DE102006031487A1 - Arrangement for contact wire lifting measuring, has contactless optical measuring device for image recording of idle state of contact wire and maximum contact wire lift, and evaluation unit records images - Google Patents

Abstract

The arrangement has a contactless optical measuring device (1) for image recording of the idle state of the contact wire (5) and the maximum contact wire lift. An evaluation unit records the images and an output unit indicates and represents the results. The evaluation unit is formed such that the recorded images are compared, and the maximum contact wire lift is determined from the image data after calibration of the arrangement. An independent claim is also included for a method for a contact wire lifting measuring.

Description

The The invention relates to an arrangement and a method for stationary Fahrdrahtanhubmessung.

When Contact wires overhead lines or catenaries are called, in the case of railways to the traction power supply of electric traction vehicles. Under Fahrdrahtanhub means the change in position of contact wires due the passage of a pantograph from electric traction vehicles.

at the assessment of the interaction between pantograph and overhead line is a rating regarding Contact wire position, contact force of the elasticity of the chain mechanism and the Lifting necessary along the route. It is necessary the lift of contact wires to measure at different points in the catenary.

Around efficient operation of electrically operated rail vehicles to ensure it required the pantograph with a defined contact pressure to press against the contact wire. The contact force leads to a change of position of the Contact wire, provided the contact wire is a lower opposite Strengthens.

Consequently exists in the prior art for a long time the problem, the contact pressure to dimension. Too little contact force leads to high resistance and a warming of the pantograph and the contact wire, and an excessive contact pressure leads to reinforced Abrasion and unwanted swinging of the in several places salaried contact wire, which also referred to as chain drive line becomes.

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 lead to high abrasion due to their high speed and possibly to a swinging of the system, which could be accompanied by an impairment or with a disturbance 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 connected to the output signal linked to the measuring device, to calculate the contact pressure. The acceleration sensor is designed so that it has a spring attached to the pantograph seismic mass, whose respective position in relation to the current collector optically detected and a corresponding light signal to a potential-separated from the pantograph opto-electric Transducer transmitted becomes.

Out the above-mentioned prior art, the need for the Recording the contact pressure - and connected with it indirectly - too the importance of determining the contact wire lift.

aggravating for the Catenary lift measurement is that the overhead lines are live, where the mains voltage is between 0.6 kV and 25 kV.

Of the State of the art for stationary Measuring the lift of overhead lines when passing current collectors electric traction vehicles is represented by the fact that at the live Measuring point a rope is attached, by a suitable guide, over rollers or similar, transmits a deflection to a measuring sensor to earth potential. The Path signal is converted in the sensor into an electrical signal, which the measuring device or the recording device is supplied.

The mentioned conventional method for measuring the trolley lift is associated with serious disadvantages.

Especially It is disadvantageous that the measuring technology in the live Overhead line must be mounted. This leads through the manufacture and Secure the voltage-free state of the overhead line to blocking pauses in railway operation during the installation and uninstallation of the measurement technology.

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

Of the Method of measurement over the change of position a rope immanently adheres to an inaccuracy, which by changes in length of the Ropes, rope sag and rope sluggishness during transmission of the measurement signal under different environmental conditions, such as different temperatures and precipitation, conditional.

By thermal expansion and elongation due to snow and ice loads as well as rain or wind, measurement inaccuracies are caused.

The The object of the invention is an arrangement and a method to measure the trolley lift, with the help of the trolley lift without intervention in the railway operation at every point of the chain work is measurable. It is a further object of the invention to provide a measuring method to disposal to provide a high accuracy at reasonable cost, respectively realized minimal effort.

The The object of the invention is an arrangement for Fahrdrahtanhubmessung with an optical measuring device for image acquisition at least the rest position of the contact wire and the maximum Fahrdrahtanhubs solved, wherein an evaluation device for the captured images and an output device for display and presentation of the results is provided, wherein the evaluation device is formed such that the recorded images compared and after calibration of the arrangement, the maximum contact wire lift (A) can be determined from the image data.

To A preferred embodiment of the invention contains the arrangement additionally Means for contactless Distance measurement between contact wire and measuring device and means for determining the measuring angle α.

In a particularly simple embodiment of the invention is used as a measuring device a camera with an automatic trigger used. Especially preferred embodiment of the invention is used as a measuring device a video camera is used, which covers the entire passage of the pantograph through the measuring point.

To the For purposes of signal processing, it is advantageous to the measuring device as a digital measuring device, as there are intermediate steps the analog, digital and digital-to-analog conversion associated with it Errors can be turned off.

• a) eine optische Messeinrichtung wird zunächst kalibriert,
• b) die Ruhelage des Fahrdrahtes wird in einer Bildebene aufgenommen, wobei der Mittelpunkt des Fahrdrahtes in Ruhelage der Schnittpunkt von Objekt- und Bildebene ist,
• c) die maximale Fahrdrahtanhubposition wird als Bild in der Bildebene aufgenommen,
• d) mittels einer Auswerteeinrichtung aus den Bildern der Ruhelage des Fahrdrahtes und der maximalen Fahrdrahtanhubposition in der Bildebene wird die Differenz des maximalen Fahrdrahtanhubs in der Bildebene bestimmt und
• e) der maximale Fahrdrahtanhub in der Objektebene wird schließlich mittels der Auswerteeinrichtung ermittelt und dargestellt.

The evaluation device for the recorded images and the output device for displaying and displaying the results is preferably realized via an ordinary personal computer. The method for contact wire lifting measurement according to the invention comprises the following steps:

• a) an optical measuring device is first calibrated,
• b) the rest position of the contact wire is received in an image plane, wherein the center of the contact wire in rest position is the intersection of object and image plane,
• c) the maximum contact wire lifting position is recorded as an image in the image plane,
• d) by means of an evaluation of the images of the rest position of the contact wire and the maximum Fahrdrahtanhubposition in the image plane, the difference of the maximum Fahrdrahtanhubs in the image plane is determined and
• e) the maximum Fahrdrahtanhub in the object plane is finally determined and displayed by means of the evaluation.

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

The Catenary lift measurement method is accompanied by various calibration procedures designed different accuracies, depending on requirements can be used.

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 IN in the image plane IN '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.

at The self-calibrating measurement will be at the measuring point in the catenary located components used as a measurement standard. The advantage exists this 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. If, however, a component in the object plane is used as normal, then the display error is automa 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 alternative method of calibrating 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 IN und Umrechnung auf die Bildebene des Messobjektes unter Beachtung des Winkels α zu IN' 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 dimension of the orthogonal image plane for the length of the foreign standard IN and conversion to the image plane of the measurement object, taking into account the angle α to IN 'and
• • Focusing the measurement object with the camera.

According to the concept the optical and non-contact Determining the maximum trolley lift is one of the boundary conditions the visibility of the pantograph. The visibility of the pantograph is given if the image width of the measurement image is larger as the distance traveled in the time between the field shots of the camera of the vehicle. This is given at 25 frames per second, if the distance traveled by the vehicle within one fiftieth of a second Path corresponds to the image width of the measurement recording.

The Assignability of rest position and rise of a measurement is given, when the measurement recording starts recording the rest position before the current collector in the Nachspannlänge the measured overhead line retracted. Post-length is the distance a guy point of a catenary to the next, whereas with field length of the Distance between two masts is named.

Especially is advantageous if the image size in the image plane digital in the form of the pixel number is captured, which by conventional Programs is readily feasible. This is an accuracy Ultimately dependent on the number of pixels and the resolution, which is already very cost effective one very high resolution and thus a high accuracy of the system can be achieved.

Especially is preferred if the picture for the maximum catenary lift from a sequence of images at the pantograph passage selected becomes. The process of the rest position of the contact wire over the Continuous current collector filmed, and the pictures are below manually or as well Programmatically selected.

A advantageous embodiment of the invention is that by the inclusion of a fixed reference object in the recorded images, like a building, a mast or a structure, mistakes can be corrected. in the Image section, the reference object is detected with, and by the Determination of the relative vertical distance from measurement to reference object is a correction of errors due to vibration of the measuring device by wind or weather influences or other vibration influences possible.

A Design of this component is that in the tunnel as Reference object for error correction a pattern on the tunnel wall or tunnel ceiling is used.

The advantages of the invention are in particular This is because the installation of the measuring 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 Realizations. Due to high-powered telephoto lenses, the contact wire lifting measurement is of different height possible. It is irrelevant whether the measuring device above or located below the top of the rail (SOK).

The Evaluation and display device can also cost-effective means a conventional one Computers are realized, so that only standard components with sufficient accuracy can be used.

All in all the accuracy of the procedure according to EN 50317 is complied with, because the approximations used have no significant impact on earnings.

With of the method stationary optical lifting measurements for Contact wire, carrying cable and all moving fittings are made. It is particularly advantageous that the measurement both at the base as well as anywhere in the longitudinal field is possible.

Likewise are several independent Measuring points can be set up.

To an embodiment of the invention is also a driving speed measurement to 350 km / h possible.

Further Details, features and advantages of the invention will become apparent the following description of embodiments with reference on the associated 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 picture 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 extends between the 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 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 image plane 2 ,

In 2 are the geometric relationships of object plane 3 and 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 image plane orthogonal to this 2 , The shift from 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 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.

• – 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 IN' 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.

The stretched IN 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. Becomes the contact wire 5 through the current collector passage in the object plane 3 shifted upwards, this shift appears in the image plane 2 at the point 5 ' , The normal known quantity is now related to the size of the measurement standard in the image plane IN ', which is the ratio of the maximum contact wire lift A in the object plane 3 and the maximum trolley lift LA 'in the 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 IN 'to the length of the normal, for example a support point clamp in mm, • Marking the rest position, • Display of the image of the current collector passage: The current collector must be 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 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 again indicates the viewing direction and the image plane orthogonal to this 2 , The shift from image plane 3 to object level 2 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 picture 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 inventive concept is transferable to movements in various levels, wherein the calibration plane is the image plane, which must be parallel to the object plane in order to exclude angular errors.

• – Fremdkalibrierte Messung an zwei aufeinanderfolgenden 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.

• - Foreign-calibrated measurement on two consecutive interpolation points: • Setup of the cameras with tripods, • Performing the externally calibrated measurement for each camera, • Start recording before the electric traction unit enters the post-tension length in which the measuring point is located, • Stop recording after all the pantographs to be measured have passed the measuring point, • transfer of the data to the evaluation computer, • start of 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 the higher accuracy by using larger normals as well as in the greater universality of applicability, as all measuring points without measuring standard are measured at or at the measuring point can be.

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 to obtain.

1

measuring device

2

Image plane / Orthogonal to the image acquisition direction

2 '

image plane in the vertical for external calibration

3

Object Level / Vertical

4

Image capture direction

5

contact wire in a quiet location

5 '

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

6

horizontal

7

track

8th

Third-Normal

X

distance Messeinrichung contact wire

O'

Foreign Normal for calibration in the vertical image plane 2 '

LN

Known Size of one 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 (15)

Arrangement for driving wire lifting measurement, characterized in that a non-contact optical measuring device ( 1 ) for image recording at least the rest position of the contact wire ( 5 ) and the maximum Fahrdrahtanhubs (A), 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 such that the recorded images are compared and after calibration of the arrangement of the maximum Fahrdrahtanhub (A ) can be determined from the image data. Arrangement according to claim 1, characterized in that additionally means for non-contact distance measurement between contact wire ( 5 ) and measuring equipment ( 1 ) and means for determining the measuring angle (α) are provided. Arrangement according to claim 1 or 2, characterized in that the measuring device ( 1 ) is designed as a camera. Arrangement according to claim 1 or 2, characterized in that the measuring device ( 1 ) is designed as a video camera. Arrangement according to one of claims 1 to 4, characterized in that the measuring device ( 1 ) is designed as a digital measuring device. Arrangement according to one of claims 1 to 5, characterized that the evaluation device for the captured images and the output device for display and presentation of the results is performed as a computer. Method for measuring contact wire lifting, in which a) an optical measuring device ( 1 ) is calibrated, b) the rest position of the contact wire ( 5 ) is recorded in an image plane, wherein the center of the contact wire ( 5 ) in rest position the intersection of object and image plane ( 3 . 2 ), c) the maximum contact wire lifting position ( 5 ' ) as an image in the image plane ( 2 ), 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 ( 2 ) the difference of the maximum contact wire lift (LA ') in the image plane ( 2 ) and e) the maximum contact wire lift (A) in the object plane ( 3 ) is determined and displayed and displayed by means of an output device. Method according to claim 7, characterized in that the calibration of the optical measuring device ( 1 ) is carried out by self-calibration, wherein a present at the measuring point component of known size IN in the image plane IN 'is determined and that the Fahrdrahtanhub A in the object plane after the measurement of the Fahrdrahtanhubs in the image plane LA' in the evaluation approximately the relationship

takes place and is displayed. Method according to claim 7, characterized in that the calibration of the optical measuring device ( 1 ) by external calibration, wherein A) the distance (X) of the measuring device ( 1 ) to the contact wire ( 5 ) is determined with the means for non-contact distance measurement, B) the measuring angle (α) as the angle between the horizontal ( 6 ) and the straight line forming the distance (X) 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 ') is determined 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 9, characterized in that for foreign calibration, the measuring device ( 1 ) parallel to the track in the horizontal ( 6 ) is pivoted and the foreign-normal ( 8th ) during the calibration in the vertical image plane ( 2 ' ) lies. Method according to one of claims 7 to 10, characterized in that the image size in the image plane ( 2 ) is detected digitally in the form of the pixel number. Method according to one of claims 7 to 11, characterized in that the image for the maximum contact wire ( 5 ' ) is selected from a sequence of images at the current collector passage. Method according to one of claims 7 to 12, characterized that a fixed reference object, such as a building, a Mast or a building, in the image section is captured and by the Determination of the relative vertical distance from measurement to reference object a correction of errors due to vibrations of the measuring device he follows. Method according to claim 13, characterized in that that in tunnels as a reference object for error correction a pattern is used on the tunnel wall or tunnel ceiling. Method according to one of claims 9 to 14, characterized in that the calibration of the measuring device ( 1 ) by the foreign standard ( 8th ) is carried out by means of characteristic curves before the measurement under laboratory conditions, wherein a plurality of characteristic curves for different distances (X) are recorded.