C B T MCommunications Based Train Management

June 14, 2004

207

CSX

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RSAC PTC Working Group

• Established Safety Objectives for Positive Train Control (PTC) systems:– Prevent Train-to-Train Collisions– Enforce Speed Restrictions– Provide Protection for Roadway Workers

• Does not imply vitality or moving block

CBTM meets these objectives

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C B T M• CBTM is an overlay, safety

enhancement system currently deployed in non-signaled territory

• Existing method of operation remains in place

• Crew maintains primary responsibility– CBTM does not display

authorities or messages unless train is enforced

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CBTM Is Not Vital• CBTM is an overlay to the existing method of

operation– There is no need to fallback to another method if CBTM fails

• CBTM is considered to be a safety-critical system– It must perform correctly to provide protection for equipment and

personnel

• CBTM performs no vital functions– Vital functions are required to be implemented in a fail safe manner, i.e.

a failure will not result in the system entering or maintaining an unsafe state or it will assume a known safe state

– A failure of CBTM has the effect of suspending the safety benefits associated with its use

CBTM provides a safety net

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CBTM SYSTEM ARCHITECTUREComputer

AidedDispatch

Oracle Database

Train(UHF)

MonitoredSwitch (VHF)

Train(UHF)

CBTMOffice ServerCOS

Zone LogicController

ZLC50

Zone LogicController

ZLC51

FEP/CC

CNS10 CNS11

BaseStation *

BaseStation *

BaseStation *

BaseStation *

* - dual mode

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Dispatcher contacts Crew

Crew acknowledges

Dispatcher“completes”

CADS

CBTM On-boardComponent

TargetInformation

DTC

CBTM OfficeComponents

Example of how a target is generated

CSX

207

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WORKZONE 25 MPH

LAURENS IRBY

IRBY SIDING

MADDENS WATERLOO

WATERLOO SIDING

GENERATION OF TARGETS

Engine CSXT 207 has an absolute south, in the Laurens and Irby blocks

207

Zero speed target at the end of the Irby block

CBTM is continuously monitoring train speed relative to the maximum permissible speed, for reactive enforcement purposes

CSX

207

Enforcement of the switch position at N. Irby

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CBTM Status• Pilot program began in 1998• Placed in revenue service in July 2000 after the

completion of both lab and field qualification testing

• Migrated on-board hardware and software to a “production ready” platform in 2002– Pilot territory is between Spartanburg (AK 590.4)

and Laurens (AK 555.2)– Program began with six locomotives

• All GE AC 4400s (CSXT 207-212)

• Began equipping more in 2003– When complete there will be a total of 63 equipped (CSXT 201-263)

• Currently data gathering to evaluate system performance

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2002 CBTM Enhancements

• Locally Controlled Power Switches are operated by the crew from the cab of a locomotive– Design has utilized alternative methods to satisfy the

requirements for signals, which are typically associated with power switch installations

– Installed at both ends of Kilgore siding

• Benefits:– Eliminates the need for crews to physically throw the

switch reducing the risk of injury– Reduces the time required during meets thereby

decreasing the average train delay

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2002 CBTM CommunicationsEnhancement

• Installation of 50 miles of UHF ATCS Spec 200 coverage is complete– Pilot territory shortened to 35 miles between

Spartanburg (AK 590.4) and Laurens (AK 555.2)– Allowed the new CBTM on-board platform to be

designed, developed and tested using the ATCS Spec 200 protocol• CBTM can now leverage the infrastructure already installed

for radio code lines

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2003 CBTM Enhancements

• TCS Development – Adapt CBTM’s enforcement capabilities to

signal territory on the Blue Ridge subdivision (138.6 miles)• Request to extend current pilot territory published

in the Federal Register• CBTM will not replace the signal system

– It will be implemented as an overlay

• Development includes non-vital rear end protection

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2004 CBTM Enhancements

• Develop a Product Safety Plan (PSP) and Risk Assessment to submit to the FRA for approval to install CBTM system-wide

• Enhance CBTM to automatically initiate the horn sequence at grade crossings if the locomotive engineer fails to do so

• Develop the functional specification for CBTM in Track Warrant Control (TWC) territory

• Install six ATCS Base Stations on the Blue Ridge subdivision to improve CBTM locomotive coverage– May use Communications Management Unit (CMU) instead

• Convert five monitored manual switches on the Spartanburg subdivision from VHF to UHF communications for use by CBTM

13CBTM On-board Display

Left hand IFD replaced with CBTM display

14CBTM On-board Equipment Enclosure

Located in the short hood

15ATCS Base Station

ATCS network specifically installed for CBTM between Spartanburg and Irby

16CBTM Wayside Monitor

U5 Controller added for CBTM

Antenna & Pole installed for CBTM

CBTM Equipment Enclosure

17NE Kilgore

All equipment installed to perform the CBTM Locally Controlled Power Switch function

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Braking Algorithm• Causing train handling issues• Trains are being enforced when under control

– E.g. trains operating southbound at 2 to 3 MPH approaching the south end of the Roebuck block on 1.5 percent descending grade using dynamic brake are being enforced

• Change to low speed operation magnified the issue– Previously, trains could received a warning, drop below 8 MPH and

creep up to the end of their authority• FRA requested a positive stop

– Forces the train to stop and then proceed• To recover the air sometimes the crew must apply hand brakes

– CSX investigating a return to original implementation

• Does not accommodate articulated cars– Looks at tons per operative brake, which is based on the number of

axles based on the number of cars• Looking for additional input into the braking algorithm that can mitigate

this issue, such as “number of axles”

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Braking Algorithm Cont’d• Operative brake

– Original pilot assume worse case, 85%– Changed in production platform to 95%

• Offset (fudge factor) is a distance added to the calculated braking distance to ensure the train never stops past its intended target– Varies by speed– Changed from original implementation, however at 30 mph, CBTM still adds

approximately 633 feet to the predicted braking distance– Will be changed again with TCS release

• Should be about half the current implementation

• Wabtec has been asked to investigate the impact to the overall risk assessment for CBTM if both these parameters were removed

• The Power Brake Regulations prevent the use of dynamic brake by the engineer from being used in CBTM's braking distance calculations– Will be changed again in TCS release to incorporate a predictor

• Predicts train location in 75 seconds (CBTM’s minimum warning distance) and then calculates braking distance from there

• Does take dynamic brake into account

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Next Steps

• Continue to gather data, identify issues, and implement fixes

• Field testing for TCS build on the Blue Ridge subdivision and Automatic Horn Sequence scheduled for later this year

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Special Thanks to:

BLE Division 598

Steve Wingo

Bill Lee

Roger Peace

DD Martin

Mike Thomas