Abstract

What is the added value of transnational cooperation for the development of transport solutions in North-Western Europe? To what extent are local stakeholders inspired by the experience and the knowledge gathered elsewhere? What are the benefits and the challenges of cooperation across national borders for the development of innovative transport solutions? The SINTROPHER project offers an excellent opportunity to address these issues and to contribute to recent academic and policy debates on the added value of transnational cooperation. Based on a comparative assessment of the development of new or improved tram projects in the five SINTROPHER partner regions, this study explores the added value of transnational cooperation for the diffusion and transfer of cost-effective transport solutions. 84294

Abstract

International audience; Tramway traffic may produce vibrations propagating in soil, which implies vibration annoyance for people living or working in neighbouring buildings. Thus vibration is one of the most important consequences to be considered when planning new lines. Dynamic performance evaluation of tramway tracks is required to validate or modify the existing means that reduce vibrations. This paper presents experimental and theoretical investigations of vibrations caused by passing tramways in Nantes, France. A method is proposed to predict ground-borne vibrations, so as to estimate a trouble gauge concerning, for example, the impact of a future tramway line. This method is applied and validated in comparison with in situ measurement data obtained previously.Numerous studies have been carried out on vibrations induced by surface railways, for example, Lefeuve-Mesgouez et al. [1], Picoux [2] and Sheng et al. [3]. In the case of a tramway line, a two-dimensional model can be used to predict the behaviour of the propagation analysis of the corresponding vibrations, considering a thin layer model for the soil and using exact dynamic stiffness matrices [4,5], expressed in the frequency-wave number domain for the layered ground and the half-space [6]. Note that other models can be applied to predict vibration propagation, such as boundary element formulations [7].In this paper, soil is characterized by measurements using the spectral analysis of surface waves, often called the SASW method. Here the usual two-station approach is used [8]. The objective is to accurately define shear moduli and layer thicknesses. Then the general Barkan relation [9] is applied to obtain the dispersion curve and the damping ratios. Soil characterisation needs further improvements using a complete inversion method such as Occam's algorithm [10]. Nonetheless this first approach, often called "equivalent depth approach" already gives sufficient soil profile information to model waves propagation.Numerical methods, such as the wavenumber matrix approach, can be used for the prediction of the soil response to a hammer impact, i.e. to obtain the transfer functions. An alternative solution is proposed: the method is based on the assumption that for each frequency, the vertical measured shear wave velocity corresponds to a homogeneous half-space [9]. The vibratory response is obtained by multiplying the load spectrum by the transfer function in order to obtain the whole contribution of tramway passage for each measurement point. Results are given in the time domain and compared with in situ measurements.