"Quiet tram track" infrastructure solutions at Athens tramway network for squealing noise attenuation

The "Quiet City Transport" (QCity) project (6th FRAMEWORK PROGRAMME: SUSTAINABLE SURFACE TRANSPORT - EU Project FP6-516420, Contract No TIP4-CT-2005-516420, 2005") aims to develop an integrated technology infrastructure for the efficient control of road and rail ambient noise. Within this project, 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 suburban area was introduced. The prototype's research, design realization & performance evaluation was based on the following actions: (a) an original campaign of monitoring squeal noise levels including 1/3 octave band analysis at a similar curved track in Athens tramway network for various vehicle speeds ("before"), (b) a 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, (c) a laboratory analysis & development of the "elastomer encapsulation material" with specified vertical & horizontal stiffness, (d) the construction of the prefab slab at the worksite and then the transport and installation in situ, & (e) the performance evaluation regarding squeal noise attenuation by performing an extended noise measurements campaign including 1/3 octave band analysis, at the test site by using the same vehicle in similar vehicle speeds conditions & geometrical characteristics of the curve as above ("after"). This prototype aims at the reduction of the squealing noise emitted in closed curves from tram operation. This activity will support European noise policy to eliminate harmful effects of noise exposure and decrease levels of transport noise creation, especially in urban areas, deriving solutions that will ensure compliance with the constraints of legislative limits. Results comparing both "After" & "Before" campaigns, for all reference speeds of 10,20 & 25 Km/h, suggests an important squeal noise diminution for each Leq passage of some 8-12 dB(A) for the distance of 7,5m & microphone height of 1,2m in the interior of each curve (internal direction)