DESCRIPTION

Field of application

The present invention relates to a system for monitoring rails. In particular, the invention relates to the technical sector of systems for controlling railway sections, intended to detect and signal obstacles along the section. The invention also relates to a method for monitoring rails.

Prior art:

Monitoring systems for detecting and signalling obstacles along rails, for example rails of a railway, tram or underground train line, are known.

These systems are based on stations, in some cases manned, installed along the line and equipped with electronic devices communicating with a control centre. The electronic devices may be controlled by an operator, who detects the obstacle locally and transmits it in the form of a text or voice signal, preferably together with pictures or videos, or may be automated, namely programmed to detect the obstacle autonomously, for example by means of sensors, digital photo cameras or video cameras, and communicate with the control station, when the obstacle is detected. Communication is performed by means of a telecommunications network known per se, for example GPRS, UMTS or Internet.

Automated systems are advantageous because they allow monitoring of the section also in the absence of personnel, and therefore a reduction in costs, while still providing important information for maintenance of the section, for transit of the rolling stock in safe conditions or for speeding up the operations for repair work and removal of the obstacles.

However, the known automated systems suffer from a number of drawbacks which occur especially in geographical areas where it is required to perform very widespread and frequent monitoring, for example owing to sudden changes in the weather conditions or working state of the track. These problems are particularly evident in Arab countries where the train lines may stretch over several hundred kilometres and also may pass through desert regions; in these locations, being able to detect immediately any movement of the sand in the vicinity of the track would help avoid delays or interruptions in the rail traffic and, in particular, serious accidents.

The same problems occur along rail sections where there may be sudden accumulations of snow or also in some cities which are affected by prolonged rainfall, with the consequent flooding of sections of underground train lines or flooding of tram lines, and also in some mountain areas where rock masses may fall onto the track.

In all these cases, the known automated systems are not sufficient to ensure efficient monitoring since they are unable to cover continuously the entire rail section and therefore are unable to detect events where no station is installed. Moreover, the frequent transmission of text or voice data, together with digital or video data, by a plurality of stations cannot be handled by the telecommunications network because of the considerable size of said data. Furthermore, even if it were possible to transmit this large amount of data via the central station, there would still be the problem of how to manage it effectively, i.e. identifying immediately the critical points along the rail section and coordinating consequently a rapid response on-site.

Finally, even assuming that the obstacle occurs in an area monitored by a station, with the known systems it is not possible to determine immediately the size of said obstacle, for example indicate the height of a sand mass which has accumulated on a track, so as to be able to coordinate in good time the necessary action for removal thereof locally. In fact, the known stations do not carry out a direct measurement of the obstacle on the track, but only provide approximate estimates, for example based on the recorded images or the information supplied by any personnel monitoring the location, with an inevitable increase in the time needed to coordinate remedial action and selection of the right equipment for removal of the obstacle. The technical problem forming the basis of the present invention is that of devising a system and a method for monitoring a track, and in particular of a railway, tram or underground train section, which, on the one hand, is able to supply to a central station information regarding the working conditions of the track, in order to verify that it is in a safe working state and allows normal transit or whether there is a reduction in the performance of the track, with a corresponding quantification of the loss of performance, and which, on the other hand, is able to check and identify in real time precise points along the track where there may be any obstacles, for example sand or rock masses or flooding, providing a direct, accurate and immediate measurement of these obstacles, including for example the height of the sand or rock mass on the track or the depth of flooding, and thus allowing coordination in an optimum manner of any measures for repairing the line, reducing the delays and dangers for persons, and substantially overcoming all the drawbacks which are currently associated with the known monitoring systems. Summary of the invention

The idea forming the basis of the present invention is to use optical fibre cables in order to measure and communicate in real time the working conditions of a track along the entire railway, tram or underground train section, and also identify, in real time and continuously along the entire section, any obstacles on the track, for example sand and rock masses or flooding, with precise measurement of the size of the obstacles, in terms of height of the sand or rock mass or depth of flooding, or the extent of their presence along the section.

In the description below the term "obstacle" is used to indicate generally any type of deposited or agglomerated mass which may have accidentally formed on a track, for example following a particular weather condition, or which has been deliberately placed on the rails, altering to a certain degree the performance of the track or even preventing transit.

However, in order to simplify illustration and provide a concrete example of embodiment, in the description in some cases explicit reference is made to a situation where the obstacle is formed by a sand mass, this example however not limiting the scope of protection of the present invention.

On the basis of the proposed solution indicated above, the proprietor of the present application more precisely has had the idea of installing optical fibre cables along the railway tracks, these being designed to detect continuously a temperature associated with the rails or the ground, whether it be the ballast supporting a railway track or the road surface of a tramway section or underground path of an underground train line, and obtain in real time, by means of temperature values of the track and the ground, information regarding the suitability of the track for travel substantially along the entire railway section. The temperature values are determined by a plurality of workstations, each connected to the cables at different connection points along the track and intended to collect the transmitted signals of the optical fibre cables, along a predetermined section of the cable.

In particular, a cable may be in contact with the rail, in order to detect signals indicating the temperature of the rail and determine the operating condition of said rail. The signals transmitted by this cable to the workstation are used to determine whether the rail is able to ensure the normal performance or whether, owing to an abnormal temperature associated with the track, it may constitute a danger for the rail traffic. In this case, the reduction in performance is quantified, for example as being all the greater the greater the difference between the detected temperature of the rail and its reference temperature under normal working conditions, and is sent to a control module which, depending on the loss of performance, may immediately order suspension of the traffic or slowing- down of the speed.

Another cable may be in contact with the ballast and be intended to detect the temperature of the ballast. Depending on the detected temperature of the ballast, the presence of an obstacle, for example sand, is determined, together with the size of the obstacle, i.e. the depth at which the rail is buried underneath the sand or the area covered by the sand mass. This information is supplied in real time to the control module which is therefore able to coordinate remedial measures with a high degree of accuracy along the entire rail section, rapidly and with precise instructions, being able for example to recruit personnel and machinery closest to the location of the obstacle and best suited for removal thereof.

Still on the basis of this proposed solution, the temperature values determined in the workstations are transmitted, together with the respective signal detection positions, to a processing station which is structured to determine said obstacles on the basis of the temperature and position values. Advantageously, as a result of the monitoring system structured in this way, it is possible to obtain a fully updated picture as to the working state of the railway sections, substantially in real time, and achieve a significant advantage, especially in those countries where the sections are not manned or are subject to rapid changes in the climate or weather conditions which have a significant effect on the morphology of the terrain, for example in Arab countries, also where the rail section extends for hundreds of kilometres through a desert region and where the rapid movement of the sand may suddenly prevent the transit of a train.

According to the proposed solution described above, the technical problem underlying the present invention is solved by a monitoring method and system according to the accompanying claims. In particular, the association of cables with the rails and/ or the ground underneath the rails allows monitoring of the rail section over a very wide geographical area and in a practically point- specific manner, and the transmission of the optical signal by means of fibre allows communication with the reference workstations along the sections substantially without any time delay. In fact, determination of the obstacle is performed following transmission of the optical signal, on the basis of temperature and position values derived from the signal, and not by means of pictures, videos or data which are large in size and extremely difficult to manage.

Advantageously, the system according to the present invention calculates the height of the sand or indicates the presence of water or a rock depending on the temperature. In particular, a relation between the degrees of temperature and the centimetres of accumulated mass of the obstacle (sand, water, rocks, etc.) on the rails is established. In fact, under normal working conditions, the cable on the ballast is substantially free from obstacles, for example is not covered by sand; when a mass of sand (or other obstacles) is formed on the cable, the temperature of the cable changes and in particular decreases in a manner proportional to the increase in a thickness of the sand mass on top of the cable, in accordance with a physical relation which associates the depth of the ground and its temperature. Said relation also considers the moment when detection is performed, for example day-time or night-time.

Further characteristic features and advantages of the method and the system according to the invention will become clear from the description hereinbelow of an example of application thereof, with reference to the attached drawings, provided purely by way of a non-limiting example.

Brief description of the attached figures

Figure 1 shows in schematic form a monitoring system according to the present invention.

Figure 2 shows in schematic form a cable of the monitoring system according to the present invention.

Figure 3 shows in schematic form a graphical component of a control module of the monitoring system according to the present invention.

Figures 4 and 5 show in schematic form other graphical components of the control module according to Figure 3. Figure 6 shows in schematic form a further graphical component of the control module according to Figure 3.

Figures 7a-7c show in schematic form other graphical components of the control module according to Figure 3.

Detailed description With reference to the attached figures a monitoring system according to the present invention is schematically shown and indicated by the reference number 1.

The system 1 is applied to rails 100 of a railway, tram or underground train line or railroad tracks and comprises at least one first optical fibre cable "a", intended to be mounted in contact with a respective rail 201, and at least one second optical fibre cable "b", intended to be fixed on top of the ballast or the ground or the sleepers of the track.

The cables "a", "b" are structured for example as shown in Figure 2, namely with a central core formed by a plurality of optical fibres (four in the figure), by a stainless steel lining tube, externally protected by a ring of steel tubes wound and retained by a screening in the form of an outer cover.

The cable "a" on the rail has the function of measuring the operating temperature of the rail and signalling any anomalies and therefore any alterations or deterioration in the mechanical properties of the rail. The cable on the ballast has the function of measuring the temperature of the ground; as explained in greater detail below, a plurality of workstations determine pairs of "temperature/ position" data depending on the signals received from the cable on the ballast and send the data to a processing system for conversion thereof into the dimensions of the obstacle, for example height and/ or depth and/ or volume values. Said dimensions of the obstacle are transmitted to a mapping module for displaying and managing the threshold values; when the obstacles exceed a predefined threshold, the mapping module activates alarms or triggers automatic procedures for removal of the obstacle.

More particularly, the cables are intended to detect continuously a plurality of signals al, a28, bl, b28 dependent on a temperature of the track (cable "a") or the ballast (cable "b") in a corresponding plurality of positions Rl, R28 along the track.

In Figure 1 the detection positions are indicated Rl,..., R28, and in the description below the signals detected and transmitted by the cable "a" in the positions Rl,..., R28 are indicated by al,..., a28 and the signals detected and transmitted by the cable "b" in the positions Rl,..., R28 are indicated by bl,..., b28. This illustration obviously does not limit the geographical density of the signals which may be detected by the cable and which may be increased, with the acquisition of signals situated closer together, or which may be reduced, i.e. with an increase in the distance between the detection points Rl,..., R28, as will become clearer below.

Still with reference to Figure 1, 4 denotes the processing system intended to receive at its input the signals al,..., a28, bl,..., b28 from the optical fibre cables a, b and to determine the temperatures Tal,..., Ta28, Tbl,..., Tb28 associated with the signals and the respective detection positions Rl,..., R28.

The detection positions Rl,..., R28 are determined, for example, depending on a time delay with which the signals al,..., a28, bl,..., b28 are received in the processing station 4: a signal al received with a delay rl is considered as coming from a detection point Rl more distant than a signal a2 received with a delay r2 from a closer detection point R2. The processing station may be programmed to read the signals at predefined intervals; at each predefined interval a set of signals, al ,..., a28, bl,..., b28 delayed with respect to each other depending on the detection distance is read. The signals ai and bi are received substantially together since they come from the same detection position Ri, but from two different cables a, b.

The processing station, on the basis of the temperature values Tal,..., Ta28, outputs one or more positions PI in which an obstacle 202 along the path of the track or a loss of performance of the rail is potentially present.

The working conditions of the rail are determined on the basis of the temperatures of the rail Tal,..., Ta28.

Determination of the position PI of the obstacle is performed on the basis of the temperatures of the ballast Tbl,..., Tb28, using a predetermined relation which associates the temperature detected with the buried or flooding depth of the rail (i.e. buried or flooding depth of the ballast on which the rail is mounted). In fact, at greater buried or flooding depths lower temperatures are detected compared to the temperatures detected on the ballast at smaller underground or flooding depths. The relation for determining the depth comprises parameters associated with the climatic or seasonal conditions, for example the ambient, day-time or night-time temperatures at the moment of detection, and compares the detected temperatures with the.reference temperatures stored in the past in similar climatic or seasonal conditions and in normal conditions of the ballast, i.e. when there are no obstacles. According to a preferred embodiment of the invention, the optical fibre cables a, b are structured to detect the signals al,..., a28, bl,..., b28 along the entire track and the processing system 4 is programmed to receive signals detected by the cables at a distance of less than one metre.

Advantageously, according to this example, each obstacle which covers an area greater than a metre or which is positioned over a detection point Rl,..., R28 causes an alteration of the signal al,..., a28, bl,..., b28 transmitted by the cable associated with the track and/or the cable associated with the rail and is processed substantially in real time in the station 4 as a possible anomaly along the section.

More specifically, the processing system 4 comprises a plurality of workstations 5x-5z. Each workstation 5x is intended to receive at its input the signals al,..., a6, bl,..., b6 detected along a predetermined section 6a of the cables "a", "b" and is programmed to determine the temperatures Ta, Ta6, Tbl, Tb6 and the detection positions Rl, R6 corresponding to the signals al,..., a6, bl, b6 received from the cables along said predetermined section 6x.

For example, in Figure 1 , the workstation 5x collects all the signals of a section 6a from the cables "a", "b", the workstation 5y collects all the signals of a section 6b from the cables "a", "b" and the workstation 5z collects all the signals of a section 6c; each workstation processes independently the temperature values and the respective detection positions along the associated cable sections. Transmission of the signal from the cable to the workstation is practically immediate since the cable "a", "b" is a fibre cable and the optical signal, and not a complex set of coded data, is used to determine the temperature. The temperature is determined with a margin of error less than one tenth of a degree C.

Advantageously, since the cable is designed to detect the signals continuously, the workstations may be arranged at a distance from each other, without the loss of control over the section.

For example, according to one embodiment, the workstations 5x-5z are intended to be arranged at a distance of between 10 and 30 kilometres from each other during use.

The system also envisages the use of a data collection and post- processing station, indicated by 7 in Figure 1, intended to receive at its input the temperatures Tal,..., Ta28, Tbl,..., Tb28 from the workstations 5x-5z and to determine the positions PI potentially associated with an obstacle or the positions in which the rail has a reduced capacity or performance. The determination of the positions PI comprises for example a comparison between the temperatures Ta2, Tb2 at a detection point R2 and expected temperatures Ta2att, Tb2att at the detection point R2 and/ or a comparison between the temperature Ta2, Tb2 at the detection point R2 and the temperatures Tal, Ta3, Tbl, Tb3 at a detection point Rl preceding or detection point R3 following the detection point R2.

In particular, the obstacle is determined if a difference between the temperatures exceeds a predefined threshold.

The expected temperatures are stored in a temperature archive, as described more precisely below. In fact, the detection of the optical signals is performed with continuity from a geographical but also time point of view, namely by sampling very frequently, for example every second, the track and the ground at the detection points Rl,..., R28.

Consequently, according to the invention, an archive of signals associated with the time (seconds, minutes, hours, days, months, seasons, year) is memorized in a database and is used for the comparison with the currently detected values, in order to determine the obstacles.

It is also envisaged that the processing step takes into account weather forecasts and then performs variations of the threshold value depending, for example, on the climatic differences between a past season and the current season.

In accordance with the above explanations, the temperatures Ta2, Tb2 at the detection point R2, the expected temperatures Ta2att, Tb2att and the temperatures Tal, Ta3, Tbl, Tb3 at a preceding detection point Rl or following detection point R3 are considered with reference to numerous detection time intervals or expected time intervals, and the comparison is carried out a corresponding number of times. The obstacle is determined if an average of the differences between the temperatures considered during the check exceeds the predefined threshold, with any adaptation to the weather forecasts. According to one aspect of the present invention, various differences between the temperatures during the check in the processing system are associated with different dimensions or covered areas or heights of the obstacle, for example the height of sand mass on the rail. It is also envisaged determining the size of the obstacle on the basis of the detected temperature of the ballast, i.e. the depth at which the rail is buried underneath the sand.

In particular, the cable associated with the rail is used to determine the working condition (temperature) of the rail and the cable associated with the ground (sleeper, ballast, etc.) is used to determine the height or the area covered by any sand masses (or other obstacles).

The area covered by the obstacle is determined by means of a number of different points PI for determining neighbouring obstacles. For example, in the case where the points Ri are situated at a distance of one metre from each other, the detection of ten consecutive obstacles P1-P10 at ten consecutive detection points R1-R10 is associated with a ground area covered by the obstacle equal to about 10 metres.

According to a preferred embodiment of the present invention, the system also comprises a third optical fibre cable "c" intended to be mounted in contact with a second rail 204 of the track and a fourth optical fibre cable "d" intended to be fixed on top of the ballast or the ground or the sleepers, in the vicinity of the second rail 204, as shown in Figure 1.

The third and fourth cables are designed to detect continuously a plurality of signals cl,..., c28, dl,..., d28 dependent on a temperature of the track (respective rail) or the ballast in the plurality of positions Rl,..., R28 along the track. The processing system 4 is therefore intended to receive at its input the signals cl,..., c28, dl,..., d28 from the third and fourth optical fibre cables and use the signals cl,..., c28, dl,..., d28 to determine a temperature Tel,..., Tc28, Tdl,..., Td28 associated with them, and is programmed to determine the positions PI affected by losses in performance of the rail or by obstacles 202 along the path of the track, depending on the temperature Tal, Ta28, Tbl,..., Tb28, Tel,..., Tc28, Tdl,..., Td28 of the track or the ballast which is determined in combination with the four cables a, b, c, d. Operation of the cables "c" and "d" and of the respective workstations is substantially similar to that already described with reference to the cables "a" and "b" and is not repeated below for the sake of brevity.

The workstations are equipped with a hardware device or hub with a high capacity (frequency) of reception of the optical signals. The hardware device receives a stream or sets of said signals al,..., a28, bl,..., b28, cl,..., c28, dl,..., d28 which are continuously sampled over time by the cables and has a sampling speed of the order of magnitude of millions of signals per second and a processor for determining the temperatures and the positions associated with the signals in the stream which have been sampled in a same time interval or instant t.

As already mentioned, the data collection and post-processing station 7 therefore comprises a module for archiving the data acquired over time and a self-learning module which predicts an expected temperature value in a predefined position along the track at a time instant tl, on the basis of the stored data.

The processing system 4 is further provided with a centralized control module receiving input data from the data collection and post-processing system 7. The control module comprises, in particular, a mapping system for displaying the obstacles and means for automatically or manually activating alarms, following detection of the obstacle. Figure 3 shows for example a geographical map of a country comprising a desert area through which a railway line runs; a plurality icons are shown on the map; the icons have a meaning, according to a predefined key, and are immediately used in the control module to detect any obstacles and their corresponding size, such as the height of the sand mass or area covered, and to coordinate remedial action along the line.

Figures 6 and 7a- 7c show in schematic form some of the graphical components of the control module. Figure 6 shows a menu by means of which it is possible to enable or disable corresponding graphics symbols on the geographical map shown in Figure 3: for example, activating the check symbol next to the icon "sensors - transverse" allows the display, along the railway line on the map, of those points affected by a transverse obstacle, i.e. covering the two rails; the transverse obstacle is also associated with a respective level or magnitude, as indicated by the enlarged icons in Figures 7a-7c which show, respectively, a transverse danger of level 7, a sand mass danger of level 1 and a train speed of 49 km/h, compatible with the speed supported by the track conditions. The train speed is indicated in a graph (Fig. 7c) which also shows a speed range considered compatible with the performance of the rails detected; such an illustration allows immediate identification of a train which is transiting at a speed not supported by the track conditions.

Figures 4 and 5 shows the level, the height or the size of the longitudinal or transverse obstacle (y axis) and the length of the section affected by the obstacle (x axis). The size is for example associated with a numerical value and the length with an alphanumeric code; the alphanumeric code is also shown on the geographical map.

The technical problem underlying the present invention is also solved by a method 1 for monitoring rails 100 of a railway line, tram line, underground train line or railroad tracks. The main steps of the method are as follows:

- continuously detecting a plurality of signals al,..., a28, bl,..., b28 dependent on a temperature of the track or the ballast in a corresponding plurality of positions Rl,..., R28 along the track, said detection step being performed by means of at least one first optical fibre cable intended to be mounted in contact with a respective rail 201, and at least one second optical fibre cable b intended to be fixed on top of the ballast or the ground or the sleepers supporting the track; - receiving at its input in a processing system 4 the signals al,..., a28, bl,..., b28 from the optical fibre cables a, b, determining in the system 4 temperatures Tal,..., Ta28, Tbl,..., Tb28 associated with said signals and outputting one or more positions PI affected by loss of performance of the rail or by obstacles 202 along the path of the track, said position PI being identified depending on the temperatures of the track and /or the ballast Ta2, Tb2.

Advantageously with the system and the method according to the invention it is possible to detect continuously over time and substantially at every point along the section any obstacles, emit corresponding signals in real time and reduce in an unusual manner the time needed for remedial action by personnel at a precise point along the section.