C B T M Communications Based Train Management

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C B T MCommunications Based Train Management

• June 14, 2004

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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 ARCHITECTURE
- dual mode
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Example of how a target is generated
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GENERATION OF TARGETS
CSX
207
LAURENS
IRBY
MADDENS
WATERLOO
IRBY SIDING
WORK ZONE
25 MPH
WATERLOO SIDING
CBTM is continuously monitoring train speed
relative to the maximum permissible speed, for
reactive enforcement purposes
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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 CBTMs 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

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Left hand IFD replaced with CBTM display
CBTM On-board Display
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Located in the short hood
CBTM On-board Equipment Enclosure
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ATCS network specifically installed for CBTM
between Spartanburg and Irby
ATCS Base Station
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Antenna Pole installed for CBTM
CBTM Equipment Enclosure
U5 Controller added for CBTM
CBTM Wayside Monitor
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All equipment installed to perform the CBTM
Locally Controlled Power Switch function
NE Kilgore
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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 Contd

• 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 (CBTMs
  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