1、Railway applications Acoustics Measurementmethod for combined roughness, track decay rates and transfer functionsPD CEN/TR 16891:2016BSI Standards PublicationWB11885_BSI_StandardCovs_2013_AW.indd 1 15/05/2013 15:06National forewordThis Published Document is the UK implementation of CEN/TR 16891:2016
2、.The UK participation in its preparation was entrusted by TechnicalCommittee EH/1, Acoustics, to Subcommittee EH/1/2, Transport noise.A list of organizations represented on this committee can be obtained onrequest to its secretary.This publication does not purport to include all the necessary provis
3、ions ofa contract. Users are responsible for its correct application. The British Standards Institution 2016.Published by BSI Standards Limited 2016ISBN 978 0 580 74370 2ICS 17.140.30; 93.100Compliance with a British Standard cannot confer immunity fromlegal obligations.This British Standard was pub
4、lished under the authority of theStandards Policy and Strategy Committee on 30 June 2016.Amendments/corrigenda issued since publicationDate Text affectedPUBLISHED DOCUMENTPD CEN/TR 16891:2016TECHNICAL REPORT RAPPORT TECHNIQUE TECHNISCHER BERICHT CEN/TR 16891 May 2016 ICS 17.140.30; 93.100 English Ve
5、rsion Railway applications - Acoustics - Measurement method for combined roughness, track decay rates and transfer functions Bahnanwendungen - Akustik - Messmethode fr kombinierte Rauheit, Gleisabklingraten und bertragungsfunktionen This Technical Report was approved by CEN on 13 May 2016. It has be
6、en drawn up by the Technical Committee CEN/TC 256. CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithua
7、nia, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey andUnited Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG CEN-CENELEC Management Centre: Avenue Marnix 17, B-10
8、00 Brussels 2016 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. CEN/TR 16891:2016 EPD CEN/TR 16891:2016CEN/TR 16891:2016 (E) 2 Contents Page European foreword . 4 Introduction 5 1 Scope 6 2 Normative references 6 3 Terms and definiti
9、ons . 7 4 Symbols and abbreviations . 8 5 Instrumentation 8 6 Installation aspects. 9 7 Measurement positions 9 8 Measured quantities . 10 9 Test procedure 10 10 Data processing . 10 11 Method to determine the track decay rate from rail vibration . 11 11.1 General . 11 11.2 Energy iteration method .
10、 11 12 Method to determine the combined roughness from vertical railhead vibration . 18 13 Method to convert roughness from frequency to wavelength domain. 20 14 Method to determine the rolling noise transfer function 22 14.1 Definition 22 14.2 Application examples . 23 15 Test report 23 16 Uncertai
11、nty and grade 23 Annex A (informative) A2factor, difference between the combined roughness and the contact point displacement 25 Annex B (informative) Benchmark examples and background information 28 B.1 General . 28 B.2 Examples of vertical decay rates determined for several different tracks . 28 B
12、.3 Comparison with direct measurements 29 B.4 Comparison of TDR methods . 33 B.5 Repeatability 35 B.6 Reproducibility . 38 B.7 Effect of accelerometer position . 42 B.8 Effect of speed and averaging 48 B.9 Effect of wheel defects 52 PD CEN/TR 16891:2016CEN/TR 16891:2016 (E) 3 B.10 Effect of temperat
13、ure 52 B.11 Effect of load . 52 Annex C (informative) Slope methods 53 C.1 Single accelerometer slope method . 53 C.2 Two accelerometer method 54 Bibliography . 55 PD CEN/TR 16891:2016CEN/TR 16891:2016 (E) 4 European foreword This document (CEN/TR 16891:2016) has been prepared by Technical Committee
14、 CEN/TC 256 “Railway applications”, the secretariat of which is held by DIN. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN shall not be held responsible for identifying any or all such patent rights. PD CEN/TR 16891:2016CEN/
15、TR 16891:2016 (E) 5 Introduction This Technical Report provides a basis for a standard on measurement of combined wheel-rail roughness, track decay rates and transfer functions from train pass-bys. The main items required for a standard are covered but also additional background information and benc
16、hmark results are included. PD CEN/TR 16891:2016CEN/TR 16891:2016 (E) 6 1 Scope This method is used to determine combined wheel-rail roughness and track decay rates from rail vibration during the pass-by of a train. By combining sound pressure measurement from the same pass-by, a vibro-acoustic tran
17、sfer function for rolling noise is determined. The track decay rate is a vibration quantity that characterizes the attenuation of rail vibration along the track for a given wheel/rail contact excitation, and thereby affects the amount of sound radiation from the track. Combined roughness is a quanti
18、ty that determines the level of excitation of wheel-rail rolling noise. It can be determined from vertical rail vibration during a train pass-by and the vertical track decay rate. The transfer function can be used to characterize the vibro-acoustic behaviour of the vehicle-track system for a given r
19、oughness excitation and in relation to rolling noise. Combined roughness, track decay rates and transfer functions are determined as one-third octave spectra. The method can be used for the following purposes: to measure track decay rates under operational conditions; to characterize the effectivene
20、ss of noise control measures in terms of combined roughness, transfer function and track decay rate; to compare the combined roughness before and after noise control measures are implemented (thereby quantifying the effect of any change in wheel or rail roughness); to monitor wheel roughness during
21、a pass-by, either of whole trains or parts of trains; to separate rolling noise from other sources; to assess a threshold for the rail roughness by measuring multiple pass-bys. The method is not for approval of sections of reference track in terms of acoustic rail roughness and track decay rates, wh
22、ich are covered by EN 15610 and EN 15461, respectively. The method is applicable to trains on conventional tracks, i.e. normal ballasted tracks with wooden or concrete sleepers and on ballastless track systems. The method has not yet been validated for: non-standard wheel types such as small wheels
23、up to 600 mm diameter, resilient tram wheels; non-standard track types such as embedded rail or grooved rail; The method is not applicable to track with rail joints. 2 Normative references The following documents, in whole or in part, are normatively referenced in this document and are indispensable
24、 for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. EN 15461, Railway applications Noise emission Characterisation of the dynamic properties of track sections for pass by
25、 noise measurements EN 15610, Railway applications Noise emission Rail roughness measurement related to rolling noise generation PD CEN/TR 16891:2016CEN/TR 16891:2016 (E) 7 EN ISO 266, Acoustics Preferred frequencies (ISO 266) 3 Terms and definitions For the purposes of this document, the following
26、terms and definitions apply. 3.1 pass-by time tps duration of vehicle pass-by from buffer to buffer 3.2 number of axles Nax- number of axles in the selected train or part of train 3.3 one-third octave band frequency fcHz centre frequency of a one-third octave frequency band 3.4 one-third octave wave
27、length m centre wavelength of a one-third octave wavelength band 3.5 sound pressure signal p(t) Pa time signal of the sound pressure measured at a fixed point 3.6 equivalent sound pressure level spectrum Lpeq,Tp(fc) dB re 2.105Paone-third octave spectrum of the sound pressure energy averaged over pa
28、ss-by time tp3.7 acceleration signal a(t) m/s2 time signal of the rail acceleration 3.8 equivalent vertical rail vibration level spectrum Laeq,Tp(fc,V) dB re 106m/s2one-third octave spectrum of the sound pressure energy averaged over pass-by time tpat runningspeed v 3.9 decay exponent m-1 decay expo
29、nent characteristic for the vibration decay in the rail PD CEN/TR 16891:2016CEN/TR 16891:2016 (E) 8 3.10 vertical track decay rate Dz(fc) dB/m decay rate of vertical rail vibrations along the rail head 3.11 lateral track decay rate Dy(fc) dB/m decay rate of lateral rail vibrations along the rail hea
30、d 3.12 combined effective roughness wavelength spectrum LRtot(), dB re 106mwavelength spectrum in one-third octaves of the combined effective wheel-rail roughness including the contact filter 3.13 combined effective roughness frequency spectrum at speed v LRtot(fc,v) dB re 106mfrequency spectrum in
31、one-third octaves of the combined effective wheel-rail roughness including the contact filter 3.14 rolling noise transfer function LHpR,tot,nl(fc) dB re 20 Pa/m transfer function in one-third octave bands between the sound pressure at a fixed point, 7,5 m, and the combined effective roughness freque
32、ncy spectrum, normalized to the axle density Nax/l 4 Symbols and abbreviations Symbol Definition Unit length of train, vehicle or train part m v train speed m/s 5 Instrumentation Instrumentation for sound pressure measurement should comply with requirements in EN ISO 3095. The whole measurement chai
33、n shall be capable of measuring in the frequency range 25 Hz to 10 kHz. The signal sample rate for acceleration and sound pressure signals should be sufficient for the frequency range required. A sample frequency of 25 kHz or 32 kHz is sufficient for a measurement range up to 10 kHz. The acceleromet
34、er type should be consistent with the expected vibration range and frequency range. The accelerometer and its measurement chain shall be selected and adjusted to cover the typical vibration range without signal clipping or overloading. Vertical railhead vibration can reach up to 5 000 m/s2or more. T
35、he dynamic range shall be at least 70 dB. The accelerometer and its connector shall be water tight especially if moisture can collect during the measurement. Optionally a thermometer should be available for measuring the rail temperature. PD CEN/TR 16891:2016CEN/TR 16891:2016 (E) 9 6 Installation as
36、pects The accelerometer should be fixed to the rail by means of a glue NOTE Magnetic fixing is also possible but may reduce the usable frequency range at higher frequencies. General guidelines on mechanical mounting of accelerometers should be taken into account as set out in ISO 5348. Attention sho
37、uld be given to firm mounting as the resonance frequency of the accelerometer on its mounting can drop below 10 kHz if not sufficiently stiff. Overloading and potential loosening or detachment should be avoided and therefore continually monitored during measurement. Further information on installati
38、on aspects can be found in 10. 7 Measurement positions For vertical track decay rate and combined roughness measurement a single accelerometer is mounted under the longitudinal axis of the rail foot or under the side of the rail head (with angle plate, see Figure 1), next to a sleeper. For lateral d
39、ecay rate measurement an accelerometer is mounted on the outer side of the rail head. If the transfer function is measured then a microphone is positioned at 7,5 m from the track centreline and at 1,2 m above the rail surface directly opposite the accelerometer. The number of accelerometers may be i
40、ncreased if required, for example to measure the combined roughness on the other rail or along the track to take potential track variations into account. a) Cross section of the rail, wheelflange on the left side b) Example of position aFigure 1 Suitable positions for measuring vertical railhead vib
41、ration a and b Mounting underneath the side of the railhead (b) should include an angle stud to ensure vertical positioning of the accelerometer. Position c indicates the position for lateral railhead vibration measurement, if required. The measurement cross-section shall not be close to unusual rai
42、l support conditions, in particular: 1) there shall be no pumping sleeper within a distance smaller than 3 m to the accelerometer;2) there shall be no missing or damaged rail clip (or fastener of any other type, if necessary) on thesupports directly adjacent to the accelerometer location;PD CEN/TR 1
43、6891:2016CEN/TR 16891:2016 (E) 10 3) the accelerometer shall not be located within 5 m of a weld; 4) the accelerometer shall not be located within 40 m of an expansion joint. 8 Measured quantities Pass-by time tpof train or train part; train speed v; vertical railhead acceleration signal a(t); sound
44、 pressure signal at 7,5 m p(t); optionally axle trigger signal z(t) should be recorded during the measurements; optionally the rail temperature should be recorded during the measurements. 9 Test procedure During a whole pass-by of a train the following is recorded: vertical railhead vibration (accel
45、eration signal) including the approach and departure of the train; sound pressure time signal, if a transfer function is required; train speed v; train length , usually determined from known vehicle lengths; number of axles Nax, counted or estimated from the vibration or trigger signal; optionally t
46、he axle trigger signal z(t). If the lateral decay rate is to be determined, then also lateral railhead vibration shall be registered. The vertical track decay rate and, if required, the lateral track decay rate shall be averaged over several pass-bys of one or more trains, rejecting outlier curves,
47、see Clause 11. An indicative result (which shall not be considered as a valid result) of the combined roughness and transfer function can be obtained from a single pass-by. The measurement uncertainty can be reduced by: averaging results over three or more pass-bys of the same train; averaging resul
48、ts over two or more train speeds of the same train at least 10 % apart. Combined roughness can be measured either on a single rail or on both rails depending on the purpose of the measurement. 10 Data processing The vertical (and if required lateral) rail acceleration time signal is processed by the
49、 method described in Clause 11 to determine the track decay rate. PD CEN/TR 16891:2016CEN/TR 16891:2016 (E) 11 The combined roughness is derived from the vertical decay rate and the equivalent rail vibration level Laeq,tpover pass-by time tpaccording to the method set out below. The transfer function is derivedaccording to Clause 14 from the equivalent sound pressure level Lpeq(fc), the combined roughnessLRtot(fc,v) and the number of axles per unit length Nax/.11 Met
