A MARKING SYSTEM FOR TRAFFIC LINES

Abstract: For localizing positions along roads and railways it is traditional to use a combination of visual observation of one or a row of kilometring markers and the use of a trip counter, but this is connected with a high potential inaccuracy. In accordance with the invention use is made of a detector that will respond to the passage of electromagnetic markers (8, 14, 20) mounted in or underneath the road, such that an automatic determination of a position is achievable either by a tachometric counting of the markers being passed, when these are mounted with a constant mutual spacing, or by the use of self-identifying position markers, combined with the use of an automatic trip counter. Such a marker system is well suited, inter alia, for use in automatic train control systems, as the markers will not interfere with maintenance works in the ballast of the permanent way (18).

Description: A marking system for traffic lines. The present invention relates to a marking system for marking length units along road stretches, be it normal roads or rail roads, principally for kilometering marking. From of old it is usual to place milestones or similar markings along highways for guiding travellers, but these markings also have another essential function which is to make it easy during road authority inspec¬ tion routines to locate such areas which should sub¬ sequently be attended to by repair teams, or which are wanted to be found again for other reasons. During an inspection round a given area may be located by noting the number of the last passed milestone or kilometric stone and add thereto the indication of a trip counter in the car, whereafter the area may be localized based on this information. However, it may demand a high degree of attention to make this method work in a reliable manner, e.g. when driving by long road stretches where the kilometering markings may well be removed. Also along railroads kilometering markings are used, and often also intermediate markings, e.g. for every 200 metres, as it may also here be essential to locate de¬ tailed areas quite accurately. However, in this connec¬ tion it has been more frequent to use trip counter indi¬ cations in connection with more sophisticated search systems, where the counting may begin e.g. when leaving a railroad station and thereafter is effected indepen¬ dently of the visual kilometric markings. However, it has been observed that this type of measuring is connec¬ ted with a surprisingly high degree of inaccuracy, whereafter it has been necessary to place special signalling means at certain locations for effecting automatic control functions, said means being e.g. rail switches or signal boxes placed next to the rails, which means may communicate wirelessly with corresponding signal boxes, so-called balises, on the running trains. However, on suburban railway systems it is used to place signalling wires on the railway, which wires are made to cross each other e.g. every 40-50 metres, whereby appro¬ priate sensor means on the train may detect these crossings and thus effect a counting of the passed length units independently of visual markings and of unreliable trip counter indications. If desired the trip counter may be used within each stretch of 40-50 metres, where the trip counter indication may be fully suf¬ ficiently correct. However, it is hereby a considerable disadvantage that the signalling wires and even also the said balises are placed in immediate connection with the permanent way track itself, inasfar as both will be in the way when reconditioning works are to be carried out on the permanent way track and its base, i.e. a complicated dismounting and remounting of these parts may be necessary. Both along highways and railroads, a more reliably functioning kilometering system may thus be needed, and according to the invention this is provided by using automatically detectible markers which are placed by or under the concerned road stretch at the desired marking places in such a manner that driving past these markers, which may be placed at every kilometer or any other appropriate length unit, will produce a counter signal in a detecting equipment in the driving car or train. The markers usable for this purpose may be of the type disclosed in EP-B-0 090 021, i.e. electromagnetically functioning markers, which may be placed once and for all underground below the concerned road stretch and thereafter be detectible by every passage of a car carried detector equipment. For registering the passed marking areas a simple data unit may be used on which a known starting point may be read in manually or auto¬ matically, and to which a trip counter is coupled such that an automatic recording of the relevant areas or road stretches may be obtained simply by activating a button on the unit. Correspondingly, a reading out of the relevant points or road stretches at a subsequent search may be effected by signal emission from the unit from the previously read-in data. For measuring done on highways it will normally be sufficient to mount markers for every kilometer, even though it may also be relevant to have a marker for e.g. only every two, five, or ten kilometers, while in connection with railroads, where the trip counter function is less accurate, it may be relevant to place a marker e.g. for every 100 metres. The markers may be placed correctly even where it is impossible to place visual markers, e.g. at road intersections. The markers may be placed as regular fixpoints at a relatively great depth and in connection with railroads at least underneath the roadbed of the permanent way track, as this roadbed may need to be cleaned or modified. However, especially if only a few markers are placed in this manner, it is perfectly possible to make use of kilometering markers immediately in or below the surface, e.g. embedded in a road paving or a railway sleeper. The markers are active without any external wire connections, and thus, e.g. when placed in railroad sleepers, they will in no manner obstruct work on the roadbed. Thereby the markers cannot be used as fixpoints, as they may easily be slightly displaced, but these displacements will seldomly be large enough to have any consequence for the accuracy required in connection with the kilometering function. All according to the effect of the markers and the sensitivity of the detector, each marking may comprise one or more markers in the transverse zone which represents a kilometering spot, or a single marker in the middle of each occurring road lane, respectively. It has been observed that the passive resonance markers may well be detected even when overrunning them at a speed of several hundreds of kilometers per hour, such that they may function as kilometering or tachometering markers with a reasonable reliability. However, it may be appropriate to couple the data unit used for the registering to a trip counter in such a manner that an occurring total counter is activated also in such rare cases where for whatever reason a failure occurs in the detecting of a marker at an expected area. A possible inaccuracy of the trip counting may then be corrected already by the following passage of an active marker. However, with the use of the concerned resonance markers, faulty detections will normally not occur, because circuits are used which are tuned to specific frequencies. On the other hand it may occur that for other reasons further markers are placed in the road between two kilometering markings, and therefore it will be appropriate that the detector or the data unit is arranged so as to be blocked for further detection* right after passing a kilometer or a tachometer marking, and that by means of the trip counter it is only reactivated shortly before passing the next ■ •ordinary" marker. It should be mentioned that the most recent development in battery technique has entailed that it is possible to produce active markers with a longevity of 30-50 years, ant that hereby it is possible to operate with markers having extra strong radiation fields which may be detected with high reliability. It applies already for passive resonance markers, but at an even higher degree to active markers of the said type, that their radiation may be modulated individually, e.g. by means of so-called PROM-units, such that they may be detected not only with respect to their presence, but also with respect to their identity, and especially in connection with markings on railroads it will hereby be of great importance that not just tachometering markers are concerned, but markers which in a selective manner give information about the kilo¬ meter number they represent, as hereby the possibility of faulty tachometering is completely removed. However, it is perfectly possible to make use of a combination of such identification markers and pure tachometering markers, e.g. with the latter placed for each 100 metres between each pair of identifying kilometer markers. This aspect of the invention is of special interest in connection with automatic train control systems, by which there has until now been a dependency of the need to register the actual arrival of the train at a given position by means of external means such as rail switches or the said balises, whereby it has then been possible - by means of optical signals on the rail or by signal transmission between the balises on the train and the rail, respectively - to give instructions to the train driver. These known systems have different disad¬ vantages, of which has already been mentioned the prac¬ tical disadvantage that both the rail switches and the rail balises are wire connected to their surroundings, which is a considerable nuisance when the roadbed is to be cleaned or reorganized. In connection with the invention the very special condition occurs that the train itself, i.e. its data unit, is permanently kept informed of the position of the train on a given road stretch, without any wiring whatsoever occurring along or across the roadbed; in this connection it is of no importance whether the markers are placed in the sleepers or in the berm under¬ neath the roadbed, as in both cases reconditioning work can be done unhinderedly on the roadbed. The only element missing for effecting a control function is a communication connection, but this may perfectly well be established without using wires touching the roadbed, e.g. already by a radio connection between the train and a control center. It may cause certain problems to use radio communication by extended traffic networks with many simultaneously driving units, but there are usable alternatives connected with the single railroad stretches, e.g. using the rails themselves as means for transmitting communication signals. A communication system may also be established from the consideration that a brief communication connection will be needed only by particular substretches, and by or along these substretches there may then be placed special communi¬ cation means of only purely local range, e.g. a local radio system which is wire connected to a principal control center or to an induction loop system which over a short stretch extends along the driving track of the train near the train side, but carried by support means mounted outside the berm or the roadbed; there may then be placed means at the concerned train side (or at both train sides) for electromagnetic communication with the elongated stationary loop. All according to the degree of coupling between the detector means of the train for detecting the kilometering markers and the central traffic control station a more or less accurate image may be produced in this station of the precise position of the train, but here based on the fact that the train itself registers its position independently of exterior or stationary detection means, whereby the very important advantage is obtained that in the control center it is possible continuously or at short regular intervals to get an indication of the exact position of the train, and that all problems are avoided with respect to the presence of wires on the roadbed when this is to be attended to for changing, cleaning, or reconditioning. In the following the invention is explained in more detail with reference to the drawing, in which Fig. 1 is a map view of a city with roads radiating therefrom, Fig. 2 is a top view of a highway provided with kilometering markers, Fig. 3 is a perspective view of a railroad stretch, and Fig. 4 is a perspective view of a stretch of Fig. 3 in a smaller scale. The city shown in Fig. 1 is designated by 2, and by 4 it is indicated that the city has a traffic junction being the center of kilometer measuring on highway stretches 6, which radiate from or to the city area 2. According to the invention, in some roads 6 are embedded kilometering markers 8 of the electromagnetic resonance type, which in being passed by an appropriate detector equipment may be detected for activating a counter in a data equipment in a measuring or inspection car, such that this equipment may currently count the number of passed markers, while a trip counter may effect a registration or indication of the partial stretches or lengths between the markers 8. The inspection or searching car must not necessarily leave from the junction 4, as e.g. outside the city limit area special starting markers 10 may be placed in the single radiating roads 6, which starting markers may be designed to emit a special modulated starting signal, which in the passing detector and data equipment brings forth an "indication" corresponding to the concerned distance to the junction 4, whereafter the kilometering markers 8 are registered with a correct distance to the junction 4. On the road stretches 6 the markers 8 are placed between the road surfaces, possibly just bedded shortly below these, and in Fig. 3 it is shown that in a two-lane road these markers may be placed in a common transverse line of the road so as to define a kilometering point, whichever direction along the road a car is taking. These points will then be detected by a data equipment in such a car which is equipped with a detector for passing the marking spots and thereby for receiving the signals which the markers emit or are caused to emit by the very passage of the car. The markers 8 should be laid out or placed with a good accuracy, which will typically be a qualified surveyor's job. Where the road is winding, such as it is shown in Fig. 2, it may be desirable by poor sight conditions to place further markers 12 in the road or right next to this for enabling a visual contact with the next kilometering point 8. These additional markers 12 may optionally be constituted by temporarily placed ranging poles, but they may very advantageously be constituted by subterranean markers corresponding to the markers 8, as hereby the entire marking system may easily be subjected to a control measuring at any later moment. These intermediate markers 12 may well be adapted to a totally different frequency than the main markers 8, but they may still potentially activate the passing detector, and it may therefore be relevant to let this be operative only at the expected moments of passage of the markers 8. Likewise, it may be relevant for a subsequent searching operation to place markers e.g. for every 500 meters, while for the driving to the relevant place it will be undesirable to register these half-kilometer markers. In Fig. 3 it is shown that along a railroad stretch kilometering markers 14 may be placed down in the road's berm basis 16 for the superjacent roadbed 18, and that furthermore markers 20 may be placed in connection with the rail sleepers 22 at selected spots between the kilo¬ metering markers 14, e.g. for every 100 meters between these. As shown in Fig. 4 these markers 20 may be placed in bores in the sleepers 22, and as mentioned above also the primary kilometering markers 14 could well be placed in this manner. For control purposes it is important that a communication connection may be established between the train or its data unit and the stationary surroundings of the train, and in Fig. 3 this is illustrated by a communication loop 24 being placed along a part of the rail stretch and being carried by masts 26 placed outside the roadbed 18, this loop being able to cooperate with a sidewise turned sender/receiver equipment on the train. Such loops may be placed at strategic places where it may be relevant to convey information, e.g. instructions for lowered driving speed along an upcoming partial stretch; the detector and control unit of the train may then itself identify the concerned stretch with good reliability, especially when the kilometering markers as mentioned above are of a self-identifying type. It may optionally be effectuated that the data unit of the train, via the rail or in a wireless manner, conveys the position of the train to a control center in which an absolutely correct image of the position of the train may be produced; this may be used for security by both visual and automatic control, and at least if the markers are placed reasonably closely, e.g. for every 100 meters, also the speed of the train can be indicated in the control center. Even though the said control possibilities may be very essential it should be emphasized, however, that the kilometering marking according to the invention is of a great importance already for accurate localizing in connection with the carrying out of repair and maintenance work. Also by markings on railroads, "master markers" may be used locally be for zero resetting the counter equipment of the trains. Optionally these markers may be particularly powerful, as they may well have an external power supply when placed e.g. underneath the roadbed. For a possible prolongation of the life of the batteries with the use of active markers, such markers may be adapted to become operative only when they are activated by a field which is radiated by a trigger unit in the train, and thereafter to remain active only for a short while, e.g. for a position reporting repeated a number of times, e.g. 3-10 times. At an oscillation frequency of the magnitude of 80-150 KHz the reporting code may well be emitted and received several times even during a fast passing of the marker. The invention may be used also in connection with further types of tracks, e.g. runways for aeroplanes, where it is necessary that the pilot or a control computer in the plane is informed of the position and the speed of the plane on the runway. Until now, mostly visual observation of length markings has been used, but by use of the disclosed position reporting markers, such information will be automatically collectible, and * also here this information will be trans ittable externally, such that an indication of the speed and exact position of the plane on the runway may be produced e.g. in a control tower. Also on taxi ways the markers may be usable, e.g. also as stop line markers, where the plane should be stopped, optionally automatically, if there is no permission to continue.

Claims: C L A I M S : 1. A marking system for localizing positions along traffic roads, comprising length unit markers placed with relevant intervals along the road, characterized in that the markers are placed in or below the road body itself, the markers being of the electromagnetic marker type which manifest themselves by a radiated field detectible from above, the system comprising relevant detector units mounted in such driving units which make use of the system. 2. A system according to claim 1, characterized in that the markers are adapted to radiate a field modulated such that they hereby manifest themselves in an individually identifiable manner. 3. A system according to claim 1, characterized in that the detectors in the driving units are connected to a registration unit which is furthermore connected to a trip counter. 4. A system according to claim 1, characterized in that the detectors in the driving units are connected to a transmission unit for wireless emission of position reportings to a control center. 5. A system according to claim 1, characterized in that the markers are placed in connection with rail sleepers along a railroad or alternatively underneath the upper roadbed of the railway. 6. A system according to claim 1 or 5, characterized in that the markers are of an active type with built-in batteries and with no external wire connections. 7. A system according to claim 1, characterized in that it forms part of a train control system in which it is responsible for localizing the position of trains on the rail stretch, means being provided at least at strategic points for transmitting communication or control signals to the train either wirelessly or via the rails. 8. A method of localizing a position by driving along a traffic road, characterized in that for effecting this, a system is used as indicated in any of the claims 1-7, optionally for successive automatic counting of the passed markers. 9. A method according to claim 8, characterized in that self-identifying markers are used as well as a detector equipment which is arranged so as to translate the marker signals to corresponding length measures. 10. A method according to claim 8, characterized in that a zero-resetting or a relevant start calibration of a used counter equipment is effected by outbound overrunning of a marker which is arranged to emit a corresponding resetting or start calibration signal.

Inventors: PEDERSEN WILLY PALLE, PEDERSEN, WILLY, PALLE
Applicants: PEDERSEN WILLY PALLE, PEDERSEN, WILLY, PALLE
Application year: 1989
Main classification: B61L25
IPC codes: B61L25