Fast Flight: The 1946 Naperville (USA) Train Collision

Max S
12 min readApr 14, 2024


Naperville is a city of 149540 people (as of 2020) in the northwestern United States of America, located in the state of Illinois 43km/27mi west of Chicago (of which it’s nowadays considered a suburb) and 96km/60mi southeast of Rockford (both measurements in linear distance).

The site of Naperville in the northeastern USA.

The city lies on what is now the Chicago Subdivision, a triple to quad-tracked non-electrified rail line running from Chicago in the east to Aurora in the west. Back in the 1940s the line was owned and operated by the Chicago, Burlington and Quincy Railroad (CBQ), a Chicago-based rail company operating trains throughout a large part of the USA on 15075km/9367mi of track at the height of their expansion.

The section of the line running through Naperville is three-tracked and often referred to as the “racetrack”, as the outer two tracks are used for freight and regional trains while express services could maintain high speeds on the center track, which was set up for operations in both directions. As of 2024 speeds on the line are limited to 110kph/70mph in regular operation, though.

The site of the accident seen from above today, both trains were coming from the east (right side of the image).

The Trains Involved

The “Advance Exposition Flyer” (typically referred to as the Advance Flyer) was an intercity express passenger service from Chicago’s union station to Oakland in the state of California. It consisted of five four-axle passenger cars, running behind 8 so-called “head-end” cars (mail, baggage and a post office car) for a total count of 13 cars. Pulling the train on the day of the accident were two CBQ E7-locomotives. The EMD E7 is a six-axle diesel locomotive introduced in 1945 specifically for heavy express passenger trains. The standard configuration is referred to as the E7A, while a special version called the E7B was also made. The E7B was a cab-less version incapable of independent operation, carrying the full propulsion system of the E7A but being intended to be controlled from an E7A coupled to it. This space-efficient version of multi-traction used to be common on US railways. Each E7A measures 21.64m/ft in length at a service-ready weight of 143 metric tons (E7B: 132 metric tons) and can reach up to 135kph/mph thanks to two supercharged 2-stroke V12 diesel engines producing a combined 1490kW/hp.

A CBQ E7A and E7B-combo, identical witht those involved in the accident, photographed in Kansas City in 1959. Note that the Advance Flyer’s cars carried the same silver finish as the locomotives.

The “Exposition Flyer” was another express passenger service offering the same connection, also operated by the CBQ starting in 1939. It consisted of 9 four-axle passenger cars on the day of the accident, notably not carrying any dedicated mail- or baggage cars, bringing it to little more than half the usual length. It was led by CBQ E5 9910A, pulling 9910B in a setup similar to that of the Advance Flyer, and was driven on the day of the accident by Mister Blaine. The EMD E5 is a six-axle diesel locomotive for heavy express services, similar to the E7, introduced in 1940. Each E5A measures 21.68m/ft in length at a service-ready weight of 143 metric tons (E5B: 132 metric tons) and can reach 185kph thanks to the same engines found on the E7, be it with different gearing for higher speeds. The type was made exclusively for the CBQ, with all units receiving a polished stainless steel bodyshell to match the stainless finish of their “Zephyr”-type passenger cars. The E5 can be differentiated from the very similar-looking E7 by the stronger slope of the front end on the A-units intended to improve aerodynamics.

Both trains carried a combined 225 passengers at the time of the accident, in addition to their crews.

CBQ #9950A, identical with 9910A involved in the accident, showing off the polished finish and sloped front end at Dallas Union Station at some point in the 1950s.

The Accident

The Advance Exposition Flyer (from here on referred to as the Advance Flyer) departs Chicago’s union station at 12:35pm on the 25th of April 1946, beginning its long journey to California on the USA’s west coast. The Exposition Flyer has the same destination and departure time, but leaves Union station in the next time slot, 2 minutes after the Advance Flyer.

The Advance Flyer thunders through Naperville approximately 20 minutes after departure from Chicago when the rear brakeman, Mister Grant, believes that he saw some undefined object flying out from under the train. He signals the locomotive crew to stop as soon as possible, not wanting to take unnecessary risks, and the train comes to a halt in downtown Naperville at 1:00pm, its back end right at the Loomis Street level crossing. Unscheduled stops require a member of the crew, referred to as the flagman, to walk back down the line behind the train to warn inbound trains in addition to the signals. Thus, while most of the crew starts to examine the train’s suspension and wheels, one crew member grabs the warning flag and walks eastbound along the tracks. He has barely left the train behind when, at 1:01pm, the Exposition Flyer comes into view around a sprawling turn trains are meant to take at full speed. The train is braking, but isn’t decelerating nearly fast enough. There’s no time to even warn anyone, and it’s unknown if the passengers or crew even saw the other train coming before, at 1:02pm, the leading locomotive of the Exposition Flyer crashes into the back of the stationary Advance Flyer at 72kph/45mph. The impact with the rear passenger car, a heavy 68-seat observation car, shaves the leading wheelset off CBQ #9910A, sending its barely-decelerated frame and body into the body of the train car. The locomotive acts like a wedge being driven into the passenger car, splitting it lengthwise in half as it crushes everything inside the train car for three quarters of the train car’s length before getting stuck. The collision shoves the entire train car forward, pushing the identical car ahead of it along. Car 12, a dining car of lighter construction, has nothing to offer against the cars behind it and can’t move the train in front, forcing it into a U-shape as it tries to handle being caught between a near-unstoppable force and an near-immovable object. The cars in front of it remain structurally largely intact, derailing and falling over as the impact pushes them against further stationary cars up front. 45 people are killed in the collision, another 125 people are injured. 44 victims were passengers aboard the Advance Flyer, 1 victim was Mister Crayton, the driver’s assistant (“Fireman”) from the Exposition Flyer, who jumped from the train when the collision was imminent.


The collision occurred literally right outside the Kroehler Manufacturing Company, a furniture factory in Naperville. Over 800 employees from the company became the first outsiders responding to the disaster, rendering first aid, rounding up survivors and turning part of the factory floor into a makeshift triage area, using their own products as hospital beds to keep injured survivors off the floor. Students from the nearby college brought mattresses and used lumber from a local construction site and the factory to create makeshift gurneys to transport injured survivors. Extensive on-site triage was incredibly important as the city was so unprepared for an event like this that they didn’t even have ambulances. Some survivors were taken to hospital aboard hearses, most of the rest was put in random trucks and station wagons, anything you could fit a person in if they lay down flat.

Most of the involved rolling stock was left fairly intact, with the remains of the Advance Flyer’s rear car sticking out in the chaos as the shiny silver locomotive from the rear train was solidly jammed in place most of the way through it, having peeled the outside walls away like a tin can to either side. Bodies of the victims were taken to a nearby lumber yard, lining them up in the chef’s office. Volunteers spent all day trying to match body parts to bodies and identify the dead. Some of the victims were soldiers who had served in World War 2 until the prior year, making their death in the accident an especially cruel twist of fate.

The fate of Mister Crayton, who died when jumping from the Exposition Flyer’s locomotive ahead of the collision, might seem similarly cruel as the locomotive ended up suffering relatively minor damage. However, not only had Mister Crayton the memory of his brother on his mind, who died in another train collision three years prior when the locomotive burst into flames post-impact, but responders also found a piece of debris having pierced the cab window right where he would have been standing, meaning he likely wouldn’t have survived if he remained on board either.

Workers from the adjacent factory try to pull survivors from one of the wrecked passenger cars.

The accident was the subject of four different, relatively independent investigations by the county’s coroner’s office, the CBQ themselves, local law enforcement and, lastly, the Interstate Commerce Commission (ICC), a government agency that served as a predecessor to the NTSB (National Transportation Safety Board). It was found that the brakes on both trains had been in perfect working order, as had the signaling system between Chicago and the site. Signal 227.1, located 2km/1.25mi from the site of the impact, had switched from green (“all clear”) to yellow (“warning/approach”) when the Advance Flyer had slowed to a stop beyond it. Mister Blaine, once he could be interviewed, stated that he had immediately applied full brakes when he passed the signal, but that the train had just been too fast to stop in the remaining distance, only shedding about half its speed before impact.

Investigators thus assembled a train identical with the Exposition Flyer involved in the accident and tested his claims, finding that the train came to a stop 120m/395ft ahead of the next signal (228.1) when slowing from 130kph/81mph. That left it a full 405m/1329ft ahead of the site of the accident. The theory that Mister Blaine had confused the two signals or had missed 227.1 and only stopped when he saw 228.1 was also considered, with a brake-test from 138kph/86mph starting at 228.1 seeing the train stop 120m/393ft beyond the point of impact. This closely matched the actual accident, where the leading locomotive had covered another 62m/205ft after impact, despite having to drill itself through another train for every single one of those meters.

A section of the mangled wreckage, with responders navigating atop the train cars.

Mister Blaine admitted that he may have been going slightly above the local speed limit of 130kph/80mph, but insisted that he had triggered a full emergency stop when seeing signal 227.1 and definitely hadn’t mis-identified or missed any signals. Some outside witnesses did support that claim, stating that they saw sparks coming from the wheels of the train, but this wasn’t backed up by the evidence at the site. Some members of the train crew also objected to their driver’s claim, saying they were sure that the train was only “service braking” ahead of the accident. This means that it would have been decelerating as much as it could without an emergency stop being triggered, which would result in a longer brake-distance at the advantage of more passenger comfort.

The behavior of the Advanced Flyer’s conductor and flagman was also questioned, with the conductor forwarding the stop-order at a point when it would bring the train to a halt just beyond a high-speed curve and the flagman perhaps not working fast enough. The conductor successfully defended themselves by arguing that they didn’t know what may be wrong with the train, and it was obviously unwise to risk a derailment when it appears that a piece of an express train’s underpinnings has departed the train at speed. The flagman also ended up being cleared of any fault, as it couldn’t be proven that he could’ve acted any faster than he did. Lastly, it’s worth noting that it was never determined what exactly, if anything, Mister Grant had seen flying from the train.

Civilian responders and doctors use ladders from the adjacent factory to scale and enter the wreckage.

The decision by Mister Blaine to only use full service braking, leaving additional deceleration capability unused, was eventually pointed out as one of the two main factors which led to the accident. No investigation could disprove his claim to have applied “full brakes” at the correct signal, but one could argue that he was telling the truth by using “full brakes” to mean “full service brakes” rather than “full braking power”. He couldn’t know why the signal he saw showed “warning/approach”, for all he knew he was just closing in on a slower train in front. And in that case, an emergency stop may have been excessive.

The second main factor that led to the accident was the combination of the train’s speed and their scheduled proximity while running on the same track. Running just 2 minutes apart at 130kph/81mph left so little space between the two trains that the slightest irregularity, as the accident showed, could lead to disaster. The CBQ reacted by extending the interval from 2 to 15 minutes between dispatches while a nationwide speed limit of 127kph/79mph was implemented (some passenger trains had seen regular speeds of up to 160kph/100mph until then).

A pile of debris from the destroyed dining car creates a wall in the wreckage.

Mister Blaine and a group of other railroad employees were charged at various points during the investigation-period, but a Grand Jury elected to have the charges dropped in October of 1946 as they saw none of the charged individuals to be of sufficient guilt on their own to justify legal consequences. As such, nobody was ever put on trial for their role in the accident.

The ICC published a ruling in 1951 that all trains meant to travel faster than the new speed limit must have systems onboard that show the setting of upcoming signals in the driver’s cab as well as an automatic train control system (ATC) which can bring a train to a halt if it breaks the speed limit or runs a red signal. The cost of implementing those systems across large networks at the time made them highly unpopular, meaning for a long time service speeds of trains in the USA didn’t advance past the 127kph/79mph speed limit.

The practice of using both “heavy” and “light”-type passenger cars within the same train was also phased out after the accident, aiming to avoid the effect that selected cars in a train would become a crumple zone for the rest of the train. Nowadays most passenger trains, especially in express services, consist either of identical cars or ones built to the same crash protection standard.

A scanned photo from the wreckage as shown on TV during a news-report about the memorial. Please excuse the poor quality of the screenshot.

The rear cars of the Advance Flyer were scrapped after the accident, while the Exposition Flyer’s locomotives were repaired and saw service until the end of the decade, as did the Advance Fyler’s locomotives. The Exposition Flyer’s leading locomotive (CBQ 9910A) was apparently last spotted in 1949, before being retired and scrapped in 1950. 15 of the just 16 EMD E5 locomotives ever made were scrapped, with only one unit remaining today, being preserved at the Illinois Railway Museum in operational condition. The EMD E7, the type that pulled the Advance Flyer, had a similar fate, with only one of its once 510 units escaping the scrappers torch, sitting in the Pennsylvania Railroad Museum in non-operational condition as of 2024.

The “Exposition Flyer” and “Advance Exposition Flyer”-services were discontinued in 1949, being replaced by the “California Zephyr” which ran until 1970 (the same year the CBQ became the Burlington Northern Railroad through a merger with two other railroads) and has seen a couple of revivals on more or less identical routes to this day, with the current version, provided by Amtrak, combining bits of the original route with bits of that of its competitor, the “City of San Francisco”-train service.

CBQ #9910A, the locomotive pulling the Exposition Flyer involved in the accident, departs Chicago Union Station in August 1949, mere months before its retirement. The B-unit behind it is unidentified, it could be #9910B from the accident.

The accident was largely forgotten over time, until 2012’s “The Tragedy at the Loomis Street Crossing”, a book written by a local resident, brought it back into the public conscience. The renewed attention led to an official memorial being commissioned, centered around a statue by a local artist which was unveiled in 2014. The piece, named “Tragedy to Triumph” stands at the site today and is meant to both remind people of the accident but also honor the way the community came together to support survivors. The statue displays two men who support a woman between them similar to how one would help an injured person walk. The single-color statue is made of 5000 railroad spikes and flanked by rusted train wheels partially sunken into the concrete floor, next to a large bronze plaque telling the story of what happened and listing all victims’ names.

“Tragedy to Triumph”, the memorial to the accident and the community’s reaction, standing at the site today.


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Max S

Train crash reports and analysis, published weekly.