Tram Types Research Articles

Tram-Pedestrian Collision Modeling Using Experimental Data—Its Validation, Repeatability, and Challenges: A Pilot Study

To satisfy the needs of growing urban populations, mitigate the impacts of climate change, and improve the environmental conditions and quality of life in cities, there has been an increasing demand for public transport, especially effective and economically beneficial trams. As a consequence, the issue of pedestrians’ safety has become more important because of a higher risk of tram-pedestrian collisions. The article is focused on the development of a computational model that can accurately simulate such collisions, and its challenges and limitations. Experiments were conducted using various types of trams, different impact speeds, and an anthropomorphic test device (dummy). Computational models of the tram front ends were created based on CAD geometry supplied by VÚKV a.s. The finite-element mesh itself used a combination of 1D, 2D, and 3D elements. Depending on the shape of the individual components, TRIA, QUAD, HEX, PENTA, and TETRA elements were used for modeling. The results showed that the consequences of these collisions are sensitive to small differences in the posture of the dummies. Therefore, it is difficult to identify a generally more pedestrian-friendly shape for trams using the dummy-tram crash test method.

Pedestrian Safety in Frontal Tram Collision, Part 1: Historical Overview and Experimental-Data-Based Biomechanical Study of Head Clashing in Frontal and Side Impacts.

This article represents the first paper in a two-part series dealing with safety during tram-pedestrian collisions. This research is dedicated to the safety of trams for pedestrians during collisions and is motivated by the increased number of lethal cases. The first part of this paper includes an overview of tram face development from the earliest designs to the current ones in use and, at the same time, provides a synopsis and explanation of the technical context, including a link to current and forthcoming legislation. The historical design development can be characterised by three steps, from an almost vertical front face, to leaned and pointed shapes, to the current inclined low-edged windshield without a protruding coupler. However, since most major manufacturers now export their products worldwide and customisation is only of a technically insignificant nature, our conclusions are generalisable (supported by the example of Berlin). The most advantageous shape of the tram's front, minimising the effects on pedestrians in all collision phases, has evolved rather spontaneously and was unprompted, and it is now being built into the European Commission regulations. The goal of the second part of this paper is to conduct a series of tram-pedestrian collisions with a focus on the frontal and side impacts using a crash test dummy (anthropomorphic test device-ATD). Four tram types approaching the collision at four different impact speeds (5 km/h, 10 km/h, 15 km/h, and 20 km/h) were used. The primary outcome variable was the resultant head acceleration. The risk and severity of possible head injuries were assessed using the head injury criterion (HIC15) and its linkage to the injury level on the Abbreviated Injury Scale (AIS). The results showed increasing head impacts with an increasing speed for all tram types and collision scenarios. Higher values of head acceleration were reached during the frontal impact (17-124 g) compared to the side one (2-84 g). The HIC15 values did not exceed the value of 300 for any experimental setting, and the probability of AIS4+ injuries did not exceed 10%. The outcomes of tram-pedestrian collisions can be influenced by the ATD's position and orientation, the impact speed and front-end design of trams, and the site of initial contact.

Developing Assumptions for the Tram Noise Attenuation Passive System Using the Noise Maps Analysis Method

The paper presents experimental research carried out to determine the possible actions to reduce the noise generated by trams in a highly urbanised area. A few design strategies affecting tram ride quality have been presented – especially in the aspect of the acoustic phenomena. Main sources of the noise in trams were characterised. The paper includes selected results of comprehensive studies of tram noise in the pass-by test based on the authors’ research methodology. The tests were carried out on various types of trams to recognise the acoustic phenomena characteristic for the rolling stock in a selected tram system. The results of the measurements were analysed both in the field of amplitudes based on noise maps and in respect to frequencies based on noise spectra. The results indicated the rolling noise as important issue demanding taking some actions in order to reduce its level. In this area, elements for the application of individual attenuation solutions, i.e. at the source and during propagation, were presented. The results of the measurements were used as input data to the assumptions of the noise attenuation passive system, which was the final outcome of the study. Dedicated external dampers were used in the case of wheel and rail pairs, where the dominant power of the noise is emitted. The acoustic properties of the bogie area and the bogie side covers were redeveloped to hamper the noise propagation, which is a novel application. The presented results indicate measurable benefits from the applied solutions on the tram noise reduction.

A Novel Method in Light-Rail Condition Monitoring Using Smartphones

Tram and track interaction inevitably generates undesirable vibration, and the magnitude of this vibration may depend on various factors, including track quality, rail type, rail profile, tram type, ride quality, and speed. To investigate the impact of track quality on vibration, all other factors should be eliminated in experiments. To remove the effects of ride quality, tram type, rail type, and rail profile, various measurements were obtained and analyzed independently for similar trams with the same driver. Another significant factor which plays a crucial role in vibration is speed. The selection of a method which can detect the influence of speed on vibration is very demanding since this evaluation needs to be based on various measurements in similar settings. Therefore, various experiments and data from the same arrangement should be obtained to evaluate the impact of speed on vibration. This paper reports on several practice tests and data acquisition via smartphone built-in sensors on a specific route to investigate the effects of speed on vibration. Two different statistical and non-statistical methods are then proposed to monitor the condition of rail tracks and schedule preventive maintenance for light rail based on Melbourne tram network data. These approaches will optimize the total investment in tram track maintenance for managing authorities.

Evaluation of the selection of proper metro and tram vehicle for urban transportation by using a novel integrated MCDM approach.

This paper presents a novel integrated multi-criteria decision-making model consists of the CRITIC (CRiteria Importance Through Intercriteria Correlation) technique and the EDAS (The Evaluation based on Distance from Average Solution) method to evaluate the selection of the urban rail vehicles operated in the public transport systems. In order to determine the selection criteria in a more realistic perspective, a board of experts consists of seven members, who perform as senior executives in the public transport institutions of the country, was constructed and many round tables meetings were organized with together the members of the board for determining the procedure to follow to reach meaningful and applicable results. At the beginning of the research, approximately fifty selection criteria were determined by the research team and some of them were eliminated during the preparation process of this study. Finally, 22 factors were determined as the selection criteria, which will be used in this research. These factors are the selection criteria directly or indirectly affecting the selection process and results. Also, rail tram types currently operated in the various cities of Turkey were determined as decision alternatives. These options were evaluated by using the proposed integrated MCDM approach. When the obtained results are evaluated, it can be seen that the proposed model has the potential to give very successful results for evaluating the selection process of the urban rail systems. Moreover, it can be implemented as a decision support system by decision-makers, who perform in the public transport authorities. Finally, it can also be applied for decision-making problems faced in the various fields.

Особенности организации работы снегоуборочной техники на трамвайных путях

Objective: To develop recommendations for the management of snow clearing of street railways in urban settlements. Methods: The article analyzes the Russian regional climatic influence on the management of street railway traffic and the current maintenance of tram tracks, and the indicators to be monitored when planning the work of snow clearing equipment. The requirements for the maintenance of tram tracks in winter in heavy snowfalls and blizzards have been described. An overview of the snow clearing equipment available in the soviet and present times, as well as its application has been discussed. Results: Recommendations for the management of various types of snow clearing equipment for various types of tram tracks are given. The justifying calculations of the size of the snow clearing fleet in relation to regional climatic indicators are presented. Practical importance: The article demonstrates the preference of introduction of special rail snow clearing equipment for the tram track routine maintenance in winter, especially in snow heavy areas, both tram type based on tram dimensions and hybrid road-rail type. Practical recommendations for the conditions for the use of various types of snow clearing equipment have been developed

Investigation of aerosol pollution inside trams in Debrecen, Hungary

Fine (PMfine) and coarse (PMcoarse) particulate matter concentrations and elemental compositions were investigated inside trams during travelling in heating and non-heating seasons. New CAF and older KCSV tramcars were involved in the study. The results obtained for the trams were compared with the outside air quality measured at a nearby urban background site. The coarse (particles with aerodynamic diameter larger than 2.5 µm) and the fine (particles with aerodynamic diameter smaller than 2.5 µm) mass concentrations were determined by gravimetric method. The elemental analysis of the collected samples was carried out by particle induced X-ray emission (PIXE) method at the Institute for Nuclear Research, Hungarian Academy of Sciences (MTA-Atomki) Debrecen, Hungary. The mass concentrations inside the vehicles were 5–20 times higher than in the outdoor air. The elemental composition was similar inside the trams and outdoors in both size fractions. However, some elements (Cr, Zn, Cu) were enriched in the trams and could be derived from outdoor sources such as the re-suspended dust, the rail abrasion, the abrasion of the overhead wire. According to the results the new CAF tram type was less polluted than the old KCSV one.

Tram Type Influence on the Frequency Spectrum Character of the Subsoil Dynamic Response

Tram Type Influence on the Frequency Spectrum Character of the Subsoil Dynamic Response

Influence of different types of trams on human perception of vibrations in buildings

In an increasingly urbanized areas transport vibration source are closer and closer to the receiver which is a building. At the same time residents requirements for comfort in rooms are higher. In this paper influence of transport vibrations from various types of trams on human perception was tested and analysed. Measurements were made in Cracow on 11 buildings located near tramway. Human perception were investigated according to ISO and Polish standard. Basic RMS method and additional VDV method were applied because of high crest factor of recorded signal. Results of both methods were compared.

Prediction and Experimental Analysis of the Effectiveness of Vibration-Isolating Tramway

In Krakow during last time, it is seen the development of tram and bus infrastructure. This is to improve the mobility of the residents as well as the comfort of using the means of mass communication. Besides this, the municipal authorities do not neglect the development works relating to the future construction of the metro. New network of tramways and roads are planned, designed and built. Many exploited for years’ tramway tracks and the road is repaired due to their poor technical condition. Insufficient technical condition of the existing tramway tracks and streets makes it necessary to repair them. The work concerns the influence of vibration induced by traffic crossing trams in one of the main streets of Krakow on people staying in buildings and passively receiving these vibrations. The study was carried out in three stages. In the first stage, before the renovation of the tramway, the measurements of vibration were done in a number of selected residential buildings with various constructions. The recorded vibrations were analyzed according to the procedure given in ISO 2631-2 due to human exposure. In a second step numerical analyzes were performed using the database of registered communication vibrations and dynamic models of buildings. The results of calculations were used for selection of the appropriate parameters (thickness, stiffness) of vibration isolation of the analyzed tramway due to the comfort of the people staying in buildings. In a third step, the checking measurements were carried out in the same places as in the first stage and from the same types of trams. Re-analyzes were made for assessing the impact of vibration on people. Comparative analysis has shown that applied vibration insulation met expectations and helped to reduce the level of vibration felt by the people.

Mastectomía radical con reconstrucción inmediata en el Instituto Autónomo Hospital Universitario de Los Andes, período junio 2012-abril 2015

IntroductionBreast reconstruction is a fundamental part of the treatment of women with mastectomies. After finding that rebuilding a negative effect on the neoplastic disease, but is critical to the physical and psychological rehabilitation of the patient, its development has been favored. Selecting the right process depends on multiple factors such as patient age, stage of disease, smoking, obesity, adjuvant treatment, experience and technical capacity of the center where they will perform the reconstruction, among other. Materials and methodsA study of prospective, observational, descriptive and comparative clinical trial type was held between myocutaneous flaps extended dorsal and TRAM, in patients undergoing elective surgery. ResultsA total of 36 patients were included, divided into 2 groups of 20 patients TRAM group and 16 expanded dorsal group, with a mean age of 45.45±9,50 years old in the TRAM and the expanded dorsal group of 56.09±9.07 years old with a BMI in both groups ranged between 25.0-29.9. They were performed in 19 patients radical modified mastectomy Madden+TRAM type representing 80%, where 15% of this group symmetrize. A Halsted+TRAM bipedicled was performed representing 5%; the dorsal group underwent modified radical mastectomy Madden 100%, symmetrize the 31.3%. Overall complications was observed in patients TRAM group predominated operative wound infection and necrosis with 25.0% each, followed by seroma and wound dehiscence with 10% each, describing only one hernia totaling 11 patients, where 3 patients had 2 or more complications associated previously described; in extended dorsal group seroma they predominated with 18.8% and 12.5% necrosis, totaling 4 patients alike with 2 associated complications. ConclusionsThe post-mastectomy breast reconstruction with different techniques is a safe procedure that must be implemented in all centers where patients with breast cancer, and our service are handled Surgical Oncology.

Analysis of Psychoacoustic and Vibration-Related Parameters to Track the Reasons for Health Complaints after the Introduction of New Tramways

Background: A change to new tramways in Graz (Austria) led to severe complaints in residential areas. To understand the underlying reasons for these complaints, a systematic measurement campaign was designed. Methods: Six locations in Graz and two locations in a comparably sized city were selected. Parallel indoor recordings of sound and vibrations were conducted from 8:00 p.m. to 8:00 a.m. (due to sleep problems) at all locations. Results: Vibration levels remained below the limits of the Austrian standard (Wm-weighting) although variability was observed among sites, tram types and pass-bys. A complex characteristic of the acoustic feature space was found with A-weighting (differences between A- and C-weighting of more than 15 dB were observed). C-weighted background to peak noise ratios clearly distinguished “old” from “new” trams. Psychoacoustic indices indicated a high variability between locations and tram types. Roughness and loudness was higher in “new” versus “old” trams at most locations. “New” trams exhibited high sharpness values and variability, especially at higher speeds—when compared with trams from a control city. Conclusions: Standard indicators of sound and vibration were not sensitive enough to uncover the reasons for the complaints. Only the integrated analysis of the ambient soundscape (high signal-to-noise-ratio), the more noticeable sound (in psychoacoustic terms) and the observed high variance of the immissions provided guidance to implement appropriate technical solutions.

Characterisation of tram noise emission and contribution of the noise sources

The recent expansion of French tram networks and the related local residential complaints mean that a better knowledge of the situations leading to negative reactions from the local inhabitants is required. Hence a research project has been conducted to evaluate and describe noise and vibration emission of trams as well as the perception by the local residents. This paper investigates tram noise emission on common straight track sections, involving two vehicle scales. First the acoustic power and the mean vertical directivity of the total tramset is assessed using an arc of microphones. Then the localisation and the analysis of the main noise sources are performed by means of a cross array during the tram pass-by. Two tram types representing two generations of French rolling stock, both running on two sites with distinct track characteristics, have been investigated considering the effect of speed, tram type, and track type on the noise source contributions and spectral features. Most sources are located in the lower part of the trams, mainly related to rolling noise, with a strong dependence on speed and track type. The tram type dependency, although globally of second importance, influences greatly the noise spectral distribution and behaviour. The HVAC was the only roof-mounted source which could be detected; its contribution towards building storeys becomes significant in configurations of low rolling noise. A tram noise emission model based on the various noise sources has been developed.

Structural safety of trams in case of misguidance in a switch

Tram vehicles mainly operate on street tracks where sometimes misguidance in switches occurs due to unfavourable conditions. Generally, in this situation, the first running gear of the vehicle follows the bend track while the next running gears continue straight ahead. This leads to a constraint that can only be solved if the vehicle's articulation is damaged or the wheel derails. The last-mentioned situation is less critical in terms of safety and costs. Five different tram types, one of them high floor, the rest low floor, were examined analytically. Numerical simulation was used to determine which wheel would be the first to derail and what level of force is needed in the articulation area between two carbodies to make a tram derail. It was shown that with pure analytical simulation, only an idea of which tram type behaves better or worse in such a situation can be gained, while a three-dimensional computational simulation gives more realistic values for the forces that arise. Three of the four low-floor tram types need much higher articulation forces to make a wheel derail in a switch misguidance situation. One particular three-car type with two single-axle running gears underneath the centre car must be designed to withstand nearly three times higher articulation forces than a conventional high-floor articulated tram. Tram designers must be aware of that and should design the carbody accordingly.

Tram noise emission: Spectral analysis of the noise source contributions

In France we can assist to a wide development of tram networks for public transportation in main cities. At the same time arises questioning on the noise emission of trams and possible consequences for resident exposure. A French research project has been conducted for studying noise and vibration emission of trams : this paper concerns the description of the noise emission of passing-by trams. A measurement campaign was achieved on the city of Nantes network, involving two kinds of trams with distinct technologies and equipment, and tested on two types of tracks having different platform surfaces. Acoustic measurement included both a 2D-array for noise source identification and a microphone set for vertical directivity analysis. The dominant noise sources are mainly the bogie areas (powered bogies, unpowered bogies) and an extended noise source along the track and the lower part of the tram, all of them involving rolling noise. This paper focuses on the spectral description of the main sources. A parametric study is presented, pointing out the effect of speed, tram type and track type on the frequency distribution of the emitted noise.

The Impact of Tram Track Fastening Systems on Noise Level

The paper presents the results of measurements of noise levels caused by traffic (tram and road traffic) in Drziceva Street in Zagreb (Croatia). Noise level measurements were conducted in cooperation with the City Office for Construction and the Zagreb Streetcar Company (ZET). The tram track in Drziceva Street represents one of the main connecting routes between the northern and southern parts of the city (a length of approximately 4km). The tram tracks are in a separate traffic area. They have been laid on a continuous concrete base and covered with crushed stone. The greater part of the tram track was constructed using the Zg 3/2 system (a direct elastic fastening system), whereas the remainder of the tram track was constructed using the DEPP system (indirect elastic fastening system). Noise level measurements were conducted at two measuring points (one measuring point was chosen for each of the fastening systems). Short-term noise level measurements were executed: two measurements in the daytime period (morning and afternoon), one measurement in the evening and one in the nighttime period. Speed and tram types were taken into consideration during result analysis, as well as geometrical irregularities of the rail running surfaces, the number and category of road vehicles and noise level protection measures already implemented. The conducted measurements have served to compare tram track fastening systems with noise level propagation when trams communicate the route. The results of the research have been of assistance in defining the extent of tram impact on noise level increase (dependent on type and speed of these) in comparison with that of road vehicles communicating the very same route. For the covering abstract see ITRD E129315.

The real sound emission of ‘‘Rasengleis’’

The ‘‘Rasengleis’’ (railway lines which are covered by meadow and bedded on conventional ballasted tracks) has indeed a lower noise emission level. Various investigations focusing on the acoustical behavior of the ‘‘Rasengleis’’ were carried out in the last years. The results were rather different. The first sequence of measurements took place before changing the construction of the second part of the railway line. That was to counterbalance errors due to locality, time (the last measurement was carried out almost 2 years later than the first one), and other ambient conditions. The levels could be easily compared among each other using the results of the reference point. Additionally, the measurements were repeated after at least a year to take aging processes of the meadow into account. Two different types of trams were used. They differ among other things in the kind of absorption used for the wheels. One wheel type contains rubber parts stressed of shearing (Tatra T4D), the other wheel rubber parts are stressed of pressure (Bochum). ‘‘Rasengleis’’ reduces noise emission depending on the kind of wheel up to 3 dB (minimum 2 dB). There will be measured levels of drive past, standardized values, and sonograms.

Mechanism of squeal noise generated by trams

Squeal noise is very often the most disturbing noise source of railway systems in older cities. At present the effect of measures to reduce or to eliminate squeal noise cannot be predicted and seems to be influenced by a large number of dependent parameters. On the basis of the measurement results of a research project in three cities with seven different tram types on various types of rail structures the influence of the most important parameters on the occurrence and the noise level was analyzed. The analytical model for squeal noise, developed by Rudd [1], was confirmed by these results. However, the model appeared to be incomplete for the influence of the rail structure such as roughness and dynamic properties. Furthermore, the model overestimates the amount of damping in the wheel which is needed to eliminate squeal. Additional knowledge is needed about the change of friction coefficient with lateral creep and about the dynamic properties of resilient wheels.