1977 Chicago Loop derailment
Encyclopedia
The 1977 Chicago Loop derailment occurred on February 4, 1977, at approximately 5:25 pm, when a Chicago Transit Authority
Chicago Transit Authority
Chicago Transit Authority, also known as CTA, is the operator of mass transit within the City of Chicago, Illinois and some of its surrounding suburbs....

 elevated train
Chicago 'L'
The L is the rapid transit system serving the city of Chicago and some of its surrounding suburbs. It is operated by the Chicago Transit Authority...

 rear-ended another on the northeast corner of the Loop at Wabash Avenue and Lake Street during the evening rush hour. The collision forced the first four cars of the rear train off the elevated tracks, killing eleven people and injuring over 180 as the cars fell onto the street below. It remains the single worst accident in the agency's history.

The crash involved a Ravenswood train composed of 6000-series cars (now called the Brown Line
Brown Line (Chicago Transit Authority)
The Brown Line starts out in northwest Chicago, at the Kimball and Lawrence Avenue terminal in Albany Park, where there is a storage yard and servicing shop for the trains to the east of the passenger station...

) and a Lake–Dan Ryan train (composed of two 2000-series and six 2200-series cars.) (a line which followed the route of the present day Green Line
Green Line (Chicago Transit Authority)
The Green Line is part of the CTA rapid transit system known as the Chicago 'L'. It is the only completely elevated route in the 'L' system. It utilizes the system's oldest segments , extending with 29 stops between Forest Park and Oak Park , through Chicago's Loop, to the South Side and Englewood...

 to the west and Red Line
Red Line (Chicago Transit Authority)
The northern terminus of the Red Line is Howard Street in the Rogers Park neighborhood of Chicago , on the City Limits farthest north. The Red Line extends southeasterly on an elevated embankment structure about a half-mile west of the lakefront to Touhy Avenue then turns south along Glenwood...

 to the south). Earlier in the day, switching problems caused a third line, the Evanston Express (now the Purple Line
Purple Line (Chicago Transit Authority)
The Purple Line of the Chicago Transit Authority is a branch line on the northernmost section of the Chicago 'L' rapid transit network. Normally, it extends south from the Wilmette terminal at Linden Avenue, passing through Evanston to Howard Street, on Chicago's northern city limits...

), to run counter-clockwise around the Loop instead of its normal clockwise route. This put it on the tracks normally used by the Ravenswood and westbound Lake–Dan Ryan trains. As a result, the Ravenswood train had to stop short of the platform as it approached the first station past the turn, waiting for the rerouted Evanston Express to clear before proceeding. However, the Lake–Dan Ryan train immediately behind the Ravenswood did not stop, and proceeded against both track
Railway signal
A signal is a mechanical or electrical device erected beside a railway line to pass information relating to the state of the line ahead to train/engine drivers. The driver interprets the signal's indication and acts accordingly...

 and cab signals. The Lake–Dan Ryan struck the back of the Ravenswood at a relatively slow speed, as the motorman, Stephan A. Martin, had just left a station. Passengers on the train reported the initial impact as nothing more than a slight bump.

However, Martin continued to apply traction power to his train after the initial impact. Since the train was composed of multiple unit
Multiple unit
The term multiple unit or MU is used to describe a self-propelled carriages capable of coupling with other units of the same or similar type and still being controlled from one driving cab. The term is commonly used to denote passenger trainsets consisting of more than one carriage...

 cars, this resulted in the rear cars continuing to push against the first four cars, which were on the bend of the track, but blocked by the Ravenswood train. Unable to move forward, the pressure caused the coupling bar
Coupling (railway)
A coupling is a mechanism for connecting rolling stock in a train. The design of the coupler is standard, and is almost as important as the railway gauge, since flexibility and convenience are maximised if all rolling stock can be coupled together.The equipment that connects the couplings to the...

 between the first two Lake–Dan Ryan cars to bend and the ends of those two cars to be pushed in the air. The motor power was still applied, eventually pushing the first three cars upwards enough to the point that they jackknifed
Jackknifing
Jackknifing means the folding of an articulated vehicle such that it resembles the acute angle of a folding pocket knife. If a vehicle towing a trailer skids, the trailer can push it from behind until it spins round and faces backwards. This may be caused by equipment failure, improper braking, or...

 and fell off the tracks. The second and third cars fell all the way to the street below, while the first fell on one of the support structures for the tracks, and the fourth car was pulled off the tracks to dangle precariously between the tracks and street. The last four cars remained on the track, still in the station.

Subsequent investigation revealed that Martin had been smoking marijuana and had four marijuana cigarettes in his shoulder bag. He also had a poor safety record and was responsible for an earlier derailment, and he had a tendency to talk to passengers while driving the train. It is theorized that, having made the normal station stop before the curve, Martin had caused the restrictive cab signal caused by the train ahead to be overridden. Distracted, he then left the station at under 15 miles per hour, which was slow enough to not trigger the automatic control, and then after the initial collision, panic or inertia
Inertia
Inertia is the resistance of any physical object to a change in its state of motion or rest, or the tendency of an object to resist any change in its motion. It is proportional to an object's mass. The principle of inertia is one of the fundamental principles of classical physics which are used to...

 caused him to move the Cineston controller forward resulting in the derailment.

As a result of the accident, the CTA forbade motormen to proceed past a red signal "on sight" without first getting permission from the Control Center.
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