1. C B T M Communications Based Train Management
207
CSX
C B T M Communications Based Train Management
June 14, 2004

2. 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

3. 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

4. CBTM Is Not Vital CBTM provides a safety net
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

5. CBTM SYSTEM ARCHITECTURE
Computer
Aided
Dispatch
Oracle Database
CBTM
Office Server
COS
Zone Logic
Controller
ZLC50
ZLC51
FEP/CC
CNS10
CNS11
Base
Station *
Let’s look at CBTM’s architecture.
It all starts with the Computer Aided Dispatching System or CADS, where the dispatcher enters a trains authority or issues messages such as speed restrictions or work zones. Included in CADS is the DTC logic which performs conflict checking to compliment the dispatcher’s operating rule knowledge.
Once the information is entered, it is passed electronically to the CBTM Office Server, which distributes the information to the appropriate Zone Logic Controller or ZLC. The dispatcher doesn’t have to do anything additional. The ZLC is where the track database resides. This is another departure from other PTC systems, that allows for the centralized management of the data.
There are two ZLC’s, one for each CBTM subdivision. The ZLC’s could be located in the field but were placed in Jacksonville for ease of support.
One ZLC could handle all of the current CBTM territory, however part of the pilot was to demonstrate the hand off between ZLC’s
The information is then forwarded to the field by the Front End Processor/Cluster Controller.
There are 7 base stations and we are working on an eighth linked to Jacksonville by two multi drop lease circuits.
These base stations are responsible for communicating with the trains and MMS sites.
Train
(UHF)
Monitored
Switch (VHF)
* - dual mode

6. CADS DTC Example of how a target is generated Dispatcher contacts Crew
CSX
207
Crew acknowledges
Dispatcher
“completes”
CADS
CBTM On-board
Component
Target
Information
DTC
CBTM Office
Components
Let’s step through how a target for enforcement gets generated.
The dispatcher contacts the crew and issues them their authority.
The crew acknowledges the authority by repeating back to the dispatcher.
At the same time, the dispatcher has completed the information in CADS.
The information is forwarded electronically to the CBTM Office Components.
The target information, including the track database segments, are sent to the CBTM On-board component where the targets for enforcement are created.

7. GENERATION OF TARGETS
CSX
207
LAURENS
IRBY
MADDENS
WATERLOO
Enforcement of the switch position at N. Irby
IRBY SIDING
WORK
ZONE
Engine CSXT 207 has an absolute south, in the Laurens and Irby blocks
207
25 MPH
Zero speed target at the end of the Irby block
WATERLOO SIDING
Lets’ see how CBTM generates targets when it receives information from CADS.
The dispatcher issues CSXT 207 an absolute block, south, in the Laurens and Irby blocks.
The first target for enforcement is the position of the switch at N. Irby.
CBTM will warn and enforce the train if this switch is in the reverse position, since the train has authority for a main line move only.
The next target, of course, is the trains end of authority at the south end of the Irby block.
In addition, CBTM is continuously monitoring the train’s speed relative to the maximum permissible speed, for reactive enforcement purposes
CBTM is continuously monitoring train speed relative to the maximum permissible speed, for reactive enforcement purposes

8. 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 )
Began equipping more in 2003
When complete there will be a total of 63 equipped (CSXT )
Currently data gathering to evaluate system performance

9. 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

10. 2002 CBTM Communications Enhancement
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

11. 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

12. 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

13. Left hand IFD replaced with CBTM display
CBTM On-board Display

14. Located in the short hood
CBTM On-board Equipment Enclosure

15. ATCS network specifically installed for CBTM between Spartanburg and Irby
ATCS Base Station

16. Antenna & Pole installed for CBTM
CBTM Equipment Enclosure
U5 Controller added for CBTM
CBTM Wayside Monitor

17. All equipment installed to perform the CBTM Locally Controlled Power Switch function
NE Kilgore

18. 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”

19. 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

20. 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

21. Special Thanks to:
BLE Division 598
Steve Wingo
Bill Lee
Roger Peace
DD Martin
Mike Thomas