A failure analysis was performed on a light rail windshield failure. In this there was a pop and the operator was showered with glass. The glass failure analysis expert witness determined that there were two leads to the windshield defogger that were in proximity and because they were improperly wired, arcing occurred between them. The arcing generated heat and pressure that caused the glass to crack and spall locally. Upper left is a photograph of the damaged region of the windshield. Upper right is a closeup of the leads that arced. One can see that the lead ends are melted.