EP1336946A2

EP1336946A2 - System and method for detecting the passage of tramcars, in particular for the purposes of coordinating traffic-light cycles for trams and traffic-light cycles for automobiles

Info

Publication number: EP1336946A2
Application number: EP02022751A
Authority: EP
Inventors: Roberto Rizzoli
Original assignee: Azienda Torinese Mobilita' SpA
Current assignee: Azienda Torinese Mobilita' SpA
Priority date: 2002-02-15
Filing date: 2002-10-11
Publication date: 2003-08-20
Anticipated expiration: 2022-10-11
Also published as: ITTO20020235A0; ATE291265T1; DE60203255T2; DE60203255D1; EP1336946A3; EP1336946B1; ITTO20020235A1

Abstract

A system for detecting the passage of tramcars, envisaged in particular for the purposes of the coordination between tram traffic-light cycles and motor-vehicle traffic-light cycles, comprises a detection device (10) associated to the overhead line (4) for supplying the tramcars; the device (10) has two sensors (S1, S2) in fixed relative positions and set apart from one another according to the direction of movement of the tramcars; the distance between the two sensors (S1, S2) is substantially equal to the distance existing between two respective excitation elements associated in fixed relative positions to the structure of a respective tramcar. In the preferred embodiment of the invention, the sensors are of an optical type, and the excitation elements comprise two sliding contacts of a pantograph of the tramcars.

Description

The present invention relates to a system and a method for detecting the passage of tramcars, envisaged in particular for the purposes of the co-ordination between tram traffic-light cycles and motor-vehicle traffic-light cycles.
As is known, the routes followed by the tramcars of a tram network do not coincide necessarily with the routes of motor vehicles; for this reason it proves necessary co-ordinate to a certain extent the operation of the traffic lights that regulate road traffic with the traffic lights that regulate the traffic on rails, above all at cross-roads.
The most traditional solution to the problem mentioned above is that of imposing traffic-light cycles of a fixed duration for both of the traffic networks. The above approach, albeit simple and economical to implement, has the effect of leading to unnecessary waiting times for road traffic in the case where, in the proximity of the cross-roads, there is no tram present.
With the aim of limiting this problem, there have thus been proposed traffic-control systems aimed at ascertaining the possible presence of a tram in the proximity of the cross-roads and, consequently, modifying temporally the traffic-light cycle of motor-vehicle traffic in favour of tramcar traffic flow.
A first system known for this purpose consists in the physical detection of the presence of the tram in the area of entry to the cross-roads, via means of contact electrically connected to the overhead contact line of the tram network.
The said means of contact have basically the shape of large metal spring-like elements, which hang from the overhead line and are designed to be physically displaced by the tram in transit, so as to cause closing of an electrical contact; the effect of the said closing is to generate an electrical signal indicating the presence of the tram, which a specially designed regulator uses for the purposes of co-ordination between the traffic-light networks of road traffic and rail traffic.
The above-mentioned means of contact are subjected to the same voltage as the overhead supply line of the tram, which is usually high (in the region of 600 V), and hence potentially dangerous in operation. A critical aspect of said detection system is also due to the fact that the above-mentioned spring-like elements do not supply an output signal that can be easily interpreted (of the on/off type), but rather a series of random pulses due to the oscillations of the spring. Said elements are moreover continuously subjected to mechanical stresses, with consequently rapid wear.
The drawbacks mentioned above are instead not present in more sophisticated detection systems, based upon the use of radio sensors. Said systems presuppose, however, the positioning of the radio sensors directly within the tramcar-track lane, so that their installation is in effect limited to the case of laying of new tram lines. The implementation of such a system in a pre-existing tram network is extremely burdensome and presupposes massive interventions on the roadway, with evident problems for the circulation of traffic.
The purpose of the present invention is to overcome the aforesaid drawbacks and in particular to provide a system for detecting the passage of tramcars that is simple and inexpensive to install, as well as being safe and reliable over time.
The above and other purposes still are achieved, according to the present invention, by a system and a method for detecting the passage of tramcars, envisaged in particular for the purposes of the co-ordination between tram traffic-light cycles and motor-vehicle traffic-light cycles, which present the characteristics specified in the attached claims, which are understood as forming an integral part of the present description.
Further purposes, characteristics and advantages of the present invention will emerge clearly from the ensuing detailed description and from the annexed drawings, which are provided purely by way of explanatory and non-limiting example and in which:

Figure 1 is a perspective view of a generic tramcar;
Figure 1a is an enlarged view of a pantograph forming part of the tram of Figure 1;
Figure 2 is a side view of a detection device used in the system according to the present invention;
Figure 3 is a view from below of the detection device of Figure 3;
Figure 4 is a cross-sectional view taken according to the line IV-IV of Figure 3;
Figure 5 is a schematic plan view of a first example of application of the system according to the invention;
Figure 6 is a schematic plan view of a second example of application of the system according to the invention.

In Figure 1 the reference number 1 designates as a whole a generic tramcar, or tram, equipped with wheels 2 engaged on tracks 3 forming part of a tram-circulation network.
Over the tramcar-track lane formed by the tracks 3 there extends an overhead contact line 4, for the electrical supply of the tram 1, on the roof of the latter there being mounted for the purpose a pantograph, designated as a whole by 5.
As may be noted in Figure 2A, the pantograph 5 is of a traditional type and comprises as such a frame 5A for supporting two sliding contacts C1 and C2, as well as for keeping them constantly in contact with the overhead line 4, for the purposes of the electrical supply of the engine of the tram 1. According to the prior art, the two sliding contacts C1 and C2, each made of graphite contained in a respective self-supporting metal support, are parallel to one another and extend in a direction substantially perpendicular to the overhead line 4.
In the case of the present invention, associated to the overhead line 4 are means aimed at detecting the passage of a tram, in particular for the purposes of management of traffic-light cycles.
For this purpose, in Figure 2 designated as a whole by 10 is a detection device built according to the invention.
The device 10 has a box-like body 11, for example made of plastic material or in any case electrically insulating material, comprising a bottom main part 11A and a lid 11B, connected together in a sealed removable way, according to modalities in themselves known.
Fixed (for example by means of bolts) in an electrically insulated way to the bottom wall of the device 10, i.e., the part 11A of the body 11, are two mutually aligned metal terminals 12. In the case illustrated in the example, the two terminals 12 are of the two-screw clinch type, but they may be of any shape, in the perspective of being fastened on the metal cable that forms the overhead line 4, so as to support the device 10 over the line itself. In the case illustrated by way of example, the above-mentioned metal cable can be made of electrolytic copper with shaped section.
As may be noted in Figure 3, in the bottom wall of the body 11 of the device 10 there are likewise defined two slots or rectangular windows, designated by 13, mutually aligned and in a position parallel to the terminals 12.
Inside the body 11 of the device 10 there is mounted, at each window 13, a respective optical sensor. The two sensors, designated in Figure 3 by S1 and S2, may be of an optical-triangulation type, for example of the type NAIS MQ-W20C-12-24VEM, and more in general sensors capable of detecting objects made of carbon or graphite (whether opaque or black), of having a range of action that can be pre-set from 4 cm to 20 cm (on the outside of which there must not be detectable objects of any kind) and of having fast response times, in particular less than or equal to 2 ms.
As will emerge clearly from what follows, the two sensors S1 and S2, which are wired on respective digital inputs of a control unit of the system, enable detection of the passage of trams, identification of the direction of travel and carrying-out of the corresponding count.
Figure 4 shows one of the two above-mentioned sensors, and in particular the optical sensor S1, which is supported at the respective window 13 by a supporting bracket 14, fixed on the bottom of the part 11A of the body 11.
From the sensor S1 there branches off a multipolar signal conductor 15, which is connected to a terminal block of a type in itself known, designated by 16. The terminal block 16, to which also the conductor of signals at output from the sensor S2 of Figure 3 is connected, is in turn interfaced, for example by means of a metal multipolar electrical cable, to the above-mentioned control unit of the system (not represented in the figures), which is located in a remote position with respect to the device 10. Of course, the body 11 of the device 10 will be purposely equipped with an output passage for the above-mentioned metal interfacing cable, with associated respective gripping means of a type in itself known, such as a cable grip.
According to a an important aspect of the present invention, the distance between the centres of the two optical sensors S1 and S2, with which the device 10 is equipped is equal to the distance between the centres of the two sliding contacts C1 and C2 of the pantograph 5 of the trams being detected. Note that the distance between the sliding contacts of a pantograph of the type in question is of a standard size. By way of example, said distance between centres may be equal to 198 mm, i.e., the distance between centres of all the sliding contacts of the pantograph that equip the tram circulating in the town of Turin. As will emerge clearly from what follows, in the preferred embodiment of the invention, the shape of the pantograph 5 is exploited for detecting the passage of a tram in a unique way.
The device 10 is, as has been said, designed to be interfaced to a control unit, which is operative for sending appropriate control signals to a traffic-light regulator, of a conception in itself known. Said regulator is a device, of conception in itself known, envisaged for handling traffic-light cycles distinguished between ordinary traffic flow and tramcar traffic flow, i.e., so that the cycles with the tram traffic-light phase are not activated except when the presence of a tram has been detected in some way.
Note that the modalities of practical embodiment of the above-mentioned control unit are irrespective of the purposes of the present invention, it being possible for it to be obtained with techniques and components in themselves known. In any case, preferably, the control logic of the control unit will be implemented by means of an electrical microcontroller, with associated respective actuators (such as relays) for the generation of signals designed for the traffic-light regulator.
Figure 5 is a schematic representation of an example of use of the system according to the invention.
In Figure 5, the letter I designates, as a whole, a generic cross-roads, traversed by a tramcar-track lane, here represented by the respective overhead contact line 4.
Designated by 10' and 10" are two detection devices, as described previously with reference to Figures 2 to 4, where the devices 10' and 10" are set, respectively, in the stretch that precedes and in the stretch that follows the cross-roads I.
Both of the devices 10' and 10" are interfaced to the above-mentioned control unit of the system, the latter being in turn connected in signal-communication with the traffic-light regulator. Note that, for greater clarity of representation, in Figure 5, the control unit, the regulator, and the traffic lights of the tram network and motor-vehicle network are not represented.
Note that, by virtue of the type of fixing described for the devices 10' and 10", the active part of the respective sensors S1 and S2 is oriented downwards, at the windows 13, i.e., in the direction of the area of passage of the sliding contacts of a pantograph of a tram.
The approach of a tram 1 to the cross-roads I is detected by means of the device 10', according to the following operating sequence:

the sensor S1 will first detect the passage of the sliding contact C1 of the pantograph of the tram 1;
next, at the same instant in which the sensor S2 detects passage of the same sliding contact C1, the sensor S1 will detect the passage of the sliding contact C2; this, evidently, is the consequence of the fact that the distance between the sensors S1 and S2 is equal to the distance between the sliding contacts C1 and C2, which enables having a uniquely determined condition of simultaneous excitation of the sensors S1 and S2 at passage of the tram 1.

The simultaneous excitation of the two sensors S1 and S2 of the device 10' constitutes, for the control unit of the system purposely programmed, the information indicative of the fact that a tram is entering the cross-roads: consequently, the control unit will see to informing the traffic-light regulator, for the purposes of starting up the tram traffic-light cycle.
The fact that, in accordance with the sequence designated above, the sensor S1 has been excited before the sensor S2 enables the control unit to recognize also the direction of travel of the tram 1.
The control unit is moreover programmed for recognizing whether, after the pantograph of the tram 1 has passed underneath the device 10', the tram itself has performed a reversing manoeuvre. In this case, in fact, the control unit will detect an excitation sequence opposite to the one previously designated; that is:

the sensor S2 will detect the passage of the sliding contact C2;
next, at the same instant in which the sensor S1 detects passage of the same sliding contact C2, the sensor S2 will detect the passage of the sliding contact C1.

In this eventuality, the control unit will be able to signal to the traffic-light regulator to return to the motor-vehicle traffic-light cycle, so as to avoid unnecessary waiting times for the private traffic.
After traversing the cross-roads I, the pantograph of the tram 1 will pass underneath the device 10", which functions exactly as the device 10'. Consequently, also in this case, the simultaneous excitation of the sensors S1 and S2 of the device 10" will constitute, for the control unit, information indicative of the fact that the tram 1, previously detected by the device 10', is leaving the cross-roads. Consequently, the control unit itself will see to controlling the traffic-light regulator, for the purposes of returning to the motor-vehicle traffic-light cycle.
It goes without saying that also in this case, by means of the device 10", the control unit will be capable of detecting a possible reversing manoeuvre on the part of the tram, so as to control the consequent return to the tram traffic-light cycle.
The control unit is likewise conveniently purposely programmed for counting the number of trams entering and/or leaving the cross-roads, between the points of reference provided by the devices 10' and 10". Should the difference between the two values be greater than zero, the control unit itself will see to sending to the traffic-light regulator the signal of tram presence on the cross-roads, so as to maintain the tram traffic-light cycle active.
According to a preferred embodiment of the invention, whenever the presence of at least one tram entering the cross-roads is detected, the control unit, in addition to signalling this fact to the traffic-light regulator, will see to starting to time the stay time of the tram within the cross-roads.
In the case where the stay within the cross-roads is prolonged beyond a pre-determined time interval (for example 5 minutes), the control unit will see to sending an alarm, for example by means of a modem integrated in the control unit itself, to signal the anomalous situation. The alarm signal can be sent on commercially available apparatus, such as ones used for search for people, teledrin, cellphones having information appearing clearly on a display, videotel terminals or PCs with emulators.
Note that, in general terms, a direct-reflection trigonometric sensor suitable for application in the system according to the invention (for example, of the type previously referred to) has a detection range of from 4 to 20 cm and a maximum detection time in the region of 2 ms. On the other hand, the object to be detected, i.e., the slider of the pantograph, has on average a width of not less than approximately 40 mm. The result is that, in the case illustrated in the example, a device 10 is capable of detecting correctly the passage of a tram up to a maximum speed of approximately 75 km/h, which is perfectly in line with the application.
Figure 6 represents a second example of use of the system according to the invention.
In this Figure, the letter I designates, as a whole, a generic cross-roads, traversed by a first tramcar-track lane, represented by the respective overhead contact line 4A, and from which there branches off a second tramcar-track lane, represented by the respective overhead contact line 4B.
The reference number 10 designates two detection devices like the ones described previously with reference to Figures 2 to 4, the devices 10 being set each in the outgoing stretch of the cross-roads I, on the line 4A and on the line 4B, respectively.
The reference CS designates control equipment of a tram points operative between the tram lines 4A and 4B. The control equipment CS is in itself known (it may, for example, be of the VETAG or VECOM type produced by Philips) and integrates an electrical contact that identifies the presence of trams at the cross-roads and the request to turn (in the case illustrated in the example of Figure 6, a turn to the right).
Both of the devices 10 and the tram-points control equipment CS are interfaced to the control unit of the system, the latter being in turn connected to the traffic-light regulator. Also in this case, for greater clarity of representation, in Figure 6 the control unit, the regulator and the traffic lights of the tram network and motor-vehicle network are not represented.
As may be intuitively appreciated, in the case of the embodiment of Figure 6, the signal that identifies the presence of a tram entering on the stretch for which there is a request for activation of the tram traffic-light cycle can be generated directly by the apparatus CS, which will be purposely interfaced to the control unit of the system.
For the rest, the system of Figure 6 presents an operation similar to the one described previously with reference to Figure 5, in the sense that the two detection devices 10 will be operative for detecting the tram leaving the area of the cross-roads, following the line 4A or the line 4B, respectively.
In general terms, in the event of a failure in one of the sensors S1 or S2, or of interruption of the electric-power supply or of the metal interfacing cable between the device 10 and the control unit, signalling of the presence of tram will be favoured even in the absence of the latter. On the other hand, with the aim of avoiding the maintenance of the tram traffic-light cycle when it is certain that there is no tram present traversing the cross-roads, on account of malfunctioning of the sensors S1 and S2 at exit from the cross-roads, or for other similar kinds of malfunctioning that are clearly identifiable, it is possible to insert:

a programming of the software of the control unit that envisages a maximum detection time, after which there will be generated a reset command in the event of faulty excitation sequences of the sensors S1 and S2;
a manual intervention with key-operated reset switch, available to authorized personnel.

From the foregoing description there emerge clearly the characteristics and the advantages of the present invention. Amongst these, it should be emphasized how the operation of the system according to the invention is based upon detection devices that are simple and economic to produce, which can be interfaced to control units of a substantially standardized type, it being possible for the latter to be easily programmed for the purposes of the implementation of the system itself.
A substantial advantage of the invention is then represented by the applicability of the system described, in a simple and inexpensive manner, to pre-existing tram networks, without the need for interventions within the framework of the tramcar-track lane or roadway.
The fact that the sensor means S1 and S2 are not subjected to the voltage of the high-tension overhead line of the tram network, but rather are insulated with respect to the latter, is altogether to the advantage of the safety of the system. In addition to this, the fact that the optical sensors are protected inside the body of the device do not detect the presence of a tram by means of physical contact is to the advantage of the reliability and durability of the system.
Finally, given that the range of action of the sensors is very limited and the detection sequence must take place according to the logic described, it is very unlikely for a generic object or a bird to be erroneously interpreted as a pantograph by the detection system.
It is clear that numerous variations to the system described herein purely by way of example are possible for a person skilled in the branch, without this implying any departure from the sphere of novelty inherent in the innovative idea, just as it also emerges clearly that, in the practical embodiment of the invention, the shapes, sizes, materials and components used may be different from the ones described herein by way of example and may be replaced with technically equivalent elements.
The control unit of the system can be purposely programmed for performing additional functions other than the co-ordination of traffic-light cycles. In this perspective, for example, the control unit can be purposely programmed for recording the number of trams crossing the cross-roads concerned and for consequently monitoring the tram traffic, also at pre-set times and for pre-set periods, so as to obtain information of a statistical nature.
Amongst the other possible variant embodiments, there is to be pointed out the possibility of envisaging a single window 13, extending longitudinally on the bottom of the body 11 of the device, on which both of the sensors S1 and S2 will face one another. The supporting means 14 of the sensors could, in this case, be of the regulatable type, with the aim of enabling the variation of the relative position of or the distance between the sensors themselves, the aim being to enable the applicability of said devices 10 to different tram networks, each characterized by a different distance between centres of the sliding contacts of the pantograph of the respective trams.
The optical sensors referred to in the embodiment of the invention described previously purely by way of example could be replaced by sensors of another sort (for example proximity sensors, inductive sensors, reeds, etc.) with modalities that are evident for a person skilled in the branch.

Claims

A system for detection of the passage of tramcars, envisaged in particular for the purposes of the co-ordination between tram traffic-light cycles and motor-vehicle traffic-light cycles, the system comprising a first detection device (10; 10") associated to an overhead line (4) for electrical supply of the tramcars (1), characterized in that said first detection device (10;10") comprises at least one first sensor (S1) and one second sensor (S2) in fixed relative positions and set apart from one another according to the direction of movement of the tramcars (1), the distance between the first and second sensors (S1 S2) being substantially equal to the distance existing between a first excitation element (C1) and a second excitation element (C2) for said sensors (S1 S2), said first and second excitation elements (C1, C2) being associated to the structure of a respective tramcar (1) in fixed relative positions and set apart from one another substantially according to the direction of movement of the tramcar (1).
The system according to Claim 1, characterized in that said first and second excitation elements (C1, C2) comprise, respectively, a first and a second sliding contact (C1, C2) of a pantograph (5) of said tramcar (1).
The system according to Claim 1 or Claim 2, characterized in that said first and second sensors (S1 S2) are of an optical type, in particular of an optical-triangulation type.
The system according to Claim 1, characterized in that said distance is approximately 198 mm.
The system according to Claim 1, characterized in that said first detection device (10; 10") comprises a container (11) to which are associated means (12) for fixing to said overhead line (4), so that the container itself will be supported on top of said overhead line (4).
The system according to Claim 5, characterized in that in the bottom wall of said container there is present a passage or slot (13) aligned to the excitable part of the sensor (S1 S2).
The system according to Claim 1, characterized in that said first and second sensors (S1, S2) are wired to respective digital inputs of a control unit, the latter being in a remote position with respect to said first detection device (10;10").
The system according to Claim 7, characterized in that said control unit is operative for sending control signals to a traffic-light regulator, the latter being operative for handling traffic-light cycles distinguished between ordinary traffic flow and tramcar traffic flow.
The system according to Claim 8, characterized in that said control unit is of the electronic-microcontroller type and comprises actuator means, such as relays, for the generation of said control signals.
The system according to Claim 1, characterized in that said first detection device (10") is set downstream of a cross-roads (I).
The system according to Claim 10, characterized in that a second detection device (10') is envisaged, built and operating in a similar way to said first detection device (10") and set upstream of said cross-roads (I).
The system according to Claim 10, characterized in that upstream of said cross-roads (I) there is envisaged control equipment of a tram points (CS) integrating means for identifying the presence of a tramcar in transit (1).
The system according to Claim 11 or Claim 12, characterized in that said control unit is operative for carrying out a count of the tramcars (1) entering and/or leaving said cross-roads (I), on the basis of signals received from said second and first detection devices (10", 10'), i.e., from said control equipment for controlling the points (CS) and said first detection device (10).
The system according to Claim 11 or Claim 12, characterized in that said control unit is operative for:

counting the stay time of a tramcar (1) in the space existing between said second and first detection devices (10", 10') i.e., between said control equipment for controlling the points (CS) and said first detection device (10); and

sending an alarm signal, should said stay time exceed a pre-determined value.
The system according to Claim 11 or Claim 12, characterized in that said control unit is operative for recording the number of tramcars (1) travelling between said second and first detection devices (10", 10') i.e., between said control equipment for controlling the points (CS) and said first detection device (10), for the purposes of obtaining information of a statistical nature.
A method for detecting the passage of tramcars in a stretch of a route subject to control, in particular for the purposes of the co-ordination between tram traffic-light cycles and motor-vehicle traffic-light cycles, characterized in that the use is envisaged of two sensors (S1 S2) set in fixed relative positions and set apart from one another substantially according to the direction of movement of the tramcars (1), and in that the attainment of a pre-determined condition of passage of a tramcar (1) is detected through the simultaneous excitation of the two sensors (S1 S2).
The method according to Claim 16, characterized in that the simultaneous excitation of the two sensors (S1, S2) is produced by respective excitation elements (C1, C2) associated to the structure of the tramcars (1), in fixed relative positions and set apart from one another substantially according to the direction of movement of the tramcar (1), the distance between the two sensors (S1, S2) being substantially equal to the distance between the two excitation elements (C1, C2).
The method according to Claim 17, characterized in that the two excitation elements are obtained from two sliding contacts (C1, C2) of a pantograph (5) of the tramcars (1).
The method according to at least one of the preceding claims, characterized in that from the excitation sequence of the two sensors (S1 S2) there is deduced the direction of travel of the tramcars (1).
The foregoing substantially as described and illustrated and for the purposes specified herein.