Background
Mississauga is a city of 717961 people (as of 2021) in southeastern Canada, located in the Province of Ontario 22.5km/14mi west of Toronto and 40km/25mi north of Hamilton on the shore of Lake Ontario (both measurements in linear distance).
Mississauga lies on what is today the Milton Line, a double-tracked unelectrified main line connecting Milton in the southwest with Toronto on 50.2km/31.2mi of track. At the time of the accident the track making up the Milton Line was near-exclusively used for freight services as part of the Quebec City — Windsor Corridor, Canada’s most frequented rail line. The line opened as that freight line in 1856, being owned by the Canadian Pacific Railway (CP), a Calgary-based rail service provider. By the late 1970s they had spent years resisting passenger services on the line as much as they could, claiming it would hinder their freight operations going into Toronto.
The accident happened near the center of Mississauga, at a level crossing with Mavis Road.
The train involved
On the day of the accident CP had loaned three EMD F40PH locomotives from GO Transit, a regional rail service provider they, somewhat ironically, fought tooth and nail to keep off their rail lines. Th F40PH is a four-axle multipurpose diesel locomotive introduced into service with various rail service providers in 1975 after being developed for USA-based Amtrak. Each unit measures 17.12m/56ft in length at a weight of 118 metric tons and can reach 166kph/103mph. The three locomotives were used to pull a heavy freight train (running as train number 54) consisting of 106 tanker cars from Windsor to Toronto. The cars were loaded with various gases and chemicals including propane, chlorine and caustic soda. At the time of the accident the train was under the command of train driver (also referred to as “engineer” or “engineman”) Mister Pruss, along with Conductor Mister Nichol and trainman Mister Krupa. The train had had a standard crew of 4 (with two trainmen) on an earlier section of the route, but staff shortage forced the crew to be reduced.
The accident
On the 10th of November 1979 Freight Train 54 is prepared to depart London (Ontario) after arriving from Chatham. It’s one of several stops the train has conducted on its journey already, having had train cars added or removed along with visual inspections of the train. At London the inspection was performed by the train’s crew themselves. As they also have to wait for an oncoming train to pass and it being already dark Pruss later stated he turned on the headlights and so-called ditch lights (additional headlights closer to the track) so that staff at the shunting yard could easier observe/check the passing oncoming train before they pulled out of the yard and proceeded to Woodstock, were further cars were added. The yard staff inspecting train 54 there found nothing out of the ordinary and soon cleared the train to proceed. For unknown reasons the train crew skipps a mandatory brake test and also accidentally starts pulling out of the yard before Mister Nichol is onboard, requiring him to run after and jump onto the train. As it pulls out of Woodstock the train measures 2.02km/1.26mi in length at a weight of 9050 metric tons. According to the reports from the inspections everything was in perfect working order at that point.
At approximately 11:30pm train 54 passes a waiting oncoming train near the city of Guelph, 49km/30.5mi linear distance from the site of the accident. A member of the waiting train’s staff, Mister Dionne, notices some smoke around the brakes of some of the train cars. This alone wasn’t cause for alarm though, as the freight train had to slow down to 15mph in the area and smoke from strong braking could linger. As such the train pulls away from the siding into the night unchecked, already carrying the makings of a massive accident. Unbeknownst to those involved one of the older train cars’ wheelsets’ journal bearings had run out of oil due to insufficient care/inspection, and had gotten hotter and hotter with every rotation of the wheel. A journal bearing is an incredibly simple construction, with the axle extending past the wheel and simply rotating in a metal cylinder (referred to as the “journal box”). The bearing is meant to be submerged in oil to keep the heat caused by the friction of metal moving on metal under control. In some cases rags or cotton pads soaked in oil are used to further reduce the friction between the two parts. Both the oil-level and, if applicable, the condition of the rags, is meant to be checked during the visual inspections at stops by lifting up a lid on the outside of the box.
As the train approaches Mississauga residents living adjacent to the rail line see sparks coming from its wheels, with some witnesses who live closer to the site of the derailment later saying they thought the train might be on fire, but they weren’t sure enough to call emergency services and/or had no way to tell them what train they were referring to. What had happened was that a bearing on car 33 had just about completely run out of lubrication and heated up to the point that the bearing had started to melt as the train reached Mississauga. It is likely that the smoke Mister Dionne had seen was actually smoke from the bearing but he chalked it up to the brakes, the more likely origin.
At 11:53pm train 54 reaches the level crossing at Burnhamthorpe Road just as the partially molten axle snapps under the load from the freight car, causing it to jam up against the frame of the train car before being ejected as the train travelled at around 72kph/45mph. A witness at the crossing watches as the red hot steel axle cartwheels 15m/50ft down the road before becoming lodged in the witness’ front lawn.
The train drags the stricken freight car along for 3km/1.8mi before it slips out of alignment at the Mavis Road level crossing, derailing and pulling the following cars along. The impact with other train cars ruptures several of the cars carrying propane, setting the wreckage ablaze in an instant. As the cars keep piling up at the crossing more and more train cars rupture, feeding the fire and, seconds after the derailment begun, cause an explosion which sends a fireball over 1500m/5000ft into the sky, witnessed by residents over 100km/62mi away.
The train had come to a stop in the derailment as the pneumatic lines had been severred as the train broke up. Mister Krupa, at the suggestion of Mister Pruss (who, by coincidence, was his father-in-law), made his way to the back of car 32, right on the edge of the fire and closed the valve, allowing Pruss to refill the system and pull the leading 32 cars a short distance down the track, keeping them safe from the growing inferno as the first responders start to reach the site. Nobody has died or been injured so far, with one couple escaping the fire by a few feet as they had been waiting at the Mavis Road crossing.
The inferno
Just after midnight a second major explosion rocks the town, a large four-axle tanker car caught up in the detonation is later found over 1km/3280ft from the wreckage. The firefighters’ efforts are nearly inconsequential against the raging flames, eleven of the burning tanker cars contain propane and, even worse, somewhere in there is a tanker car with 90 metric tons of chlorine. The fire department tries to slow the spread of the flames, hoping to keep as many train cars out of the fire as they can. By 1:30am paperwork arrives that allows responders to locate the chlorine car in the wreckage. They find it engulfed in flames, it’s impossible to tell if it ruptured. The police knows that the heat can change chlorine gas to phosgene, an even more poisonous chemical that killed thousands when used deliberately during WW1. 6000 people in the immediate area are evacuated as the firefighting is focused on the tanker car carrying the chlorine. By 4am another major explosion goes off, the evacuation order is extended with another 26000 people being forced to leave their homes.
By 6am firefighters can finally approach the chlorine car close enough to inspect it, and they discover a 1m/3ft hole in the side of it. The gas is leaking. From now on the propane is allowed to largely burn off, with firefighters keeping all hoses on the chlorine tanker car to try and cool it down. With changing winds in the morning hours the evacuation-radius is expanded several more times, by the evening of November the 11th almost 250 thousand people have been evacuated. Some people had to move several times as the places they had been evacuated to were also evacuated. Miss McCallion, at the time the mayor of the city, says the city is “closed until further notice”. Nobody not involved in the emergency response is to be found in the area. It’s the largest peacetime evacuation in North American history and will remain such until Hurricane Katrina struck the USA in 2005.
In the early morning hours of the 13th of November the fire is finally extinguished, experts estimate that 68 tons of chlorine gas escaped into the atmosphere. By 1pm the first residents are allowed to return and “prepare to evacuate”-orders as far out as Toronto are withdrawn. By the 16th of November the last residents return home, no residential houses were lost and nobody was injured or killed in the inferno. At last, the chlorine is completely pumped out of the wreckage and the site is handed over to investigators. Despite the scale of the accident there is no record of any injuries to anyone.
Aftermath
Investigators retrieve the axle that was flung from the train ahead of the derailment and talk to various witnesses. There is little left of the train cars to be examined, so trying to reconstruct the phase before the fire along with examining the axle is the best they can do. They also talk to the train crew, and immediately stumble over a problem. Mister Pruss mentions having used ditch lights on his locomotive earlier in the evening, something the locomotive he drove isn’t equipped with. This, along with a yard worker claiming impossibly short timeframes for the inspection, leads the investigation to suspect that the men worked at least partially “on autopilot”. As the report points out, there is no evidence of purposeful negligence, after years or decades on the job they may just have fallen into a habit of going through standard procedures without actually paying attention. Pruss had little experience with the borrowed locomotives, so it’s entirely possible that he recalled turning on the ditch lights despite not actually having that option that night. He may have just been used to locomotives he worked with having them.
The accident is quickly traced to the journal bearing on car 33 running out of lubrication due to insufficient attention being paid to it during several inspections ahead of the derailment. Since the accident’s cause thus can’t be blamed on a certain individual or certain individuals no legal consequences ever take place. Nowadays journal bearings have all but disappeared from Canadian rail lines, being replaced with roller bearings which are far less likely to overheat at the price of a more complex construction. Regulators in the USA and Canada also made “hotbox detectors” mandatory on lines carrying hazardous goods into or through populated areas, these installations consist of heat sensors that check a train’s wheel bearings as the train passes through and trip an alarm if certain temperature limits are breached.
Mister Krupta was recommended for the “Order of Canada”, the country’s second-highest honor, but was rejected. He was, however, introduced into the North American Railway Hall of Fame for helping to avoid an even worse disaster. The city of Mississauga originally sued CP for the massive bill they were left to foot after the accident, but dropped the effort when CP agreed to stop fighting against passenger services on the line, allowing the introduction of GO Transit’s Milton Line.
Miss McCallion, at the time in her first term as mayor, was continuously re-elected until her retirement in 2014 at the age of 93. The evacuation she oversaw was so fast and efficient that several cities have since modelled their emergency plans after its example.
At some point after the accident the level crossing was replaced with an underpass, and with journal bearings being a thing of the past a repeat of the accident is just about impossible. Furthermore, advancements in tanker car designs have improved their crash safety overall, making them less likely to rupture in a derailment.
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A kind reader has started posting the installments on reddit for me, I cannot interact with you there but I will read the feedback and corrections. You can find the post right here.
