The website quoted says that the truck driver had "fallen between the cab and the trailer of his truck, breaking the air hose", presumably the hose of the air-braking system. It continues "The nozzle pierced his buttock and began pumping air into his body, which expanded dramatically." Presumably it was the driver's skin which acted like a balloon and did the expanding. Considering that such air hoses are likely to be of suitably robust construction for their purpose and working environment, the absence of other information leaves us wondering why and how the air hose (or perhaps its coupling) broke as it reportedly did. Therefore, are there any forum users with knowledge of HGVs who might be able to suggest what might have happened or went wrong? Allied to this, when the coupling for an air hose between a HGV tractor and an articulated unit is being connected or disconnected, does the tractor part of the coupling incorporate a self-sealing valve or do drivers have to use a separate valve in or outside the tractor cab to isolate the air supply beforehand? There are indeed shut of valves contained within the air hose connectors and these allow the air lines to be disconnected and connected without the need to fill air resevoir tanks every time, but it would appear that it was the air line itself that broke. This is surprisingly common (they can get caught between 5th wheel and trailer on a tight turn and sheared) but I must confess to wondering how this guy impaled himself on one, as most are fitted in the horizontal plane and they require some force to break clean and not just leak. They are desgined to move as the vehicle turns and are not fixed other than at the connectors. When this happens, the contents of the air tanks on both trailer and tractor will empty pretty fast as the air-supply is a 'circuit' system. As Air brakes on HGVs fail safe, lack of sufficient air pressure in the system will apply the brakes and they can't be released until air pressure builds again. This is why you will often see HGV drivers first thing in the morning revving their engines to build air with a buzzer going in the background as the air pressure has dropped overnight due to a small leak in the system. A compressor in the tractor unit keeps the pressures up and can more than cope with minor air leaks, but not a break or burst. It's not clear from the article if it was the air from the tractor unit or air contained in the trailer tanks, but both will have an emergency air dump fitted to them. The trailer's is easist to use (next time you see a HGV trailer, look underneath at the cable attached to the cylinders that contain the air and that's it) Hope this helps, but this guy was both unlucky to have been involved in such a freak accident, given the orientation of air lines and lucky to have survived such high pressure air injected into his body.