MDK02 is a measuring device intended for the measurement of rail surface roughness for the needs of railway track noise assessment, and for the measurement of corrugation. It is able to independently measure uninterrupted segments in a length of several metres, evaluate the acquired data and compute the resulting third-octave band analysis in conformity with the standard EN15610-41.
Sensors can be easily adjusted into the centre of smooth rut run by vehicles on the rail head. For the measurement, MDK02 uses two independent versines with contact sensors placed perpendicular to longitudinal axis of the rail.
MDK02 consists of measuring trolley and external computer. Measuring trolley includes sensors with the necessary drive and electronic unit which transfers the acquired data to a computer. Trolley is controlled from external computer (PDA, touchpad or notebook). Trolley is driven by its own small electric motor (in case of measuring roughness), therefore, it can be handled without the necessity of standing in trackage. Wireless transmission of the data from the trolley proceeds via standard Bluetooth interface. The trolley also allows connection via RS-232.
When measuring roughness, wireless connection is recommended. This is for several reasons. Operating personnel is not connected with the trolley via cable, having thus free hands to handle the trolley. This is convenient for the measurement conducted on tracks under operation. In addition, operating personnel during the measurement need not stand in clearance profile but may walk along the track and not hamper train sets running, for example, on the neighbouring track.
MDK02 is easily transportable also by passenger car. It can be dismounted into two parts. A single-rail trolley with the measuring systems, batteries and electronics form one compact unit. Four screws serve for the fixing of supporting leg which during the chart run leans on the opposite not measured rail head.
MDK02 may be fitted with several stand-alone measuring units:
• roughness measuring unit,
• corrugation measuring unit
• both measuring units concurrently.
The data from both measuring units are independent.
MDK02 is easily operated. Chart is placed at the beginning of the measured rail segment. For the measurement of roughness, rail head has to be degreased and cleaned from dust. Measuring mechanism on the chart is unblocked from transport to operating position. Control computer via control programme triggers the measurement. Chart starts moving to carry out continuous data acquisition. Chart itself maintains travel speed, abstractedly from operating personnel.
Operator slowly follows the chart along the track. At the end of the measured segment, operator stops the measurement by pressing the button on control computer display and removes the chart from the track. Simultaneously, the acquired data are automatically evaluated in control computer. During the data evaluation, chart may already be disconnected and put aside the track. Chart is fitted with automatic interlock which stops it and terminates the measurement after travelling the maximal length of a measured segment. This prevents uncontrolled behaviour of the chart in the event of noised wireless communication or control computer defect.
MDK02 is furnished with controlling and evaluating software which from the acquired data computes all filters required to process the data in conformity with the standard EN15610-41. The following blocks for signal processing are used:
• filtering of outlying peaks (spike filter),
• filtering of the measured data within the scope required for noise evaluation,
• filtering through diameter 375 mm wheel travel (pits filter),
• calculation of average spectrum with 50% overlapping,
• calculation of the resultant logarithmic third- band spectrum and its comparison with TSI limit.
MDK02 stores the acquired data into control computer, using standard binary and ascii formats for the data transfer. These formats are open and can be easily loaded into database or into Matlab/MS Excel for potential further analysis. For the processing, user software is installed in control computer. Software images the course of the measured signal during the data acquisition and after the termination of the measurement it automatically computes the resultant third-octave band analysis.
MDK02 has the following technical parameters:
Measurement of roughness:
Maximal length of measured segment: 15 m
Speed of measurement: 100 mm/s
Scanning interval: 1 mm
Sensor resolution: 0.1 um
Sampling frequency: 64 kHz
Measurement of corrugation:
Maximal length of measured segment: unlimited
Speed of measurement: 300mm/s
Scanning interval: 5mm
Sensor resolution: 1um
Sampling frequency: 0.6 kHz
Battery operation time: 4-8 hours for trolley, control computer depends on type.
Weight: 14 kg
Transport dimensions: 830 x 190 x 190 mm and 1100 mm long supporting leg