Patent Grant
8332086
The invention relates to a process for managing operations in a railroad switchyard. The invention also encompasses a technological platform and individual components thereof to implement the process.
A railroad network normally contains one or more switchyards in which railcars are routed from tracks leading from a departure point to tracks going to a destination point. A typical switchyard has four main components, namely receiving tracks, a railcar switching mechanism, a set of classification tracks and a set of departure tracks. Incoming trains deliver railcars in the receiving tracks. The railcars are processed by the switching mechanism that routes individual railcars to respective classification tracks.
Two types of switching mechanisms are in use today. The first one is a hump switch. Switchyards that use a hump switch are referred to as hump yards. A hump switchyard uses a hump over which a railcar is pushed by a locomotive. At the top of the hump the railcar is allowed to roll on the other side of the hump under the effect of gravity. Retarders keep the railcar from reaching excessive speeds. The hump tracks on which the railcar rolls down the hump connect with the classification tracks. A track switch establishes a temporary connection between the hump tracks and a selected one of the classification tracks such that the railcar can roll in the classification tracks. A departure train is constituted when the requisite number of railcars has been placed in a set of classification tracks. When the departure train leaves the switchyard, the set of classification tracks become available for building a new departure train.
The second type of switch mechanism is a flat switch. The principle is generally the same as a hump yard except that instead of using gravity to direct railcars to selected classification tracks, a locomotive is used to push the railcar from the receiving tracks to the selected set of classification tracks.
In order to increase the efficiency of switching operations railway companies have developed the concept of railcar blocking. Under this concept, a block of railcars, hence the name “blocking”, may be logically switched as a unit in a switchyard. A block is established on a basis of certain properties shared by the railcars belonging to the block. For instance railcars that have a common destination point on their route can be blocked together. A “block” is therefore a logical entity that helps making switching decisions. For reference it should be noted that generally, two types of blocks exist. There is the so called “yard block” and a “train block”. For clarity, the term “block” alone in the present specification encompasses either a yard block or a train block.
The principle of blocking, either yard blocking or train blocking increases the efficiency with which railcars are processed at switchyards. However, it also brings constraints. Very often a train block must be assembled from railcars that arrive on different incoming trains. The train block will be complete and available for departure only when all the railcars that make up the train block have arrived at the switchyard. If one or more of the railcars are delayed the train block cannot be completed and the entire departure train that pulls this train block may leave without the delayed railcars. Such occurrence may create a cascading effect throughout entire segments of the railroad network and have significant financial repercussions for the railroad operator. Specifically, it is not uncommon for an operator to guarantee railcar arrival times to customers and delays incur financial penalties that may be significant.
In general switchyard operations planning is done either manually or via simple management tools. In order to increase the efficiency of those operations there is a need to provide an automated system that can forecast the outbound workload and thus provide the yard master with a projection of the traffic that can be available to departure trains.
As embodied and broadly described herein, the invention includes a system for forecasting the outbound workload in a switchyard. The system has a processing entity for which receives information on railcar traffic for handling by the switchyard, wherein the railcar traffic includes railcars that are yet to be switched into classification tracks of the switchyard. For every departure train of two or more departure trains, the processing entity applies logic rules to the information to compute a forecast of railcar traffic that will be available to the departure train for transport out of the switchyard. An output releases data derived from the forecast of railcar traffic, describing the traffic available for each train of the two or more departure trains.
As embodied and broadly described herein, the invention also provides a method for forecasting the outbound workload in a switchyard. The method comprises the step of receiving information on railcar traffic for handling by the switchyard, wherein the railcar traffic includes railcars that are yet to be switched into classification tracks of the switchyard. The method also includes the steps of, for each of two or more departure trains, applying logic rules to the information to compute a forecast of railcar traffic that will be available to the departure train for transport out of the switchyard, and releasing data derived from the forecast of railcar traffic, for describing to a user the traffic available for each train of the two or more departure trains.
As embodied and broadly described herein, the invention further includes a system for forecasting the outbound workload in a switchyard. The system comprises a processing entity for:
As embodied and broadly described herein, the invention further includes a method for forecasting the outbound workload in a switchyard. The method includes:
As embodied and broadly described herein, the invention further includes a system for forecasting the outbound workload in a switchyard. The system includes:
A detailed description of examples of implementation of the present invention is provided hereinbelow with reference to the following drawings, in which:
In the drawings, embodiments of the invention are illustrated by way of example. It is to be expressly understood that the description and drawings are only for purposes of illustration and as an aid to understanding, and are not intended to be a definition of the limits of the invention.
The receiving tracks 12 lead to the hump 14. The hump 14 includes a set of tracks 20 that lead to the hump crest 18 that is the highest elevation of the hump 14. railcars are pushed by a locomotive on the tracks 20 up to the hump crest 18 at which point the railcar rolls down the hump 14 by gravity toward the set of classification tracks 16. The railcar passes through retarders 22 that will reduce its speed allowing it to gently coast in anyone of the selected classification tracks 16. A track switch 24, located downstream the retarders 22 temporarily connects the hump track 12 to a selected one of the classification tracks 16 such as to direct the railcar to the desired classification track 16.
The receiving tracks 12, therefore, form a switching queue in which railcars that are delivered to the switching yard 10, await to be switched.
The classification tracks 16 lead to the departure tracks 17. Specifically, the classification tracks are arranged into groups, where each group leads to a departure track 17. The hump switchyard 10 shown in the drawings includes 10 classification tracks organized into two groups of five tracks. Each group of five tracks connects to the departure track 17.
Generally, the classification tracks 16 are used to assemble train blocks. Train blocks are pulled out of the classification tracks into the departure tracks 17 where the actual departure train is built. The departure tracks 17 allow assembling trains having more railcars than a single classification track can hold. When a complete train (short train) is assembled into a single classification track 16, the departure train leaves that track directly by passing through the departure track 17.
It should be appreciated that
The hump switchyard 10 also includes a reswitching track that allows to “recirculate” railcars from a position downstream of the switch 24 to a position upstream of the switch 24. In a typical hump switchyard, such as the yard 10 the reswitching track is called “rehump track”. The rehump track is shown at 26 in
The following description of a non-limiting example of implementation of a switchyard management process will be done in connection with a hump switchyard 10 of the type described earlier. However, it should be expressly noted that the principles of the invention apply equally well to a flat switchyard. Accordingly, the invention should not be limited to a hump switchyard but encompasses a flat switchyard as well. A flat switchyard operates generally in the same way as described earlier in that incoming trains deliver railcars at the input side of the flat switchyard, a switching device routes the individual railcars to classification tracks to assemble departure trains in departure tracks.
The SRS component 30 includes a processing function that is illustrated as a single block, but it can be implemented also in a distributed fashion.
It should be expressly noted that the SRS component 30 is merely an example of a railway traffic management system and other railway traffic management systems can be used without departing from the spirit of the invention.
The HPCS component 32 operates the track switch in the hump switchyard 10. Essentially, the HPCS component 32 is a railcar switch control system that determines on the basis of inputs the position of the track switch 24 such that a railcar or a series of railcars over the hump, will be directed to the desired classification track 16. Broadly stated, the HPCS component 32 has two main goals, namely:
As in the case with the SRS component 30, the HPCS component 32 is illustrated as a single block but it can be implemented in a distributed fashion.
It should be expressly noted that the HPCS component is merely an example of a railcar switch control system and other railcar switch control systems can be used without departing from the spirit of the invention.
As shown by
Note the communication link 35 between the HPCS component 32 and the SRS component 30. This link 35 illustrates the exchange of data between the two components, for instance the HPCS component 32 notifying the SRS component 30 of events or conditions occurring in the hump switchyard 10.
Note that while the diagram at
The functionality of the OM controller 46 is software defined. In other words, the logic that computes preferred humping sequences and also that determines how railcars are to be switched is implemented by executing software by the processor 47. The software in the form of program code is stored in the memory 49. The software reads data inputs received from the SRS component 30, and from the user interface 53. On the basis of those inputs, the OM controller 46 generates outputs to the user interface 53. The output to the user interface 53 is intended to display information to inform the user on the recommended hump sequences and switching solutions the OM controller 46 has reached. Optionally, an output may also be directed to the HPCS component 32, which contains switching commands that determine the positions of the track switch 24 and effectively implement the switching solutions developed by the OM controller 46.
In the example illustrated in
In order to make hump sequence recommendations and classification track assignments to individual railcars, the OM controller 46 creates representations in the memory 49 of the rolling stock that transits through the hump switchyard 10 by using hierarchal objects. Generally, three types of objects exist:
Normally, train objects that represent incoming trains will cease to exist when the train arrives at the hump switchyard 10 since the train is dismantled. An exception to this is a situation where the incoming train transits through the hump switchyard 10 in which case it remains intact. Departure trains are represented by train objects that begin their existence at the hump switchyard 10, having been assembled from railcars that originate from one or more dismantled incoming trains. Incoming train block objects may cease to exist if the train block is disassembled and the individual railcars are used to make up other train block objects. For example a train block arriving at the hump switchyard 10 may contain railcars having different destinations. For the sake of this example, say that half of the railcars need to be delivered to city A while the other half to city B. In such case the train block is disassembled and the railcars that go to city A are switched to form, alone or in combination with other railcars from a different train, a new train block that will travel to city A. The railcars directed to city B are switched in a similar manner. In this situation, two new train blocks are created at the hump switchyard 10, from one or more incoming train blocks. Another possibility is for train blocks to be modified, instead of ceasing to exist or beginning to exist. A train block can be modified by augmenting the train block, such as by adding to it one or more railcars or diminished by removing from it one or more railcars. Finally, a train block may remain unchanged such as when it simply transits through the hump switchyard 10. In such case, the train block is physically dismantled into individual railcars but the switching operation is conducted such as to reassemble the original train block. Alternatively, the train block can be routed directly to the departure tracks 17 such as to circumvent the switch 24.
As far as individual railcar objects, they remain unchanged as they transit through the hump switchyard 10.
The OM controller 46 receives from the SRS component 30 data that describes the incoming trains so that the OM controller 46 can determine the details of the rolling stock to be processed. The OM controller 46 also receives information on the departure trains that the hump switchyard 10 is expected to assemble.
In a specific example of implementation, the OM controller 46 receives form the SRS component 30 the following information:
Once the OM controller 46 is made aware of incoming trains and the requirement to build departure trains, the train ID information allows the OM controller 46 to determine all the necessary information down to the individual railcar. More particularly, the train ID allows determining the properties of the train object and the properties of the train block objects derived via the train object and the properties of the railcar objects derived via the train block objects. This data will then allow the OM controller 46 to compute switching solutions.
It should be expressly noted that the above description of the manner in which information is provided to the OM controller 46 is strictly an example and should not be constructed in any limiting manner. Many different ways to deliver information to the OM controller 46 exist that allow characterizing the incoming trains and the departure trains without departing from the spirit of the invention.
A detailed example of a recommended hump sequence computation by the OM controller 46 will be described below in conjunction with the process flowchart in
The flowchart at
The process includes a start step 500 that is followed by step 502 during which a number of possible sequences in which the railcar cuts can be switched. For example, if three railcar cuts exist, say cut 1, cut 2 and cut 3, a first switching sequence may be cut 1, cut 2 and cut 3, a second possible switching sequence can be cut 2, cut 1 and cut 3, a third possible switching sequence can be cut 3, cut 2 and cut 1, etc. While it is possible at this stage to determine all possible sequences of cuts this is not an absolute requirement. In fact, for large number of cuts that exist in the switching queue and await switching, the determination of all the possible permutations may lead at the next step of the process that is described below to a heavy computational burden, which may not be required in practice. Generally, the number of sequences that will be determined in order to find a preferred sequence is dependent on the computational resources available. At least two sequences need to be available in order to choose a preferred one, but in most practical cases more sequences will be considered to make a choice.
At step 504 the cut sequences determined at the earlier step are evaluated and a preferred sequence is selected. By “preferred” is meant a sequence that offers an advantage over another sequence that is being evaluated. What constitutes an advantage is a matter of choice and dependent on the specific application. For example, if the user of the switchyard considers preferable to minimize the time railcars spent in the switchyard, the metric that will be used to evaluate the sequences and select the preferred one will be the dwell time of the railcars in the switchyard. In such example, step 504 evaluates the different sequences and selects the one that allows reducing the dwell time of the railcars in the switchyard.
In another possible example, the metric used to evaluate the sequences is the number of missed connections. By “missed connection” is meant that a railcar that was destined to be part of a departure train is not available when the train departs. In such case the sequences are evaluated on the basis of missed connections and a preferred sequence is selected.
In many cases, the metric that is being applied may be refined by making a distinction between different types of railcars. For example one may want to distinguish between loaded railcars which usually have a commitment in terms of delivery date or time to a customer versus empty railcars that have no such commitment. If such distinction is made, a higher priority can be given to loaded railcars than to empty railcars. In the case of the “missed connection” metric, the computation could be done in a way to provide more weight to loaded railcars than to empty railcars. In this fashion, the resulting switching sequence will tend to favor loaded railcars such that they make their connections at the expense of empty railcars.
The selection of preferred sequence among the sequences that are being evaluated includes, in one specific example, the computation of a performance status of the switchyard that would be reached for each sequence. In other words, the process will compute a performance status for the switchyard for every sequence and then compare the performance statuses to select the preferred sequence. In one example, when the metric to evaluate sequences is based or factors in railcar dwell time, the performance status of a given sequence can be expressed as a value that reflects the dwell time of all the railcars in the switchyard or a subset of those railcars. In the example where the metric is missed connections (or alternatively successfully made connections) then the performance status of a given sequence can be expressed as a value that reflects the number of missed (or realized) connections with departure trains.
At step 506 the results of the evaluation made at step 504 area displayed to a user. This is done to describe to the user the preferred sequence such that the user can use this recommendation into making a final decision on what the switching sequence will be. The description of the preferred sequence can be done in many different ways without departing from the spirit of the invention. For instance, the preferred sequence can be shown on the display of the user interface 53 alone or listed with the other less preferred sequences to show the user possible options.
A more detailed example of the process for selecting a switching sequence will now be described in connection with
The process starts at 600. During this start step, the user will fix the order of the first few cuts to be humped. The process will then consider the remaining cuts and generate possible sequences of those cuts in order to find a preferred sequence. The evaluation of the possible sequences may be limited to a reasonable number according to the computational resources available.
The score for anyone of the given sequences to be evaluated is the total of the score for all the railcars in the cut (without intent to be bound by any specific definition, in the railroad industry a “cut” refers to any number of railcars attached to be pulled by an engine). Generally, the score for a railcar depends on the objective departure train and the scenario train for that railcar and the departure times of these trains.
At step 602, the objective departure train for each railcar in the cuts being considered is determined. The objective departure train for a railcar is the one that the railcar should connect to based on the process standard in the switchyard. For example, that standard may be set such that railcars that arrive on an incoming train, that need to be humped, have a minimum of 8 hours to connect to departure trains. The scheduled arrival time of the inbound train is used as the starting point for the connection standard, as long as the train arrived early or within 2 hours of its scheduled arrival. If the train is more than 2 hours late, the actual arrival time is used. For trains that are enroute, the same logic is used. For instance, Expected Time of Arrival (ETA)+8 hours if the train is running more than 2 hours late otherwise Scheduled Time of Arrival (STA)+8 hours.
The information necessary to make the objective departure train determination for each railcar is made available from SRS 30 (Refer to
After the computation at step 602 is completed the results are stored in the memory 49, such as for example as a list mapping the railcars to their respective objective departure trains.
Step 604 determines the volume of railcars that are committed to the departure trains. This is done to assess what is the available space in the departure trains for railcars yet to be switched. The volume of railcars already committed includes:
At step 606 a hump sequence is generated. This is done mathematically based on the cuts that are to be evaluated. The following steps 608, 610 and 612 evaluate the sequence. This loop is repeated for all the sequences to be evaluated and a final selection is made later at step 616.
For the sequence selected at step 606, the expected switching time for each railcar in the cuts is determined. The selected sequence is the sequence of cuts which may be cuts that are presently in the switchyard and await switching, cuts on the rehump tracks or cuts expected to arrive (enroute trains).
The computation of the expected switch time for a given railcar is an approximation of the time at which the railcar is expected to be available for switching. Several factors can be used in making this determination, for example:
Factor (a) and factor (b) allow determining, at any given time, how many railcars will be in the queue awaiting switching. Recall that this information is readily available to the OM controller 46 from the SRS component 30. Factor (c) can be a rate computed on the basis of the operations in the hump switchyard 10 that occurred in the past couple of hours. For example, a railcar switching rate can be computed on the basis of the number of railcars switched in a given time frame, say the last two hours. A railcar switching rate can also be computed theoretically by taking into account resources available (factor d) in the switchyard to perform the operations necessary to prepare the railcars for switching. One such operation is the mechanical inspection of the railcars. One such resource is the number of crews that can perform the preparation for switching, namely the mechanical inspection. By considering the average number of railcars that a crew can mechanically inspect it is possible to compute the rate at which railcars can be made available for switching. Another possibility is to take into account the rate computed on the basis of switching activities that have occurred in the past previous hours and adjust it to take into account variation in the number of crews, for instance increase the predicted rate if the number of crews increases or decrease the rate if fewer crews will be available.
The OM controller 46 can, on the basis of the above factors, determine for a given railcar, the number of railcars that precede it in the humping queue. Then on the basis of the switching rate, an expected switching time for the railcar can be computed.
Note that the expected switching time for a given railcar is dependent on the particular switching sequence determined at step 604. As the sequence changes, the expected switching times for the railcars will change since the railcars are switched in a different order.
In a specific example of implementation, the following rules are used to compute an expected switch time for each railcar in the sequence:
After the expected switching time for each railcar of the sequence has been computed, the process continues with step 610 where a scenario departure train is determined for each railcar. A scenario departure train is the earliest train with a cut-off time after the railcar's expected switch time that can carry the railcar's outbound block, and the train has space for this railcar.
The assignment of a scenario departure train is an iterative process. The railcars are examined in the order of their expected switching time. A railcar is assigned to the earliest train in a set of candidate departure trains, which has a cut-off time after the railcar's expected switching time and that can carry the railcar's outbound block and the train has space for this railcar, in other words, the train and block capacities have not been exceeded.
Before assigning a scenario train to a railcar, first, candidate departure trains for that railcar are determined. A candidate departure train is any departure train that can carry the railcar's outbound block as a core block or as a filler block and whose cut-off time is after the railcar's arrival time in the switchyard and the switchyard processing standard, as discussed earlier. Obviously, a candidate departure train also takes into account the destination of the railcar. Departure trains that cannot carry the railcar to the intended destination are not considered. Also, departure trains that have a Scheduled Departure Time (SDT) that is before or after the objective departure train's SDT, can be suitable candidate departure trains, hence they are considered when determining the scenario train. However, note that in this example, a departure train that has an SDT that is before the SDT of the objective train can be a suitable candidate departure train only when it can carry the railcar in a filler block.
The set of candidate departure trains determined for each railcar may be augmented to include departure trains that depart before the railcar's arrival time plus the switchyard processing standard. This option may be useful in instances where the railcar is processed earlier than the switchyard standard and is able to connect to this train.
Before starting the iterative process, the remaining capacities of the candidate departure trains (for all railcars) are initialized by subtracting from the actual capacities the space taken up by railcars already processed and committed to the trains as per step 604 above.
The iterative process is a series of passes that consider all the candidate departure trains and assign each railcar to a candidate departure train that becomes the scenario departure train for that railcar.
The iterative process starts with a first pass. As indicated earlier the railcars are examined in the order of their expected switching time. In this pass only those candidate departure trains that have a core block for a railcar are considered for assignment. For instance, consider the first railcar of the first cut in the sequence. This railcar is processed before any other railcar since it has the earliest expected switching time. The OM controller 46 that has previously identified the candidate departure trains for that railcar will select the one that has:
The selected train by the OM controller 46 is tentatively assigned to the railcar as a scenario departure train and that departure train and block remaining capacities are reduced by one.
Once the first pass is completed a second pass is initiated which performs a broader assessment and attempts to find space for the railcar in a departure train either in a core block or in a filler block. The second pass processing first determines if there are any activated filler blocks on anyone of the candidate departure trains determined for the railcar. If there are no activated filler blocks on anyone of the candidate departure trains then the second pass is not required and the scenario departure train tentatively assigned to the railcar during the first pass is now confirmed as actual scenario departure train. On the other hand, if there are activated filler blocks on one or more of the candidate departure trains, first a computation is done to assess the capacity of the filler blocks. The capacity of a filler block is computed as the train's capacity minus the space taken up by all the core block railcars assigned to this train, such as the railcars assigned in the first pass. Note that if more than one filler block for a given candidate departure train has been activated, then the filler block capacity computed above is jointly shared by the several filler blocks and it will be allocated on a First-In, First-Out (FIFO) basis.
The second pass implements a broader assessment because candidate departure trains that include both core and filler blocks are considered for assignment. A railcar will be assigned to the first eligible train that can carry the railcar, either in a core block or in a filler block (which implies that the train has sufficient remaining block and train capacity). For example, in a case where a candidate departure train that can carry the railcar in a filler block but it has a cut-off time that is after the cut-off time of the scenario departure train, then the OM controller 46 will retain the scenario departure train determined during the first pass. However, in an opposite case, where a candidate departure train with a filler block is available and it has a cut-off time earlier than the cut-off time of the scenario departure train tentatively assigned during the first pass, then the tentative solution is disregarded and the scenario departure train assigned to the railcar becomes the one with the filler block. Once this assignment is made, the train capacities are adjusted. The adjustment includes:
1. reducing the filler block capacity of the newly assigned scenario departure train by one;
In certain cases a third pass may also be required. For instance, consider the situation where a train TA has a filler block for block B and train TB has a core block for block B and TA departs before TB. Now let's say there is a block C for which the core block is on train TC and a filler block on train TB and TB departs before TC. In such situation, a block B railcar may shift to train TA and thus release capacity on TB. If block C railcars are overflowing TC then they should be shifted forward to TB. For this reason a third pass may be desirable.
In general, the process may benefit from as many additional instances of the third passes as the length of the chain of blocks connected in the way described above, minus one. For instance, if there is a chain of three blocks linked in this way the third pass may need to be repeated twice.
Note that before any instance of the third pass is initiated the capacities of the filler blocks should be updated. This is done by examining the solution from the previous pass as follows:
Finally, a check is performed for a last pass. If at the end of an instance of the third pass the three conditions described above under 1 are met then another instance may be necessary, otherwise not.
Note that even if three conditions are met, it may happen that no railcar that has been assigned to a later train can shift up to an earlier train (which was underutilized in the previous pass instance) due to expected switching time constraints. In this case there will be no change in train length from one pass to the next. If this condition is verified then no more instances of the third pass are made.
The above-described process is repeated for every railcar in the sequence generated at step 606. So, when step 610 is completed, the OM controller 46 produces a list that associates each railcar with a given scenario train, as well as the candidate trains and their respective capacities. This list will be used in the next step to compute a score.
Step 612 follows step 610 and computes for each railcar a score that is used as a basis to rank the various switching sequences. More specifically, step 612 applies scoring rules based on the objective train, the scenario train and the candidate trains for the railcar. Below is a possible example of scoring rules:
Step 612 computes a score for each railcar using the above rules. It should be expressly noted that those rules are mere examples and different rules can be implemented without departing from the spirit of the invention.
The step 612 completes by computing a collective score for the sequence generated at step 606. The collective score is the sum of the individual scores of the railcars making up the entire sequence. In this example, the collective score expresses the performance status of the switchyard 10 that would be reached should the railcar sequence be run.
Step 614 is a decision step. If the sequence processed last is the last sequence, in other words step 606 cannot generate any other different sequence, then step 614 is answered in the negative and the process continues at step 616. Otherwise the processing returns to step 606 where a new sequence is generated and processed by steps 608, 610 and 612 as discussed earlier. This continues until all the sequences have been exhausted.
Step 616 compares the collective scores for all the sequences and selects the preferred one. In this particular example, the preferred sequence is the one that has the highest collective score. In other words, the preferred sequence is the one that would put the switchyard in the highest performance status. In the event there is a tie, a possible approach is to select the sequence that has the lowest number of missing connections for certain railcars, for example loaded railcars versus empty railcars. Another possible approach to break the tie is to select a sequence among the sequences that are tied that is closest to the current sequence, so as to deviate least from the current yard work plan. Again, the reader will appreciate that other factors can be relied upon in selecting a sequence in the event of a tie, as missed connection or similarity to the current sequence are only examples of metrics that can be used.
The above example of implementation uses a computational method that evaluates all the possible sequences in a given number of cuts. For some applications, in particular those where the number of cuts to evaluate exceeds 10, the computational requirements become significant since the number of possible sequences grows to large numbers. In this case variants can be implemented to reduce the computational complexity. One such variant is the so called “Strong Optimality” (SO) property that can be used to limit the number of sequences that need to be considered. Assume for the sake of this example that sequences of 10 cuts need to be evaluated. An evaluation method based on the SO property does not look only at complete sequences of the 10 cuts. Rather, the method builds up from smaller sub-sequences (a sequence of a subset of the 10 cuts) and reduces the search space through evaluation of these sub-sequences.
For the purpose of this example, a sequence is considered Strongly Optimal (SO) if it has the highest score of all other sequences of the same cuts and its hump completion times is not greater than that of any other sequence.
Consider the following example:
If the method is to evaluate 5 cuts—Cut Nos. 1, 2, 4, 6 and 7, there are 5!=120 possible sequences. Let's say S(1,6,4,2,7) is the score of sequence 1,6,4,2,7, and T(1,6,4,2,7) is its completion time. If 1,6,4,2,7 is an SO sequence then for any other sequence, say 1,2,4,6,7, S(1,6,4,2,7) is >=S(1,2,4,6,7) and T(1,6,4,2,7) <=T(1,2,4,6,7).
The SO property implies that an extended sequence derived from an SO sequence will be superior to a similar extension of any other sequence. That is, in the above case the sequence 1,6,4,2,7,N will be better than the sequence 1,2,4,6,7,N in terms of score whatever the cut N is.
A point to note is that the SO sequence may not be unique (a tie situation). There can be two or more sequences with the same highest score. In that case a possible approach is to arbitrarily choose one of those SO sequences for further consideration and neglect the remaining ones, or use anyone of the solutions discussed earlier for breaking the tie.
In some cases a possibility may arise that an SO sequence does not exist for a subset of the cuts. In that situation two or more non-Strongly Optimal or NSO sequences will be in existence.
Using the same example as above:
Let's say 1,6,4,2,7 is the sequence with the highest score but its completion time is longer than that of another sequence. That is, S(1,6,4,2,7)>S(1,2,4,6,7) but T(1,6,4,2,7)>T(1,2,4,6,7). Then both 1,6,4,2,7 and 1,2,4,6,7 are NSO sequences. In this case it cannot be said that the score of the extended sequence 1,6,4,2,7,N is greater than that of 1,2,4,6,7,N because the hump start time of cut N in the latter case may be earlier. This could avoid some missed connections and increase the additional score associated with the cut N.
When a subset of cuts does not have an SO sequence a set of NSO sequences can be identified such that all other sequences not in this set have both a lower score and a longer completion time than any of the NSO sequences. The number of NSO sequences may be quite large (in the extreme case all possible sequences of a subset of cuts may be NSO).
In order to enhance optimality it has been found advantageous to keep track of all the NSO sequences as the process builds upon them. As longer sequences are being built, the set of NSO sequences can expand or contract. However, in order to limit the computation one possible option is to keep no more than say, 3 NSO sequences for any subset of the cuts being considered, realizing that this may cause some loss of optimality. The choice of the number to keep is a trade-off between computation speed and solution quality.
The process under this variant generates and evaluates sub-sequences in iterations rather than generating complete sequences as in the complete enumeration technique described earlier. It starts by looking at sequences of length 2 in the first iteration, then in the second iteration it looks at sequences of length 3, and so on. One possible implementation is to consider, at most, 10 workloads/cuts for optimization (that is, if the switchyard operator has fixed the hump sequence of the first 3 cuts, say, then the OM controller will determine the best sequence for the cuts numbered 4 through 13).
The sequence generation is described below for the simple case where the SO property holds for every subset of cuts.
1. First Iteration
2. Second Iteration
3. Subsequent Iterations
4. Ninth and Last Iteration
5. Case with NSO Sequences
The outbound workflow forecasting module is software implemented and generates a series of views that show to the user information pertaining to the railcar traffic that will be available to scheduled departure trains for transport out of the switchyard. Certain safeguards are also included in the system to show when the available railcar traffic exceeds the capacity of departure train, allowing the user to manually adjust settings to correct the situation.
In
In addition, the outbound workflow forecasting module also receives information from SRS about the departure trains, such as the identification of each train, the estimated time of departure of each train and the train blocks making up the trains. The information that is available from SRS is discussed earlier in the specification.
The information that is output by the outbound workflow module 700 is conveyed to the user interface 53. In the specific example of implementation, the user interface includes a display on which the information is shown to the user. The user interface also includes inputs, which allow the switchyard operator to input data in the outbound workflow forecasting module 700, as it will be discussed below.
The process performed by the outbound workflow module on the information that is input into it is depicted by the process shown at
The rough projection, referred to as “traffic offered”, is computed at steps 802 and 804. Specifically, the objective train information for each railcar in the switchyard (including those on incoming trains) for which this parameter is computed is classified per train block and subsequently per train to which the railcars belong. The purpose is to obtain a rough projection valid at the ETD of every departure train, of the railcars that will be available for pick-up by that train. This is shown by processing step 804. Traffic offered could be from various locations, namely en route trains, receiving tracks of the switchyard, classification tracks of the switchyard or departing tracks of the switchyard. To include a railcar in the traffic offered in connection with a particular departure train, the objective train of that railcar should be that particular departure train.
Note that the traffic offered is not static and changes as the objective train information changes. As the objective train may be periodically recomputed, the objective train may change over time. This change will have an impact on the traffic offered. Accordingly, the projection of traffic that will be available to departure trains will change as railcars are being processed by the switchyard. Those changes will be greatest for departure trains having the furthest ETD. This is because the traffic offered projection is based on objective train computations for railcars that are in the early switchyard processing stages or have not yet arrived and for those railcars the objective train computations can change. In contrast, as the railcars progress through the switchyard, in particular as the railcars are switched and classified, the objective train information is much less likely to be changed. Therefore, as the EDT for a given train approaches the current time, the traffic offered projection progressively firms up to a point where it is fixed and no longer changes.
The refined projection of the railcar traffic, referred to as “consist forecast” is computed at steps 807 and 806. Specifically At step 807 the scenario train information is processed to generate at step 806 the consist forecast. The consist forecast would typically be a subset of the traffic offered and it is generated on the basis of the scenario train information input into the outbound work flow forecasting module 700. Typically, the processing step 807 will examine all the railcars in the group of railcars that constitute the traffic offered for the present departure train to extract those having a scenario train which matches the present departure train. Recall that the objective train for a railcar is, in the specific examples provided earlier, a connection standard computed on the basis of the time of arrival of the railcar to which is added a certain time processing standard. In contrast, the scenario train, in the examples provided earlier is a refined version of the objective train that takes into account the various processes taking place in the switchyard. For instance, the scenario train of a railcar may change depending on the computed switching sequence for that railcar. Accordingly, the consist forecast is a more accurate projection of the railcar traffic that will be available to the departure train.
In addition, the processing at step 807 also determines if the consist forecast established on the basis of the scenario train information will fit the capacity of the departure train. Several capacity limits can be considered, namely train length limit, train weight limit or number of railcars limit. If any of those limits is exceeded, a message is produced to advise the user. The limits applicable to a given departure train can be input into the system in different fashions. For instance this information can be associated with the train object describing the departure train, manually input by the user or inferred depending on particular conditions, such as for example the specific departure track the train occupies. The departure track may be limited in length and, therefore accept a limited number of railcars. This limit condition only applies to departure trains that occupy that particular departure track; longer departure tracks will not have those limits. Also, there may be instances where access to motive power is limited and thus the departure train may be assigned fewer locomotives than the projected traffic offered requires. In such instances, a weight limit will be enforced and a message will be issued to the switchyard operator to indicate that a limit has been exceeded and also to indicate the maximal train weight permissible for the available motive power.
Corrective action that may be taken when the consist forecast computed on the basis of the scenario train information exceeds the capacity of a departure train can be manual or automatic. A manual corrective action will normally require the user to specify what corrective action is to be implemented by entering commands via the user interface 53. Specifically, the user may chose to close one or more train blocks earlier such as to limit the number of railcars in the departure train. The choice of the blocks to close earlier is left to the discretion of the user. An automatic corrective action may also be considered where train blocks are closed in a random fashion or by applying any suitable logic rules.
Once a corrective action has been input into the system, which is depicted in
As the new scenario train for the railcars left behind is computed, the consist forecast computed on the basis of the scenario train information will change to reflect the fact that the railcars are now planned to be part of a subsequent departure train.
The corrective actions and the subsequent adjustments to the traffic offered occur in most instances before the departure train is being built. Accordingly, the forecasting operation not only allows to “view” what departure trains will look like but also to proactively adjust the trains composition such that they fit existing limits.
The information produced by the outbound workflow forecasting module 700 is displayed to the user via the user interface 53. This is also shown at step 808 in
The following columns of information are displayed on the main grid:
The table can be sorted by Schedule Departure time (STD), Estimated Departure time (ETD) or Train ID.
The table can be filtered to show train departure by yard area.
From the screen in
The user can do outbound management (adjust the train block, add a fill block, close the block, set the block footage and change the train block cut-off to correct overflow situations). This will be described in connection with
The outbound railcar traffic that will make up the train will be forecasted automatically by the system, as discussed earlier. The user can also manually forecast the traffic that will make up the departure train via the Train details screen to generate an outbound forecast, as discussed in connection with
The following rules are applied in connection with the various parameters presented in
The train details screen, shown in
The columns displayed in the train details screen are:
The user can expand a specific train to the location level by selecting the desired train. This is shown in
The user can expand a specific location to the railcar level by selecting the desired Location. Alternatively, for tracks at the track/train level, the user can go directly to the railcar Level by selection the desired Track. The columns displayed in the location level section shown at
The following rules are applied in connection with the screens shown in
Now, with reference to
A calculator selection (new column in
The following rules are applied in connection with the screens shown in
Although various embodiments have been illustrated, this was for the purpose of describing, but not limiting, the invention. Various modifications will become apparent to those skilled in the art and are within the scope of this invention, which is defined more particularly by the attached claims.
The present application is a continuation-in-part of prior U.S. application Ser. No. 11/601,338 filed on Nov. 17, 2006. The contents of the aforementioned document are incorporated by reference herein.
| Number | Name | Date | Kind |
|---|---|---|---|
| 1681131 | Prescott | Aug 1928 | A |
| 2045695 | Brown | Jun 1936 | A |
| 2910578 | Karlet et al. | Oct 1959 | A |
| 3307031 | Frielinghaus et al. | Feb 1967 | A |
| 3316400 | Dosch et al. | Apr 1967 | A |
| 3480773 | McCune et al. | Nov 1969 | A |
| 3483367 | McCune et al. | Dec 1969 | A |
| 3543020 | McGlumphy et al. | Nov 1970 | A |
| 3598990 | Convey | Aug 1971 | A |
| 3727559 | McCune et al. | Apr 1973 | A |
| 3736420 | Elder et al. | May 1973 | A |
| 3861316 | Yamazaki et al. | Jan 1975 | A |
| 3865042 | DePaola et al. | Feb 1975 | A |
| 3944986 | Staples | Mar 1976 | A |
| 3946973 | Budway et al. | Mar 1976 | A |
| 4028531 | Cottin et al. | Jun 1977 | A |
| 4034677 | Frank | Jul 1977 | A |
| 4151969 | Wood | May 1979 | A |
| 4361300 | Rush | Nov 1982 | A |
| 4610206 | Kubala et al. | Sep 1986 | A |
| 4883245 | Erickson, Jr. | Nov 1989 | A |
| 5129605 | Burns et al. | Jul 1992 | A |
| 5465926 | Brown | Nov 1995 | A |
| 5499583 | Blumel | Mar 1996 | A |
| 5623413 | Matheson et al. | Apr 1997 | A |
| 5685507 | Horst et al. | Nov 1997 | A |
| 5758848 | Beule | Jun 1998 | A |
| 5794172 | Matheson et al. | Aug 1998 | A |
| 6076067 | Jacobs et al. | Jun 2000 | A |
| 6135396 | Whitfield et al. | Oct 2000 | A |
| 6154735 | Crone | Nov 2000 | A |
| 6304801 | Doner | Oct 2001 | B1 |
| 6377877 | Doner | Apr 2002 | B1 |
| 6397130 | Carr et al. | May 2002 | B1 |
| 6418854 | Kraft | Jul 2002 | B1 |
| 6449536 | Brousseau et al. | Sep 2002 | B1 |
| 6516727 | Kraft | Feb 2003 | B2 |
| 6519595 | Rose | Feb 2003 | B1 |
| 6587738 | Belcea | Jul 2003 | B1 |
| 6637343 | Stephan et al. | Oct 2003 | B2 |
| 6766228 | Chirescu | Jul 2004 | B2 |
| 6789005 | Hawthorne | Sep 2004 | B2 |
| 6832204 | Doner | Dec 2004 | B1 |
| 6856865 | Hawthorne | Feb 2005 | B2 |
| 6876300 | Ponziani | Apr 2005 | B2 |
| 6903658 | Kane et al. | Jun 2005 | B2 |
| 6961682 | Doner | Nov 2005 | B2 |
| 6978195 | Kane et al. | Dec 2005 | B2 |
| 7006957 | Doner | Feb 2006 | B2 |
| 7239943 | Peltz | Jul 2007 | B2 |
| 7350754 | Pierson | Apr 2008 | B2 |
| 7353093 | Bamfield et al. | Apr 2008 | B2 |
| 7428453 | Davenport et al. | Sep 2008 | B2 |
| 7433766 | Ruckser | Oct 2008 | B2 |
| 7441506 | Bruns | Oct 2008 | B2 |
| 7457691 | Muinonen et al. | Nov 2008 | B2 |
| 7546185 | Muinonen et al. | Jun 2009 | B2 |
| 7657348 | Muinonen et al. | Feb 2010 | B2 |
| 7751952 | Muinonen et al. | Jul 2010 | B2 |
| 7792616 | Muinonen et al. | Sep 2010 | B2 |
| 7813846 | Wills et al. | Oct 2010 | B2 |
| 7818101 | Muinonen et al. | Oct 2010 | B2 |
| 7831342 | Muinonen et al. | Nov 2010 | B2 |
| 7885736 | Muinonen et al. | Feb 2011 | B2 |
| 7937193 | Philp et al. | May 2011 | B2 |
| 7983806 | Muinonen et al. | Jul 2011 | B2 |
| 8019497 | Muinonen et al. | Sep 2011 | B2 |
| 8055397 | Pathak et al. | Nov 2011 | B2 |
| 8060263 | Muinonen et al. | Nov 2011 | B2 |
| 8112189 | Peltz et al. | Feb 2012 | B2 |
| 20010034642 | Doner | Oct 2001 | A1 |
| 20020045975 | Carr et al. | Apr 2002 | A1 |
| 20020082814 | Doner | Jun 2002 | A1 |
| 20020096081 | Kraft | Jul 2002 | A1 |
| 20020128757 | Chirescu | Sep 2002 | A1 |
| 20020173884 | Clawson | Nov 2002 | A1 |
| 20030040853 | Brousseau et al. | Feb 2003 | A1 |
| 20030093195 | Ishikawa | May 2003 | A1 |
| 20030105561 | Nickles et al. | Jun 2003 | A1 |
| 20030178534 | Peltz et al. | Sep 2003 | A1 |
| 20030236598 | Villarreal Antelo et al. | Dec 2003 | A1 |
| 20040015276 | Kane et al. | Jan 2004 | A1 |
| 20040030466 | Rezk | Feb 2004 | A1 |
| 20040104784 | Enriquez | Jun 2004 | A1 |
| 20040111309 | Matheson et al. | Jun 2004 | A1 |
| 20040167687 | Kornick et al. | Aug 2004 | A1 |
| 20050209777 | Peltz | Sep 2005 | A1 |
| 20050240289 | Hoyte et al. | Oct 2005 | A1 |
| 20050240545 | Schachtely et al. | Oct 2005 | A1 |
| 20050262236 | Schachtely et al. | Nov 2005 | A1 |
| 20060027133 | Suematsu | Feb 2006 | A1 |
| 20060212184 | Philp et al. | Sep 2006 | A1 |
| 20070005200 | Wills et al. | Jan 2007 | A1 |
| 20070150130 | Welles et al. | Jun 2007 | A1 |
| 20070156300 | Muinonen et al. | Jul 2007 | A1 |
| 20070156302 | Muinonen et al. | Jul 2007 | A1 |
| 20070156303 | Muinonen et al. | Jul 2007 | A1 |
| 20070156304 | Muinonen et al. | Jul 2007 | A1 |
| 20070156307 | Muinonen et al. | Jul 2007 | A1 |
| 20070156309 | Muinonen et al. | Jul 2007 | A1 |
| 20070179688 | Muinonen et al. | Aug 2007 | A1 |
| 20070299570 | Muinonen et al. | Dec 2007 | A1 |
| 20080119973 | Pathak et al. | May 2008 | A1 |
| 20100026570 | Amidi | Feb 2010 | A1 |
| 20100114810 | Hoyte et al. | May 2010 | A1 |
| 20100222948 | Muinonen et al. | Sep 2010 | A1 |
| 20100235021 | Muinonen et al. | Sep 2010 | A1 |
| 20110017693 | Thomas et al. | Jan 2011 | A1 |
| Number | Date | Country |
|---|---|---|
| 1 253 244 | Apr 1989 | CA |
| 1 269 749 | May 1990 | CA |
| 1 293 960 | Jan 1992 | CA |
| 2 198 855 | Mar 1996 | CA |
| 2 143 875 | Sep 1996 | CA |
| 2 175 776 | Aug 1997 | CA |
| 2 196 631 | Sep 1997 | CA |
| 2 279 528 | Aug 1998 | CA |
| 2 281 604 | Aug 1998 | CA |
| 2 281 683 | Aug 1998 | CA |
| 2 291 057 | Nov 1998 | CA |
| 2 392 972 | Mar 2001 | CA |
| 2 395 062 | Jul 2001 | CA |
| 2 395 064 | Jul 2001 | CA |
| 2 395 065 | Jul 2001 | CA |
| 2 395 395 | Jul 2001 | CA |
| 2 395 821 | Jul 2001 | CA |
| 2 356 760 | Mar 2002 | CA |
| 2 364 152 | May 2002 | CA |
| 2 364 153 | May 2002 | CA |
| 2 364 155 | May 2002 | CA |
| 2 364 157 | May 2002 | CA |
| 2 429 520 | May 2002 | CA |
| 2 431 868 | Jul 2002 | CA |
| 2 413 080 | Aug 2002 | CA |
| 2 433 737 | Aug 2002 | CA |
| 2 374 166 | Sep 2002 | CA |
| 2 476 400 | Aug 2003 | CA |
| 2 484 720 | Nov 2003 | CA |
| 2 486 532 | Nov 2003 | CA |
| 2 494 145 | Feb 2004 | CA |
| 2 449 181 | May 2004 | CA |
| 2 500 797 | May 2004 | CA |
| 2 454 739 | Jul 2004 | CA |
| 2 459 212 | Aug 2004 | CA |
| 2 459 213 | Aug 2004 | CA |
| 2 431 636 | Dec 2004 | CA |
| 1176907 | Mar 1998 | CN |
| 10194720 | Nov 2004 | DE |
| 1 490 253 | Dec 2004 | EP |
| 2 310 871 | Apr 2011 | EP |
| 05-278504 | Oct 1993 | JP |
| 2000255418 | Sep 2000 | JP |
| 2002183258 | Jun 2002 | JP |
| 2004-359154 | Dec 2004 | JP |
| 2011-159140 | Aug 2011 | JP |
| WO 0149547 | Jul 2001 | WO |
| 0242142 | May 2002 | WO |
| 03070537 | Aug 2003 | WO |
| 03090397 | Oct 2003 | WO |
| 2004074067 | Sep 2004 | WO |
| 2004074068 | Sep 2004 | WO |
| 2006099387 | Sep 2006 | WO |
| 2007149629 | Dec 2007 | WO |
| 2010014493 | Feb 2010 | WO |
| 2010063245 | Jun 2010 | WO |
| 2012017550 | Feb 2012 | WO |
| Number | Date | Country | |
|---|---|---|---|
| 20120022729 A1 | Jan 2012 | US |
| Number | Date | Country | |
|---|---|---|---|
| 60754601 | Dec 2005 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 11702864 | Feb 2007 | US |
| Child | 13249487 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 11601338 | Nov 2006 | US |
| Child | 11702864 | US | |
| Parent | 11387347 | Mar 2006 | US |
| Child | 11601338 | US |
