at the Tarragona plant stated they heard Imbernón heatedly arguing with someone on the phone and demanding money for the motorway toll. Enpetrol initially declined any responsibility, claiming that the delivery of the cargo was the carrier's responsibility, and they had not received any complaint. The official inquiry determined that the truck had been severely overloaded, and also lacked emergency pressure release valves, which are designed to help prevent a boiling liquid expanding vapor explosion (BLEVE) in case of a fire. However, these valves were no longer mandatory in 1978 as they previously had been. The truck was due for an inspection check-over in 1980, and it had passed the previous inspection. The tank container was manufactured on 13 December 1973 by a workshop from Bilbao, and at that time it did not meet the requirements for carrying flammable liquids, since it lacked emergency pressure release valves. Therefore, the tank had been used to carry other substances, some of which were highly corrosive. Tests on the remnants of the steel tank revealed microscopic stress cracks consistent with corrosion caused by previous loads of improperly overpressurized anhydrous ammonia. Combined with whether the tanker suffered an impact that caused additional structural damage, these factors likely led to the almost instantaneous rupture of the tank when the flames flashed back into the tanker. Even without safety valves, a structurally sound and properly filled tanker should have been able to maintain structural integrity in a fire long enough to at least allow nearby people to escape. The inquiry also revealed that overloading of tankers was common practice at Enpetrol refineries. The Tarragona facility lacked either a meter to measure the amount of gas dispensed or an automatic shut-off device to prevent overfilling, and consequently most tanks were consistently overloaded. The driver was neither informed of the overloading, nor about the type and class of the cargo, and there was no means for him to check the pressure level of the tank before he departed or to monitor it in transit. He had not attended the hazmat training program for drivers of dangerous goods, because the company considered his experience of twenty years as a truck driver to be sufficient. The inquiry also determined that, between 3 January and 7 July that year, 32 tanks left the Tarragona refinery overloaded, with drivers other than Imbernón. Legacy After the tragedy, the transit of populated areas by