Patent Publication Number: US-2020298896-A1

Title: Method and System of Leveraging Onboard Positive Train Control Equipment

Description:
RELATED U.S. APPLICATION DATA 
     This application claims the benefit of Provisional Patent Application No. 62/646,898, entitled “Method and System of Leveraging Onboard Positive Train Control Equipment” filed Mar. 22, 2018, by the present inventor and which is incorporated herein by reference in its entirety. 
    
    
     BACKGROUND—PRIOR ART 
     Prior Art—Cost Considerations 
     The Rail Safety and Improvement Act of 2008, the Positive Train Control Enforcement and Implementation Act of 2015, and ensuing regulations in 49 CFR 236, Subpart I, mandated most railroads in the U.S. to implement a comprehensive train control system known as Positive Train Control (PTC) and to install onboard PTC equipment upon nearly 20,000 locomotives and unpowered passenger cab cars in their fleets. The 2008 act created an unfunded mandate for railroads to invest as much as $22 billion in a complex, extensive infrastructure that had to be developed from a fragmented collection of relatively primitive train control systems. The mandate has been especially burdensome to cash-strapped commuter railroads and small, short line railroads. The 2008 act established a completion target of Dec. 15, 2015. Funding constraints, issues of technological readiness, radio spectrum constraints, and the sheer volume of work to develop, manufacture, install, and commission the system put the target out of reach. The 2015 act extended the deadline to Dec. 31, 2018, with a further extension to Dec. 31, 2020, to be made on a case-by-case basis, if substantial progress toward implementation had been made. As of Dec. 31, 2018, the Federal Railway Administration (FRA) reported that the railroads had retrofitted onboard PTC equipment onto essentially all their locomotives and cab cars that travel in PTC territories. Nevertheless, the railroads will make further investments in onboard equipment as they place new locomotives and cab cars into service, and as the installed equipment fails or becomes outdated. The high cost of retrofitting PTC onto older locomotives or low-utilization locomotives may not be justified, rendering them as stranded assets, even though they may be otherwise useful as standby or helper locomotives in PTC territories. 
     Prior Art—Failures 
     PTC has been subject to occasional failures on various levels. It is instructive that the word “failure” appears no fewer than 161 times in 49 CFR 236, Subpart I. Section 236.1029 gives detailed procedures in the event of an en-route failure, particularly the failure of onboard equipment. In many cases, the regulations require the train to operate at restricted speed, disrupting its own schedule and the schedules of other rail traffic in the area. It may be possible to rearrange the locomotive consist to move a unit with failed equipment out of the controlling position, but this can also delay the train, and a proximate siding or turnout is required. Section 236.1029(b)(6) states that a train with failed onboard PTC equipment may continue no farther than the next forward designated location for the repair or exchange of the equipment. Not only are on-road failures disruptive and costly, but they compromise the safety of the affected train and potentially of rail work crews and other rail traffic in the vicinity. 
     Prior Art—Interoperability Issues 
     Interoperability is the area where PTC progress is most lagging. FRA reported that, as of Dec. 31, 2018, only 16% of required tenant railroads had achieved interoperability with their host railroads&#39; PTC systems. There are four principal PTC systems in use in the U.S.:
         1. I-ETMS® (Interoperable—Electronic Train Management System) is a product of Wabtec Corporation and is the most widely system in the U.S.   2. ACSES (Advanced Civil Speed Enforcement System) is a product of Alstom and in use by Amtrak and other railroads on the Northeast corridor.   3. ITCS (Incremental Train Control System) is a sole-sourced product of Alstom and is in use in the upper Midwest by Amtrak.   4. E-ATC (Enhanced Automatic Train Control) is a low-cost system based on legacy automatic train control, upgraded to conform to PTC requirements. It is used by smaller commuter railroads and is the only system of the four not to use the 220 MHz PTC radio band.       

     None of the four systems listed above are interoperable fully, if at all. Lack of interoperability may arise from a host of issues, from fundamentally different system architectures to incompatible radio spectra. This can be a constraint upon the common practice of freight railroads leasing locomotives from other railroads. If the lessor and lessee have different PTC systems, the non-interoperable locomotive will be restricted to a trailing position in the consist, or compatible onboard PTC equipment will have to be retrofitted at considerable cost. 
     Prior Art—Push-Pull Passenger Trains 
     Push-pull passenger trains operate in both directions, with a locomotive in the controlling position in pull mode and an unpowered cab car in the controlling position in push mode. The practice to date has been to duplicate a full onboard PTC installation in both the locomotive and the cab car. Equipping only the locomotive would require turning the train at each end of the line, defeating the purpose of a push-pull train: Most push-pull trains are operated by commuter railroads that have very limited capital resources. For example, the Rail Runner Express commuter line in New Mexico, which has nine trains, is facing a cost of $55 to $60 million to implement PTC, more than 25 times its annual fare receipts of $2.15 million. 
     DETAILED DISCUSSION 
     Advantages 
     Under 49 USC 236, Subpart I, a train operating in a Positive Train Control (PTC) territory must be disposed with a full complement of onboard PTC equipment. This led railroads to the practice of fully equipping all their locomotives that operate in PTC territories. The disclosed embodiments have the following advantages:
     1) Cost Savings: A PTC remote locomotive  16 , as disclosed, can operate in the leading position in a PTC territory by leveraging the resources of a PTC host locomotive  18  elsewhere in the consist. The scope and cost of equipping a two-unit locomotive consist or a locomotive-cab car pair with PTC according to the disclosed embodiments is about one-half of equipping both with PTC according to the prior art. Beyond the capital cost savings, the railroad would save one half of the recurring cost of subscriptions for a 220-MHz PTC data radio.   2) Stranded Assets: The cost of retrofitting full PTC onto older and low-utilization locomotives may not be justified, rendering them as stranded assets. In contrast, the low cost of the disclosed embodiments may justify retrofitting these locomotives, extending their economic lives.   3) Operations: The disclosed leveraging principle can provide railroads more flexibility by equipping a helper or standby locomotive as a remote locomotive  16  and coupling it into the leading position of a consist. Rearranging locomotive consists to position a PTC-equipped locomotive in the leading position requires time and effort and suitable track arrangements.   4) PTC Failures: A disclosed embodiment applies the leveraging principle to quickly rescue a leading locomotive which has an on-road failure of onboard PTC, eliminating the disruption of rearranging the locomotive consist, replacing or repairing the failed equipment, or operating under onerous speed restrictions.   5) Interoperability: As noted in the prior art discussion, the several PTC systems in use across the U.S. are generally not interoperable. As shown in  FIG. 9 , Case G, a disclosed embodiment allows a non-interoperable locomotive to operate as a leading locomotive, as long as a locomotive in the consist is interoperable with the local PTC environment. This can broaden the pool of leased locomotives available to a lessor, even though they may not be interoperable with the local PTC environment.   

     THE DRAWINGS 
     In the following discussion, reference numerals less than 20 refer to rail vehicles. Reference numerals 24 and greater, but less than 50, apply to elements within rail vehicles without PTC onboard equipment installed, according to the prior art. Reference numerals 50 and greater, but less than 100, apply to elements that comprise onboard PTC equipment, according to the prior art. Reference numerals 100 and greater apply to elements that comprise PTC onboard equipment, according to the embodiments disclosed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  is a schematic of elements of a locomotive without Positive Train Control (PTC) according to the prior art. 
         FIG. 1B  is a schematic of an automatic brake valve that is cut out according to the prior art. 
         FIG. 2  is a schematic of a locomotive disposed with a full complement of onboard PTC according to the prior art. 
         FIG. 3  is a schematic of a first embodiment of a System of Leveraging Onboard Positive Train Control Equipment. 
         FIG. 4  is a schematic of ant alternative embodiment that employs a Remote Terminal to aggregate signals and data and exchange with the onboard computer by means of a wired or wireless data connection. 
         FIG. 5A  is a flowchart of a PTC penalty brake application according to the prior art. 
         FIG. 5B  is a flowchart of a PTC emergency brake application according to the prior art. 
         FIG. 6  is a flowchart of a PTC penalty brake application by all disclosed embodiments. 
         FIG. 7  is a flowchart of a PTC emergency brake application by all disclosed embodiments. 
         FIG. 8  is a diagram of examples of locomotive consists, including some examples according to the prior art. 
         FIG. 9  is a diagram of further examples of locomotive consists, including one example according to the prior art. 
     
    
    
     DETAILED DISCUSSION—FIG.  1 A AND  1 B 
       FIG. 1A  is a schematic of elements of a locomotive  14  without onboard Positive Train Control (PTC) equipment according to the prior art. The elements shown relate to both the prior art and to the disclosures herein. A train is composed of one or a plurality of locomotives that provide motive power to the train, and one or a plurality of unpowered railcars. To provide the motive power required by a typical train, a railroad will often assemble a locomotive consist of two or more coupled locomotives. Front coupler  36  and rear coupler  38  couple locomotive  14  to other locomotives or to railcars. The leading locomotive of a consist is also the controlling locomotive, which has operative control of the train. The one or more locomotives behind it are referred to as trailing locomotives. A pneumatic brake pipe  28  runs through the length of a train and has two functions: to distribute compressed air for braking to each railcar in the train, and to signal each railcar to apply or release its brakes by means of pressure changes in the brake pipe  28 . 
     Each locomotive  14  in the train has an automatic brake valve (ABV)  26  with a connection to the brake pipe  28 . When running, the ABV  26  in the controlling locomotive regulates the pressure in the brake pipe  28  at nominal values, typically 90 pounds per square inch (PSI) for freight trains and 110 PSI for passenger trains. Reducing the pressure in the brake pipe  28  results in a coordinated application of the brakes throughout the train. To make a service brake application, the ABV  26  in the controlling locomotive reduces the pressure in the brake pipe  28  at a measured, service rate. The braking effort is roughly proportional to the pressure reduction, up to a limit known as full-service braking which corresponds to a reduction of about 20 PSI. A further reduction produces no further braking effort, provided it occurs at the service rate. Braking effort in excess of full-service may be obtained by making an emergency brake application which vents the brake pipe  28  rapidly and completely. Only the ABV  26  in the controlling locomotive may connected to the brake pipe  28 . Every other ABV  26  must be isolated, or it will charge the brake pipe  28  when a service reduction is attempted in the controlling locomotive, thereby counteracting the reduction and rendering the air brakes inoperable. Setting the MU valve  24  to the “lead” or “cut-in” position as shown schematically in  FIG. 1A  will connect ABV  26  to the brake pipe  28 . In every trailing locomotive in the consist, the MU valve  24  must be set to the “trail” or “cut-out” position, as shown schematically in  FIG. 1B , thereby isolating the ABV  26  from the brake pipe  28 . 
     A Multiple Unit, or MU, trainline  34  runs the length of the consist and operatively connects all locomotives in the consist. Operating controls  32  in the controlling locomotive impose electrical control signals on specific wires in the trainline  34 , coordinating the application of power, the application of dynamic braking, and the direction of movement. 
     A pressure switch, known synonymously as a Power Cut-out Switch, a Pneumatic Control Switch, or PCS  30 , and operating controls  32  are features of every locomotive and are related to PTC functionality. 
     DETAILED DISCUSSION—FIG.  2   
       FIG. 2  is a schematic of a locomotive  14  disposed with a full complement of onboard PTC equipment according to the prior art. PTC consists of three major segments, operatively and continuously connected by wired or wireless communications: an office segment comprising principally a remote server and central database; a wayside segment comprising principally track signaling systems, track monitoring systems and track sensors; and, an onboard segment. The onboard segment comprises PTC equipment installed within a locomotive or cab car. The heart of the onboard segment is an onboard computer  50  that collects data through a plurality of signal and data input and output (I/O) ports, including:
         a) Geo-location data from a GPS receiver  66  equipped with a GPS antenna  68     b) Data from two-way radios  70 , which operate in 220-MHz PTC band, the cellular band, the IEEE 802.11 Wi-Fi band, and possibly other bands, each receiving and transmitting through antennas depicted collectively as two-way radio antenna  72 .   c) Signals from the operating controls  32     d) Signals from the MU trainline  34     e) Signals representing the pressure in the brake pipe  28     f) Signals from a speed sensor  78  which receives and interprets pulse signals from an axle speed generator  76     g) A signal indicating whether the PCS  30  is opened or closed, the signal being sent through a PCS connection  74     h) A signal from a pressure switch  82  indicating whether the ABV  26  is cut in or isolated, the signal being sent through pressure switch connection  84 .       

     The onboard computer  50  writes operational data to a PTC event recorder  80 , which records the data for logging and for forensic purposes. In addition, the onboard computer  50  transmits video signals though connection  62  to a cab display  60  that presents train status, including warnings of train control actions, to the engineer. Optionally, an audible alert  64  will sound with a visual warning. During a warning period, the engineer may take preemptive action to slow or stop the train by applying braking, removing traction power, or both, thereby avoiding a PTC enforcement. In the event the PTC system determines that a hazard on the track ahead requires immediate enforcement action, it will make the appropriate brake application without a warning. 
     PTC employs a braking algorithm to predict when a brake application must be initiated to stop the train short of a hazard identified on the tracks ahead. To precisely determine the position of the train, the onboard computer is configured with the offset distance, DIM. “G”, from the GPS antenna to the front coupler  36 . The position of the rear coupler  38  is similarly relevant when the locomotive is operating in reverse. Dim “K” is the distance between the front coupler  36  and rear coupler  38 . 
     PTC enforcement defaults to a penalty brake application which has the following characteristics: the pressure reduction is made at the service rate; the reduction is large enough to make a full-service brake application; the reduction retains enough pressure in the brake pipe  28  to make a subsequent emergency brake application; and, the application cannot be cancelled by the engineer. The onboard computer  50  initiates a penalty application by opening penalty solenoid valve  52  through penalty solenoid valve connection  54 . 
     During braking, PTC will constantly and precisely monitor the position and speed of the train. If the PTC algorithm determines that the penalty application is insufficient to stop the train short of the hazard, then the onboard computer  50  will initiate an emergency brake application by energizing through connection  58  a large-capacity, emergency solenoid valve  56  that is directly connected to the brake pipe  28 , venting the pressure contained therein quickly and completely. 
     The PCS  30  opens whenever PTC initiates a brake application. The opening of the PCS  30  unlatches a relay in the operating controls  32  that de-energize the throttle and generator field control wires in the MU trainline  34 . This causes the engine in every locomotive in the consist to drop to idle speed and removes all traction power. PTC-initiated penalty and emergency brake applications differ in the following salient ways:
         a) A PTC-initiated penalty application must be made through the penalty solenoid valve  52  that acts upon the ABV  26  that is cut in.   b) A PTC-initiated penalty application will open only the PCS  30  associated with that ABV  26 , in the controlling locomotive, thereby removing traction power through the MU trainline  34 , as described.   c) A PTC-initiated emergency application may be initiated by an emergency solenoid valve  56  located in any locomotive or cab car along the brake pipe  28 .   d) A PTC-initiated emergency application will open the PCS  30  in every locomotive in the consist.       

     DETAILED DISCUSSION—FIG.  3 —A FIRST EMBODIMENT 
       FIG. 3  shows a First Embodiment of a System of Leveraging Onboard Positive Train Control Equipment according to claim  1 . It is useful at this point to define the terms “remote locomotive”  16  and “host locomotive”  18  as they relate to the disclosed embodiments. A host locomotive  18 , shown in partial view, hosts a full complement of onboard PTC equipment as shown schematically in  FIG. 2 . A remote locomotive  16  is equipped with a minimum complement of PTC equipment such that it can operate in the leading position in a PTC territory by leveraging the resources of the host locomotive  18  operating in a trailing position in the consist. 
     Regulations in 49 CFR 236.1006 state that “onboard PTC apparatus may be distributed among multiple locomotives . . . ”, and further state that “The controlling locomotive shall be equipped with a fully operative interface . . . ”. This requirement may be satisfied by installing a remote cab display  100  in the remote locomotive and a cab display data link  104  to the onboard computer  50 . As described in the foregoing discussion, the ABV  26  in the host locomotive  18 , in the trailing position must be cut out. This disables the penalty application function there, requiring the installation of a remote penalty solenoid valve  106  in the remote locomotive  16 . A penalty signal link  108  operatively connects remote penalty solenoid valve  106  to the onboard computer  50 . 
     In many PTC systems, the onboard computer  50  monitors the status of the operative PCS  30  and ABV  26 , both of which are now located in the remote locomotive  16 . A first auxiliary signal link  114  operatively connects the PCS  30  in the remote locomotive to the onboard computer  50 . A remote pressure switch  110  is installed to monitor the status of ABV  26  in the remote locomotive  16 . A second auxiliary signal link  112  operatively connects the remote pressure switch  110  in the remote locomotive to the onboard computer  50 : Claims  2  and  3  pertain to the features in this paragraph. 
     When the remote locomotive  16  is coupled to the front of the train, distance DIM. “G” from the GPS antenna  68  in the host locomotive  18  to the front coupler of the remote locomotive  16  will increase by the length over its couplers DIM “K”. The onboard computer  50  will be configured with the total of DIM “G” and DIM “K” which is DIM “T”. 
     Comparing the full complement of onboard PTC equipment shown in  FIG. 2 , the savings in the cost and scope of equipment associated with the first embodiment in  FIG. 3  are apparent. CL DETAILED DISCUSSION— FIG. 4 —AN ALTERNATIVE EMBODIMENT 
       FIG. 4  is a schematic diagram of an alternative embodiment according to claim  4 . It differs from  FIG. 3  in the manner in which the remote locomotive  16  and host locomotive  18  are operatively connected. In  FIG. 4  introduces a remote terminal  116  with a plurality of input-output (I/O) and data ports  118  and an aggregated data link  120  to onboard computer  50 . The aggregated data link may be wired or wireless. 
     The remote cab display  100  connects to the I/O and data ports  118  through cab display data link  104 . The remote penalty magnet valve  106  connects to the I/O and data ports  118  through a penalty signal link  108 . The PCS  30  connects to the I/O and data ports  118  through a first auxiliary signal link  114 . The remote pressure switch  110  connects to the I/O and data ports through a second auxiliary signal link  112 . The remote terminal encodes and decodes data and signals and manages communications with the onboard computer through the aggregated data link  120 . 
     The configurations of the remote locomotive  16  in  FIGS. 3 and 4  can also apply to a cab car in a push-pull passenger train as described in claim  5 . 
     DETAILED DISCUSSION—FIG.  5 A—FLOWCHART OF PTC PENALTY BRAKE APPLICATION ACCORDING TO THE PRIOR ART 
       FIG. 5A  is a flowchart showing the steps by which PTC carries out a penalty brake application according to the prior art. PTC initiates each process by identifying a hazard on the tracks ahead that requires enforcement. The process occurs entirely with the controlling locomotive, except: (1) the penalty application of brakes is propagated throughout the train by the brake pipe  28 , and (2) the removal of the traction power is coordinated through the locomotive consist by the MU trainline  34 . 
     DETAILED DISCUSSION—FIG.  5 B—FLOWCHART OF PTC EMERGENCY BRAKE APPLICATION ACCORDING TO THE PRIOR ART 
       FIG. 5B  is a flowchart showing the steps by which PTC carries out an emergency brake application according to the prior art. PTC initiates each process by identifying a hazard on the tracks ahead that requires enforcement. The processes in  FIGS. 5A and 5B  differ in how the pressure reduction in the brake pipe is made, and the amount of the reduction. Note that the penalty application in  FIG. 5A  only opens the PCS  30  in the controlling locomotive, whereas the emergency application in  FIG. 5B  opens the PCS  30  in all the locomotives. 
     DETAILED DISCUSSION—FIG.  6 —FLOWCHART OF PTC PENALTY BRAKE APPLICATION ACCORDING TO THE DISCLOSED EMBODIMENTS 
     The flowchart in  FIG. 6  is a flowchart showing the process steps whereby the onboard computer  50  in the host locomotive  18  initiates a penalty brake application in the remote locomotive  16 . Comparing  FIGS. 5A and 6  shows how the enforcement functions of braking and power removal are moved to the remote locomotive  16 . 
     DETAILED DISCUSSION—FIG.  7 —FLOWCHART OF PTC EMERGENCY BRAKE APPLICATION ACCORDING TO THE DISCLOSED EMBODIMENTS 
     The flowchart in  FIG. 7  differs from that in  FIG. 6  in that the braking enforcement function, an emergency braking application, remains in the host locomotive  18 . As noted, an emergency braking application causes every PCS  30  in the locomotive consist to open, including the PCS  30  in the remote locomotive  16 . It is this PCS  30  opening that causes power to be removed through the MU trainline  34 . 
     DETAILED DISCUSSION—FIGS.  8  AND  9   
       FIG. 8 —Examples of Locomotive Consists (Including Prior Art)— 
       FIG. 8  is a diagram showing various locomotive consists, both according to the prior art, and incorporating the embodiments disclosed in ways that reduce the scope of PTC equipment required for legal operation in a PTC territory. Comparing Cases A, B, and C, it is evident that the embodiment in Case C provides the operational flexibility of Case B, allowing movement of the consist in both directions without having to turn the consist. It is possible that the distance from the front coupler of a train to the GPS antenna  68  in the host locomotive  18  exceeds the configuration limit of a particular PTC system. This is especially true for push-pull passenger trains that may be several hundred feet long. Case D shows a solution that places a remote GPS receiver proximate to the front coupler of the remote locomotive or the cab car. 
       FIG. 9 —Further Examples of Consists (Including Prior Art) 
       FIG. 9  shows various locomotive consists that include a locomotive equipped with PTC that is non-interoperable in the territory being travelled, and also a locomotive with failed onboard PTC. Case F depicts an embodiment that pertains to a locomotive that is non-interoperable with the local PTC environment. Case G depicts the embodiment that pertains to rescuing a locomotive with failed PTC onboard equipment. 
     SUMMARY 
     The disclosed embodiments relate to train control, specifically onboard Positive Train Control (PTC) equipment. Onboard PTC equipment is expensive and complex. The onboard segment of most widely used PTC system, Wabtec Corporation&#39;s I-ETMS® comprises: an onboard computer with a plurality of analog and digital inputs; an array of sensors throughout the locomotive measuring pressures, voltage, current, and track speed; eight radio receivers or transceivers in the GPS, Wi-Fi, cellular, and 220-MHz PTC data radio bands; an event recorder; a cab display; a penalty solenoid valve; an emergency solenoid valve; and power supplies. Practice among railroads has been to so equip every locomotive that operates as a controlling locomotive in a PTC territory. Locomotives often travel in coupled consists of two or more units, with a controlling locomotive in the leading position and one or more trailing units. Disclosed are embodiments of a system whereby a controlling (remote) locomotive, with a reduced complement of onboard PTC equipment, leverages the equipment in a fully disposed (host) trailing locomotive in a PTC territory. The reduced complement in the remote locomotive comprises principally a cab display and a penalty solenoid valve, both operatively connected to the onboard computer in the host locomotive. The many input signals required by PTC are available to the computer in the host, in valid form; they do not have to be duplicated in the remote locomotive. In the first embodiment, the operative connections between the remote and the host locomotives are direct-wired signal and data links. In another embodiment, the signals and data in the remote locomotive are aggregated into a remote terminal and communicated to the onboard computer through an aggregated link. Another embodiment pertains to push-pull passenger trains where an unpowered cab car is disposed in the same manner as a remote locomotive. Disclosed are variations of the basic principle where a locomotives with failed or non-interoperable PTC equipment can be adapted to operate as controlling locomotives in a PTC territory. All embodiments of the system retain the essential enforcement functions of PTC: when a hazard is detected on the track ahead, the system initiates a penalty or emergency application of the train brakes and removes all traction power.