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Journal of Modern Transportation
Journal Prestige (SJR): 0.354

Citation Impact (citeScore): 1
Number of Followers: 9

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ISSN (Print) 2095-087X - ISSN (Online) 2196-0577
Published by SpringerOpen

[261 journals]

The VILMA intelligent vehicle: an architectural design for cooperative
control between driver and automated system
- Abstract: Abstract Intelligent autonomous vehicles have received a great degree of attention in recent years. Although the technology required for these vehicles is relatively advanced, the challenge is firstly to ensure that drivers can understand the capabilities and limitations of such systems and secondly to design a system that can handle the interaction between the driver and the automated intelligent system. In this study, we describe an approach using different strategies for an autonomous system and a driver to drive a vehicle cooperatively. The proposed strategies are referred to as cooperative planning and control and determine when and how the path projected by the autonomous system can be changed safely by the driver to a path that he wishes to follow. The first phase of the project is described, covering the design and implementation of an autonomous test vehicle. Experiments are carried out with a driver to test the cooperative planning and control concepts proposed here.
  PubDate: 2018-04-26
Feasibility in assessing the dipped rail joint defects through dynamic
response of heavy haul locomotive
- Abstract: Abstract The feasibility of monitoring the dipped rail joint defects has been theoretically investigated by simulating a locomotive-mounted acceleration system negotiating several types of dipped rail defects. Initially, a comprehensive locomotive-track model was developed using the multi-body dynamics approach. In this model, the locomotive car-body, bogie frames, wheelsets and driving motors are considered as rigid bodies; track modelling was also taken into account. A quantitative relationship between the characteristics (peak–peak values) of the axle box accelerations and the rail defects was determined through simulations. Therefore, the proposed approach, which combines defect analysis and comparisons with theoretical results, will enhance the ability for long-term monitoring and assessment of track systems and provides more informed preventative track maintenance strategies.
  PubDate: 2018-03-05
Re-adhesion control strategy based on the optimal slip velocity seeking
method
- Abstract: Abstract In the railway industry, re-adhesion control plays an important role in attenuating the slip occurrence due to the low adhesion condition in the wheel–rail interaction. Braking and traction forces depend on the normal force and adhesion coefficient at the wheel–rail contact area. Due to the restrictions on controlling normal force, the only way to increase the tractive or braking effect is to maximize the adhesion coefficient. Through efficient utilization of adhesion, it is also possible to avoid wheel–rail wear and minimize the energy consumption. The adhesion between wheel and rail is a highly nonlinear function of many parameters like environmental conditions, railway vehicle speed and slip velocity. To estimate these unknown parameters accurately is a very hard and competitive challenge. The robust adaptive control strategy presented in this paper is not only able to suppress the wheel slip in time, but also maximize the adhesion utilization performance after re-adhesion process even if the wheel–rail contact mechanism exhibits significant adhesion uncertainties and/or nonlinearities. Using an optimal slip velocity seeking algorithm, the proposed strategy provides a satisfactory slip velocity tracking ability, which was demonstrated able to realize the desired slip velocity without experiencing any instability problem. The control torque of the traction motor was regulated continuously to drive the railway vehicle in the neighborhood of the optimal adhesion point and guarantee the best traction capacity after re-adhesion process by making the railway vehicle operate away from the unstable region. The results obtained from the adaptive approach based on the second-order sliding mode observer have been confirmed through theoretical analysis and numerical simulation conducted in MATLAB and Simulink with a full traction model under various wheel–rail conditions.
  PubDate: 2018-03-01
A methodology for calculating the passenger comfort benefits of railway
travel
- Abstract: Abstract A comfortable environment in railway passenger coaches can be regarded as a resource for social consumption during the transport process. Railway passenger comfort benefits (RPCBs) can be regarded as a special generalized cost. In this paper, we select a series of objective and subjective indexes to formulate a quantitative method of calculating the RPCB with considering ticket fares. This method includes three steps: make the initial data dimensionless, calculate the weight of each index, and finally calculate the RPCBs. The proposed method was validated with the data collected from two types of trains: G13 from Beijing South to Shanghai Hongqiao and T109 from Beijing to Shanghai. Also, questionnaire survey was conducted in both trains. After data processing, the results show that there is a linear relationship between the RPCB and ticket fare with a correlation coefficient of 0.9616.
  PubDate: 2018-02-05
Modeling the effects of rainfall on vehicular traffic
- Abstract: Abstract Traffic management and drainage system are two vital issues for any metropolitan city. Like other big cities, Karachi is also facing problems due to lack of traffic management and poor drainage system. The main objective of the study is to model the interdisciplinary issues of storm water and its effect on the traffic of Karachi. The specific objectives are: (1) to calibrate and validate urban hydraulic and traffic micro-simulation models and (2) to model storm water and traffic for future conditions. This study is carried out on a 3-km section of arterial road. In this study, loose coupling of two models is done. For urban drainage, PCSWMM, and for traffic, VISSIM is used. Both models are calibrated for an existing situation on rainfall event of August 3, 2013, and then used for prediction of future scenario based on 50-year and 100-year return periods of rainfall. Sensitivity analysis of VISSIM is performed. Locations and lengths of road sections, where ponding happens for the future scenario, are identified using PCSWMM. These lengths are then marked in VISSIM as low-speed areas, and delays are measured. Analysis of PCSWMM shows that for 100-year return period, there is maximum 0.318 ha-m (3180 cubic meters) water stored in the depressions of the road after 10 h of rainfall. Analysis of VISSIM shows that for a 100-year return period, there is a maximum delay of 35 min on NIPA to Hasan Square section of University Road.
  PubDate: 2018-01-15
Vibration and sound radiation of a rotating train wheel subject to a
vertical harmonic wheel–rail force
- Abstract: Abstract The rapid development of high-speed railway networks requires advanced methods for analysing vibration and sound radiation characteristics of a fast rotating train wheel subject to a vertical harmonic wheel–rail force. In order to consider the rotation of the wheel and at the same time increase the computational efficiency, a procedure is adapted in this paper taking advantage of the axial symmetry of the wheel. In this procedure, a recently developed 2.5D finite element method, which can consider wheel rotation but only requires a 2D mesh over a cross section containing the wheel axis, is used to calculate the vibration response of the wheel. Then, the vibration response of the wheel is taken as acoustic boundary condition and the 2.5D acoustic boundary element method, which only requires a 1D mesh over the boundary of the above cross section, is utilised to calculate the sound radiation of the wheel. These 2.5D methods and relevant programs are validated by comparing results from this procedure with those from conventional 3D analyses using commercial software. The comparison also demonstrates that these 2.5D methods have a much higher computational efficiency. Using the 2.5D methods, we study the wheel rotation speed influences on the factors including the vertical receptance of the wheel at wheel–rail contact point, sound pressure level at a pre-defined standard measurement point, radiated sound power level, directivity of the radiation, and contribution of each part of the wheel. It can be concluded that the wheel rotation speed splits most peaks of the vertical receptance at the wheel–rail contact point, sound pressure levels at the field, and the sound power level of the wheel into two peaks. The directivity and power contribution of the wheel are also significantly changed by the wheel rotation speed. Therefore, the rotation of a train wheel should be taken into account when calculating its vibration and sound radiation.
  PubDate: 2018-01-08
Microscopic and macroscopic diagnosis of the effect of winter weather
conditions on distribution pattern of truck types in regional commuter
road
- Abstract: Abstract It has been reported in the past literature that total traffic volume and passenger car volume are affected by snowfall and cold temperature, but trucks are not significantly affected. This paper aims to confirm that the distribution of truck types is not affected by winter weather conditions through combined statistical analysis in the framework of microscopic and macroscopic impact analysis. A micro-level analysis was conducted to investigate the effect of snowfall and temperature on changes in truck type distribution. A macro-level analysis was also conducted to investigate the effect of the months (or seasons) on changes in truck type distribution. Truck traffic data were collected for 5 years at the weigh-in-motion site in Highway 2A, which is used for regional commuters near the City of Leduc, Alberta, Canada. The trucks were subdivided into straight unit truck, single trailer and multi trailer unit and then analyzed by applying a nonparametric Chi-squared test combined with the binomial probability test. As a result of the nonparametric test, the truck type distribution was stable irrespective of the severity of winter weather conditions, which are microscopic factors such as snowfall and temperature, and was not influenced by changes in months and seasons, which are macroscopic factors.
  PubDate: 2017-12-27
Gap acceptance behavior of drivers at uncontrolled T-intersections under
mixed traffic conditions
- Abstract: Abstract Explicit traffic control measures are absent in uncontrolled intersections which make them susceptible to frequent conflicts and resulting collisions between vehicles. In developing countries like India, drivers at such intersections do not yield to higher priority movements which cause more crashes between vehicles. The objective of this study is to analyze and model the gap acceptance behavior of minor street drivers at uncontrolled T-intersections considering their aggressive nature. Three intersections in the northeast region of India have been selected as the case study area. Preliminary analysis of the data revealed that drivers behave aggressively, not because they have to wait for a long time at the stop line, but because of their lack of respect for traffic rules. Binary logit models are developed for minor road right turning vehicles which show that gap acceptance behavior is influenced by gap duration, clearing time and aggressive nature of drivers. The equations obtained were used to estimate the critical gaps for aggressive and non-aggressive drivers. Critical gaps are also calculated using an existing method called clearing behavior approach. It is also shown that the estimation of critical gap is more realistic if clearing time and aggressive behavior of drivers are considered.
  PubDate: 2017-12-15
A novel handover scheme using torch nodes and adaptive measurement
aggregation mechanism to improve QoS in high-speed railway communication
- Abstract: Abstract Technological advancement in the field of transportation and communication is happening at a faster pace in the past few decades. As the demand for high-speed transportation increases, the need for an improved seamless communication system to handle higher data traffic in a highly mobile environment becomes imperative. This paper proposes a novel scheme to enhance the quality of service in high-speed railway (HSR) communication environment using the concept of torch nodes (TNs) and adaptive measurement aggregation (AMA). The system was modeled using an object-oriented discrete event simulator, and the performance was analyzed against the existing single-antenna scheme. The simulation results show that the proposed scheme with its minimal implementation overhead can efficiently perform seamless handover with reduced handover failure and communication interruption probability.
  PubDate: 2017-12-01
Experimental study on the applicability of Westergaard’s formula for
calculating earthquake-induced hydrodynamic pressure in small lake
- Abstract: Abstract Moraine-dammed lake outbursts usually threaten highways, railways, and key facilities in alpine regions. The varying amplitudes and distribution of hydrodynamic pressures significantly affect the stability of the dam. We utilize a shaking table to investigate the development of hydrodynamic pressure caused by different sinusoidal waves and seismic Wolong wave. A series of shaking table tests indicate that the hydrodynamic pressure variation significantly follows seismic acceleration wave motion. The maximum hydrodynamic pressures calculated by Westergaard’s equation are compared with the experimental values under different waves. It is shown that the Westergaard’s values are lower than the experimental ones under the sinusoidal waves. However, the Westergaard’s method is able to predict the earthquake-induced hydrodynamic pressure caused by Wolong wave in small lake with desirable accuracy.
  PubDate: 2017-11-17
Public priorities and consumer preferences for selected attributes of
automated vehicles
- Abstract: Abstract Public opinion and consumer preferences are among the various constraints on the rollout of automated cars, as they will affect the decision-making of both automotive industry actors and public-sector regulators. This study contributes to the growing body of the literature regarding this issue, through a moderate-scale survey (n = 370) that incorporated both prioritization/attitudinal questions (regarding public opinion) and a stated-preference module (to identify consumer preferences). The survey protocol includes a stated-preference approach to investigate consumers’ preferences for the possibility of very high rates of speed in automated cars on long-distance journeys. We found separately identifiable effects for average travel speeds (manifested as journey duration) and maximum travel speed in the stated-preference scenarios. In the ‘prioritization’ component of the survey, respondents ranked having the ‘highest possible level of safety’ as the single most important benefit that they would like automated cars to deliver, ahead of benefits such as being able to performing activities while traveling or having traffic congestion reduced. This result has consequences for the car-following distances that are programmed into the control algorithms of automated cars. Documenting this finding is important, as decisions must be made in the near future by driving-algorithm designers, public-sector regulators, and ultimately the judiciary regarding the guidelines for acceptable automated driving-behavior instructions.
  PubDate: 2017-11-16
Advances of research on high-speed railway catenary
- Abstract: Abstract The interaction between the catenary and pantograph is one of the most crucial factors that determine the train operation in high-speed railway. The bad state of catenary is able to directly influence the power supply safety of traction power system. In this paper, four aspects on the catenary research of high-speed railway are reviewed in detail, namely the solution methods for catenary equilibrium state, the dynamic modeling methods of catenary, non-contact detection methods of catenary, and the static and dynamic evaluation methods of catenary. In addition, their recent advances are described. For the low solution accuracy of the initial equilibrium state of catenary, the structure finding method with multi-objective constraint and nonlinear finite element procedure are introduced to solve the problem. For the catenary’s dynamic modeling, considering the influence of environmental wind on the catenary, environmental wind simulations and wind tunnel tests are used to obtain the aerodynamic coefficients and build the wind field along the catenary for analysis of its wind vibration characteristics. In order to improve the detection accuracy of non-contact detection for the catenary, the deep learning theory and real-time detection algorithms should be adopted in the future. In view of the lack of dynamic assessment method for the catenary, the modern spectrum evaluation, time–frequency analysis, big data technology and their combinations will be the important means for future catenary evaluation.
  PubDate: 2017-11-10
A multifunctional battery module design for electric vehicle
- Abstract: Abstract Reducing the overall vehicle weight is an efficient, system-level approach to increase the drive range of electric vehicle, for which structural parts in auto-frame may be replaced by battery modules. Such battery modules must be structurally functional, e.g., energy absorbing, while the battery cells are not necessarily loading–carrying. We designed and tested a butterfly-shaped battery module of prismatic cells, which could self-unfold when subjected to a compressive loading. Angle guides and frictionless joints were employed to facilitate the large deformation. Desired resistance to external loading was offered by additional energy absorption elements. The battery-module behavior and the battery-cell performance were controlled separately. Numerical simulation verified the experimental results.
  PubDate: 2017-11-06
Optimal energy saving in DC railway system with on-board energy storage
system by using peak demand cutting strategy
- Abstract: Abstract A problem of peak power in DC-electrified railway systems is mainly caused by train power demand during acceleration. If this power is reduced, substation peak power will be significantly decreased. This paper presents a study on optimal energy saving in DC-electrified railway with on-board energy storage system (OBESS) by using peak demand cutting strategy under different trip time controls. The proposed strategy uses OBESS to store recovered braking energy and find an appropriated time to deliver the stored energy back to the power network in such a way that peak power of every substations is reduced. Bangkok Mass Transit System (BTS)-Silom Line in Thailand is used to test and verify the proposed strategy. The results show that substation peak power is reduced by 63.49% and net energy consumption is reduced by 15.56% using coasting and deceleration trip time control.
  PubDate: 2017-10-22
The role of microstructure and its stability in performance of wheels in
heavy haul service
- Abstract: Abstract Thermal or thermo-mechanical loading is one of the major causes of wheel surface damage in Australian heavy haul operations. In addition, multi-wear wheels appear to be particularly sensitive to thermo-mechanical damage during their first service life. Such damage can incur heavy machining penalties or even premature scrapping of wheels. The combination of high contact stresses as well as substantial thermal loading (such as during prolonged periods of tread braking) can lead to severe plastic deformation, thermal fatigue and microstructural deterioration. For some high-strength wheel grades, the increased sensitivity to thermo-mechanical damage observed during the first service period may be attributed to the presence of a near-surface region in which the microstructure is more sensitive to these loading conditions than the underlying material. The standards applicable to wheels used in Australian heavy haul operations are based on the Association of American Railroads (AAR) specification M-107/M-208, which does not include any requirements for microstructure. The implementation of acceptance criteria for the microstructure, in particular that in the near-surface region of the wheel, may be necessary when new wheels are purchased. The stability of wheel microstructures during thermo-mechanical loading and the effects of alloying elements commonly used in wheel manufacturing are reviewed. A brief guide to improving thermal/mechanical stability of the microstructure is also provided.
  PubDate: 2017-10-03
Stress concentration coefficients of optimized cope-hole welded detail
- Abstract: Abstract The fatigue performance of optimized welded detail has been investigated by fatigue experiments of three welded specimens under different loadings. In addition, local finite element models of this welded detail were established using finite element software ANSYS. The influences of different factors such as plate thickness, plate gap and initial geometric imperfections on the stress concentration coefficient (SCC) were discussed. The experimental results indicate that the fatigue life of three specimens for this welded detail is 736,000, 1,044,200 and 1,920,300 times, respectively. The web thickness, the filler plate thickness and the initial geometric imperfection have relatively less effect on the SCCs of this welded detail. However, cope-hole radius is influential on the SCCs of the web and the weld. The SCC of weld is significantly affected by the weld size and plate gap, but the SCCs of other parts of the welded detail are hardly affected by the plate gap.
  PubDate: 2017-09-18
Longitudinal train dynamics of electric multiple units under rescue
- Abstract: Abstract Once operating trains are disabled on the railway lines, an efficient manner is to utilize the train for train rescue. Owning to the different train and coupler types, it is difficult to formulate uniform regulations for train to train rescue. In this paper, the longitudinal train dynamics of electric multiple units under rescue were analyzed by field and laboratory tests. The angling behavior of the braking-induced coupler under compressed in-train forces was analyzed. A dynamic model for the train and draft gear system was developed considering accurate boundary limitations and braking characteristics. The safety indices and its limits for the coupled rescue train were defined. The dynamic evaluations of different train to train rescue scenarios were analyzed. It is indicated that the coupler vertical rotation occurs during the emergency braking applied by the assisting train. The vertical force components of in-train forces lead to the carbody pitch behavior and even cause local destructions to the coupler system. The carbody pitch motion can arise the inference of in-train devices. Based on the safety evaluation of train and coupler system, the regulations for typical train to train rescue scenarios were formulated.
  PubDate: 2017-09-15
A select link analysis method based on logit–weibit hybrid model
- Abstract: Abstract Select link analysis provides information of where traffic comes from and goes to at selected links. This disaggregate information has wide applications in practice. The state-of-the-art planning software packages often adopt the user equilibrium (UE) model for select link analysis. However, empirical studies have repeatedly revealed that the stochastic user equilibrium model more accurately predicts observed mean and variance of choices than the UE model. This paper proposes an alternative select link analysis method by making use of the recently developed logit–weibit hybrid model, to alleviate the drawbacks of both logit and weibit models while keeping a closed-form route choice probability expression. To enhance the applicability in large-scale networks, Bell’s stochastic loading method originally developed for logit model is adapted to the hybrid model. The features of the proposed method are twofold: (1) unique O–D-specific link flow pattern and more plausible behavioral realism attributed to the hybrid route choice model and (2) applicability in large-scale networks due to the link-based stochastic loading method. An illustrative network example and a case study in a large-scale network are conducted to demonstrate the efficiency and effectiveness of the proposed select link analysis method as well as applications of O–D-specific link flow information. A visualization method is also proposed to enhance the understanding of O–D-specific link flow originally in the form of a matrix.
  PubDate: 2017-09-04
Risk assessment: method and case study for traffic projects
- Abstract: Abstract A comprehensive project evaluation and decision-making method considering multiple objectives, stakeholders, and attributes of proposed traffic treatments is inherently complicated. Although individual techniques in evaluating operations, safety, economic, and stakeholder objectives are available, a practical method that integrates all these risk factors and their uncertainties into a multi-attribute decision-making tool is absent. A three-level project decision-making process was developed to model and assess multiple-attribute risk in a proposed traffic treatment from the perspective of multiple stakeholders. The direct benefits from reducing delay and safety risk (basic objectives of traffic treatments) are computed in Level 1 with established methods. Feasibility and performance analysis in Level 2 examine site-specific constraints and conduct detailed performance analysis using advanced analysis tools. In Level 3, this paper introduces an innovative and integrated multiple attributes evaluation process under fuzziness and uncertainty (MAFU) process for evaluation and decision-making. The MAFU is a comprehensive and systematic assessment and decision-making procedure that can assess the magnitudes of project performance and to integrate conflicting interests and trade-offs among stakeholders. A case study illustrates the application of MAFU for the selection of a traffic alternative involving several evaluation attributes and stakeholders. Results show that the MAFU produced the smallest variance for each alternative. With traditional cost–benefit evaluation methods, the uncertainty associated with performance of a traffic project in terms of operation, safety, environmental impacts, etc., is unrestricted and cumulative. Therefore, a reliable multi-attribute evaluation of complex traffic projects should not be made with conventional cost–benefit analysis alone but with a process like MAFU.
  PubDate: 2017-07-29
Travelers’ attitudes toward carpooling in Lahore: motives and
constraints
- Abstract: Abstract Traffic congestion has become a critical issue in developing countries, as it tends to increase social costs in terms of travel cost and time, energy consumption and environmental degradation. With limited resources, reducing travel demand by influencing individuals’ travel behavior can be a better long-term solution. To achieve this objective, alternate travel options need to be provided so that people can commute comfortably and economically. This study aims to identify key motives and constraints in the consideration of carpooling policy with the help of stated preference questionnaire survey that was conducted in Lahore City. The designed questionnaire includes respondents’ socioeconomic demographics, and intentions and stated preferences on carpooling policy. Factor analysis was conducted on travelers’ responses, and a structural model was developed for carpooling. Survey and modeling results reveal that social, environmental and economic benefits, disincentives on car use, preferential parking treatment for carpooling, and comfort and convenience attributes are significant determinants in promoting carpooling. However, people with strong belief in personal privacy, security, freedom in traveling and carpooling service constraints would have less potential to use the carpooling service. In addition, pro-auto and pro-carpooling attitudes, marital status, profession and travel purpose for carpooling are also underlying factors. The findings implicate that to promote carpooling policy it is required to consider appropriate incentives on this service and disincentives on use of private vehicle along with modification of people’s attitudes and intentions.
  PubDate: 2017-07-03