Patent Publication Number: US-9845023-B2

Title: Route feature identification system and method

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. application Ser. No. 14/685,751, filed 14 Apr. 2015 and to be issued as U.S. Pat. No. 9,469,320 on 18 Oct. 2016, which claims priority to U.S. Provisional Application No. 61/985,088, which was filed 28 Apr. 2014 (the “088 application”). The entire disclosures of the application Ser. No. 14/685,751 and 61/985,088 are incorporated by reference. This application is related to U.S. patent application Ser. No. 14/016,310, which was filed 5 Sep. 2013 and claims priority to U.S. Provisional Application No. 61/729,188, which was filed on 21 Nov. 2012. The entire disclosures of the application Ser. No. 14/016,310 and 61/729,188 are incorporated by reference. 
    
    
     TECHNICAL FIELD 
     Embodiments of the subject matter disclosed herein relate to examining routes traveled by vehicles, for example to identify features of a route passed over by a vehicle. 
     BACKGROUND 
     As vehicles, such as rail vehicles, traverse a route, it may be desirable to know the position of a vehicle, for example, for scheduling or dispatching purposes, or to help prevent the use of the same portion of the route by two or more vehicles at the same time (e.g., to avoid collisions). Conventional approaches, for example, that may use a geographic positioning system (GPS), may not provide sufficient accuracy to discriminate between two or more adjacent tracks. To determine which of parallel or near parallel tracks on which a vehicle is traveling, additional inputs may be required, for example a position of a switch when the vehicle passes over the switch. However, conventional approaches for communicating the position of a switch to the vehicle or identifying the position of a switch require expensive trackside equipment to monitor the switch position and to communicate the switch position to the rail vehicle. 
     BRIEF DESCRIPTION 
     In an embodiment, a system includes at least one application device, a control unit, and at least one processor. The at least one application device is configured to be at least one of conductively or inductively coupled with at least one of a first conductive track or a second conductive track of a route being traveled by a vehicle. The control unit is configured to control supply of electric current from a power source to the at least one application device to electrically inject at least one examination signal into the conductive tracks via the at least one application device. The at least one processor configured to be disposed onboard the vehicle. The at least one processor configured to monitor one or more electrical characteristics of at least one of the first or second conductive tracks in response to the at least one examination signal being injected into the conductive tracks, and to identify a construction feature of the route based on an examination of the one or more electrical characteristics, the construction feature corresponding to a man-made aspect of the route. 
     In another embodiment, a system includes a first application device, a second application device, a control unit, and at least one processor. The first application device and the second application device are configured to be at least one of conductively or inductively coupled with at least one of a first conductive track or a second conductive track of a route being traveled by a vehicle. The control unit is configured to control supply of electric current from a power source to the first and second application devices to electrically inject a first examination signal via the first application device and a second examination signal via the second application device into the conductive tracks. The first and second examination signals include respective unique identifiers. The at least one processor is configured to be disposed onboard the vehicle. The at least one processor is configured to monitor one or more electrical characteristics of at least one of the first or second conductive tracks in response to the first and second examination signals being injected into the conductive tracks; to identify a construction feature of the route based on an examination of the one or more electrical characteristics, wherein the construction feature corresponding to at least one of a switch, a diamond crossing, or a bridge; to determine a location of the vehicle based on the construction feature; and to control at least one device onboard the vehicle based on the location that is determined. 
     In another embodiment, a method includes injecting, via at least one application device disposed upon a vehicle, at least one examination signal into at least one of first or second conductive tracks of a route being traveled by the vehicle. The method also includes monitoring, via at least one detection device disposed upon the vehicle, one or more electrical characteristics of at least one of the first or second conductive tracks in response to the at least one examination signal being injected into the at least one of the first or second conductive tracks. Also, the method includes identifying a construction feature of the route based on the one or more electrical characteristics. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Reference is made to the accompanying drawings in which particular embodiments and further benefits of the invention are illustrated as described in more detail in the description below, in which: 
         FIG. 1  is a schematic illustration of a rail route including a switch; 
         FIG. 2  is a schematic illustration of an embodiment of an examining system; 
         FIG. 3  is a schematic illustration of an embodiment of an examining system on a vehicle of a vehicle system traveling along a route; 
         FIG. 4  depicts examination signals corresponding to a facing diverging move; 
         FIG. 5  depicts examination signals corresponding to a trailing diverging move; and 
         FIG. 6  is a flowchart of an embodiment of a method for identifying a construction feature of a route being traveled by a vehicle system from onboard the vehicle system. 
     
    
    
     DETAILED DESCRIPTION 
     The term “vehicle” as used herein may be defined as a mobile machine that transports at least one of a person, people, or a cargo. For instance, a vehicle may be, but is not limited to being, a rail car, an intermodal container, a locomotive, a marine vessel, mining equipment, construction equipment, an automobile, and the like. A “vehicle system” includes at least one vehicle. In some embodiments, a vehicle system may include two or more vehicles that are interconnected with each other to travel along a route. For example, a vehicle system may include two or more vehicles that are directly connected to each other (e.g., by a coupler) or that are indirectly connected with each other (e.g., by one or more other vehicles and couplers). A vehicle system may be referred to as a consist, such as a rail vehicle consist. 
     “Software” or “computer program” as used herein includes, but is not limited to, one or more computer readable and/or executable instructions that cause a computer or other electronic device to perform functions, actions, and/or behave in a desired manner. The instructions may be embodied in various forms such as routines, algorithms, modules or programs including separate applications or code from dynamically linked libraries. Software may also be implemented in various forms such as a stand-alone program, a function call, a servlet, an applet, an application, instructions stored in a memory, part of an operating system or other type of executable instructions. “Computer” or “processing element” or “computer device” or “processor” or “processing unit,” as used herein includes, but is not limited to, any programmed or programmable electronic device that may store, retrieve, and process data. “Non-transitory computer-readable media” include, but are not limited to, a CD-ROM, a removable flash memory card, a hard disk drive, a magnetic tape, and a floppy disk. “Computer memory”, as used herein, refers to a storage device configured to store digital data or information which may be retrieved by a computer or processing element. “Controller,” “unit,” “component,” and/or “module,” as used herein, may refer to the logic circuitry and/or processing elements (e.g., one or more computer processors) and associated software or program. The terms “signal”, “data”, and “information” may be used interchangeably herein and may refer to digital or analog forms. 
     Embodiments of the inventive subject matter relate to methods and systems for identifying one or more construction features along a route being traveled upon by a vehicle system, for example, in order to identify a location of the vehicle system along the route and/or a particular one of parallel routes upon which the vehicle system is traveling. For example, the vehicle system may examine the route by injecting an electrical signal into the route from a first vehicle in the vehicle system as the vehicle system travels along the route and monitoring the route at another, second vehicle that also is in the vehicle system. As another example, an electrical signal may be injected into the route by the same vehicle that monitors the route. Further, in some embodiment, multiple transmitters may be used to inject different examination signals into the route and/or multiple receivers may be used to monitor the examination signals. For example, a first transmitter and a first receiver may be disposed on a first side (e.g., left side) of a vehicle, and a second transmitter and a second receiver may be disposed on a second side (e.g., right side) of a vehicle. The route, for example may be a track of a rail vehicle system. The electrical signal that is injected into the route may be powered by an onboard energy storage device, such as one or more batteries, and/or an off-board energy source, such as a catenary and/or electrified rail of the route. 
     When the construction feature is identified, one or more actions may be initiated. For example, the location may be compared with a location determined or provided via a different technique to check or confirm the result provided by the different technique. As another example, the location may be communicated to an off-board facility, for example, for scheduling or dispatching purposes. 
     In various embodiments, electronic signatures (e.g., one or more electrical characteristics of one or more examination signals) observed, collected, or obtained as a vehicle passes over a route (e.g., a section of track) may be used to determine or confirm the route of travel (and/or location along the route of travel). For example, electronic signatures may be generated by coupling a frequency signal or signals to a track from a vehicle by inductive or magnetic coupling, and monitoring the injected signal at one or more other points on the vehicle. (For a more detailed discussion of injection of examination signals, see the &#39;310 application.) A sampled waveform of the monitored examination signals may be indicative of one or more construction features of the route. As used herein, a construction feature may be understood as a designed, or man-made, feature of the route, such as, by way of example, a switch or portion of a switch, a cross-over (e.g., a combination of two or more switches), a diamond crossing (e.g., a location where two sets of tracks cross each other), or a length of track passing over a structure (e.g., a bridge). A rolling surface construction feature may be understood as used herein as a man-made aspect or portion of a route that includes a discontinuity or other variation along a surface of a route being traveled (e.g., a surface of a rail that is contacted by wheels of a vehicle traveling the rail). For example, a rolling surface construction feature may include a switch, cross-over, or diamond crossing, but does not include a bridge or other support structure. A structural support construction feature may be understood as used herein as a man-made support structure that supports a route being traveled. For example, a bridge is an example of a structural support construction feature. The sampled waveform, for example, may be indicative of whether the vehicle (e.g., a rail vehicle) is traveling on normal track, or through a turnout or track switch. Further, if the vehicle is traveling through a turnout or switch, the signatures may indicate whether the vehicle is traveling in a facing direction (e.g., along a direction in which two tracks separate at a switch) or in a trailing direction (e.g., along a direction in which two tracks are joined or merged at a switch), and/or may indicate whether the vehicle is moving over the switch when the switch is in a normal (e.g., straight) position, or in a reverse (e.g., diverging) position. 
     Injection of examination signals into a track in various embodiments produces unique or otherwise identifiable waveforms corresponding to construction features of the track that are passed over by a vehicle. The waveforms may be identifiable in that the waveforms may be sufficiently different that the waveforms can be distinguished from each other. These types of waveforms can be referred to as distinguishable waveforms. The unique or otherwise identifiable waveforms may be created by changes in the amount and/or shape of ferrous materials in the track structure below the vehicle as the vehicle passes the feature. For example, various components of a track switch, such as a point rail, cross rail, frog, heelblock, or the like, can affect the shape of the waveform and characterize the signature. The shape of the waveform may be altered in that a magnitude of one or more portions of the waveform may increase or decrease, a width dimension of one or more portions of the waveform may change, a frequency of the waveform may change, a slope of one or more segments of the waveform may change, an area bounded by one or more portions of the waveform may grow or shrink, or the like. 
     A signature may correspond, for example, to a particular attribute of a switch, such as a point rail or frog. A signature may also correspond, to a particular sequence of attributes. For example, a particular sequence of attributes may be identified to determine if the vehicle is traveling in a facing direction or trailing direction, or if the switch is in the normal position or reverse position. Further still, the distance (and/or time elapsed) between attributes of a switch may be used to distinguish the switch from other switches (e.g., to distinguish a relatively long switch from a relatively short switch). For example, the size or angle of a turnout may be determined by evaluating the length of a signature waveshape with respect to direction of travel of the vehicle, as well as speed of travel and elapsed time between one or more attributes of the waveshape. It may be noted that the generation of unique signatures regarding, for example, switches (and/or positions of switches), may be enhanced by inductively coupling transmitters and/or receivers of the examination signal(s) to the track structure. The mass and/or shape of the track material (e.g., steel, iron) changes underneath the receivers as the vehicle traverses over a switch, shaping the signals. Use of induction may yield a more meaningful or distinguishable signature then when using a contact method for sending signals through a conductive loop. 
     A technical effect of various embodiments includes improved detection of vehicle location and/or direction. A technical effect of various embodiments includes improved safety. A technical effect of various embodiments includes reduction of risk in vehicle systems and/or networks (e.g., due to improved determination of location of a vehicle). A technical effect of various embodiments includes improved determination and/or confirmation of a switch position. 
       FIG. 1  is a schematic illustration of a route  100  including a switch  110  that is used to direct a vehicle along a first track  112  or a second track  114 . The vehicle may be traveling in a facing direction  101  or in a trailing direction  103 . The route  100  may be understood as having a right side  102  and a left side  104  as shown in  FIG. 1 . It may be noted that “right” and “left” are used as labels only for ease of clarity in  FIG. 1 , and that the “right” and “left” sides of the track may vary in other embodiments, for example, depending on direction of travel. When the vehicle is traveling in the facing direction  101  and the switch  110  is set in the normal position, the vehicle is directed along the first track  112  (e.g., straight up as seen in  FIG. 1 ). When the vehicle is traveling in the facing direction  101  and the switch  110  is set in the reverse position, the vehicle is directed along the second track  114  (e.g., to the right as seen in  FIG. 1 ). In  FIG. 1 , the switch  110  is shown in the reverse position, so that the vehicle is directed along path  106  when traveling in the facing direction  101 . 
     As seen in  FIG. 1 , the route  100  includes a first insulated joint  150 , a second insulated joint  160 , a third insulated joint  170 , and a fourth insulated joint  180 . The first insulated joint  150 , third insulated joint  170 , and fourth insulated joint  180  each correspond to a corresponding signal, while the second insulated joint  160  corresponds to the switch  110 . As the vehicle passes over the various insulated joints, the monitored waveforms may experience a noticeable drop in amplitude or strength due to the insulation of the insulated joints. By identifying these drops in amplitude or strength, the passage of a vehicle over insulated joints may be identified. The distance between the insulated joints (e.g., using the speed of the vehicle and time elapsed between passage over insulated joints) may be used in identifying a construction feature or differentiating between construction features. For example, if two switches have a generally similar configuration, but have distinguishable distances between insulated joints of associated signals, the distances between the insulated joints may be used to differentiate passage over the two switches. 
     The switch  110  includes various features or attributes. For example, the switch  110  includes a first attribute  120  along the right side  102  of the first track  112  and second track  114 . The first attribute  120  may vary as a function of switch position. For example, when the switch  110  is in the reverse position as shown, and the vehicle is traveling in the facing direction  101  as shown in  FIG. 1 , there may be a gap  121  between the right side  102  of the first track  112  and the right side  102  of the second track  114  proximate the first attribute  120  to allow passage of the wheels on the right side of the vehicle through the gap to allow the vehicle to pass through the switch and travel along the second track  114  along the path  106  in the facing direction  110 . However, when the switch  110  is in the normal position, the right side  102  of the second track  114  may be placed at or near contact with the right side  102  of the first track  112  proximate the first attribute  120  to direct the vehicle along the first track  110 . The signature of the examination signal as the vehicle passes over the first attribute  120  may be affected by the presence or absence of the gap. Thus, the signature may be used to identify whether the switch  110  is in the normal or reverse position. 
     As another example, the switch  110  includes a second attribute  130  along the left side  104  of the first track  112 . When the switch  110  is in the reverse position as shown, the left side  104  of the second track  114  may be placed at or near contact with the left side  104  of the first track  112  proximate the second attribute  130  to direct the vehicle from the first track  110  to the second track  114 . However, when the switch  110  is in the normal position, there may be a gap (not shown in  FIG. 1 ) between the left side  104  of the first track  112  and the left side  104  of the second track  114  proximate the second attribute  130  to allow passage of the wheels on the left side of the vehicle through the gap to allow the vehicle to pass through the switch and travel along the first track  112  in the facing direction  110 . The signature of the examination signal as the vehicle passes over the second attribute may be affected by the presence or absence of the gap. Thus, the signature may be used to identify whether the switch  110  is in the normal or reverse position. 
     As one more example, the switch  110  includes a third attribute  140 . The third attribute  140  includes a section of the route  100  where rails of the first track  112  (e.g., the right side  102  of the first track  112 ) cross rails of the second track  114  (e.g., the left side  104  of the second track  114 ). Such an attribute may be called a frog or switch frog, and may include a relatively large amount of track material (e.g., iron or ferrous material) providing an identifiable signature to the monitored examination signal corresponding to passage over the frog. For example, if the third attribute  140  is encountered by the right side of the vehicle after the insulated joint  160  has been passed, the vehicle may be understood to be traveling along the first track  112  in the facing direction  101 . As another example, if the third attribute  140  is encountered by the left side of the vehicle after the insulated joint  160  has been passed, the vehicle may be understood to be traveling along the second track  114  in the facing direction  101 . On the other hand, if the third attribute  140  is encountered before the second insulated joint  160 , the vehicle may be understood to be traveling in the trailing direction  103 , with the side of the vehicle that encounters the third attribute  140  providing information on the position of the switch  110  and the identification of the track from which the switch  110  is approached. 
     While, as discussed herein, portions of a monitored examination signal corresponding to individual attributes (e.g., first attribute  120 , second attribute  130 , third attribute  140 ) may provide information describing or corresponding to the direction of travel, the setting of a switch, and the differentiation of a switch from other switches, greater precision and/or reliability may be achieved by a consideration of multiple attributes of a monitored examination signal, including the sequence of the attributes as well as the time elapsed between attributes. (The time elapsed between attributes of the monitored examination signal may also provide the distance between corresponding attributes of the route based on the speed of the vehicle.) Thus, a combination of characteristics of a monitored examination signal corresponding to one or more attributes, aspects, or features of a route being traveled over may be used to determine the identity of a particular construction feature (e.g., to identify the feature as a switch and to distinguish the switch from other switches along the route) and/or to determine the setting of a switch and the direction of travel (which may be used to determine a particular one of generally parallel or otherwise close tracks upon which a vehicle is traveling). 
     For instance, in one example scenario corresponding to  FIG. 1 , a monitored examination signal may include a signature corresponding to one or more of encountering no gap at the second attribute  130  along the left side of a vehicle, encountering a gap at the first attribute  120  along the right side of the vehicle, and the third attribute  140  being encountered by the left side of the vehicle. Accordingly, it may be determined that the vehicle is traveling in the facing direction  101 , that the switch  110  is in the reverse position, and that the vehicle is traveling along the second track  114  after passage through the switch  110 . Additionally or alternatively, the distance between pulses of the examination signal caused by insulated joints may be determined, with the distances providing information on the direction of travel and the setting of the switch (provided that the distances between the second insulated joint  160  and the other insulated joints are different from each other). 
     It may be noted that the particular configuration of the switch  110  and the aspects of the example scenario discussed above are provided by way of example only, and that other switches or construction features or aspects thereof may be examined and/or other characteristics of a signal or portions of a signature utilized. Generally, signatures or characteristic waveforms of one or more portions of a monitored examination signal may be used to differentiate between construction features encountered by a vehicle. By identifying, for example, the particular features encountered, as well as the sequence and/or time of encountering the particular features, the location of the vehicle may be determined along a length of a route, as well as identifying a particular track (e.g., a particular one of two or more generally parallel tracks) upon which the vehicle is traveling. In some embodiments, a database of signatures characterizing each feature such as switches, crossings, bridges, or the like of a route may be developed. For features that are not symmetric along the length of the route, a separate signature for each direction of travel may be maintained. For features such as switches that have different settings, separate signatures may be maintained in the database for the different positions as well as direction of travel. 
     By comparing an obtained examination signal signature with the database and identifying the stored signature that most closely resembles the obtained examination signature (or that resembles or otherwise matches the obtained examination signature more than one or more other stored signatures, but not necessarily all other stored signatures), the identity of the feature (as well as any settings of the feature and/or the direction of travel) may be determined using known locations of the construction features. In some embodiments, a series of construction features previously encountered may be used to estimate a location, for example to confirm a construction feature and/or location selected from a databased, to narrow a field of construction features searched or compared (e.g., based on location within a predetermined range of the location estimated using previously encountered construction features), and/or to help select among viable alternative signatures that are each similar to the examined signature. With the features being passed over by the vehicle being determined (as well as the direction of travel), the location of the vehicle may be determined. It may be noted that the duration of a signal may be used to help identify a construction feature. For example, a bridge may have an increased amount of iron resulting in a recognizable signature that has a duration corresponding to the length of the bridge. Thus, the duration of the signal may be used to identify that the vehicle has passed over a particular bridge (e.g., a longer bridge may have a longer associated signature than a shorter bridge of otherwise generally similar construction). 
       FIG. 2  is a schematic illustration of an embodiment of an examining system  200 . The examining system  200  is depicted in  FIG. 2  as distributed between a first vehicle  202  and a second vehicle  204  in the same vehicle system; however, in other embodiments the examining system  200  may be disposed on a single vehicle. In other examples, the examining system  200  may be distributed among three or more vehicles. The route  208  may be a body, surface, or medium on which the vehicle system  100  travels. In an embodiment, the route  208  may include or represent a body that is capable of conveying a signal between vehicles in the vehicle system  200 , such as a conductive body capable of conveying an electrical signal (e.g., a direct current, alternating current, radio frequency, or other signal). 
     The examining system  200  includes several components described below that are disposed onboard the vehicles  202 ,  204 . For example, the illustrated embodiment of the examining system  200  includes a control unit  208 , an application device  210 , an onboard power source  212  (“Battery” in  FIG. 2 ), one or more conditioning circuits  214 , a communication unit  216 , and one or more switches  224  disposed onboard the first vehicle  202 . The examining system  200  also includes a detection module  218 , an identification module  220 , a detection device  230 , and a communication unit  222  disposed onboard the second vehicle  204 . Alternatively, one or more of the control unit  208 , application device  210 , power source  212 , conditioning circuits  214 , communication unit  216 , and/or switch  224  may be disposed onboard the second vehicle  204  and/or another vehicle in the same vehicle system, and/or one or more of the detection module  218 , identification module  220 , detection device  230 , and communication unit  222  may be disposed onboard the first vehicle  202  and/or another vehicle in the same vehicle system. It may be noted that in the illustrated embodiment, the detection device  230  and the application device  220  are schematically depicted as being disposed in intermediate positions between axles of different vehicles. For example, the detection device  230  and application device  210  in various embodiments may be located as shown and may be configured to transmit and receive signals via an additional rail not in electrical communication with the axles of the vehicles  202 ,  204 . In other embodiments, the detection device  230  and application device  210  may be configured to transmit and receive signals transmitted through tracks contacted by wheels of the vehicles  202 ,  204 , and may be disposed at nearest ends of adjacent vehicles, without any axles interposed between the detection device  230  and the application device  210 , to reduce any signal transmission issues that may be affected by shunting by the axles. 
     The control unit  206  controls supply of electric current to the application device  210 . In an embodiment, the application device  210  includes one or more conductive bodies that engage the route  208  as the vehicle system that includes the vehicle  202  travels along the route  208 . For example, the application device  210  may include a conductive shoe, brush, or other body that slides along an upper and/or side surface of a track such that a conductive pathway is created that extends through the application device  210  and the track. Additionally or alternatively, the application device  210  may include a conductive portion of a wheel of the first vehicle  202 , such as the conductive outer periphery or circumference of the wheel that engages the route  208  as the first vehicle  202  travels along the route  208 . In another embodiment, the application device  210  may be inductively coupled with the route  208  without engaging or touching the route  208  or any component that engages the route  208 . 
     The application device  210  is conductively coupled with the switch  224 , which may represent one or more devices that control the flow of electric current from the onboard power source  212  and/or the conditioning circuits  214 . The switch  224  may be controlled by the control unit  206  so that the control unit  206  may turn on or off the flow of electric current through the application device  210  to the route  208 . In an embodiment, the switch  224  also may be controlled by the control unit  206  to vary one or more waveforms and/or waveform characteristics (e.g., phase, frequency, amplitude, and the like) of the current that is applied to the route  208  by the application device  210 . 
     The onboard power source  212  represents one or more devices capable of storing electric energy, such as one or more batteries, capacitors, flywheels, and the like. Additionally or alternatively, the power source  212  may represent one or more devices capable of generating electric current, such as an alternator, generator, photovoltaic device, gas turbine, or the like. The power source  212  is coupled with the switch  224  so that the control unit  206  may control when the electric energy stored in the power source  212  and/or the electric current generated by the power source  212  is conveyed as electric current (e.g., direct current, alternating current, an RF signal, or the like) to the route  208  via the application device  210 . 
     The conditioning circuit  214  represents one or more circuits and electric components that change characteristics of electric current. For example, the conditioning circuit  214  may include one or more inverters, converters, transformers, batteries, capacitors, resistors, inductors, and the like. In the illustrated embodiment, the conditioning circuit  214  is coupled with a connecting assembly  226  that is configured to receive electric current from an off-board source. For example, the connecting assembly  226  may include a pantograph that engages an electrified conductive pathway  228  (e.g., a catenary) extending along the route  208  such that the electric current from the catenary  228  is conveyed via the connecting assembly  226  to the conditioning circuit  214 . Additionally or alternatively, the electrified conductive pathway  228  may represent an electrified portion of the route  208  (e.g., an electrified rail) and the connecting assembly  226  may include a conductive shoe, brush, portion of a wheel, or other body that engages the electrified portion of the route  208 . Electric current is conveyed from the electrified portion of the route  208  through the connecting assembly  226  and to the conditioning circuit  214 . 
     The electric current that is conveyed to the conditioning circuit  214  from the power source  212  and/or the off-board source (e.g., via the connecting assembly  226 ) may be altered by the conditioning circuit  214 . For example, the conditioning circuit  214  may change the voltage, current, frequency, phase, magnitude, intensity, waveform, and the like, of the current that is received from the power source  212  and/or the connecting assembly  226 . The modified current may be the examination signal that is electrically injected into the route  208  by the application device  210 . Additionally or alternatively, the control unit  206  may form the examination signal by controlling the switch  224 . For example, the examination signal may be formed by turning the switch  224  on to allow current to flow from the conditioning circuit  214  and/or the power source  212  to the application device  210 . 
     In an embodiment, the control unit  206  may control the conditioning circuit  214  to form the examination signal. For example, the control unit  206  may control the conditioning circuit  214  to change the voltage, current, frequency, phase, magnitude, intensity, waveform, and the like, of the current that is received from the power source  212  and/or the connecting assembly  226  to form the examination signal. 
     The examination signal is conducted through the application device  210  to the route  208 , and is electrically injected into a conductive portion of the route  208 . For example, the examination signal may be conducted into a conductive track of the route  208 . In another embodiment, the application device  210  may not directly engage (e.g., touch) the route  208 , but may be wirelessly coupled with the route  208  in order to electrically inject the examination signal into the route  208  (e.g., via induction). 
     The conductive portion of the route  208  that extends between the first and second vehicles  202 ,  204  during travel of the vehicle system may form a track circuit through which the examination signal may be conducted. The first vehicle  202  may be coupled (e.g., coupled physically, coupled wirelessly, among others) to the track circuit by the application device  210 . The power source (e.g., the onboard power source  212  and/or the off-board electrified conductive pathway  228 ) may transfer power (e.g., the examination signal) through the track circuit toward the second vehicle  204 . 
     By way of example and not limitation, the first vehicle  202  may be coupled to a track of the route  208 , and the track may be the track circuit that extends and conductively couples one or more components of the examining system  200  on the first vehicle  202  with one or more components of the examining system  200  on the second vehicle  204 . 
     In an embodiment, the control unit  206  includes or represents a manager component. Such a manager component may be configured to activate a transmission of electric current into the route  208  via the application device  210 . In another instance, the manager component may activate or deactivate a transfer of the portion of power from the onboard and/or off-board power source to the application device  210 , such as by controlling the switch and/or conditioning circuit. Moreover, the manager component may adjust parameter(s) associated with the portion of power that is transferred to the route  208 . For instance, the manager component may adjust an amount of power transferred, a frequency at which the power is transferred (e.g., a pulsed power delivery, AC power, among others), a duration of time the portion of power is transferred, among others. Such parameter(s) may be adjusted by the manager component based on at least one of a geographic location of the vehicle or the device or an identification of the device (e.g., type, location, make, model, among others). 
     The manager component may leverage a geographic location of the vehicle or the device in order to adjust a parameter for the portion of power that may be transferred to the device from the power source. For instance, the amount of power transferred may be adjusted by the manager component based on the device power input. By way of example and not limitation, the portion of power transferred may meet or be below the device power input in order to reduce risk of damage to the device. In another example, the geographic location of the vehicle and/or the device may be utilized to identify a particular device and, in turn, a power input for such device. 
     The detection module  218  disposed onboard the second vehicle  204  as shown in  FIG. 2  monitors the route  208  to attempt to detect the examination signal that is injected into the route  208  by the first vehicle  202 . The detection module  218  is coupled with the detection device  230 . In an embodiment, the detection device  230  includes one or more conductive bodies that engage the route  208  as the vehicle system that includes the vehicle  204  travels along the route  208 . For example, the detection device  230  may include a conductive shoe, brush, or other body that slides along an upper and/or side surface of a track such that a conductive pathway is created that extends through the detection device  230  and the track. Additionally or alternatively, the detection device  230  may include a conductive portion of a wheel of the second vehicle  204 , such as the conductive outer periphery or circumference of the wheel that engages the route  208  as the second vehicle  204  travels along the route  208 . In another embodiment, the detection device  230  may be inductively coupled with the route  208  without engaging or touching the route  208  or any component that engages the route  208 . 
     The detection module  218  monitors one or more electrical characteristics of the route  208  using the detection device  230 . For example, the voltage of a direct current conducted by the route  208  may be detected by monitoring the voltage conducted by from the route  208  to the detection device  230  and/or the current (e.g., frequency, amps, phases, or the like) of an alternating current or RF signal being conducted by the route  208  may be detected by monitoring the current conducted by the route  208  to the detection device  230 . The detection module  218  determines one or more electrical characteristics of the signal (e.g., voltage, frequency, phase, waveform, intensity, or the like) that is received (e.g., picked up) by the detection device  230  from the route  208  and reports the characteristics of the received signal to the identification module  220 . If no signal is received by the detection device  230 , then the detection module  218  may report the absence of such a signal to the identification module  220 . For example, if the detection module  218  does not detect at least a designated voltage, designated current, or the like, as being received by the detection device  230 , then the detection module  218  may not detect any received signal. Alternatively or additionally, the detection module  218  may communicate the detection of a signal that is received by the detection device  230  only upon detection of the signal by the detection device  230 . 
     In an embodiment, the detection module  218  may determine the characteristics of the signals received by the detection device  230  in response to a notification received from the control unit  206  in the first vehicle  202 . For example, when the control unit  206  is to cause the application device  210  to inject the examination signal into the route  208 , the control unit  206  may direct the communication unit  216  to transmit a notification signal to the detection device  230  via the communication unit  222  of the second vehicle  204 . The communication units  216 ,  222  may include respective antennas  232 ,  234  and associated circuitry for wirelessly communicating signals between the vehicles  202 ,  204 , and/or with off-board locations. The communication unit  216  may wirelessly transmit a notification to the detection module  218  that instructs the detection module  218  as to when the examination signal is to be input into the route  208 . Additionally or alternatively, the communication units  216 ,  222  may be connected via one or more wires, cables, and the like, such as a multiple unit (MU) cable, train line, or other conductive pathway(s), to allow communication between the communication units  216 ,  222 . 
     The detection module  218  may begin monitoring signals received by the detection device  230 . For example, the detection module  218  may not begin or resume monitoring the received signals of the detection device  230  unless or until the detection module  218  is instructed that the control unit  206  is causing the injection of the examination signal into the route  208 . Alternatively or additionally, the detection module  218  may periodically monitor the detection device  230  for received signals and/or may monitor the detection device  230  for received signals upon being manually prompted by an operator of the examining system  200 . 
     The identification module  220  receives the characteristics of the received signal from the detection module  218 . In the illustrated embodiment, The detection module  218 , identification module  220 , and communication unit  222 , along with a memory  221  (e.g., a tangible and non-transitory computer storage medium storing one or more instruction sets for performing tasks disclosed herein, storing one or more databases correlating signatures to construction features and/or location, or the like) are shown as part of a processing unit  219 . The processing unit  219  may include one or more processors. Alternatively, one or more aspects of the processing unit  219  may be a portion of an additional processing unit. In various embodiments the processing unit  219  includes processing circuitry configured to perform one or more tasks, functions, or steps discussed herein. It may be noted that “processing unit” as used herein is not intended to necessarily be limited to a single processor or computer. For example, the processing unit  219  may include multiple processors and/or computers, which may be integrated in a common housing or unit, or which may distributed among various units or housings. It may be noted that operations performed by the processing unit  219  (e.g., operations corresponding to process flows or methods discussed herein, or aspects thereof) may be sufficiently complex that the operations may not be performed by a human being within a reasonable time period. For example, the analysis of electrical characteristics of a signal, the analysis of a signature, the identification of a signature from a database corresponding to a currently analyzed signature, or the like, may rely on or utilize computations that may not be completed by a person within a reasonable time period. 
     The identification module  220  examines one or more electrical characteristics (e.g., a shape of a waveform, a strength of a signal, a duration of one or more portions of a signal, or the like) of a monitored examination signal, and identifies a construction feature corresponding to the monitored signal to identify a construction feature (e.g., switch, diamond crossing, bridge, or the like) that the vehicle passed over corresponding to the monitored examination signal. For example, as also discussed in connection with  FIG. 1 , the identification module  220  may identify a switch, as well as the direction of travel through the switch and the setting of the switch based on the one or more electrical characteristics. For example, a signature determined or generated based on the one or more electrical characteristics may be compared to a database of signatures for known construction features along the route. It may be noted that more than one examination signal may be analyzed. For example, separate detectors and transmitters may be positioned on each side of a vehicle, resulting in four signals that may be analyzed (e.g., a first signal transmitted from the left side and received at the left side, a second signal transmitted from the left side and receive at the right side, a third signal transmitted from the right side and received at the right side, and a fourth signal transmitted from the right side and received at the left side). Various characteristics or attributes of the signals (and/or sequences and/or durations of characteristics or attributes of the signal) may be used to identify a particular feature over which the vehicle has passed. Settings of the feature may also be determined. For example, the setting of a switch over which the vehicle has passed may be determined. 
     The identity and/or setting of the features passed over may be used to determine a location of the vehicle. The identification module  220  may determine the location of a vehicle along a route. For example, the identification module  220  may determine the position of the vehicle along a length of the route. In some embodiments, the location of construction features along a length of the route may be maintained, for example in a database. Thus, by identifying the time of passage over a given construction feature along with the time elapsed since passing over the construction feature and the speed of the vehicle during the time elapsed, along with the direction of travel, the position of the vehicle may be determined (or an otherwise determined location may be confirmed). Alternatively or additionally, for a vehicle traveling among a group of generally parallel paths, the particular path upon which the vehicle is traveling may be determined by the identification unit. For example, by identifying a particular switch passed over, as well as the direction of travel and setting of the switch, a particular path to which the switch has directed the vehicle may be determined. 
     It may be noted that a duration of one or more characteristics of the signal and/or a duration between characteristics may also be utilized to identify a feature (and, as a result, it identify a location) by the identification module  220 . For example, the duration of characteristics of a signal corresponding to a switch may correlate to or provide information regarding the size of the switch, helping to distinguish the switch from differently sized switches. As another example, the duration of characteristics corresponding to travel over a bridge may provide information correlating to or providing information regarding the length of the bridge, helping to distinguish the bridge from differently sized bridges. As one more example, the duration between pulses associated with insulated joints (e.g., insulated joints of a switch and signals on either side of the switch) may correlate to or provide information regarding the distance between the signals and the switch, helping to distinguish the switch (as well as the direction of travel) from switches having signals placed at different distances relative to the switch. 
     The identification module  220  may include or be communicatively coupled (e.g., by one or more wired and/or wireless connections that allow communication) with a location determining unit that may determine the location of the vehicle  204  and/or vehicle system. For example, the location determining unit may include a GPS unit or other device that may determine where the first vehicle and/or second vehicle are located along the route  208 . The distance between the first vehicle  202  and the second vehicle  204  along the length of the vehicle system may be known to the identification module  220 , such as by inputting the distance into the identification module  220  using one or more input devices and/or via the communication unit  222 . The location determined by the identification module  220  may be compared to the location provided by the location determining unit as a check or to confirm the location. 
       FIG. 3  is a schematic illustration of an embodiment of an examining system  300  on a vehicle  302  of a vehicle system (not shown) traveling along a route  304 . The examining system  300  may represent the examining system  200  shown in  FIG. 2 . In contrast to the examining system  200 , the examining system  300  is disposed within a single vehicle  302 .  FIG. 3  may be understood as a top-down view looking at least partially through the vehicle  302 . The vehicle  302  may be one of multiple vehicles of the vehicle system  302 . 
     The vehicle  302  includes multiple transmitters or application devices  306  disposed onboard the vehicle  302 . The application devices  306  may be positioned at spaced apart locations along the length of the vehicle  302 . For example, a first application device  306 A may be located closer to a front end  308  of the vehicle  302  relative to a second application device  306 B located closer to a rear end  310  of the vehicle  302 . The designations of “front” and “rear” may be based on the direction of travel  312  of the vehicle  302  along the route  304 . As shown in  FIG. 3 , the first application device  306 A and second application device  306 B may be disposed on different sides (e.g., left or right in the direction of travel) of the vehicle  302 . 
     The route  304  includes conductive tracks  314  in parallel, and the application devices  306  are configured to be conductively and/or inductively coupled with at least one conductive track  314  along the route  304 . For example, the conductive tracks  314  may be rails in a railway context. In an embodiment, the first application device  306 A is configured to be conductively and/or inductively coupled with a first conductive track  314 A, and the second application device  306 B is configured to be conductively and/or inductively coupled with a second conductive track  314 B. As such, the application devices  306  may be disposed on the vehicle  302  diagonally from each other as shown in  FIG. 3 . The application devices  306  are utilized to electrically inject at least one examination signal into the route. For example, the first application device  306 A may be used to inject a first examination signal into the first conductive track  314 A of the route  304 . Likewise, the second application device  306 B may be used to inject a second examination signal into the second conductive track  314 B of the route  304 . 
     The vehicle  302  also includes multiple receiver coils or detection units  316  disposed onboard the vehicle  302 . The detection units  316  are positioned at spaced apart locations along the length of the vehicle  302 . For example, a first detection unit  316 A may be located towards the front end  308  of the vehicle  302  relative to a second detection unit  316 B located closer to the rear end  310  of the vehicle  302 , with the first detection unit  316 A disposed on an opposite or different side of the vehicle  302  along a direction of travel (e.g., left or right) than the second detection unit  316 B. The detection units  316  are configured to monitor one or more electrical characteristics of the route  304  along the conductive tracks  314  in response to the examination signals being injected into the route  304 . The electrical characteristics that are monitored may include an amplitude of a current, a phase shift, a modulation, a frequency, a voltage, an impedance, and the like. For example, the first detection unit  316 A may be configured to monitor one or more electrical characteristics of the route  304  along the second track  314 B, and the second detection unit  316 B may be configured to monitor one or more electrical characteristics of the route  304  along the first track  314 A. As such, the detection units  316  may be disposed on the vehicle  302  diagonally from each other. In an embodiment, each of the application devices  306 A,  306 B and the detection units  316 A,  316 B may define individual corners of a test section of the vehicle  302 . Optionally, the application devices  306  and/or the detection units  316  may be staggered in location along the length and/or width of the vehicle  302 . Optionally, the application device  306 A and detection unit  316 A and/or the application device  306 B and detection unit  316 B may be disposed along the same track  314 . The application devices  306  and/or detection units  316  may be disposed on the vehicle  302  at other locations in other embodiments. 
     In an embodiment, two of the conductive tracks  314  (e.g., tracks  314 A and  314 B) may be conductively and/or inductively coupled to each other through multiple shunts  318  along the length of the vehicle  302 . For example, the vehicle  302  may include two shunts  318 , with one shunt  318 A located closer to the front  308  of the vehicle  302  relative to the other shunt  318 B. In an embodiment, the shunts  318  are conductive and together with the tracks  314  define an electrically conductive test loop  320 . The conductive test loop  320  represents a track circuit or circuit path along the conductive tracks  314  between the shunts  318 . The test loop  320  moves along the tracks  314  as the vehicle  302  travels along the route  304  in the direction  312 . Therefore, the section of the conductive tracks  314  defining part of the conductive test loop  320  changes as the vehicle  302  progresses on a trip along the route  304 . 
     In an embodiment, the application devices  306  and the detection units  316  are in electrical contact with the conductive test loop  320 . For example, the application device  306 A may be in electrical contact with track  314 A and/or shunt  318 A; the application device  306 B may be in electrical contact with track  314 B and/or shunt  318 B; the detection unit  316 A may be in electrical contact with track  314 B and/or shunt  318 A; and the detection unit  316 B may be in electrical contact with track  314 A and/or shunt  318 B. 
     The two shunts  318 A,  318 B may be first and second trucks disposed on a rail vehicle. Each truck  318  includes an axle  322  interconnecting two wheels  324 . Each wheel  324  contacts a respective one of the tracks  314 . The wheels  324  and the axle  322  of each of the trucks  318  are configured to electrically connect (e.g., short) the two tracks  314 A,  314 B to define respective ends of the conductive test loop  320 . For example, the injected first and second examination signals may circulate the conductive test loop  320  along the length of a section of the first track  314 A, through the wheels  324  and axle  322  of the shunt  318 A to the second track  314 B, along a section of the second track  314 B, and across the shunt  318 B, returning to the first track  314 A. 
     In an embodiment, alternating current transmitted from the vehicle  302  is injected into the route  304  at two or more points through the tracks  314  and received at different locations on the vehicle  302 . For example, the first and second application devices  306 A,  306 B may be used to inject the first and second examination signals into respective first and second tracks  314 A,  314 B. One or more electrical characteristics in response to the injected examination signals may be received at the first and second detection units  316 A,  316 B. Each examination signal may have a unique identifier so the signals may be distinguished from each other at the detection units  316 . For example, the unique identifier of the first examination signal may have a base frequency, a modulation, an embedded signature, and/or the like, that differs from the unique identifier of the second examination signal. 
       FIG. 4  depicts examination signals corresponding to a facing diverging move (e.g., travel in the facing direction  101  through the switch  110  to the second track  114  via the path  106 ), and  FIG. 5  depicts examination signals corresponding to a trailing diverging move (e.g., travel in the trailing direction  103  from the second track  114  to the first track  112  via the switch  110 ). 
       FIG. 4  depicts a signature  400  having four different signals corresponding to a vehicle traveling in a facing direction through a switch in a reverse (or diverging) position. The four signals include a first signal  402  collected at a first detector from a first transmitter at a first frequency, a second signal  403  collected at the first detector from a second transmitter at a second frequency, a third signal  404  collected at a second detector from the first transmitter at the first frequency, and a fourth signal  405  collected at the second detector from the second transmitter at the second frequency. The signature  400  is plotted as signal amplitude along a horizontal axis of time travelled. The time travelled may be converted to distance travelled using the speed of the vehicle. The first transmitter and first detector may be on a first side of the vehicle (e.g., left), and the second transmitter and the second detector may be on a different side of the vehicle (e.g., right). 
     As the vehicle travels through the switch and surrounding area, a first pulse  410 , or sudden drop in amplitude, is experienced as the vehicle passes an insulated joint associated with a signal before the switch is encountered. After passing the signal, the pulse  410  terminates and the signal exhibits characteristics corresponding to an approach to the switch. A second pulse  420  corresponds to an insulated joint associated with the switch. For example, the second signal  403  includes a fairly steep drop  428  (followed by a short rise) immediately before the second pulse  420 , and the first signal  402  includes a fairly steep rise  426  (followed by a relatively shorter drop) immediately before the second pulse  420 . The drop  428  and the rise  426  may correspond to a particular attribute of a switch (e.g., a point rail, two adjacent rails at or near contact, two adjacent rails separated by a gap, or the like). The drop  428  and rise  426  are provided as examples only, as additional or alternate characteristics of the signals may also be identified in various embodiments. As the vehicle travels through and past the switch, the signature  400  includes a third pulse  430  corresponding to an insulated joint disposed past the switch along the facing direction. It may be noted that the distance between the third pulse  430  and the second pulse  420  is greater than the distance between the first pulse  410  and the second pulse  420 . Thus, by observing the distances between the pulses, the order in which the pulses were encountered may be determined and used to determine a direction of travel of the vehicle, based, for example, on stored information describing the location of the signals relative to a given switch identified using the signature  400 . 
     It may be noted that the signals may have generally similar characteristics during passage through the insulated joints of the signals (e.g., first pulse  410  and third pulse  430 ); however, the characteristics encountered during the second pulse  420  (associated with an insulated joint of the switch) differ from those of the pulses associated with signals. For example, the first signal  402  includes a drop  422  and the third signal  405  includes a characteristic  424  not seen in the first pulse  410  or third pulse  430 . Thus, characteristics during a pulse as well as near a pulse may provide information regarding a feature that may be used to identify the type of feature (e.g., switch) as well as to distinguish the feature from other features of the same type but having different configurations (e.g., different sizes, diverging in different directions, or the like). 
     Generally, because the signals are sent and/or received from different sides of the vehicle, various characteristics of the four signals or relationships between the characteristics of the four signals may provide information regarding along which side of a route a particular attribute of a switch is encountered. Thus, a given signature (e.g., a collection of characteristics of the four signals over a span of time) may be associated not only with particular attributes of a switch (e.g., frog) but also associated with a side of the route along which those particular attributes are encountered. Thus, the signatures may provide or correspond to not only the size and type of feature, but also to direction of travel and configuration of feature. Thus, the various characteristics, as well as the order of characteristics, the identification of the particular signal in which a given characteristic is located, and/or the distance between characteristics may provide information that may be used to identify the type of construction feature as well as to differentiate between particular construction features. In some embodiments, a database of signatures associated with each feature (and, optionally, settings of some or all of the features and/or direction of travel) may be developed and used to identify features corresponding to signatures collected during travel along the route. 
       FIG. 5  depicts a signature  500  having four different signals corresponding to a vehicle traveling in a trailing direction through a switch in a reverse (or diverging) position. The switch and signals encountered in  FIG. 5  thus may be similar to the switch and signals encountered in  FIG. 4 ; however, the direction of travel is reversed in  FIG. 5  relative to  FIG. 4 . The four signals include a first signal  502  collected at a first detector from a first transmitter at a first frequency, a second signal  503  collected at the first detector from a second transmitter at a second frequency, a third signal  504  collected at a second detector from the first transmitter at the first frequency, and a fourth signal  505  collected at the second detector from the second transmitter at the second frequency. The signature  500  is plotted as signal amplitude along a horizontal axis of time travelled. The time travelled may be converted to distance travelled using the speed of the vehicle. As discussed in connection with  FIG. 4 , the first transmitter and first detector may be on a first side of the vehicle (e.g., left), and the second transmitter and the second detector may be on a different side of the vehicle (e.g., right). 
     The first signature includes a first pulse  530  (corresponding to the same insulated joint associated with the third pulse  430 ), a second pulse  520  (corresponding to the same insulated joint associated with the second pulse  420 ), and a third pulse  510  (corresponding to the first pulse  410 ). The insulated joints in  FIG. 5  are encountered in reverse order compared to  FIG. 4 . Generally similar to  FIG. 4 , in  FIG. 5 , the second pulse  520  (associated with an insulated joint of the switch) includes characteristics  522 ,  524  that differ from characteristics of the first pulse  530  and the third pulse  510 . 
     Because the switch is the same switch in the same position (reverse or diverging), certain characteristics of the signature  500  may correspond at least loosely to certain characteristics of the signature  400 . However, because the direction of travel is different, the order of the characteristics as well as the precise shape or configuration of the characteristics may vary. 
     For example, the first signal  502  includes a drop  526  after the vehicle passes the insulated joint associated with the second pulse  520  in the trailing direction that corresponds to the rise  426 . Characteristic  526  is a drop instead of a rise due to the direction of travel. The precise shape of the characteristics are not true mirror images of each other in the illustrated embodiment, but, as seen in  FIG. 5 , exhibit a correlation or general similarity. Similarly, the second signal  503  includes a rise  528  that corresponds to the drop  426 . The differences in these characteristics thus may help identify not only a feature encountered but a direction of travel as well. Additionally or alternatively, the distance between pulses of insulated joints may be used to determine direction of travel. For example, in  FIG. 4 , a shorter distance between pulses is encountered first followed by a longer distance, while, in  FIG. 5 , a longer distance between pulses is encountered first followed by a shorter distance, indicating the direction of travel is different for the two signatures  400 ,  500 . 
     Each construction feature of a route may be studied (e.g., by performing test runs and collecting signatures) to provide a representative signature of the feature for each setting and direction of travel possible for the feature. The signature may also include distances between surrounding insulating joints of signals disposed on opposite sides of the feature. The representative signatures may be stored in a database and used to identify features for signatures encountered during performance of a mission (e.g., via comparison with the stored representative signatures to identify the most similar stored representative signature, or a most similar signature within a predetermined range of an estimated location). 
     Thus, the positioning of features (e.g.,  426 ,  428 ,  526 ,  528 ) relative to an insulated joint, and the sequence of and/or distance between insulated joints (e.g., the order in which insulated joints are encountered determined, for example, based on distances between the insulated joints) may be used to not only identify a particular switch but also to identify a direction of travel and/or a setting of the switch. 
       FIG. 6  is a flowchart of a method  600  for identifying a construction feature encountered along a route in accordance with an example of the present inventive subject matter. The method  600 , for example, may employ or be performed by structures or aspects of various embodiments (e.g., systems and/or methods and/or process flows) discussed herein. In various embodiments, certain steps may be omitted or added, certain steps may be combined, certain steps may be performed simultaneously, certain steps may be performed concurrently, certain steps may be split into multiple steps, certain steps may be performed in a different order, or certain steps or series of steps may be re-performed in an iterative fashion. In various embodiments, portions, aspects, and/or variations of the method  600  may be able to be used as one or more algorithms to direct hardware (e.g., one or more aspects of the processing unit  219 ) to perform one or more operations described herein. 
     At  602 , examination signals are transmitted. For example, one or more transmitters disposed onboard a vehicle may inject examination signals into tracks of a route. In some embodiments, plural transmitters may be disposed on different sides of a vehicle and/or different points along length. For example, a first transmitter and a second transmitter, each transmitting at a distinct and recognizable frequency, may be disposed on different sides (e.g., left and right) of a vehicle. It may be noted that the transmitters may be disposed on the same vehicle within a vehicle system (e.g., consist) or on different vehicles within a vehicle system. The examination signals may be transmitted at regular intervals and/or in connection with construction features expected to be encountered based on a schedule or trip plan for the vehicle, and/or responsive to detection of an upcoming construction feature (e.g., detection of an insulated joint, reception of a message from a signal and/or switch, or the like). 
     At  604 , the examination signals are monitored. For example, the examination signals that have been injected into the track at  602  may be detected via detection units communicably coupled to the track. Similar to the transmitters, plural detection units on different sides of a vehicle may be employed. In some embodiments, one or more detection units may be disposed on the same vehicle as one or more transmitters. In various embodiments, one or more detection units may be disposed on a different vehicle than one or more transmitters. 
     At  606 , one or more construction features (bridge, switch, diamond crossing) passed over by the vehicle are identified. For example, a signature including characteristics of one or more examination signals may be compared to representative signatures for known construction features along the route to determine the feature passed over. Not only may a construction feature such as a switch by identified using the examination signals, but a setting of the switch (e.g., normal or reverse) as well as a direction of travel may be determined. In various embodiments, identifying one or more construction features may include one or more substeps, such as substeps  608  or  610 . 
     At  608 , a collected signature (e.g., one or more signals obtained via one or more detectors over a span of time as a vehicle passes by a given construction feature) is compared to stored signatures for each feature along a route. For example, a database of signatures for each feature of a route (as well as for each setting and/or direction of travel) may be examined to identify a signature most similar to a recently obtained signature. 
     At  610 , individual characteristics are studied to identify corresponding attributes (e.g., point rail, frog) of the signature. For example, by identifying particular attributes of a signature, as well as the sequence of and distance between the attributes, the type of feature (e.g., switch, diamond crossing bridge) as well as, optionally, a setting of the feature (e.g., reverse and normal positions of a switch) and/or direction of travel may be determined. Further, by distinguishing between the distances between attributes of a switch, and/or and the position of attributes on different sides of a route, and/or the distance of signals (indicated by pulses caused by insulated joints associated with the signals) from the switch, individual switches may be distinguished between. 
     At  612 , the location is determined. For example, the vehicle may have stored thereon or otherwise accessible to the vehicle a database or map indicating the location of each construction feature. Once a construction feature has been identified as being passed over, the location of the construction feature, the time elapsed since passing over the construction feature, and the speed of train may be used to determine the location of the vehicle. For increased reliability, multiple construction features may be identified and used to check or confirm a location determined using a single identified construction feature. In some embodiments, the location may describe or depict a location along a length of the route. Alternatively or additionally, the location may describe or depict a particular path among a plurality of paths upon which the vehicle is traveling. For example, by identifying a particular switch the vehicle has passed over (e.g., identifying the most recently passed over switch), as well as the setting of the switch and the direction of travel, the specific path upon which the vehicle is traveling may be determined based on the path resulting from passing over the switch in the specified direction with the switch at the specified setting. 
     In an embodiment, a system includes at least one application device, a control unit, and at least one processor. The at least one application device is configured to be at least one of conductively or inductively coupled with at least one of a first conductive track or a second conductive track of a route being traveled by a vehicle. The control unit is configured to control supply of electric current from a power source to the at least one application device to electrically inject at least one examination signal into the conductive tracks via the at least one application device. The at least one processor configured to be disposed onboard the vehicle. The at least one processor configured to monitor one or more electrical characteristics of at least one of the first or second conductive tracks in response to the at least one examination signal being injected into the conductive tracks, and to identify a construction feature of the route based on an examination of the one or more electrical characteristics, the construction feature corresponding to a man-made aspect of the route. 
     In one aspect, the at least one application device is configured to be disposed onboard the vehicle. 
     In one aspect, the at least one application device includes first and second application devices configured to be disposed onboard the vehicle, with the first and second application devices each configured to be at least one of conductively or inductively coupled with one or more of the conductive tracks. The control unit is configured to control supply of electric current from the power source to the first and second application devices in order to electrically inject a first examination signal of the at least one examination signal via the first application device into the one or more of the conductive tracks to which the first application device is coupled, and to electrically inject a second examination signal of the at least one examination signal via the second application device into the one or more of the conductive tracks to which the second application device is coupled. The system further includes first and second detection devices configured to be disposed onboard the vehicle on different sides of the vehicle. 
     In one aspect, the at least one processor is operably coupled to a database including locations correlated to construction features, and the at least one processor is configured to identify a location of the vehicle based on the construction feature that is identified as cross-referenced by the database. 
     In one aspect, the at least one processor is configured to identify a location of the vehicle along a length of the route. 
     In one aspect, the at least one processor is configured to identify a particular one of a group of at least two or more generally parallel paths upon which the vehicle system is traveling. 
     In one aspect, the construction feature includes a switch, and the at least one processor is configured to identify a direction of travel of the vehicle system and a setting of the switch based on the one or more electrical characteristics. 
     In one aspect, the construction feature includes at least one of a diamond crossing or a bridge. 
     In one aspect, the at least one processor is configured to identify the construction feature based upon a duration of the one or more electrical characteristics. 
     In another embodiment, a system includes a first application device, a second application device, a control unit, and at least one processor. The first application device and the second application device are configured to be at least one of conductively or inductively coupled with at least one of a first conductive track or a second conductive track of a route being traveled by a vehicle. The control unit is configured to control supply of electric current from a power source to the first and second application devices to electrically inject a first examination signal via the first application device and a second examination signal via the second application device into the conductive tracks. The first and second examination signals include respective unique identifiers. The at least one processor is configured to be disposed onboard the vehicle. The at least one processor is configured to monitor one or more electrical characteristics of at least one of the first or second conductive tracks in response to the first and second examination signals being injected into the conductive tracks; to identify a construction feature of the route based on an examination of the one or more electrical characteristics, wherein the construction feature corresponding to at least one of a switch, a diamond crossing, or a bridge; to determine a location of the vehicle based on the construction feature; and to control at least one device onboard the vehicle based on the location that is determined. 
     In another embodiment, a method includes injecting, via at least one application device disposed upon a vehicle, at least one examination signal into at least one of first or second conductive tracks of a route being traveled by the vehicle. The method also includes monitoring, via at least one detection device disposed upon the vehicle, one or more electrical characteristics of at least one of the first or second conductive tracks in response to the at least one examination signal being injected into the at least one of the first or second conductive tracks. Also, the method includes identifying a construction feature of the route based on the one or more electrical characteristics. 
     In one aspect, injecting the at least one examination signal includes electrically injecting first and second examination signals into the first and second conductive tracks of the route being traveled by the vehicle, with the first and second examination signals being injected at spaced apart locations along a length of the vehicle. Also, in one aspect, monitoring the one or more electrical characteristics of at least one of the first or second conductive tracks includes monitoring the first and second conductive tracks at first and second monitoring locations disposed onboard the vehicle in response to the first and second examination signals being injected into the conductive tracks. 
     In one aspect, the first examination signal is injected into the first conductive track and the second examination signal is injected into the second conductive track. 
     In one aspect, the first and second examination signals include respective unique identifiers configured to allow for distinguishing the first examination signal from the second examination signal in the one or more electrical characteristics of the conductive tracks. 
     In one aspect, identifying the construction feature includes identifying a switch. 
     In one aspect, identifying the switch includes identifying a direction of travel through the switch based on the one or more electrical characteristics. 
     In one aspect, identifying the switch includes identifying a setting of the switch based on the one or more electrical characteristics. 
     In one aspect, the method includes identifying a location of the vehicle based on the construction feature identified. 
     In one aspect, identifying the location includes identifying a position of the vehicle along a length of the route based on the one or more electrical characteristics. 
     In one aspect, identifying the location includes identifying a particular one of a group of at least two or more generally parallel paths upon which the vehicle is traveling based on the one or more electrical characteristics. 
     It is to be understood that the above description is intended to be illustrative, and not restrictive. For example, the above-described embodiments (and/or aspects thereof) may be used in combination with each other. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the inventive subject matter without departing from its scope. While the dimensions and types of materials described herein are intended to define the parameters of the inventive subject matter, they are by no means limiting and are exemplary embodiments. Many other embodiments will be apparent to one of ordinary skill in the art upon reviewing the above description. The scope of the inventive subject matter should, therefore, be determined with reference to the appended clauses, along with the full scope of equivalents to which such clauses are entitled. In the appended clauses, the terms “including” and “in which” are used as the plain-English equivalents of the respective terms “comprising” and “wherein.” Moreover, in the following clauses, the terms “first,” “second,” and “third,” etc. are used merely as labels, and are not intended to impose numerical requirements on their objects. Further, the limitations of the following clauses are not written in means-plus-function format and are not intended to be interpreted based on 35 U.S.C. §112(f), unless and until such clause limitations expressly use the phrase “means for” followed by a statement of function void of further structure. 
     This written description uses examples to disclose several embodiments of the inventive subject matter and also to enable a person of ordinary skill in the art to practice the embodiments of the inventive subject matter, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the inventive subject matter may include other examples that occur to those of ordinary skill in the art. Such other examples are intended to be within the scope of the clauses if they have structural elements that do not differ from the literal language of the clauses, or if they include equivalent structural elements with insubstantial differences from the literal languages of the clauses. 
     The foregoing description of certain embodiments of the inventive subject matter will be better understood when read in conjunction with the appended drawings. To the extent that the figures illustrate diagrams of the functional blocks of various embodiments, the functional blocks are not necessarily indicative of the division between hardware circuitry. Thus, for example, one or more of the functional blocks (for example, processors or memories) may be implemented in a single piece of hardware (for example, a general purpose signal processor, microcontroller, random access memory, hard disk, and the like). Similarly, the programs may be stand-alone programs, may be incorporated as subroutines in an operating system, may be functions in an installed software package, and the like. The various embodiments are not limited to the arrangements and instrumentality shown in the drawings. 
     As used herein, an element or step recited in the singular and proceeded with the word “a” or “an” should be understood as not excluding plural of said elements or steps, unless such exclusion is explicitly stated. Furthermore, references to “an embodiment” or “one embodiment” of the inventive subject matter are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features. Moreover, unless explicitly stated to the contrary, embodiments “comprising,” “including,” or “having” an element or a plurality of elements having a particular property may include additional such elements not having that property. 
     Since certain changes may be made in the above-described systems and methods without departing from the spirit and scope of the inventive subject matter herein involved, it is intended that all of the subject matter of the above description or shown in the accompanying drawings shall be interpreted merely as examples illustrating the inventive concept herein and shall not be construed as limiting the inventive subject matter.