Deliverable D 5.2.2

TIP4-CT-2005-516420 Page 1 of 28 QCITY issued: 30-01-09

DELIVERABLE D 5.2.2 CONTRACT N° TIP4-CT-2005-516420 PROJECT N° FP6-516420 ACRONYM QCITY TITLE Quiet City Transport Subproject 5 Noise propagation & receiver perception Work 5.2 Performance report of a low squeal track solution Package in Athens Tram Network

Written by Prof. Konstantinos VOGIATZIS TT&E, UTH, CDM, TRAM & APT

Date of issue of this 30-01-09 report PROJECT CO-ORDINATOR Acoustic Control ACL SE PARTNERS Accon ACC DE Akron AKR BE Amec Spie Rail AMEC FR Alfa Products & Technologies APT BE Banverket BAN SE Composite Damping Material CDM BE Havenbedrijf Oostende HOOS BE Frateur de Pourcq FDP BE Goodyear GOOD LU Head Acoustics HAC SE Heijmans Infra HEIJ BE Royal Institute of Technology KTH SE Vlaamse Vervoersmaatschappij DE LIJN LIJN BE Lucchini Sidermeccanica LUC IT NCC Roads NCC SE Stockholm Environmental & Health Administration SEA SE Société des Transports Intercommunaux de STIB BE Bruxelles Netherlands Organisation for Applied Scientific TNO NL Research Trafikkontoret Göteborg TRAF SE Tram SA TRAM GR TT&E Consultants TTE GR University of Cambridge UCAM UK University of Thessaly UTH GR Voestalpine Schienen VAS AU Zbloc Norden ZBN SE Union of European Railway Industries UNIFE BE PROJECT START February 1, 2005 DATE DURATION 48 months Project funded by the European Community under the SIXTH FRAMEWORK PROGRAMME PRIORITY 6 Sustainable development, global change & ecosystems

Performance report of a low squeal track solution Athens Tram Network

TIP4-CT-2005-516420 Page 2 of 28 QCITY issued: 30-01-09

TABLE OF CONTENTS

page 1 Introduction 3 2 “BEFORE” Test site, Instrumentation & Reference field measurements results 5 3 Tram squeal noise model including a suitable model for the roll- 10 slip excitation of the wheel and rail 3.1 Squeal generation 10 3.2 Lumped parameter model with non-linear friction element 11 3.2.1 Justification of the model 11 3.2.2 Short description of the model 12 3.2.3 Implementation of the model 12 4 Squeal calculations with Voula curve parameters 13 5 The Voula curve location : Low squeal track solution Elastomer’s characteristics - Stiffness data of CDM Comfort Plus 15 6 Preparation & Installation of prefab low squeal elements in the Athens Tram’s Voula extension 17 7 “AFTER” VOULA test site, Instrumentation & Field measurements results 20 8 Discussion and concluding remarks 24 9 References 27

Annexes

ANNEX 1 Reference Acoustic Field measurements results : «BEFORE» ANNEX 2 FORTRAN code for specific non linear "squeal" element ANNEX 3 Input file for FE model. ANNEX 4 Acoustic Field measurements results : «AFTER»

Performance report of a low squeal track solution Athens Tram Network

TIP4-CT-2005-516420 Page 3 of 28 QCITY issued: 30-01-09

1. INTRODUCTION

The Quiet City Transport project (QCity) within the SIXTH FRAMEWORK PROGRAMME: SUSTAINABLE SURFACE TRANSPORT [1] aims to develop an integrated technology infrastructure for the efficient control of road and rail ambient noise by considering the attenuation of noise creation at source at both vehicle/infrastructure levels. Qcity’s specialized Sub Package 5 aims to a detailed design of selected mitigation measures for hot spots to be studied – among other European cities – also in a designated Athens validation site d under the topic: “Quiet tram tracks” in order to minimize wheel squeal emissions.

Athens Tram has performed during last years an extended Noise &Vibration Study including both airborne & ground borne noise & vibration levels calculations. could decrease dramatically the equivalent sound levels (depending also to tram type & relevant noise emissions) for the majority of nearby residents even though the relevant noise criterion in Greece was set to 67 dB(A) for the index Leq (18hours) based on the total daily operation of the system.

One of the major problems raised during operation is the squeak noise parameter and the present report describes the setup of the relevant measurement campaign & research in the matter and also a complete evaluation, relevant concluding remarks aiming to practical & effective recommendations.

The relevant Work Package (WP5.2) introduces among other tasks the development & implementation of a prototype "Quiet tram track” elastically encapsulated in a prefabricated concrete slab, at Voula extension of the Athens Tramway line to Glyfada area.

The present Deliverable describes the relevant prototype research, realization & evaluation with emphasis to the following internal phases :

¤ Reference campaign of squeal noise measurements & 1/3 octave band analysis at an existed curved track in Athens Tramway network i.e. Diadochou Pavlou street Tram section (measurement phase : “Before”) ¤ Model analysis of a prototype "Fastener less embedded resilient tram track for squeal noise reduction including the ROLL - SLIP excitation of the wheel & rail and a time domain analysis considering constant crabbing velocity yields wheel and rail vibrations” ¤ Laboratory analysis & development of an adequate new "elastomer encapsulation material” with specified vertical & horizontal stiffness ¤ Selection of a curve location with similar geometrical characteristics with the existed curve track measured as described above i.e. Voula curved section – Glyfada Athens and precisely at Alkyonidon Avenue crossing section

Performance report of a low squeal track solution Athens Tram Network

TIP4-CT-2005-516420 Page 4 of 28 QCITY issued: 30-01-09

¤ construction of a specialized prefab slab including the new "elastomer encapsulation material” at the worksite prior to installation on site ¤ Installation in situ at the selected tram line section at Voula-Athens ¤ campaign of squeal noise measurements & 1/3 octave band analysis at the new prefab curved track in Athens tramway network i.e. Voula (measurement phase : “After”) ¤ evaluation of noise attenuation results towards a future development and use of such "prefab quite track" solutions at the forthcoming Piraeus extension of Athens Tram

Following relevant meetings in Athens (TRAM SA offices) and in Budapest and Bruxelles with the participation of all participants for the WP 5.2, and the analysis of the internal phases above, the following important internal coordination & construction actions were planned & executed :

1. Selection of the Demo site at Athens TRAM network i.e. the extension to Voula, for the implementation of the «squeal noise track solution». The chosen implementation location for the new prototype «Quiet tram track» in Athens Tram Voula extension - already under operation – is the intersection of the new extension tramway axis and Leoforos Alkionidon. 2. Realisation and testing of a prototype by CDM including also manufacturing and transportation of a complete enhanced prefab curve module by CDM to the site including also installation in collaboration with TRAM SA, and the local track work contractor. The squeal solution was installed during track work construction. For this specific construction CDM’s plant in Soignies has provided a “Modulix” prefab element in which a “comfort low squeal track” was incorporated equipped with special elastomer “jacquettes” with a low lateral stiffness. The installation was taken place together with the other regular crossing parts of the tram’s alignment.

Performance report of a low squeal track solution Athens Tram Network

TIP4-CT-2005-516420 Page 5 of 28 QCITY issued: 30-01-09

2. “BEFORE” TEST SITE, INSTRUMENTATION & REFERENCE FIELD MEASUREMENTS RESULTS

In this chapter a “Before” test site was selected for the reference measurement campaign and described in detail hereafter. This site in Diadochou Pavlou street Athens Tram’s network area, was selected to present similar geometrical characteristic with the test site in the “After” measurements campaign, presented hereafter as well. In order to maintain the highest degree of compatibility between the “before” & “after” study as well as the extraction of valuable conclusions to be used in the following model analysis of a prototype "Fastener less embedded resilient tram track for squeal noise reduction including the ROLL - SLIP excitation of the wheel & rail and a time domain analysis considering constant crabbing velocity yields wheel and rail vibrations”, the same vehicle was used in the same range of speeds (i.e. 10, 20 & 25+ to 30 Km/h) during all measurements.

The location of the “Before” Reference acoustic measurements campaign is presented in the fig.1 hereafter :

Fig.1 : Reference test site

Performance report of a low squeal track solution Athens Tram Network

TIP4-CT-2005-516420 Page 6 of 28 QCITY issued: 30-01-09

The Standard EN ISO 3095:2005 that has been prepared by Technical Committee CEN/TC 256 “Railway applications”, the secretariat of which is held by DIN, in collaboration with Technical Committee ISO/TC 43 "Acoustics" was enforced in this measurements campaign.

This standard is applicable for type testing & periodic monitoring testing and the results may be used,:

D to characterize the noise emitted by these trains; D to compare the noise emission of various vehicles on a particular track section; D to collect basic source data for trains.

According to the standard and in view of the particularities of the present Athens Tram Reference Test site (Diadochou Pavlou street area) the noise quantities measured at all microphone positions presented hereafter are :

D For whole trams moving at constant speed the Transit Exposure Level, TEL, or the A-Weighted equivalent continuous sound pressure level on the pass by time, LpAeq. D The measurement quantity for accelerating or braking tests the maximum AF-weighted sound pressure LpAFmax. D For the present campaign a frequency analysis was also required, made at least in one third octave bands according to EN ISO 266: at least from 31,5 Hz to 8 kHz. ensuring that the lower frequency limit is chosen to ensure that the product of the lowest bandwidth and signal duration exceeds unity. For this campaign a frequency range from 20 Hz to 20 KHz was introduced. D Add. to the above a complete 1/3 octave band freq analysis was also executed for the “nosiest bogie” of the vehicle for each passage at all speed intervals.

The instrumentation system, including the microphones, cables and recording devices was in accordance with the requirements for a type 1 instrument specified in EN 61672-1. “Symphonie” noise recording and 1/3 octave band analysis system from 01dB (FR) was used ensuring :

D 2 synchronized micros all with suitable windscreens

The microphones have an essentially flat frequency response in a free sound field. The 1/3 octave band filters met the requirements of class 1 according to EN 61260. Before and after each series of measurements a sound calibrator meeting the requirements of class 1 according to EN 60942 was applied to the microphone(s) for verifying the calibration of the entire measuring system. The compliance of the instrumentation system with the requirements of EN 61672-1 and EN 61672-2 was verified.

Performance report of a low squeal track solution Athens Tram Network

TIP4-CT-2005-516420 Page 7 of 28 QCITY issued: 30-01-09

Reference Test site conditions : The necessary conditions were ensured for the test site, including free sound propagation with a ground essentially flat (with a max level variation from 0 m to -0,20 m, relative to the top of rail). The free field area around the microphones has a radius more that 3 times the measurement distance on both sides free of large reflecting objects like barriers, hills, rocks, bridges or buildings. In the vicinity of the microphones, no obstacles disturbing the sound field were permitted including persons. Furthermore the area between the tram vehicle and the microphones was completely free as possible of sound absorbing matter (e.g. snow, tall vegetation, other tracks) or reflective covering (e.g. water, ice). The ground cover in both test sites was an asphalt (tarmac) coverage. Regarding the meteorological conditions during the test the wind speed measured at the microphone height was below 1 m/s and there was no falling rain or snow. Temperature was between 8 & 12o C and humidity, in normal levels (some 70 to 80%).

The microphone positions axis was always horizontal and directed perpendicularly to the track.

The microphone positions as per the relevant Standard EN ISO 3095:2005 are shown in the adjacent schematic.

The microphone positions were selected were in one side (opposite site not available due to topographic conditions and the marina area) ensuring basic distances of 1,5 & 7,5 m from the track axis, at a height of 1,2 m above the top of rail. The Athens Tram vehicle measured in the “Before” reference site was in its normal operating conditions and already run in normal conditions at least 1 000 km on track with normal traffic. During all measurements, the doors and windows of the vehicle were kept closed, and all auxiliary equipment on the test vehicles that normally operates during the run was in action.

The referenced embedded track was laid in both sites without rail joints (welded rail) and free of visible surface defects such as rail burns or pits and spikes caused by the compression of external material between wheel and rail: no audible impact noise due to welds was present. All measurements conducted during late night in order to eliminate environmental background noise.

The photographic / schematic presentation of the site and the relevant measurement’s setup is presented hereafter in fig.2 :

Performance report of a low squeal track solution Athens Tram Network

TIP4-CT-2005-516420 Page 8 of 28 QCITY issued: 30-01-09

Fig 2 : Reference Acoustic measurements : “BEFORE” test site

Performance report of a low squeal track solution Athens Tram Network

TIP4-CT-2005-516420 Page 9 of 28 QCITY issued: 30-01-09

A total of 3X5=15 tram pass byes of the same vehicle, were recorded and analyzed in this reference test site according to the setup described above for various speeds possible for the given curve i.e 10, 20, & 25 Km/h (5 pass bys per speed).

The analytical results per pass by & per speed are presented (including full 1/3 octave band analysis) in Annex 1 hereafter for both :

D Leq descriptors (per tram/speed passage) and D Lmax for the nosiest bogie are presented in the tables and relevant graphs and provide valuable data regarding squeal generation and relevant frequencies for the modeling described hereafter.

Performance report of a low squeal track solution Athens Tram Network

TIP4-CT-2005-516420 Page 10 of 28 QCITY issued: 30-01-09

3. TRAM SQUEAL NOISE MODEL INCLUDING A SUITABLE MODEL FOR THE ROLL-SLIP EXCITATION OF THE WHEEL AND RAIL

3.1 SQUEAL GENERATION

There are two possible mechanisms for wheel squeal (see also : Quiet City Transport Design & implementation of solutions at validation sites Athens - Quiet tram tracks Fastener less embedded resilient tram track - type CDM Comfort Plus - for squeal noise reduction at Athens Tram, Voula extension : Patrick Vanhonacker, APT, REPORT TIP4-CT-2005-516420 FP6-516420 QCITY, June 13, 2007 [2] ) :

D longitudinal stick-slip due to the different translation velocities between two wheels on a rigid axle; D crabbing of the wheel across the top of the rail: lateral stick-slip (rolling slip).

Due to the finite length of the 2-axles truck and the radius of curvature of the rail, both axles cannot lie upon curve radius, as shown on fig. 3. This figure shows the geometrical relation between the creep angle ξ, the wheel base l and the curve radius R. Under actual conditions, however, the leading axle of the truck rides toward the outside of the curve, while the trailing axle travels between the two rails, i.e. a reduction of the creep angle at the trailing axle, but an increase of the creep angle at the leading axle, as shown on fig. 4.

Fig. 3 Fig. 4 Truck crabbing under actual conditions

Performance report of a low squeal track solution Athens Tram Network

TIP4-CT-2005-516420 Page 11 of 28 QCITY issued: 30-01-09

The EC SQUEAL project has demonstrated that in metro systems with solid wheels both mechanisms can generate squeal whilst in tram systems with resilient wheels, the lateral roll-slip mechanism is the most likely mechanism for squeal. Since we are considering tram systems, we will only consider lateral roll-slip.

The radiated sound power by the wheel during squeal can be calculated as:

where :

As a first approximation, and for a track in open air without major screen effect, the squeal sound pressure level can be calculated by:

3.2 LUMPED PARAMETER MODEL WITH NON-LINEAR FRICTION ELEMENT

3.2.1 Justification of the model

Wheel squeal originates from frictional instability in curves between the wheel and rail. Stick-slip oscillations (more accurately referred to as roll-slip) are amplified by the wheel web. The accepted model for tram systems with resilient wheels involves Top Of Rail (TOR) frictional instability under lateral creep conditions leading to excitation of out of plane wheel bending oscillations. These are radiated and heard as squeal. The starting point for squeal is lateral creep forces that occur as a bogie goes through a curve and the wheel / rail contact patch becomes saturated with slip (creep saturation).

A critical component in all the modelling work is the requirement that beyond the point of creep saturation, further increases in creep levels lead to lower coefficient of friction. This is known as negative friction, referring to the slope of the friction creep curve at saturated creep conditions.

In more general terms, this would be equated to changes in sliding velocity. This leads to roll-slip oscillations between the wheel and the rail which are amplified in the wheel. Performance report of a low squeal track solution Athens Tram Network

TIP4-CT-2005-516420 Page 12 of 28 QCITY issued: 30-01-09

The squeal noise generation is thus a non-linear process. It is therefore necessary to establish a mathematical model that will incorporate the non- linearity of the process.

3.2.2 Short description of the model

The lumped parameter model includes two damped single-degree-of- freedom systems (representing wheel and rail) on each side of a non-linear friction element. The system is driven to self-sustained vibrations by pulling the wheel end of the system with a constant velocity similar to the constant crabbing velocity occurring when a two-axle bogie with fixed axles is passing through a curved track. The model, shown in summarised form in fig. 5, includes one mode of the wheel (shown to the left of the friction element) and one mode of the rail (shown to the right of the friction element).

Fig. 5 Conceptual sketch of the lumped parameter model for prediction of wheel/rail squeal noise

3.2.3 Implementation of the model

The model has been implemented within the SYSTUS finite element software. A specific dedicated non linear element (squeal element) has been created: see relevant model code in annex 2.

Performance report of a low squeal track solution Athens Tram Network

TIP4-CT-2005-516420 Page 13 of 28 QCITY issued: 30-01-09

4. SQUEAL CALCULATIONS WITH VOULA CURVE PARAMETERS

Base case : A vehicle is considered with a 2 m axle spacing crabbing, velocity of 7 m/s. The primary wheel mode is represented by following equivalent one degree of freedom parameters:

The lateral rail dynamic behaviour is represented by following equivalent parameters:

These parameters are derived from the technical information provided by CDM. A typical non-linear friction characteristics of the contact between the wheel and the rail is stored as a (numerical) function in a finite element model and is based on measurements of actual wheel/rail friction, see figure 6 hereafter

Fig. 6

Performance report of a low squeal track solution Athens Tram Network

TIP4-CT-2005-516420 Page 14 of 28 QCITY issued: 30-01-09

Carrying out a time domain analysis considering constant crabbing velocity yields wheel and rail vibrations, see figure 5. The input parameters for this model are given in annex 3. The wheel is squealing during 0.4 s but is then damped out; the rail is squealing at its low resonance frequency (not audible). It is observed that as soon as the rail squeal vibration velocity reaches the wheel squeal vibration velocity, the wheel vibration is damped out to a very small value: no wheel squeal is occurring any more (fig.7).

Fig. 7

The squeal noise is basically generated by lateral wheel rail stick slip. The rail roughness is not a really relevant parameter, as it is in rolling noise. It has just been checked that the rail is in a good condition. The above model was based on the Athens Tram wheel and rail parameters, and the relevant simulation has been carried out in order to see what lateral rail stiffness (how low) and what lateral rail damping (how high) had to be selected in order to avoid squeal.

Performance report of a low squeal track solution Athens Tram Network

TIP4-CT-2005-516420 Page 15 of 28 QCITY issued: 30-01-09

5. THE VOULA CURVE LOCATION : LOW SQUEAL TRACK SOLUTION ELASTOMER’S CHARACTERISTICS - STIFFNESS DATA OF CDM COMFORT PLUS

The effective behavior of the above principle has been first tested in Antwerp in an ‘open’ curve with discrete rail fixation systems with high lateral damping and high lateral resiliency. The results were excellent. The principle has now been integrated in a continuously supported rail system without fasteners.

The jackets have low dynamic stiffness and the high damping is mainly obtained by the continuous pad under the rail. This pad supports the rail, which is mainly rotating on this pad when the vehicle is passing in the curve. CDM, then has made the relevant product selection and testing in order to obtain the required system characteristics.

The stiffness data for the new prototype CDM COMFORT PLUS based on the above analysis were determined as follows :

¤ Vertical stiffness: 13 MN/m/m (static), ¤ Horizontal stiffness: 4.7 MN/m/m (static), ¤ Dynamic horizontal stiffness: 7.5 MN/m/m (ratio 1.5) and the equivalent model for 2 m long rail section:

D rail mass (Ri60): 2*60 = 120 kg D horizontal dynamic stiffness: 2*7.5 = 15 MN/m according to the performance results hereafter :

Performance report of a low squeal track solution Athens Tram Network

TIP4-CT-2005-516420 Page 16 of 28 QCITY issued: 30-01-09

Fig. 8

The above special elastomer “jacquettes” with a low lateral stiffness were produced at CDM’s plant in Soignes and incorporated in a “Modulix” prefab element (see fig.9) according to the following plans approved by TRAM SA to be installed at Leof. Alkyonidon crossing (see fig.10) in Voula Athens where curve geometrical characteristics where identical to Reference test site at Diadochou Pavlou street :

Performance report of a low squeal track solution Athens Tram Network

TIP4-CT-2005-516420 Page 17 of 28 QCITY issued: 30-01-09

Fig. 9 Fig. 10

Performance report of a low squeal track solution Athens Tram Network

TIP4-CT-2005-516420 Page 18 of 28 QCITY issued: 30-01-09

6. PREPARATION & INSTALLATION OF PREFAB LOW SQUEAL ELEMENTS IN THE ATHENS TRAM’S VOULA EXTENSION

Following the design of the new prototype CDM-COMFORT+ & the relevant testing of the CDM-COMFORT+ Jacket in CDM laboratory the preparation of the prefab slabs in Athens and their installation in the Alkyonidon site (see fig 15 hereafter) was concluded in several phases with in situ operation kept the construction to a minimum time frame taking in to account the heavy traffic conditions [3] in the relevant crossing (see also figures 11,12, & 13).

The site completed and in full operation is presented in various photos in fig. 14.

Performance report of a low squeal track solution Athens Tram Network

TIP4-CT-2005-516420 Page 19 of 28 QCITY issued: 30-01-09

Fig. 11 : 1st Phase - Preparation of slabs at the worksite Jacketing/Positioning of rails & reinforcements

Fig. 12: 2nd Phase - Preparation of slabs at the worksite - Formwork & Concreting

Fig. 13 : 3nd Phase - Preparation of prefab slabs - Transport & Installation in situ

Performance report of a low squeal track solution Athens Tram Network

TIP4-CT-2005-516420 Page 20 of 28 QCITY issued: 30-01-09

Fig. 14

Performance report of a low squeal track solution Athens Tram Network

TIP4-CT-2005-516420 Page 21 of 28 QCITY issued: 30-01-09

7. “AFTER” VOULA TEST SITE, INSTRUMENTATION & FIELD MEASUREMENTS RESULTS

In order to achieve a comprehensive evaluation of the noise attenuation results towards a future development and use of such "prefab quite track" solutions a full campaign of squeal noise measurements & 1/3 octave band analysis was executed by TTE, UTH & TRAM SA at the new prefab curved track in Athens tramway network i.e. Voula (measurement phase : “After”).

The location of the “After” acoustic measurements campaign in Voula extension of Athens Tram network is presented in the fig.15 hereafter:

Fig. 15

Performance report of a low squeal track solution Athens Tram Network

TIP4-CT-2005-516420 Page 22 of 28 QCITY issued: 30-01-09

As per the measurements setup the Standard EN ISO 3095:2005 was enforced in this measurements campaign as per the reference test site measurements in the Diadochou Pavlou similar curve site of Athens Tram network (i.e. Voula site in Glyfada Athens). According to the standard and in view of the particularities of the “After” Athens Tram test site in Voula the noise quantities measured at all microphone positions are :

D For whole trams moving at constant speed the Transit Exposure Level, TEL, or the A-Weighted equivalent continuous sound pressure level on the pass by time, LpAeq. D The measurement quantity for accelerating or braking tests the maximum AF-weighted sound pressure LpAFmax. D For the “after” campaign a frequency analysis was also required, made at least in one third octave bands according to EN ISO 266: at least from 31,5 Hz to 8 kHz. ensuring that the lower frequency limit is chosen to ensure that the product of the lowest bandwidth and signal duration exceeds unity. For this campaign a frequency range from 20 Hz to 20 KHz was introduced. D Additionally to the above a complete 1/3 octave band freq analysis was also executed for the “nosiest bogie” of the vehicle for each passage at all speed intervals.

The instrumentation system, including the microphones, cables and recording devices was in accordance with the requirements, for a type 1 instrument specified in EN 61672-1 and as used in the reference site,. “Symphonie” noise recording and 1/3 octave band analysis system from 01dB (FR) was used ensuring :

D 2 synchronized micros all with suitable windscreens

The microphones had an essentially flat frequency response in a free sound field. The 1/3 octave band filters met the requirements of class 1 according to EN 61260. Before and after each series of measurements a sound calibrator, meeting the requirements of class 1 according to EN 60942, was applied to the microphone(s) for verifying the calibration of the entire measuring system. The compliance of the instrumentation system with the requirements of EN 61672-1 and EN 61672-2 was also verified.

“After” Voula Test site conditions : The necessary conditions were ensured for this test site, as per the reference site, including free sound propagation with a ground essentially flat (with a max level variation from 0 m to -0,20 m, relative to the top of rail). The free field area around the microphones has a radius more that 3 times the measurement distance on both sides free of large reflecting objects like barriers, hills, rocks, bridges or buildings. In the vicinity of the microphones, no obstacles disturbing the sound field were permitted including persons. Furthermore the area between the tram vehicle and the microphones was completely free as possible of sound absorbing matter (e.g. snow, tall vegetation, other tracks) or Performance report of a low squeal track solution Athens Tram Network

TIP4-CT-2005-516420 Page 23 of 28 QCITY issued: 30-01-09 reflective covering (e.g. water, ice). The ground cover in both test sites was an asphalt (tarmac) coverage. Regarding the meteorological conditions during the test the wind speed measured at the microphone height was below 1 m/s and there was no falling rain or snow. Temperature was between 8 & 12o C and humidity, in normal levels (some 70 to 80%). The microphone positions axis was always horizontal and directed perpendicularly to the track. The microphone positions were as per the relevant Standard EN ISO 3095:2005 and the reference site setup, ensuring basic distances of 1,5 & 7,5 m from the track axis, at a height of 1,2 m above the top of rail. The Athens Tram vehicle was the same used in the “Before” reference site measurements in its normal operating conditions with no recent maintenance interventions especially in both bogie & wheels between the two measurements campaign in order to maintain a high degree of compatibility between the two setups. During all measurements, the doors and windows of the vehicle were kept closed, and all auxiliary equipment on the test vehicles that normally operates during the run was in action.

The new CDM’s special elastomer “jacquettes” with a low lateral stiffness plant in Soignes incorporated in a “Modulix” prefab element was installed in the “after” test site at Leof. Alkyonidon crossing: no audible impact noise due to welds was present. All measurements conducted during late night in order to eliminate environmental background noise by introducing also important traffic deviations with the help of traffic police forces aiming at a full stop of circulation during vehicle passage in order to eliminate road traffic environmental noise. The photographic / schematic presentation of the “After” site and the relevant measurement’s setup is presented hereafter in fig.15. A total of 3X5=15 tram pass byes of the same vehicle, were recorded and analyzed in the Voula “after” test site, for similar speeds scenarios, as per the reference site, i.e 10, 20, & 25 Km/h (5 pass bys per speed). The analytical results per pass by & per speed are presented (including full 1/3 octave band analysis) in Annex 4 hereafter for both :

D Leq descriptors (per tram/speed passage) and D Lmax for the nosiest bogie are presented in the tables and relevant graphs and provide valuable data regarding a comprehensive comparison “before” & “after” as presented hereafter.

Performance report of a low squeal track solution Athens Tram Network

TIP4-CT-2005-516420 Page 24 of 28 QCITY issued: 30-01-09

Fig. 16

Performance report of a low squeal track solution Athens Tram Network

TIP4-CT-2005-516420 Page 25 of 28 QCITY issued: 30-01-09

8. DISCUSSION AND CONCLUDING REMARKS

Following the results of both “Before” reference test site & “After” Voula site measurements campaigns in diagrams hereafter a comprehensive comparison is presented based on the characteristics listed here below :

D Noise descriptors compared : Leq (per tram/speed passage) and Lmax for the nosiest bogie D Typical speed ranges identical fo both campaigns i.e. 10,20 & 25 Km/h D Similar geometrical characteristics regarding curve diameter in both locations D Same tramway vehicle with no add. maintenance interventions that could affect behavior & acoustic results D No squealing noise attenuation interventions were executed in rails (as per biodegradable component RYLER-300 BIO usually used in Athens Tram network), or maintenance actions on vehicle wheels prior to both measurements campaigns D Use of the Standard EN ISO 3095:2005 that has been prepared by Technical Committee CEN/TC 256 “Railway applications”, the secretariat of which is held by DIN, in collaboration with Technical Committee ISO/TC 43 "Acoustics" for both measurements campaign. D Comparison is for the distance of 7,5m & microphone height of 1,2m in the interior of each curve (internal direction) D All necessary conditions were ensured for both test sites, especially including free sound propagation with a ground essentially flat. D Radical diminution of the environmental background noise levels ensuring minimized effect on all acoustic recordings

In figures 17, 18 & 19 all relevant comparative diagrams (based on data presented in Annexes 1 & 4) are presented hereafter.

NOTE : Furthermore is useful however to point out that rail conditions in “After” test site were new with some months of operation comparing to rails in “Before” reference site already in use since 2004 but currently under maintenance, and also the fact that for speeds more than 15-20Km/h aerodynamic noise tends to effect the acoustic recordings reducing noise attenuation due to the new rail encapsulation.

Performance report of a low squeal track solution Athens Tram Network

TIP4-CT-2005-516420 Page 26 of 28 QCITY issued: 30-01-09

Comparison of Tramway passage Leq & Lmax noise indices at 7,5m Comparison of Nosiest bogie Leq & Lmax indices at 7,5m "BEFORE" & "AFTER" CONDITIONS "BEFORE" & "AFTER" CONDITIONS Tramway vehicle passage speed = 10Km/h Tramway vehicle passage speed = 10Km/h 105,0 91,6 105,0 95,0 95,0 84,6 88,8 85,0 79,4 85,0 71,1 71,1 75,0 67,5 75,0 68,1 65,0 65,0 55,0 55,0 ) ) A A 45,0 45,0 ( ( "AFTER" "AFTER" 35,0 35,0 dB REFERENCE "BEFORE" dB REFERENCE "BEFORE" 25,0 ATTENUATION AT 7,5M 25,0 ATTENUATION AT 7,5M 15,0 15,0 5,0 5,0 -5,0 -5,0 -15,0 -15,0 -11,8 -25,0 -16,5 -17,7 -25,0 -20,5 Leq Lmax Leq Lmax TRAMWAY PASSAGE NOISE INDICES NOISEST BOGIE INDICES

Fig. 17

Comparison of Tramway passage Leq & Lmax noise indices at 7,5m Comparison of Nosiest bogie Leq & Lmax indices at 7,5m "BEFORE" & "AFTER" CONDITIONS "BEFORE" & "AFTER" CONDITIONS Tramway vehicle passage speed = 20Km/h Tramway vehicle passage speed = 20Km/h 105,0 105,0 94,5 95,0 90,0 95,0 95,0 86,3 81,4 82,4 85,0 78,2 85,0 77,9 75,0 75,0 65,0 65,0 55,0 55,0 45,0 "AFTER" 45,0 "AFTER" REFERENCE "BEFORE" 35,0 REFERENCE "BEFORE" dB(A) 35,0 ATTENUATION dB(A) ATTENUATION 25,0 25,0 15,0 15,0 5,0 5,0 -5,0 -5,0 -15,0 -8,5 Leq Lmax -12,6 -15,0 -25,0 -11,8 -13,0 -25,0 Leq Lmax TRAMWAY PASSAGE NOISE INDICES NOISEST BOGIE INDICES

Fig. 18

105,0 97,5 105,0 96,3 95,0 88,3 95,0 91,8 84,0 80,2 83,7 85,0 85,0 81,0 75,0 75,0 65,0 65,0 55,0 55,0 "AFTER" 45,0 45,0 REFERENCE "BEFORE" "AFTER" 35,0 dB(A) ATTENUATION dB(A) 35,0 REFERENCE "BEFORE" 25,0 25,0 ATTENUATION 15,0 15,0 5,0 5,0 -5,0 -5,0 -15,0 -15,0 -8,1 -13,6 -10,8 -12,6 -25,0 Leq Lmax -25,0 Leq Lmax TRAMWAY PASSAGE NOISE INDICES NOISEST BOGIE INDICES

Fig. 19

Performance report of a low squeal track solution Athens Tram Network

TIP4-CT-2005-516420 Page 27 of 28 QCITY issued: 30-01-09

Regarding the comparison in the above diagrams we deduct a very important diminution of both Leq & Lmax noise descriptors for tramway passage and nosiest bogie respectively, for the given point according to EN ISO 3095:2005 as follows :

» Vehicle Speed 10 Km/h : Leq =-11.8dB(A) & Lmax=-20,5 dB(A) » Vehicle Speed 20 Km/h : Leq =- 8.5dB(A) & Lmax=-12,6 dB(A) » Vehicle Speed 25 Km/h : Leq =- 8.1dB(A) & Lmax=-13,6 dB(A) » Furthermore in Fig 20 hereafter the SEL comparison for both test sites is also presented indicating noise attenuation from -8,7 to -11 ,4 dB(A) for the respective vehicle speeds.

It is quite clear that the proposed new solution of “CDM-COMFORT+” Jacket in a prefab slab CDM’s “Modulix” type in Athens Tram network suggests an important positive effect on squealing noise levels emitted in close curves. This positive evaluation of the achieved noise attenuation results (even though thos results may be less effective - taking in to account the above note – is quite important especially towards a future development and use of such "prefab quite track" solutions within the imminent “Piraeus extension” project of Athens Tram.

Comparison of Tramway passage SEL noise index at 7,5m "BEFORE" & "AFTER" CONDITIONS Tramway vehicle passage speeds : 10,20 & 25Km/h

105,0 98,1 98,8 92,4 95,0 88,4 90,1 85,0 81,0 75,0 65,0 55,0 REFERENCE "BEFORE" 45,0 "AFTER"

dB(A) 35,0 ATTENUATION AT 7,5m 25,0 15,0 5,0 -5,0 -15,0 -11,4 -9,7 -8,7 -25,0 10 20 25 VEHICLE SPEED Km/h Fig. 20

Performance report of a low squeal track solution Athens Tram Network

TIP4-CT-2005-516420 Page 28 of 28 QCITY issued: 30-01-09

9. REFERENCES

¤ [1] Quiet City Transport (Akronym: QCITY) - EU Project FP6-516420, Contract No TIP4-CT-2005-516420, 2005 ¤ [2] Vanhonacker Patrick: Technical Report TIP4-CT-2005-516420 “Fastenerless embedded resilient tram track - typeCDM Comfort Plus - for squeal noise reduction at Athens Tram, Voula extension” (APT- EU Project FP6-516420) ¤ [3] Vogiatzis K. & Eliou N., Research Program “Athens Tram’s Noise & vibration Monitoring Program from train operation, (University of Thessaly, Faculty of Civil Engineers, February 2006)

Performance report of a low squeal track solution Athens Tram Network