, aluminum or wood which additionally more evenly distribute the load across the roadway. The decking panels are dimensioned so as not to overly interfere with storing and carrying the roadway in its rolled configuration. The panels do not prevent the automatic unrolling of the roadway.

When, however, the roadway is chosen to function as a smooth bearing surface of an air bearing, it greatly increases the capabilities and the applications of an air bearing. Air bearings are widely used to transfer heavy cargo loads usually in a loading area or within warehouses. Most of them function on the principle that when a sufficient volume of pressurized air is blown through venteral ducts and under a peripheral skirt, a relatively heavy load is borne by a cushion of air. This air cushion is relatively frictionless and little effort is needed to move the load from one place to another.

A limitation inherent in the use of air bearings is that they must pneumatically react with a smooth surface. Consequently, their use has been somewhat restricted to areas having relatively smooth floors or slabs.

The present invention greatly increases the areas where air bearings are employed by providing the needed smooth surface. Noting FIG. 3, a load of heavy cargo 21 is being transported across a dock 24 having a standard slotted decking 24a. The slots between adjacent planks are universally employed for drainage and to help reduce the weight of the dock. As a consequence, air bearings have been considered generally unsuitable for the unloading of the heavy containers used in marine shipping. Deploying the inflatable roadway as described above bridges the slots and an air bearing now can be used to off load a ship. In this application, however, decking sections 20 are not included.

Cargo 21 is located on a palate supported by an air bearing 22. A hose 22a feeds substantial volumes of compressed air from a compressor 23 to the bearing and the cargo is supported on a cushion of air. A small force moves the heavy cargo the length of the inflatable roadway. Several roadways can be interconnected at their opposite ends to provide a passageway from a ship to a warehouse.

Another application of the instant invention which speeds up the off-loading time of heavy cargo is shown in FIG. 4. A modified inflatable roadway 10 is deployed as described across a sandy beach. The modifications are with respect to being built larger and of more rugged materials to accommodate extremely heavy loads. Otherwise, roadway is essentially the same as the previously described.

A smooth exposed surface 19 of elongate upper panel 12 provides a proper surface over a sandy beach 25. One section of inflatable roadway is placed on a lighter barge 26 before cargo module 21 and air bearing 22 are unloaded from a ship. The lighter barge closely approaches the sandy beach and the inflatable roadways on the lighter barge and on the beach are inflated. A pressurized gas source, not shown, activates air bearing 22 and a pair of tractors 27 pulls the cargo module to an unloading area 28. In the unloading area or storage yard the cargo module is unpacked and distribued.

By reason of the functionally cooperating structure described hereinbefore a novel method for expediting a cargo transfer has been created. First, there is a placing 29 of the roadway on the near side of an unfirm area such as sand, water, swamp, etc. Next, there follows a coupling 30 of a source of pressurized gas to the roadway and an unrolling 31 of the roadway as pressurized gas fills a longitudinal envelope or chamber contained within. Further pressurizing 32 the roadway distends the longitudinal envelope so that there is a maintaining 33 of a smooth, exposed upper surface. A placing 34 of an air bearing on the smooth outer surface and an actuating 35 of the air bearing by its interconnection to a compressor allows the moving 36 of the cargo the length of the inflatable roadway within minimum effort.

Obviously, many modifications and variations are possible in the light of the above teachings, and, it is therefore understood that the invention may be practiced otherwise than as specifically described.