DE102006031487B4 - Method for contact wire lifting measurement - Google Patents

Abstract

Method for contact wire lifting measurement, in which
a) an optical measuring device (1) is installed and calibrated outside the danger zone and the overhead line area of a track (7),
b) the rest position of the contact wire (5) in an image plane of the optical measuring device (1) is received, wherein the center of the contact wire (5) in the rest position, the intersection of the object plane (3) and a parallel image plane (2) in a plan view,
c) the maximum contact wire lifting position (5 ') is recorded as an image in the image plane of the optical measuring device (1),
d) by means of an evaluation from the pictures of the rest position of the contact wire (5) and the maximum Fahrdrahtanhubposition (5 ') in the image plane of the optical measuring device (1) a difference as maximum Fahrdrahtanhub (LA') in the parallel image plane (2) is determined and
e) a maximum Fahrdrahtanhub (A) in the object plane (3) determined and displayed and displayed by means of an output device, wherein the calibration of the optical measuring device (1) by external calibration is carried out by
A) the distance ...

Description

The invention relates to a method for stationary Fahrdrahtanhubmessung. As contact wires overhead lines or catenaries are called, which serve in trajectories for traction power supply of electric traction vehicles. Under Fahrdrahtanhub means the change in position of contact wires due to the passage of a pantograph of electric traction vehicles.

When assessing the interaction between the pantograph and the overhead contact line, an evaluation of the contact wire position, the contact force of the elasticity of the catenary and the lift along the track is necessary. It is necessary to measure the lift of contact wires at different points in the catenary.

To ensure efficient operation of electrically operated rail vehicles, it is necessary to press the current collector with a defined contact force against the contact wire. The contact force leads to a change in position of the contact wire, if the contact wire applies a lower opposite force.

Thus, there has long been a problem in the prior art to dimension the contact pressure. Too low a contact force leads to high resistance and heating of the pantograph and the contact wire, and too high contact force leads to increased abrasion and to an unwanted swinging of the content Erten in several places contact wire, which is also referred to as chain drive line.

For example, in the DE 690 10 966 T2 seen in this, to regulate the contact force of the pantograph pantograph against a contact wire, to ensure the contact wire lift consistently. This is particularly important for high-speed rail vehicle units, as they may cause high levels of abrasion and, possibly, swinging of the system due to their high speed, which could be accompanied by an impairment or disruption of the system.

The concept of generating a defined contact force also pursues the DE 199 05 015 A1 , Therein a method for generating a defined contact force between a pantograph and a contact wire is described, wherein the contact force of the pantograph is determined from a difference.

A device for detecting the contact force between a contact wire and a current collector is in the DE 199 06 162 A1 disclosed. The device has a measuring device for the static contact force, which is determined from the dependent of the static contact pressure distance between two elastically interconnected components of the pantograph. Furthermore, a current collector is provided which is coupled to an acceleration sensor in the direction of the contact pressure.

The output signal of the acceleration sensor is linked to the output signal of the measuring device in order to calculate the contact pressure. The acceleration sensor is designed so that it has a resiliently attached to the pantograph seismic mass, the respective position detected with respect to the pantograph optically and a corresponding light signal is transmitted to a potential-separated from the pantograph opto-electrical converter.

From the aforementioned prior art, the necessity of detecting the contact pressure - and thus indirectly connected - also the importance of the determination of the Fahrdrahtanhubs out.

In the WO 02/21 445 A2 discloses a method and apparatus for detecting a change in a reference object.

Inspection of the route with the investigation of the contact wire serves the purpose of determining whether there are foreign objects in the route and in the overhead line, which could lead to a disruption of the driving operation. The method thus serves to detect changes per se and not the specific determination of the quantity of change which is required for a contact wire lifting measurement.

After WO 95/35 478 A1 discloses a method for monitoring overhead lines, wherein the determined parameters are too imprecise for a contact wire lifting measurement. In addition, the measuring arrangements are installed on the pylons, which precludes a transfer of the measuring principle to the problem of the contact wire lifting measurement.

In the textbook Luhmann, T .: Nahbereichsphotogrammetrie 2nd edition, 2003, various application examples for this field are presented. In particular, these examples relate to the detection of object movements, which emanate from the recording of the time of an object space with stationary reference point field.

The US 2003/0 142 297 A1 describes an apparatus for measuring characteristic parameters of contact wires. In particular, the detection of the profile of the contact wire is in the frame the wear measurement revealed by the use of an additional defined light source. By determining the shape can be concluded that the state of the object. The disadvantage is that the track and catenary area must be used when using this method.

An aggravating factor for the contact wire lifting measurement is that the overhead lines are live, the mains voltage being between 0.6 kV and 25 kV.

The state of the art for stationary measurement of the lift of overhead lines in the passage of pantographs of electric traction units is represented by the fact that at the live measuring point a rope is attached, which transmits a deflection to a measuring sensor to earth potential by a suitable guide, on rollers or the like. The path signal is converted in the sensor into an electrical signal which is fed to the measuring device or to the recording device.

The mentioned conventional method for measuring the contact wire lifting has serious disadvantages.

A particular disadvantage is that the measurement technology must be mounted in the live overhead line area. By establishing and securing the voltage-free state of the overhead line, this leads to blocking pauses in railway operation during the installation and uninstallation of the measuring technology.

Another disadvantage is that no free choice of the measuring point in the field of the catenary of the contact wire is possible because the mounting on a mast in the catenary area is necessary. Thus, only overhead lines can be detected.

The method of measuring the change in position of a rope immanent adheres to an inaccuracy, which is due to changes in length of the rope, the rope sag and rope inertia in the transmission of the measurement signal under different environmental conditions, such as different temperatures and precipitation.

The thermal expansion and elongation caused by snow and ice loads as well as rain or wind cause measurement inaccuracies.

The object of the invention is to provide an arrangement and a method for measuring the Fahrdrahtanhubs, with the help of the Fahrdrahtanhub can be measured at any point of the catenary without interference in the railway operation. It is a further object of the invention to provide a measuring method which realizes a high accuracy with reasonable effort and minimal effort.

The Fahrdrahtanhubmessung is realized by an arrangement for Fahrdrahtanhubmessung with an optical measuring device for image recording at least the rest position of the contact wire and the maximum Fahrdrahtanhubs, wherein an evaluation device for the recorded images and an output device for displaying and displaying the results is provided, wherein the evaluation device is designed in that the recorded images are compared and, after calibration of the arrangement, the maximum contact wire lift (A) can be determined from the image data.

According to one embodiment, the arrangement additionally contains means for non-contact distance measurement between contact wire and measuring device and means for determining the measuring angle α.

In a particularly simple embodiment, a camera with an automatic triggering is used as a measuring device. In a particularly preferred embodiment, a video camera is used as the measuring device, which receives the entire passage of the current collector through the measuring point.

For the purpose of signal processing, it is advantageous to design the measuring device as a digital measuring device, as thus intermediate steps of the analog, digital and digital-to-analog conversion can be switched off with associated errors.

• a) eine optische Messeinrichtung außerhalb des Gefahrenbereichs und des Oberleitungsbereichs eines Gleises (7) installiert und kalibriert wird,
• b) die Ruhelage des Fahrdrahtes in einer Bildebene einer optischen Messeinrichtung aufgenommen wird, wobei der Mittelpunkt des Fahrdrahtes in Ruhelage der Schnittpunkt von Objektebene und einer Parallelbildebene in einer Draufsicht ist,
• c) die maximale Fahrdrahtanhubposition als Bild in der Bildebene der optischen Messeinrichtung aufgenommen wird,
• d) mittels einer Auswerteeinrichtung aus den Bildern der Ruhelage des Fahrdrahtes und der maximalen Fahrdrahtanhubposition in der Bildebene der optischen Messeinrichtung eine Differenz als maximalen Fahrdrahtanhub in der Parallelbildebene bestimmt wird und
• e) ein maximaler Fahrdrahtanhub in der Objektebene ermittelt und mittels einer Ausgabeeinrichtung angezeigt und dargestellt wird.

The object of the invention is achieved by a method for Fahrdrahtanhubmessung, in which

• a) an optical measuring device outside the danger zone and overhead area of a track ( 7 ) is installed and calibrated,
• b) the rest position of the contact wire is received in an image plane of an optical measuring device, wherein the center of the contact wire in rest position is the intersection of the object plane and a parallel image plane in a plan view,
• c) the maximum contact wire lifting position is recorded as an image in the image plane of the optical measuring device,
• d) by means of an evaluation device from the images of the rest position of the contact wire and the maximum Fahrdrahtanhubposition in the image plane of the optical measuring device a difference is determined as the maximum contact wire lift in the parallel image plane, and
• e) a maximum Fahrdrahtanhub determined in the object plane and displayed and displayed by means of an output device.

According to the concept of the invention, the measurement exposure takes place visually or optically by recording the measurement point movement by means of a camera or a video camera.

The method for Fahrdrahtanhubmessung is designed by different calibration operations with different accuracies, which can be used as required.

berechnet und dargestellt.The calibration of the optical measuring device takes place once by self-calibration, wherein a component located at the measuring point of known size LN in the image plane LN 'is determined. The Fahrdrahtanhub A in the object plane is after the measurement of the Fahrdrahtanhubs in the image plane LA 'in the evaluation approximately the relationship

calculated and displayed.

In self-calibrating measurement, components located at the measuring point in the catenary are used as the measurement standard. The advantage here is that no measurement of the arrangement is necessary.

The measurement object is shortened by the projection from the object plane to the image plane. In order to compensate for this aberration in the height measurement, therefore, the angle α would have to be known, if one wants to determine exactly the conditions in the object plane trigonometrically. However, if a component in the object plane is used as normal, the display error is automatically compensated. The automatic compensation arises from the application of the same trigonometric function to the measured and normal size, which are each in the numerator and denominator of the ratio equation in the Anhubermittlung. Thus, the geometry of the measuring arrangement does not have to be detected. It is important to note that the normal must lie in the object plane. Other standards require the angle correction, otherwise a deviation from object to image is too large.

• A) der Abstand X der Messeinrichtung zum Fahrdraht wird mit den Mitteln zur berührungslosen Entfernungsmessung bestimmt,
• B) der Messwinkels α als Winkel zwischen der Horizontalen und der den Abstand X bildenden Gerade zwischen Messeinrichtung und Fahrdraht wird weiterhin bestimmt,
• C) das Verhältnis eines Fremd-Normals bekannter Objektgröße O im Abstand X in der Bildebene wird zur Bildobjektgröße O' bestimmt und
• D) anschließend erfolgt die Bestimmung und Ausgabe des maximalen Fahrdrahtanhubs A in der Objektebene näherungsweise durch die Beziehung
  

The inventive method of calibration of the optical measuring device by external calibration is characterized by the following procedure:

• A) the distance X of the measuring device to the contact wire is determined by the means for contactless distance measurement,
• B) of the measuring angle α as an angle between the horizontal and the straight line forming the distance X between the measuring device and the contact wire is further determined,
• C) the ratio of a foreign standard known object size O at a distance X in the image plane is determined to the image object size O 'and
• D) Subsequently, the determination and output of the maximum contact wire lift A in the object plane takes place approximately through the relationship
  

• • Aufbau des Stativs und Fokussierung des Messobjektes mit der Kamera des Messpunktes auf dem Stativ; dabei ist zu beachten, dass der Standort und die Einstellungen des Stativs nicht mehr geändert werden dürfen, ausgenommen Bewegungen des Stativkopfes,
• • Messung der Entfernung Stativ-Messobjekt,
• • Messung des Winkels α,
• • Schwenken des Stativkopfes parallel zur Eisenbahntrasse,
• • Einrichten des Fremd-Normals in gleicher Entfernung vom Stativ wie die Strecke Stativ-Messobjekt nur bei waagerechter Ausrichtung des Stativkopfes,
• • Aufnahme des Fremd-Normals durch die Kamera auf dem Stativ, wobei die Objektebene gleich der Bildebene ist,
• • Bestimmung des Bildmaßes der orthogonalen Bildebene für die Länge des Fremd-Normals LN und Umrechnung auf die Bildebene des Messobjektes unter Beachtung des Winkels α zu LN' und
• • Fokussierung des Messobjektes mit der Kamera.

External calibration is the method in which the image size, for example as pixel size, is calculated by measuring a foreign standard and taking into account the geometric arrangement of the measurement setup. The method can be described by the following steps:

• • Construction of the tripod and focusing of the object to be measured with the camera of the measuring point on the tripod; It should be noted that the location and the settings of the tripod must not be changed, except movements of the tripod head,
• • measuring the distance tripod-measuring object,
• Measuring the angle α,
• • pivoting the tripod head parallel to the railway line,
• • Setting up the foreign standard at the same distance from the tripod as the distance Tripod measuring object only with horizontal alignment of the tripod head,
• • Taking the foreign standard by the camera on the tripod, where the object plane is the same as the image plane,
• • Determination of the image size of the orthogonal image plane for the length of the foreign standard LN and conversion to the image plane of the measurement object, taking into account the angle α to LN 'and
• • Focusing the measurement object with the camera.

According to the design of the optical and non-contact determination of the maximum trolley lift, one of the boundary conditions is the visibility of the pantograph. The visibility of the pantograph is given if the image width of the measurement image is greater than the distance traveled in the time between the field shots of the camera path of the vehicle. This is given at 25 frames per second when the distance covered by the vehicle within fifty-seconds of the image corresponds to the imaging width of the measurement.

The assignability of rest position and rise of a measurement is given when the measurement recording begins with the recording of the rest position before the pantograph is retracted in the Nachspannlänge the measured catenary. Post-tension length is the distance between a guying point of an overhead line and the next, whereas the distance between two masts is named as the field length.

It is particularly advantageous if the image size in the image plane is detected digitally in the form of the number of pixels, which can easily be achieved by conventional programs. This accuracy is ultimately dependent on the number of pixels and the resolution, which is very cost effective, a very high resolution and thus high accuracy of the system can be achieved.

It is particularly preferable if the image for the maximum contact wire lift is selected from a sequence of images at the current collector passage. In this case, the process is continuously filmed from the rest position of the contact wire via the current collector passage, and the images are subsequently selected manually or else programmatically.

An advantageous embodiment of the invention is that errors can be corrected by the inclusion of a fixed reference object in the recorded images, such as a building, a mast or a building. In the image section, the reference object is also detected, and the determination of the relative vertical distance from the measurement object to the reference object makes it possible to correct errors caused by the wind or weathering of the measuring device or other vibration influences.

An embodiment of this component is that a pattern on the tunnel wall or tunnel ceiling is used in the tunnel as reference object for error correction.

The advantages of the invention are in particular that the installation of the measurement technology outside the danger zone and the overhead line area is possible. The self-calibration and external calibration can still be carried out outside the overhead line area and can also be checked between the measurements. This ensures in an excellent way that there is no impairment of railway traffic during the measurement and in particular during the installation of the measurement technology.

The use of standard components for the measuring device, such as digital video cameras or cameras, leads to cost-effective implementations. Through strong telephoto lenses the Fahrdrahtanhubmessung of different height is possible. It is irrelevant whether the measuring device is above or below the top of the rail (SOK).

The evaluation and display device can also be realized inexpensively by means of a conventional computer, so that only standard components can be used with sufficient accuracy.

Overall, the accuracy of the method according to EN 50317 is complied with since the approximations used have no significant effect on the result.

The method allows stationary optical lifting measurements for contact wire, suspension cable and all moving fittings. It is particularly advantageous that the measurement is possible both at the base and at any point in the longitudinal field.

Likewise, several independent measuring points can be set up.

According to one embodiment of the invention, a driving speed measurement up to 350 km / h is also possible.

Further details, features and advantages of the invention will become apparent from the following description of exemplary embodiments with reference to the accompanying drawings. Show it:

1 : Sketch of the arrangement for determining the maximum contact wire lift,

2 : Section of the image and object plane in the measurement by means of self-calibration and

3 : Section of image and object plane for external calibration.

In 1 the basic structure of the measuring arrangement is shown with the various geometric relationships. With the reference number 1 is the measuring device provided, which is designed as a camera or video camera. At a distance X to the measuring device 1 is the contact wire 5 in its rest position, both in the object plane 3 as well as in the parallel image plane 2 lies.

The angle α of the straight line of the measuring device 1 to contact wire 5 in relation to the horizontal 6 is called the measurement angle α. With the reference number 7 For the sake of completeness, the track is designated.

The method is based on the approximation that the angle α is equal to the angle α ', whereby the triangle, which lies between the parallel image plane 2 and the object plane 3 forms, as a right triangle represents and thus simple trigonometric functions for the calculation of the in the parallel image plane 2 represented relations to the object plane 3 be available. This approximation is justified, since the geometric conditions in reality allow this. The distance X from measuring device 1 to contact wire 5 is eight to twelve meters at a height of the contact wire 5 over the tracks 7 between 5.30 m to 5.50 m. The contact wire lift A is approximately 10 cm to 12 cm, so that there is an angle difference α to α 'of less than one degree. The hypotenuse of the triangle is the maximum contact wire lift A in the object plane 3 , the Ankathete of the angle α is the maximum Fahrdrahtanhub LA 'in the parallel image plane 2 ,

• – Selbstkalibrierende Messung des Fahrdrahtanhubs am Stützpunkt: • Aufbau der Kamera 1, so dass das Messobjekt fokussiert werden kann, • Start der Aufnahme vor Einfahrt des elektrischen Triebfahrzeugs in die Nachspannlänge, in der der Messpunkt sich befindet, • Beenden der Aufnahme, nachdem alle zu messenden Stromabnehmer den Messpunkt passiert haben, • Überspielen der Daten auf den Auswerterechner zur digitalen Auswertung, • Kalibrierung des Messprogramms durch Zuordnung der Pixelzahl der Länge LN' zur Länge des Normals, beispielsweise einer Stützpunktklemme in mm, • Markierung der Ruhelage, • Anzeige des Bildes des Stromabnehmerdurchgangs: Der Stromabnehmer muss auf mindestens einem Halbbild (jede zweite Bildzeile) erkennbar sein, • Markierung der Lage und Bestimmung der Pixelzahl für LA', • Berechnung des Anhubs aus LN/LN'·LA', • Messung weiterer folgender Stromabnehmer oder Ende der Auswertung und • Protokollierung der Messwerte.

In 2 are the geometric relationships of object plane 3 and parallel image plane 2 enlarged in the measuring point for the procedure of self-calibration. The image capture direction 4 indicates the viewing direction and thus the orthogonal parallelepiped plane 2 , The shift of parallel image plane 2 to object level 3 leads to the requirement of calculating the trolley lift A in the object plane 3 , The contact wire 5 is at the beginning for the first comparison measurement at rest in both the parallel image plane 2 as well as in the object plane 3 , Particularly advantageous in the measurement method of self-calibration is that by using a known object in the immediate vicinity of the measurement point as the measurement standard calibration can be made in the system even with the least effort. In the exemplary embodiment, the self-calibration is performed by means of a contact wire clamp. The LN stretch is the known size of a component in the object plane 3 , which is located in the catenary in the immediate vicinity of the measuring point or represents the measuring point itself. Will the contact wire 5 through the current collector passage in the object plane 3 shifted upwards, this shift appears in the parallel image plane 2 at the point 5 ' , The normal known quantity is now set in relation to the size of the measurement standard in the image plane LN ', resulting in the ratio of maximum contact wire lift A in the object plane 3 and the maximum trolley lift LA 'in the parallel image plane 2 , which with the measuring device 1 is determined, the maximum Fahrdrahtanhub in the object plane A is calculable. The self-calibrating measurement of the contact wire lift A at the base takes place by way of example by the following steps:

• - Self-calibrating measurement of the contact wire lift at the base: • Camera setup 1 so that the object to be measured can be focused, • start the recording before entering the electric traction unit in the Nachspannlänge in which the measuring point is located, • termination of the recording, after all to be measured pantograph have passed the measuring point, • dubbing the data on the Evaluation computer for digital evaluation, • Calibration of the measuring program by assigning the pixel number of length LN 'to the length of the normal, for example, a support point clamp in mm, • Marking the rest position, • Display of the image of the pantograph passage: The pantograph must on at least one field (every second • marking of the position and determination of the number of pixels for LA ', • calculation of the lift from LN / LN' · LA ', • measurement of further following current collectors or end of the evaluation and • logging of the measured values.

In 3 is the enlarged section of parallel image plane 2 and object level 3 with reference to the externally calibrated measurement. If, in contrast to the self-calibrated measurement, there is no reliable information about the object sizes of a measurement standard in the catenary area, the external calibration is required in order to reliably calculate the maximum contact wire lift A in the object plane 3 to ensure. The image capture direction 4 indicates in turn the viewing direction and the orthogonal to this parallelepicture plane 2 , The shift of parallel image plane 2 to object level 3 leads to the requirement of calculating the trolley lift A in the object plane 3 , The foreign-normal 8th with the object size O is before the evaluation of the image data by pivoting the measuring device 1 in the horizontal 6 in the parallel image plane 2 ' measured in the vertical and the image size O 'of the foreign standard 8th in the image plane of the external calibration 2 ' certainly. It is important that the foreign-normal 8th doing so in the vertical object plane, which is equal to the image plane 3 is, and that is the foreign-normal 8th at a distance X of the measuring device to the measurement object, the contact wire 5 , is measured. The idea of the invention is transferable to movements in the most varied planes, wherein the calibration plane is the image plane, which must be parallel to the object plane in order to exclude angle errors.

• – Fremdkalibrierte Messung an zwei aufeinander folgenden Stützpunkten: • Aufbau der Kameras mit Stativen, • Durchführung der fremdkalibrierten Messung für jede Kamera, • Start der Aufnahme vor Einfahrt des elektrischen Triebfahrzeugs in die Nachspannlänge, in der der Messpunkt sich befindet, • Beenden der Aufnahme, nachdem alle zu messenden Stromabnehmer den Messpunkt passiert haben, • Überspielen der Daten auf den Auswerterechner, • Start des Auswerteprogramms; je Messpunkt die gleiche Prozedur, • Markierung der Ruhelage, • Anzeige des Bildes des Stromabnehmerdurchgangs: Der Stromabnehmer muss auf mindestens einem Halbbild (jede zweite Bildzeile) erkennbar sein, • Markierung der Lage und Bestimmung der Pixelzahl für LA', • Berechnung des Anhubs, • Messung weiter folgender Stromabnehmer, • Auswertung des nächsten Messpunktes oder Ende der Auswertung und • Protokollierung der Messwerte.

In the embodiment according to 3 the externally calibrated measurement is performed at two consecutive interpolation points.

• - Externally calibrated measurement at two consecutive interpolation points: • Setup of the cameras with tripods, • Execution of the externally calibrated measurement for each camera, • Start of the recording before entering the electric traction unit in the Nachspannlänge in which the measuring point is located, • Stop recording, after all the pantographs to be measured have passed the measuring point, • transfer the data to the evaluation computer, • start the evaluation program; the same procedure for each measuring point, • mark the position of rest, • display of the image of the pantograph passage: the pantograph must be recognizable on at least one field (every other picture line), • mark the position and determine the number of pixels for LA ', • calculate the lift, • Measurement of the following pantographs, • Evaluation of the next measuring point or end of the evaluation and • Logging of the measured values.

The advantages of this arrangement are in particular in the higher accuracy by using larger standards and in the greater universality of applicability, since all measurement points without measurement standard can be measured in or at the measuring point.

According to a further preferred embodiment of the invention, a characteristic of the respective measuring device is in the run-up to measurements 1 determined. This is particularly advantageous since the required distance X to the object to be measured is known in the order of magnitude and can then be set exactly on site by means of a tripod. Furthermore, it is advantageous to determine a plurality of characteristic curves under exactly defined conditions, in order thereby degrees of freedom of the device of the measuring device 1 under field conditions.

LIST OF REFERENCE NUMBERS

1

measuring device

2

Parallel image plane / orthogonal to the image acquisition direction

2 '

Parallel image plane in the vertical for external calibration

3

Object Level / Vertical

4

Image capture direction

5

Contact wire in rest position

5 '

Contact wire in maximum contact wire lifting position in the image plane

6

horizontal

7

track

8th

Third-Normal

X

Distance measuring device contact wire

O'

Foreign Normal for calibration in the vertical image plane 2 '

LN

Known size of a component

LN '

Size of the known component in the image plane 2

A

Maximum contact wire lift in the object plane 3

LA '

Maximum contact wire lift in the image plane 2

O

Object size foreign normal 8th

Claims (7)

Method for measuring contact wire lifting, in which a) an optical measuring device ( 1 ) outside the danger zone and overhead area of a track ( 7 ) is installed and calibrated, b) the rest position of the contact wire ( 5 ) in an image plane of the optical measuring device ( 1 ), wherein the center of the contact wire ( 5 ) in rest position the intersection of object plane ( 3 ) and a parallel image plane ( 2 ) is in a plan view, c) the maximum contact wire lifting position ( 5 ' ) as an image in the image plane of the optical measuring device ( 1 ), d) by means of an evaluation device from the images of the rest position of the contact wire ( 5 ) and the maximum contact wire lifting position ( 5 ' ) in the image plane of the optical measuring device ( 1 ) a difference as the maximum contact wire lift (LA ') in the parallel image plane ( 2 ) and e) a maximum contact wire lift (A) in the object plane ( 3 ) and displayed and displayed by means of an output device, wherein the calibration of the optical measuring device ( 1 ) by external calibration by: A) the distance (X) of the measuring device ( 1 ) to the contact wire ( 5 ) is determined by means for non-contact distance measurement, B) the measurement angle (α) as the angle between the horizontal ( 6 ) and the distance (X) forming the line between the measuring device ( 1 ) and contact wire ( 5 ), C) the ratio of a foreign standard ( 8th ) known object size (O) at a distance (X) in the image plane ( 2 ' ) to the image object size (O ') at the distance (X) in the parallel image plane ( 2 ) and D) the maximum contact wire lift (A) in the object plane ( 3 ) approximately through the relationship

is determined and issued. A method according to claim 1, characterized in that for foreign calibration, the measuring device ( 1 ) parallel to the track ( 7 ) in the horizontal ( 6 ) is pivoted and the foreign-normal ( 8th ) during the calibration in a vertical parallel image plane ( 2 ' ) lies. Method according to claim 1 or 2, characterized in that an image dimension in the image plane of the optical measuring device ( 1 ) is detected digitally in the form of the pixel number. Method according to one of claims 1 to 3, characterized in that the image for the maximum Fahrdrahtanhub ( 5 ' ) is selected from a sequence of images at the current collector passage. Method according to one of claims 1 to 4, characterized in that a fixed reference object, such as a building, a mast or a building, is detected in the image section and by the determination of the relative vertical distance from measurement to reference object, a correction of vibrations the measuring device errors occurred. A method according to claim 5, characterized in that in tunnels as a reference object for error correction, a pattern on the tunnel wall or tunnel ceiling is used. Method according to one of claims 1 to 6, characterized in that the calibration of the measuring device ( 1 ) is carried out by characteristic curves obtained by taking the image object size O 'of the foreign standard ( 8th ) at different distances (X) before the measurement.

Images