Highways and trains are often the cause of sound nuisance. In densly populated areas a lot of noise and exhaust gases have to be dealt with. To reduce these problems Practical Solution invented the inflatable tunnel. The first concept you see here. The problem with this solution is that peel stresses will break open all sealed areas. Due to the air pressure (needed to make the tunnel form stable and overcome a windload) these for glue connections negative tensions arise. This will mean high demands on the glue and fabrication process raising costs.
To make the tunnel cheaper and reduce peel tensions a second design was made. The only thing to look at is vandal proofness. There are plastics on the arket that are not flammable. When a vandal makes a hole in the tunnel the fan will keep the tunnel upright. Of course it is also possible to fill the elements of this tunnel with a sound reducing foam. Top elements can stay open for entrance of light. This will still give a high noise reduction. Then also vandal proof is not a problem anymore. A big fan can also send exhaust fumes to a place where these gasses can be removed. Due to electrostatic properties of the plastic also the plastic can remove dust and dirt particles out of the air. The plastic gets electrotatically loaded due to friction of the wind produced by all the moving cars.
By inflating the separate segments of the tunnel, all elements want to expand and reach a round shape. To make the tunnel stable in its shape (also resisting wind loads) a plastic fabric is placed over the tunnel. Such a kind of plastic may also be necessary inside the tunnel. The fabrics are anchored to the ground and make the shape of the tunnel stable.