Intro on March 26 1999 firefighters were conducting a rescue operation inside the Montblanc tunnel the longest tunnel in Europe at the time just two days earlier a severe fire had broken out here raging for a staggering 53 hours temperatures of the tunnel's core soar to 1000 degrees Celsius causing cement and ceramic vehicles to completely melt firefighters ventured deep into the tunnel capturing the scene you see now many items inside still bore the outlines from before the fire yet all details had blurred this event known as the Montblanc Tunnel disaster continues to influence tunnel design and driving safety today why is it mandatory to reduce speed upon entering a tunnel why must vehicles maintain a distance of at least 100 metres inside tunnels and why are the traditional ventilation fans of tunnel tops becoming increasingly rare and newer constructions these seemingly insignificant rules and designs are almost all linked to the Montblanc tunnel disaster Story the Montblanc tunnel is located at the border between France and Italy spanning 11.6km it was completed in 1965 and by 1995 it had been operating smoothly for 35 years it drastically reduced travel time between France and Italy from 7 hours to just 15 minutes making it incredibly busy with a large volume of trucks and cars passing through daily the tunnel is divided between the two countries with monitoring rooms on both ends every 600 meters inside the tunnel there is a refuge area designed to withstand temperatures up to 800 degrees Celsius for four hours there are a total of 77 emergency phones along the tunnel and emergency response teams are stationed at both ends ready to act at a moment's notice despite being hailed as one of the safest tunnels ever everything changed on March 1995 at 10 47 a m a heavy duty truck rated level 10 entered the tunnel from the French side at a speed of 60km per hour the truck was carrying 9 tons of butter and 12 tons of flour driven by a 25 year old driver named Gilbert two minutes later Gilbert noticed something amiss as oncoming cars were flashing their lights at him but from his perspective everything appeared normal unbeknownst to him white smoke had begun emanating from the rear of his truck and his blind spot despite the presence of 9 smoke sensors in the tunnel they failed to trigger an alarm investigators later explained that the smoke concentration at that moment was just below the alarm threshold compounded by unclear monitor footage where the smoke appeared too slight to notice Gilbert continued driving forward until the smoke alarm finally sounded normally both monitoring rooms on the French and Italian sides would respond promptly by closing off the tunnel to prevent more vehicles from entering however the Italian side's alarm had been manually turned off due to a mistaken alert the previous day after the accident vehicles were halted from entering the French side of the Montblanc tunnel but on the Italian side cars continued to be funneled in six minutes later at 1053 a Gilbert stopped his truck because thick smoke made it impossible to see the road ahead he turned on his hazard lights shut off the engine and waited for rescue however just as he exited the vehicle the entire cabin burst into flames followed by a massive explosion engulfing the entire truck Gilbert ran towards the Italian side unaware that 25 cars behind him were stuck due to close proximity and unable to move one minute later at 1054 a m the Italian control room received a call reporting a fire at the center of the tunnel however dense smoke had already obscured the cameras making it impossible for staff to pinpoint the source of the fire cars that had already entered from the Italian side saw the fire and hastily turned around to flee towards the Italian exit viewed by control room staff as a desperate attempt to escape to ensure the safety of those trying to flee the control room increased fan speeds to push large amounts of oxygen into the tunnel intensifying the fire inadvertently normally tunnel fire safety protocols call for bi directional ventilation to quickly expel deadly smoke unfortunately the Italian operators neglected this step flooding the tunnel with excessive oxygen causing thick black smoke to shoot out directly from the French entrance French rescue teams responded swiftly but upon entering the tunnel they found their efforts feudal as smoke quickly obscured visibility forcing them to abandon their vehicles in attempt to proceed on foot yet the low oxygen levels prevented their vehicles from igniting with no contact with headquarters they eventually found refuge in a maintenance room beside the tunnel becoming rescuees themselves meanwhile Italian volunteer rescue teams had advanced to within 300 metres of the fire zone but were forced to retreat as rising temperatures caused tunnel walls to collapse triggering explosions of successive vehicles at 11 11am the professional firefighters from Italy arrived fully equipped and entered the tunnel they received word that the French firefighting team who had entered earlier not only failed to complete their mission but also lost contact with headquarters the Italian captain decided it was necessary to simultaneously rescue the French team for hours the captain searched refuge areas but found nothing and their oxygen supplied dwindled dangerously low by 11 30 a m the inferno had raged for over half an hour heating the tunnel to between 1 000 and 1200 degrees Celsius vehicle frames melted swiftly turning the tunnel into a furnace where even the road surfaces and walls melted into molten maga the firefighting teams were forced to announce a complete suspension of rescue operations firefighters from both Italy and France stood at the tunnel mouth helpless witnesses as the fire ravaged what was once touted as the safest tunnel in history 53 hours later the fire was finally extinguished leaving behind a pathway reminiscent of hell itself a swift investigation commenced considering scenarios or the fire originated from sparks in the truck's cab or potentially a discarded cigarette that ignited near Gilbert's vehicle regardless of the initial cause the presence of 9 tons of butter and 12 tons of flour in the truck acted as significant accelerance releasing intense heat capable of melting concrete investigations also highlighted fatal operational errors in the Italian control room their mismanagement allowed excessive oxygen to flood in from the Italian side pushing dense smoke at a rate of 4.5 meters per second towards the French side displacing oxygen and causing all vehicles to stall instantly pedestrians both inside and outside vehicles inhaled lethal smoke and toxic gases Outro in 2005 security personnel and former CEOs of the tunnel operating company were sentenced to prison terms ranging from two months to six months Gilbert the truck driver received a four month prison sentence the tunnel company compensated victims families with a total of 17.5 million dollars following the accident Thermal sensors were installed on both sides of the Montblanc Tunnel and strict speed and distance limits were enforced inside each refuge area underwent renovations with enhanced monitoring for immediate response capability additionally a central temporary rescue station was refurbished in the tunnels midpoint subsequent tunnel designs worldwide have drawn lessons from the Montblanc tunnel disaster especially in ventilation systems traditional exhaust fans are avoided in favor of designs resembling pipe systems to prevent similar tragedies today a memorial Monument at the entrance of the Montblanc Tunnel serves as a reminder with each metal rod symbolizing a victim lost it stands as a poignant plea for road safety vigilance to prevent such tragedies from recurring alright that's the end of today's story see you next time