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About 2:49 a.m. on March 24, 2014, Chicago Transit Authority train No. 141 collided with the bumping post near the end of the center pocket track at O’Hare Station. The lead car rode over the bumping post and went up an escalator at the end of the track. The escalator provided public access to enter O’Hare International Airport from the platform in the station, but no one was using it at the time of the accident. About 50 people were on the train at the time of the accident. Thirty-three injured passengers and the injured train operator were taken to the hospital. The estimated damage was $11,196,796. The accident occurred in an underground station that was not impacted by weather conditions. The National Transportation Safety Board determines that the probable cause of the accident was the failure of the train operator to stop the train at the appropriate signal due to falling asleep as a result of fatigue, which was the result of the challenges of working shiftwork, circadian factors, and acute sleep loss resulting from her ineffective off-duty time management. In addition, Chicago Transit Authority failed to effectively manage the operator’s work schedule to mitigate the risk of fatigue. Contributing to the severity of the accident was Chicago Transit Authority’s failure to identify the insufficient stopping distance and inadequate speed restriction at the center pocket track at O’Hare Station.
TO THE CHICAGO TRANSIT AUTHORITY: Install a transmission-based train control system on all passenger train routes.
Original recommendation transmittal letter:
Open - Acceptable Response
Chicago, IL, United States
Preliminary Report Railroad DCA14FR007
Chicago Transit Authority Train Collides with Bumping Post and Escalator at O’Hare Station
Addressee(s) and Addressee Status:
Chicago Transit Authority (Open - Acceptable Response)
Safety Recommendation History
Chicago Transit Authority
We understand that you have assessed the cost of fully implementing a transmission based train control system and have found that implementation poses significant financial and time challenges for you. The NTSB has repeatedly concluded that technological solutions have great potential to reduce the number of serious train accidents by providing redundant safety systems—which use multiple methods for stopping a train—to protect against human performance failures. We note that you plan to immediately add provisions to your current fleet and infrastructure replacement programs to support migration to a transmission-based train control system. Accordingly, Safety Recommendation R-15-024 is classified OPEN—ACCEPTABLE RESPONSE.
Chicago Transit Authority
-From Reginald A. Mason, Chief Safety and Risk Management Officer, Chicago Transit Authority: Thank you for the December 1, 2015, letter to Mr. Dorval Carter, President of the Chicago Transit Authority (CTA) regarding our response to Recommendation R-15-024. Although the CTA continues to assert that its existing train control system provides a highly reliable, efficient and safe operating environment for our passengers, the Authority acknowledges the National Transportation Safety Board's (NTSB) recommendation to implement a more advanced "Transmission-Based" train control system. A system that is consistent with your recommendations will require significant and costly upgrades to CTA's existing wayside and carborne train control systems. On a mature and geographically dispersed transit system like the CTA, where rail car fleets are frequently moved across the many rail lines, full implementation of such an upgrade must be done simultaneously across the rail car fleet, and on all rail lines. Recognizing the cost and time requirements to prepare for a full and simultaneous implementation of this technology, the CTA will immediately take steps to include provisions in its current fleet and infrastructure replacement programs to accommodate a future migration to a "Transmission-Based" train control system. These provisions will include spare equipment rack space, spare cabling and surplus power. In closing, the CTA will continue to make every effort to improve the performance of its existing train control system, and we are confident that immediate implementation of the provisions outlined above will eventually allow the CTA to migrate towards the more advanced train control system as recommended by the NTSB.
Chicago Transit Authority
As a result of the investigation, we determined that the CTA signal and train control system provided for enforcement of stop signals, but enforcement occurred only if a train operator had failed to comply with a signal that was displaying a restrictive aspect. As illustrated in this accident investigation, the reactive enforcement of the trip mechanism did not provide sufficient braking capability for trains traveling above certain speeds approaching terminal locations at which a safe braking distance was not provided. Upon review, we recognized that CTA’s system was not designed to provide the intended safety functionality that a transmission based train control system would provide. We appreciate the steps you have taken toward assessing the design errors for the speed control circuit of the middle track at the O’Hare terminal, the maximum speed for safe operation of trains entering the terminal, and the inadequacy of the placement and impact-dissipation qualities of the bumping post associated with the accident. We also appreciate your post accident review and subsequent actions to minimize and prevent future safety incidents, such as making the allowable cab signal speed for trains entering the terminal decrease to zero (so that all trains must come to a full stop before reaching the bumping post) and relocating the fixed trip away from the bumping post on all three terminal tracks. The CTA’s design improvements may prevent the exact scenario as the O’Hare Station accident from recurring. However, the CTA signal and train control system is not a transmission based train control system, nor will these modifications be an alternative to a transmission-based train control system. The current or modified system does not proactively monitor train operations in a manner that would intervene by taking some control of the train away from the train operator and stopping the train before a signal violation can occur. We encourage you to reconsider the installation of a transmission-based train control system. Because your train control system is not such a system, Safety Recommendation R-15-24 is classified OPEN—UNACCEPTABLE RESPONSE.
Chicago Transit Authority
-From David Kowalski, Senior Advisor, President’s Office: In response to the NTSB's recommendation dated May 13, 2015, the CTA would like to begin by acknowledging our full support of the NTSB's conclusion that a "transmission-based train control system" is an essential feature in maintaining safe operations on modern, heavy-rail transit systems. Furthermore, the CTA respectfully affirms that a "Transmission-Based Train Control System" has been in operation on all CTA revenue tracks for many years leading up to the incident. The CTA's train control system is designed to maintain continuous speed control to ensure safe train separation, and to ensure safe speeds in approach to (and through) civil speed constraints. The system utilizes wayside track circuits to continuously detect train occupancy, and sophisticated wayside-based logic that calculates and "transmits" the maximum allowable speed to the train via a high frequency code injected into the running rail system. The system is designed to alert the train operator when a speed reduction is required, and it will automatically force the train to brake to zero speed if the train operator fails to begin braking the train in response to the alert. The train control system manages train speeds in increments of 0, 15, 25, 35, 55 and 70 mph. The train control system also utilizes a wayside trip system at strategic locations - these trips (either fixed or moveable) will trigger an aggressive braking profile on a train if the train passes the trip in the tripping position. The severity of the March 24, 2014 incident at O'Hare Airport Terminal Station was exacerbated in part due to errors in the design of, and limitation to, the CT A's Transmission Based Train Control System installed at the time of the incident. These errors and limitations included: 1. The original design of the signal system (circa 1979) included an error in the design of the speed control circuit that controls maximum train speed entering the middle track at the terminal. This error allowed for a maximum train speed of 25 mph in approach to the fixed trip and bumping post. CTA's design criteria for approaching a terminal requires a maximum speed of 15 mph. 2. The original design of the signal system included an error in the location of the fixed trip in advance of the bumping post - the fixed trip was too close to the bumping post by as much as 60 feet for a 15 mph maximum approach speed (i.e. even if the approach speed had been properly limited to a maximum speed of 15 mph, the fixed trip would have been too close to the bumping post). 3. The bumping post installed at the time of the incident was not designed to accommodate a 15 mph maximum speed (let alone the maximum 25 mph speed that was allowed by the design error described in item #1 above). The bumping post would have failed to perform properly, even at a speed much lower than 15 mph. 4. The CTA transmission-based train control system is limited to enforcing train speeds in increments, the lowest (besides zero speed) being 15 mph. This limitation is sometimes supplemented with a timed signal system that enforces maximum speeds less than 15 mph using a moveable trip that clears after a timer has run that is consistent with the desired lower speed. The O'Hare Terminal middle track did not include such a timed signal at the time of the incident. In response to the incident, the CTA immediately implemented a number of changes to the signal system at O'Hare Terminal, including 1. The allowable cab signal speed for trains entering the terminal was dialed down to zero speed. This forced all trains entering the terminal to come to a full stop well before reaching the bumping post (and well before the normal berthing position). The trains were then allowed to proceed under a rule R6.4 which is essentially line-of-site operation at a controlled speed not to exceed 15 mph. 2. The fixed trip was relocated further away from the bumping post on all three terminal tracks- the new trip location was consistent with bringing a train to a complete stop before impacting the bumping post. The CTA also re-evaluated all of its other terminals for similar errors in the signal system design and/or fixed trip locations. The CTA determined that similar concerns existed at 3 other terminals, including Cottage Grove (Green Line), Linden (Purple Line), Midway (Orange Line). Similar short-term changes to those described above were implemented at these three terminals. Within a few months of the incident, the CTA re-designed the train control system on all three O'Hare Terminal tracks to bring trains to their normal berthing location at a speed lower than 15 mph using a timed signal system with moveable trips. Similar improvements have since been completed at Cottage Grove Terminal and Linden Terminal. Permanent improvements will be completed at Midway Terminal by the end of 2015. Longer term, the CTA is in the process of implementing additional improvements to its train control system, and to associated infrastructure. These improvements include: 1. A 6 mph maximum speed is being added to the incremental speed options associated with the existing train control system. The 6 mph maximum speed will allow the CTA to better manage train speeds when entering a terminal station. This change must be introduced on all rail cars in the fleet so it will take a few years to fully implement. 2. A new bumping post is being installed in the middle track at O'Hare Terminal. This bumping post is designed to absorb significantly higher energy than the bumping post that was installed at the time of the incident and will be able to sustain an impact of a train travelling up to 11 mph without damage to the bumping post. This new bumping post should be installed by the end of 2015. In closing, the CTA is confident that the above explanation reinforces CTA's affirmation that, in accordance with NTSB's recommendation, a "transmission-based" train control system has been installed for many years leading up to the incident, and that improvements/corrections to this system subsequent to the March 24, 2014 incident will significantly improve the ability to effectively control safe train speeds at CTA's various terminals and other locations."
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