Learning Behavioural Context

The original publication is available at www.springerlink.co

Research related to vibrations from high speed railway traffic

We discuss here recent results from several research programmes related to dynamic aspects and vibrations induced by high speed railway traffic, developed at the computational mechanics group, within the “Escuela de Ingenieros de Caminos” of the Technical University of Madrid. The first part of this work concerns the dynamic response of railway bridges and structures under high speed traffic. The study of vertical dynamic effects in bridges has lead recently to improved understanding and practical design concepts, embodied in the new engineering codes [1,2,3,4,5]. Some special and seldom considered features of the dynamic response are also discussed. In the second part we present some results for lateral dynamic effects. These have not been so widely studied as the vertical vibrations, however they may pose significant problems for bridges. Finally, in the third part we discuss recent results of ongoing research for the mechanical response of slab track and ballast track, focusing on the vertical vibration of the track and the associated dynamic traffic loads

Vehicle Speed Influence on Ground-borne Vibrations Caused by Road Transport when Passing Vertical Traffic Calming Measures

Traffic calming is the combination of mainly physical measures that reduce the negative effects of motor vehicle use, alter driver behaviour and improve conditions for non-motorized street users. Vibration measurements were performed by the authors of this paper near the roads with traffic calming devices. The measurements were taken throughout two seasons: in the winter and in the summer in order to evaluate the influence of soil freezing on traffic-induced vibrations. The only car measured was Fiat Doblo (weight 1,405 kg), and its driving speed when passing a speed bump or a speed table was controlled (20 km/h; 30 km/h; 40 km/h). The results show that the Peak Particle Acceleration (PPA) values were higher in the winter season compared with the summer. The vehicles passing over the speed tables induce lower PPA values than those passing over the speed bumps.</p

Impact of vertical traffic calming devices on environmental noise

Sve veći broj stanovnika u urbanim sredinama izložen je štetnom djelovanju buke okoliša, koja u značajnoj mjeri narušava njihovo zdravlje i kvalitetu života. Dominantan izvor buke okoliša u takvim područjima je cestovni promet, a jedna od učestalo primjenjivanih mjera za smanjenje razina buke je smanjenje brzine vožnje. U radu je analizirano kako oprema za smirivanje prometa, koja se uobičajeno primjenjuje radi povećanja sigurnosti prometa, utječe na smanjenje razina buke. Analiza je provedena na sedam dvotračnih dvosmjernih gradskih cestovnih prometnica na kojima su ugrađeni različiti tipovi umjetnih izbočina i uzdignutih ploha.Increasing numbers of people living in urban areas are being exposed to harmful action of environmental noise, which severely affects their health and quality of life. The predominant source of environmental noise in such areas is road traffic, and a frequently used measure to curb down this noise involves reduction of driving speed. The influence of vertical traffic calming devices, normally used to improve traffic safety, on the degree of noise reduction, is analysed in this study. The analysis was carried out on seven urban two-lane two-way roads, on which various types of speed bumps and speed humps are installed

Analysis of Lateral Displacements in Large Railway Viaducts Under Traffic Loads. Impact on Ride Safety and Passenger Comfort.

The increasing design speed of the new high speed lines and the stringent requirements on track alignment parameters are leading to a sustained increase of the number of railway viaducts. The relevant standards impose limiting values on lateral vibrations. Both the Spanish and European standards establish a minimum value for the first natural frequency of lateral vibration of a span, that should not be lower than fh0 = 1,2 Hz. This limit was originally proposed by ERRI committee D181, which assessed the lateral forces in railway bridges. This limit was proposed in order to avoid lateral resonance in railway vehicles going across the structure, taking into account that the frequencies of lateral vibration of railway vehicles are, in general, not greater than 1,0 Hz. In the case of large continuous viaducts with high piers, the lateral deformations occurring during a train pass-by can be significant and the natural frequencies of the first mode of vibration of the deck can be very low. In these cases it is not clear whether the required verifications must be applied to spans considered independently, to several successive spans or to the whole viaduct. There is currently no analysis methodology allowing to assess this situation and check the viaduct design against the requirements of ride safety and passenger comfort. This paper analyzes the lateral deformations of a large continuous viaduct and the infrastructure vehicle interaction effects due to the circulation of freight trains and several types of high speed train sat different speeds. The application of this methodology will allow an optimized design of viaducts with significant lateral deformations that cannot be justified only by using the simplified criteria of the current applicable standards. In such cases, the compliance with standards may lead to over dimensioning or in other cases to neglect the limits without the adequate verification of the proper infrastructure behavior once it has been commissioned. As it is the case for vertical deformations, for which the European standards require the assessment of dynamic effects, we stress the need for a dynamic analysis of the effects of lateral deformations in large railway viaducts

Coupled models for the dynamics of bridges under high-speed rail traffic

The dynamic effects of high-speed trains on viaducts are important issues for the design of the structures, as well as for determining safe running conditions of trains. In this work we start by reviewing the relevance of some basic moving load models for the dynamic action of vertical traffic loads. The study of lateral dynamics of running trains on bridges is of importance mainly for the safety of the traffic, and may be relevant for laterally compliant bridges. These studies require 3D coupled vehicle-bridge models and consideration of wheel to rail contact. We describe here a fully nonlinear coupled model, formulated in absolute coordinates and incorporated into a commercial finite element framework. An application example is presented for a vehicle subject to a strong wind gust traversing a bridge, showing the relevance of the nonlinear wheel-rail contact model as well as the interaction between bridge and vehicle

On the Complexity of an Unregulated Traffic Crossing

The steady development of motor vehicle technology will enable cars of the near future to assume an ever increasing role in the decision making and control of the vehicle itself. In the foreseeable future, cars will have the ability to communicate with one another in order to better coordinate their motion. This motivates a number of interesting algorithmic problems. One of the most challenging aspects of traffic coordination involves traffic intersections. In this paper we consider two formulations of a simple and fundamental geometric optimization problem involving coordinating the motion of vehicles through an intersection. We are given a set of $n$ vehicles in the plane, each modeled as a unit length line segment that moves monotonically, either horizontally or vertically, subject to a maximum speed limit. Each vehicle is described by a start and goal position and a start time and deadline. The question is whether, subject to the speed limit, there exists a collision-free motion plan so that each vehicle travels from its start position to its goal position prior to its deadline. We present three results. We begin by showing that this problem is NP-complete with a reduction from 3-SAT. Second, we consider a constrained version in which cars traveling horizontally can alter their speeds while cars traveling vertically cannot. We present a simple algorithm that solves this problem in $O(n \log n)$ time. Finally, we provide a solution to the discrete version of the problem and prove its asymptotic optimality in terms of the maximum delay of a vehicle

Design and analysis of a tool for planning and simulating dynamic vertical transport

Nowadays, most of the main companies in the vertical transport industry are researching tools capable of providing support for the design process of elevator systems. Numerous decisions have to be taken to obtain an accurate, comfortable, and high-quality service. Effectively, the optimization algorithm is a key factor in the design process, but so are the number of cars being installed, their technical characteristics, the kinematics of the elevator group, and some other design parameters, which cause the selection task of the elevator system to be a complex one. In this context, the design of decision support tools is becoming a real necessity that most important companies are including as part of their strategic plans. In this article, the authors present a user-friendly planning and simulating tool for dynamic vertical traffic. The tool is conceptualized for giving support in the planning and design stage of the elevator system, in order to collaborate in the selection of the type of elevator (number, type of dynamic, capacity, etc.) and the optimization algorithm

Research on Spatial Optimization of Shopping Center under the Background of Epidemic Situation : A Case Study of Weilaishi Shopping Center in Handan

In the current social background of frequent epidemics, shopping centers, as commercial buildings with a large number of people, it is very important to reduce the risk of environmental infection. This paper takes the Weilaishi Shopping Center in Handan as an example, summarizes the epidemic prevention status of five types of spatial nodes through field investigation, and analyzes the shortcomings of the existing emergency design of the Weilaishi Shopping Center. Based on the analysis results, this paper puts forward the optimization strategy from the spatial level, which provides a certain reference value for the research on the improvement of shopping center space environment emergency capability