Control system for operating long vehicles

Abstract

A method for operating a train comprising two or more locomotives, the method comprising the steps of: a) Setting one or more locomotive control levels and choosing a selected route of travel; b) Calculating a target train speed profile and a target in-train force profile over at least a portion of the selected route; c) Measuring one or more operating parameters related to the operation of the train; d) Calculating a future train speed profile and a future in-train force profile for a future period based on at least one of the one or more operating parameters, at least one of the one or more locomotive control levels and one or more pieces of information relating to the selected route; e) Calculating adjusted locomotive speed control levels relating to the one or more operating parameters based on a difference between the target train speed profile and the future train speed profile, the adjusted locomotive control levels being adapted to maintain the target train speed profile over the future period; f) Calculating adjusted in-train force control levels relating to the one or more operating parameters based on a difference between the target in-train force profile and the future in-train force profile, the adjusted in-train force control levels being adapted to maintain the target in-train force profile below a target level over the future period; g) Dividing the adjusted locomotive control levels and the adjusted in-train force control levels between the two or more locomotives to form locomotive-specific locomotive control levels for each of the two or more locomotives, the locomotive-specific locomotive control levels being at least partially adapted to control and/or balance in-train force levels below the target level h) Provide locomotive-specific locomotive control levels for communication to each of the two or more locomotives; and i) Operating each of the two or more locomotives according to the locomotive-specific locomotive control levels.

Claims

1. A method for operating a train comprising two or more locomotives, the method comprising the steps of: setting one or more locomotive control levels and choosing a selected route of travel; calculating a target train speed profile and a target in-train force profile over at least a portion of the selected route; measuring one or more operating parameters related to the operation of the train; calculating a future train speed profile and a future in-train force profile for a future period based on at least one of the one or more operating parameters, at least one of the one or more locomotive control levels and one or more pieces of information relating to the selected route; calculating adjusted locomotive speed control levels relating to the one or more operating parameters based on a difference between the target train speed profile and the future train speed profile, the adjusted locomotive control levels being adapted to maintain the target train speed profile over the future period; calculating adjusted in-train force control levels relating to the one or more operating parameters based on a difference between the target in-train force profile and the future in-train force profile, the adjusted in-train force control levels being adapted to maintain the target in-train force profile below a target level over the future period; dividing the adjusted locomotive control levels and the adjusted in-train force control levels between the two or more locomotives to form locomotive-specific locomotive control levels for each of the two or more locomotives, the locomotive-specific locomotive control levels being at least partially adapted to control and/or balance in-train force levels below the target level provide locomotive-specific locomotive control levels for communication to each of the two or more locomotives; and operating each of the two or more locomotives according to the locomotive-specific locomotive control levels.

2. The method according to claim 1 wherein the method is performed using an electronic control system installed in a locomotive or in a train signalling control room.

3. The method according to claim 1 wherein the one or more locomotive control levels include one or more of throttle power, dynamic or regenerative brakes, on-board energy storage management, train brake operation, train consist, train load, train load distribution and a target value of in-train forces.

4. The method according to claim 1 wherein the locomotive control levels are set in a locomotive control module in electronic communication with the train.

5. The method according to claim 4 wherein the locomotive control module is in electronic communication with a locomotive-specific control module associated with each of the two or more locomotives.

6. The method according to claim 4 wherein the target train speed profile and the target in-train forces profile are calculated using a processor associated with the locomotive control module.

7. The method according to claim 1 wherein the target train speed profile and the target in-train force profile are calculated over each of a plurality of portions of the selected route.

8. The method according to claim 1 wherein the operating parameters include one or more travel parameters, train operational parameters or data relating to the one or more locomotive control levels.

9. The method according to claim 6 wherein the one or more pieces of information relating to the selected route are included in a route database electronically connected to the locomotive control module and/or the processor.

10. The method according to claim 1 wherein the future train speed profile and the future in-train forces profile are calculated by providing the one or more locomotive control levels and/or the one or more operating parameters with weightings.

11. The method according to claim 6 wherein the adjusted locomotive control levels are calculated by the processor and/or the locomotive control module.

12. The method according to any claim 1 wherein dividing the adjusted locomotive control levels between the two or more locomotives to form the locomotive-specific locomotive control levels id determined using one or more of the following parameters: present location of the train and/or each of the two or more locomotives, train length and mass, track profile or track topography to be encountered during the future period, train consist, and location of the two or more locomotives within the train.

13. The method according to claim 1 wherein the locomotive-specific locomotive control levels are calculated so that the performance of one locomotive is not optimised at the expense of other locomotives or the train.

14. The method according to claim 1 wherein the locomotives are operated according to the locomotive-specific locomotive control levels for at least a portion of the future period.

15. The method according to claim 1 wherein at or just before the end of the future period, the method is repeated for a new future period.

16. A control system for controlling the operation of a train comprising two or more locomotives, the system comprising an electronic control module adapted to set and adjust one or more locomotive control levels associated with each of the two or more locomotives, a processor electronically associated with the electronic control module and adapted to receive, from one or more sensors, data relating to one or more operating parameters related to the operation of the train and an electronic route database electronically associated with the processor, the electronic route database including one or more pieces of information relating to a selected route of travel, wherein the processor is adapted to: calculate a target train speed profile and a target in-train force profile over at least a portion of the selected route; calculate a future train speed profile and a future in-train force profile over a future period of time based on the data received from the one or more sensors, the one or more locomotive control levels and the one or more pieces of information relating to the selected route; calculate adjusted locomotive speed control levels relating to the one or more operating parameters based on a difference between the target train speed profile and the future train speed profile, the adjusted locomotive speed control levels being adapted to maintain the target train speed profile over the future period of time; calculate adjusted in-train force control levels relating to the one or more operating parameters based on a difference between the target in-train force profile and the future in-train force profile, the adjusted in-train force control levels being adapted to maintain the target in-train force profile below a target level over the future period; divide the adjusted locomotive control levels and the adjusted in-train force control levels between the two or more locomotives to form locomotive-specific locomotive control levels for each of the two or more locomotives; and electronically communicate the locomotive-specific locomotive control levels to the control module to adjust the one or more locomotive control levels associated with each of the two or more locomotives.

17. A method for operating a train comprising a locomotive, the method comprising: setting one or more locomotive control levels and choosing a selected route of travel; calculating a target train speed profile and a target in-train force profile over at least a portion of the selected route; measuring one or more operating parameters related to the operation of the train; calculating a future train speed profile and a future in-train force profile for a future period based on at least one of the one or more operating parameters, at least one of the one or more locomotive control levels and one or more pieces of information relating to the selected route; calculating adjusted locomotive speed control levels relating to the one or more operating parameters based on a difference between the target train speed profile and the future train speed profile, the adjusted locomotive control levels being adapted to maintain the target train speed profile over the future period; calculating adjusted in-train force control levels relating to the one or more operating parameters based on a difference between the target in-train force profile and the future in-train force profile, the adjusted in-train force control levels being adapted to maintain the target in-train force profile below a target level over the future period; operating the locomotive according to the adjusted locomotive speed control levels and adjusted in-train force control levels.

18. A control system for controlling the operation of a train comprising a locomotive, the system comprising an electronic control module adapted to set and adjust one or more locomotive control levels associated with the locomotive, a processor electronically associated with the electronic control module and adapted to receive, from one or more sensors, data relating to one or more operating parameters related to the operation of the train and an electronic route database electronically associated with the processor, the electronic route database including one or more pieces of information relating to a selected route of travel, wherein the processor is adapted to: calculate a target train speed profile and a target in-train force profile over at least a portion of the selected route; calculate a future train speed profile and a future in-train force profile over a future period of time based on the data received from the one or more sensors, the one or more locomotive control levels and the one or more pieces of information relating to the selected route; calculate adjusted locomotive speed control levels relating to the one or more operating parameters based on a difference between the target train speed profile and the future train speed profile, the adjusted locomotive speed control levels being adapted to maintain the target train speed profile over the future period of time; calculate adjusted in-train force control levels relating to the one or more operating parameters based on a difference between the target in-train force profile and the future in-train force profile, the adjusted in-train force control levels being adapted to maintain the target in-train force profile below a target level over the future period; and electronically communicate the adjusted locomotive speed control levels and the adjusted in-train force control levels to the control module to adjust the one or more locomotive control levels associated with the locomotive.

19. The method for operating a train comprising two or more locomotives according claim 1 wherein the locomotive control levels are configured to use one or more of traction, dynamic braking and air braking in order to improve control of the operation of the train.

20. The control system according to claim 16 wherein the locomotive control levels are configured to use one or more of traction, dynamic braking and air braking in order to improve control of the operation of the train.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) Preferred features, embodiments and variations of the invention may be discerned from the following Detailed Description which provides sufficient information for those skilled in the art to perform the invention. The Detailed Description is not to be regarded as limiting the scope of the preceding Summary of the Invention in any way. The Detailed Description will make reference to a number of drawings as follows:

(2) FIG. 1 illustrates a functional diagram of the method and control system according to an embodiment of the present invention.

(3) FIG. 2 illustrates a method of calculation of the control error for a future period of time according to an embodiment of the present invention.

(4) FIG. 3 illustrates an example of the position of a train along a section of track.

(5) FIG. 4 illustrates a method for calculating the distributed power (DP) division between locomotives according to an embodiment of the present invention in the case of a request for additional power.

(6) FIG. 5 illustrates a method for calculating the distributed power (DP) division between locomotives according to an embodiment of the present invention in the case of a request for reduced power.

DESCRIPTION OF EMBODIMENTS

(7) FIG. 1 illustrates a functional diagram of the method and control system 10 according to an embodiment of the present invention. In very general terms, a train (not shown) is being operated under certain locomotive control levels according to a target train speed profile. The target train speed profile is adapted to give an optimised target speed profile to ensure efficient operation of the train based over a particular section of the train's route. By efficient operation, it is meant that the train will be operated in such as manner as to minimise fuel and/or energy consumption and in-train forces while complying with speed restrictions, delivery timeframes and so on.

(8) As previously stated, the target train speed profile covers a section of the train's route under which the train is operated according to preselected locomotive control levels. For a future section of the route, a future train speed profile 11 is calculated. The optimised future train speed profile 11 is calculated over a future section of the train's route and is calculated using data from a number of sources. For instance, network data 12, preferably retrieved from one or more electronic databases associated with the train is used to calculate the optimised future train speed profile 11. In the embodiment of the invention shown in FIG. 1, the network data 12 includes information regarding the track 13 (including grades, curves, track condition and so on), speed restrictions 14 and train signal information 15.

(9) In addition to the network data 12, train data 16 obtained from sensors associated with the train is used to calculated the future train speed profile 11. The telemetry data 16 in this embodiments of the invention includes train speed 17, GPS position 18 and information received from train sub-systems 19 (such as in-train forces, fuel and/or energy consumption and so on).

(10) In this embodiment of the invention, other data, such as operator-inputted data 20 (for instance the train consist selection 21) or other data 22 transmitted wirelessly to the train.

(11) Once the future train speed profile 11 is calculated, adjusted locomotive control levels 23 are calculated. The adjusted locomotive control levels 23 determine the manner in which the train is to be operated (brake operation, throttle power, dynamic operation and so on) over the future period in order to optimise the performance of the train through minimisation of in-train forces and energy/fuel consumption.

(12) The adjusted locomotive control levels 23 are then divided between the two or more locomotives in the train to form locomotive-specific locomotive control levels 24. The locomotive-specific locomotive control levels 24 are based in part on the present location of each locomotive and the conditions to be encountered by each locomotive during the future period. This will be discussed further in connection with FIG. 3.

(13) Once the locomotive-specific locomotive control levels 24 are calculated, the locomotive-specific locomotive control levels 24 are communicated electronically to each locomotive and the driving controls 25 of each locomotive are set so as to match or comply with the locomotive-specific locomotive control levels 24

(14) A specific example of the calculations used in the present method is provided below. In a first step, the target speed profile for the trip or part of the trip that satisfies imposed speed limits and optimises the trip from the point of view of selected criteria (such as brake operation, throttle power etc.) The target speed profile could be either calculated prior to the trip or calculated during the trip in real time.

(15) The difference between the target speed profile and the actual train speed profile for the future period is calculated. This is calculated using the following formula:
?V(t.sub.i)=V.sub.target(t.sub.i)?V.sub.predicted(t.sub.i),
i=0,1,2, . . . ,n, and n=T.sub.forecast/t.sub.0,
Where T.sub.forecast is the future period, and t.sub.0 is the time period of calculating speed forecast.

(16) Next, with reference to FIG. 2 of the present application, the control error is calculated according to the following formula:
?E(t.sub.0)=?k.sub.weight(t.sub.i)?V(t.sub.i),i=0,1,2, . . . ,n
Where k.sub.weight(t.sub.i) is a unity function with weight coefficients k.sub.weight(t.sub.i) derived from a train dynamic response to a step control input.

(17) It is envisaged that the Control Value CV(t.sub.0) is proportional to the control error ?E(t.sub.0):
CV(t.sub.0)=k.sub.p?E(t.sub.0)

(18) The Control Value represents a control percentage and may be fixed in the range of ?200% to 100%, where the ranges 0 to 100% are tractive effort, ?100% to <0% are dynamic brake, and <?100% is train brake. If the new Control Value is less than 1% variation from the previous Control Value it may be ignored. This may be used to ensure integral accumulation of the control error does not occur and also aligns with the discrete nature of the locomotive tractive and dynamic braking efforts.

(19) Once the incremental change to the control signal is calculated, a check is performed by the locomotive control module that the train speed will continue to satisfy the speed limit during the predetermined forecast period, i.e.
V.sub.predicted(t.sub.i)<=V.sub.limit(t.sub.i)
and remains within the required threshold value from the target speed profile:
|V(t.sub.i)?V.sub.Target(t.sub.i)|<=V.sub.threshold

(20) The calculated Control Value CV is then forwarded to a Distributed Power Control (DPC) module (referenced by the locomotive-specific locomotive control levels 24 in FIG. 1). The DPC unit calculates the optimal split of the required control adjustment between train locomotives using the present and the future delineated track profile under the train.

(21) For a train with M locomotives the DPC module splits the required control value CV between train locomotives, so

(22) $CV=\underset{i}{\overset{M}{.Math.}}CVi$
where i=1, 2 . . . M.

(23) It is envisaged that in-train forces could be controlled by monitoring and maintaining the force differentials applied to consecutive parts of train located above delineated pieces of track. The DPC module operation is based in this concept.

(24) The split of the control input is the variable that could be used for minimising the steady components of in-train forces and keeping them within the required limit while closely following the optimal or target train speed profile. The method and system of the present invention splits the required additional control signal in such a way to achieve a closest possible to the balanced distribution of forces applied to each section of the train located above a delineated piece of track. Another objective of the DP control algorithm is to ensure that F.sub.diff.sup.i(t) remains within the required safe threshold limits F.sub.T all the time.

(25) The equation below describes the total forces acting on each section of the train:

(26) $\begin{array}{cc}F\mathrm{section}\left(i\right)=\underset{j}{\overset{Ni}{.Math.}}\left[\mathrm{Fgrade}\left(j\right)+\mathrm{Frr}\left(j\right)\right]+\underset{s}{\overset{Mi}{.Math.}}\left[F\mathrm{loco}\left(s\right)\right]& \end{array}$

(27) Where j=1, 2 . . . Ninumber of train vehicles located on T section of the track, F.sub.Grade(j) and F.sub.rrrespectively gravity and rolling resistance forces applied to j.sup.th vehicle located on the grade, and s=1, 2 . . . M.sub.ithrottle or brake force generated by an sth loco located on the same linear section of the track, and where ?M.sub.i=M, the total number of locomotives in the train.

(28) In general, at the time of calculating a DP split the train could be located on L track sections, so i=1, 2 . . . L. Providing L=1, the control request is split equally between train locomotives.

(29) Assuming that CV(t.sub.0)>0, i.e. additional traction effort (TE) is required for the precise follow of target speed profile. FIG. 4 illustrate the process where an increase in the traction effort is required.

(30) The controller creates a descending ordered list of section force differentials:
F.sub.diff.sup.i=|F.sub.section.sup.i?F.sub.section.sup.i-1|
where i=1, 2 . . . L.

(31) The convention is that the Smallest Force Differential (SFD) is the section with the force value closest to 0. The Largest Force Differential (LFD) is therefore the section with force value furthest from 0. The premise is the same whether the sections form a peak or a trough.

(32) Starting at the top of the descending list the controller checks whether locomotive/s are available inside the region of the SFD and whether these locomotive/s are at max TE. The method for assigning a proportion of power to the locomotives depend on available information.

(33) If no locomotives are available in the SFD, the additional traction is added to any other locomotive where the power increase would deliver the largest reduction of the maximum section differential existing in the train. If the reduction of the maximum differential is not possible, the power is added to the locomotive that would increase the maximum section differential by a minimal value, providing that after the increase F.sub.diff.sup.i(t) remains within the required threshold value F.sub.T during the entire predetermined period of forecast.

(34) In exceptional cases, when the forecasted section differential would exceed the chosen threshold at some point in time within the chosen period of forecast, the request for additional power is ignored as the implementation of the request may make train operation unsafe. In some extreme cases the need to keep force differential within the required limit may cause reduction of the power in order to ensure safe train operation. In this case the controller checks that the required reduction of the power would not cause the train to stall.

(35) It will be a common in long trains where a grade section will contain no locomotives at all. However, the described method always has the effect of reducing the maximum force differential in the train. The flowchart illustrated in FIG. 5 illustrates the process when a traction effort decrease is required.

(36) Similar to the case of Tractive Effort (TE) increase, the controller analyses the list of descending section force differentials. The SFD and LFD conventions are the same as in the TE increase case described previously. In the TE decrease scenario power is first removed from the locomotive of the LFD to reduce the maximum section force differential providing there is a locomotive available. Once all power has been removed from the LFD locomotive/s, the request to reduce power is forwarded to another locomotive in the train, providing the reduction of its power would result in the largest decrease in the forecasted maximum force differential. In case there is no other locomotive that would achieve reduction of the maximum section force differential, then the request is forwarded to the locomotive where the reduction in the power would cause the smallest increase in the maximum section force differential, providing that following the decrease F.sub.diff.sup.i(t) remains within the required threshold value FT during the entire predetermined period of forecast.

(37) Once the TE is reduced to zero for all locomotives, and a further speed reduction is still required the controller must then determine if a Dynamic or regenerative Brake (DB) application can be made.

(38) In classic driving control a pause is imposed between entering idle from the last TE application and the first DB application. The necessity for this approach in the patented method is not required as all in-train force effects are predicted and therefore handled implicitly by the method. The evaluation of the force differentials in the train will disallow a DB application until it is determined that the differentials will remain under F.sub.T value. Balancing of DB applications is carried out using the same methodology of differential comparison, but with control action to speed relationships reversed. Therefore, an increase in DB reduces speed and a decrease in DB to allow increase in speed. When maximum safe braking effort from DB is reached and further speed reduction is still required a train pneumatic braking application is necessary. This might need to occur when CV is <?100%. This is realised in the same way that TE is constrained to maintain safe in-train forces.

(39) Train braking in long trains is either performed by conventional pneumatic braking or by Electronically Controlled Pneumatic Brakes (ECPB). The two systems have very different performance characteristics. Pneumatic braking takes significantly longer to actuate brakes in long trains and has the potential to introduce significant in-train forces, whereas, the electrical signalling characteristics of ECPB ensure all brakes are actuated in parallel. An important difference inherent in all pneumatic brakes is that these systems have response times governed by gas dynamics. Furthermore for conventional pneumatic brakes certain levels of control must be chosen and certain times must elapse between changes. Pneumatic braking is therefore added as discrete control levels and durations following normal brake and train operation rules and policies.

(40) Due to these differences in performance the characteristics of the safe use of these brake systems should preferably be included in the prediction. Then, in the same way that power is either increased or decreased, the train brake contribution is set by the controller to keep within the safe operating constraints of the train and the brake system.

(41) The methodology uses a combination of directly measured train performance and known parameters of performance in its prediction of future train state. For non-measured parameters these must be synchronised to actual train performance to ensure prediction accuracy.

(42) In FIG. 3 there is illustrated an example of the position of a train 26 along a section of track 27. The train 26 is travelling along the track 27 in the direction of travel indicated by arrow 28.

(43) In this embodiment of the invention, the train 26 includes three locomotives: a lead locomotive 29 and two remote locomotives 30, 31. Each locomotive 29, 30, 31 is separated from the other locomotives 29,30, 31 by at least one unit of rolling stock 32.

(44) It will be noted that the lead locomotive 29 is positioned at or near the top of an uphill section of the track 27, while the first of the remote locomotives 30 is positioned partway along a downhill section of track 27. The second of the remote locomotives 31 is located at the bottom of an uphill section of track 27. Given that the train 26 may be several kilometres in length, it may take some time for remote locomotive 30 to reach the position of the lead locomotive 29, and even longer for remote locomotive 31 to reach the position of the lead locomotive 29. During these periods of time, each locomotive 29, 30, 31 will encounter different environmental conditions (such as track topography) at different times. Thus, operating each locomotive 29, 30, 31 according to the specific environmental conditions that the locomotive 29, 30, 31 will encounter during the future period will assist in improving locomotive performance while reducing in-train forces.

(45) In the example illustrated in FIG. 3, as the lead locomotive 29 is approaching the top of an uphill section of the track 27, increased throttle power may be required so that the lead locomotive 29 may crest the hill. However, increased braking may be required as the lead locomotive begins to travel downhill. Simultaneously, increased braking may initially be required by the first remote locomotive 30 as it completes the downhill section of track 27, but increase throttle power will be required as the first remote locomotive 30 begins to ascend the uphill section of track on which the first locomotive 29 is currently positioned.

(46) On the other hand, the second remote locomotive 31 will require a relatively long period of increased throttle power as it climbs the uphill section of track 27 on which is it presently located.

(47) It will be understood, however, that each locomotive 29, 30, 31 cannot be simply operated only according to the environmental conditions it will encounter. Instead, each locomotive 29, 30, 31 should be operated so as to take into consideration the operation of the other locomotives 29, 30, 31 within the train. For example, while minimal braking may optimise the performance of the first remote locomotive 30 on the downhill section of track 27, minimal braking may increase in-train forces between rolling stock at the top of hill 33 to an unacceptable level because the second remote locomotive 31 may be unable to travel fast enough uphill to keep up with the first remote locomotive 30, or the second remote locomotive 31 may be uphill to travel fast enough uphill to keep up with the first remote locomotive 30 but doing so would result in unacceptably high fuel and/or energy consumption.

(48) Thus, it will be understood that while the locomotive-specific locomotive control levels may not permit individual locomotives 29, 30, 31 to operate at optimal; conditions for that locomotive, the locomotive-specific locomotive control levels function to ensure that individual locomotives 29, 30, 31 operate in a manner that optimises the performance of the train 26, in terms of minimising fuel and/or energy consumption and in-train forces, while also ensuring that the train 26 complies with external factors such as speed restrictions, signalling and any deadlines the train 26 is required to meet.

(49) It should be noted that the DP train example given in FIG. 3 is just one of many possible variations. The example in FIG. 3 is known as a headmidtail configuration, and it is also true that the mid locomotive may be positioned at different locations in-train. A list of the possible configurations for three locomotives includes: headmidtail or headin-traintail. In the latter configuration, the in-train locomotive may be located at any suitable position within the length of the train. For instance, the in-train locomotive may be positioned at 20%, 50%, 66%, 75% etc. of the length of the train.

(50) In embodiments of the invention in which two locomotives are present, it is envisaged that the configuration of the two locomotives may be either headtail or headin-train, with the second locomotive positioned at, for example, 20%, 50%, 66%, 75% etc. of the length of the train. It is also envisaged that a train with 4 locomotives may be utilised. In this embodiment of the invention, the configuration of the 4 locomotives will be headin-trainin-traintail, with the two in-train locomotives being positioned at any suitable location along the length of the train between the front (head) and back (tail).

(51) Some specific examples of DP train consists are set out below:

(52) Two Locomotives: HeadTail

(53) A combination of:

(54) head locomotive(s) (comprising a single locomotive or a locomotive group); and tail locomotive(s) (comprising a single locomotive or a locomotive group).
Two Locomotives: HeadIn-Train
A combination of: head locomotive(s) (comprising a single locomotive or a locomotive group); and in-train locomotive(s) (comprising a single locomotive or a locomotive group).
Three Locomotives: HeadIn-TrainTail
A combination of: head locomotive(s) (comprising a single locomotive or a locomotive group); in-train locomotive(s) (comprising a single locomotive or a locomotive group); and tail locomotive(s) (comprising a single locomotive or a locomotive group).
Three Locomotives: HeadIn-TrainIn-Train
A combination of: head locomotive(s) (comprising a single locomotive or a locomotive group); first in-train locomotive(s) (comprising a single locomotive or a locomotive group); and second in-train locomotive (s) (comprising a single locomotive or a locomotive group).

(55) It will be understood that the configurations listed above are intended to be illustrative only and are by no means an exhaustive list of possible train configurations.

(56) In all of the examples given above, it will be understood that the locomotives will be separated from one another in the train consist by a wagon rake or group comprising one or more wagons.

(57) In the present specification and claims (if any), the word comprising and its derivatives including comprises and comprise include each of the stated integers but does not exclude the inclusion of one or more further integers.

(58) Reference throughout this specification to one embodiment or an embodiment means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, the appearance of the phrases in one embodiment or in an embodiment in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more combinations.

(59) In compliance with the statute, the invention has been described in language more or less specific to structural or methodical features. It is to be understood that the invention is not limited to specific features shown or described since the means herein described comprises preferred forms of putting the invention into effect. The invention is, therefore, claimed in any of its forms or modifications within the proper scope of the appended claims (if any) appropriately interpreted by those skilled in the art.