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Marjana Petrović, Daniela Todorova
2013 (Vol 25), Issue 6

Ahmadreza Ghaffari, Ali Tavakoli Kashani, Sayedbahman Moghimidarzi
2013 (Vol 25), Issue 6
Identifying crash “black-spots”, “hot-spots” or “high-risk” locations is one of the most important and prevalent concerns in traffic safety and various methods have been devised and presented for solving this issue until now. In this paper, a new method based on the reliability analysis is presented to identify black-spots. Reliability analysis has an ordered framework to consider the probabilistic nature of engineering problems, so crashes with their probabilistic na -ture can be applied. In this study, the application of this new method was compared with the commonly implemented Frequency and Empirical Bayesian methods using simulated data. The results indicated that the traditional methods can lead to an inconsistent prediction due to their inconsider -ation of the variance of the number of crashes in each site and their dependence on the mean of the data.

Qun Chen, Haibo Chen
2013 (Vol 25), Issue 6
A new discrete network design problem (DNDP) was pro-posed in this paper, where the variables can be a series of integers rather than just 0-1. The new DNDP can determine both capacity improvement grades of reconstruction roads and locations and capacity grades of newly added roads, and thus complies with the practical projects where road capacity can only be some discrete levels corresponding to the number of lanes of roads. This paper designed a solution algorithm combining branch-and-bound with Hooke-Jeeves algorithm, where feasible integer solutions are recorded in searching the process of Hooke-Jeeves algorithm, lend -ing itself to determine the upper bound of the upper-level problem. The thresholds for branch cutting and ending were set for earlier convergence. Numerical examples are given to demonstrate the efficiency of the proposed algorithm.


Ondrej Cyprich, Vladimír Konečný, Katarína Kiliánová
2013 (Vol 25), Issue 6
The purpose of the paper is to identify and analyse the forecasting performance of the model of passenger demand for suburban bus transport time series, which satisfies the statistical significance of its parameters and randomness of its residuals. Box-Jenkins, exponential smoothing and multiple linear regression models are used in order to design a more accurate and reliable model compared the ones used nowadays. Forecasting accuracy of the models is evaluated by comparative analysis of the calculated mean absolute percent errors of different approaches to forecasting. In accordance with the main goal of the paper was identified the ARIMA model, which fulfils almost all statistical criterions with an exception of the model residuals normality. In spite of the limitation, the best forecasting abilities of identified model have been proven in comparison with other approaches to forecasting in the paper. The published findings of research will have positive influence on increasing the forecasting accuracy in the process of passenger demand forecasting.

Tomas Micunek, Zuzana Schejbalova, Drahomir Schmidt
2013 (Vol 25), Issue 6

Solid barriers represent danger for the driver in case of traffic lane escape. This threat can be represented by a drainage ditch culvert face. The access bridge is not usually conspicuous enough near the traffic lane so that the driver could ditch and crash this barrier in case of an exceptional situation such as avoidance manoeuvres. This work deals with a technical solution of access bridges with an integrated deformation zone which was designed on the ground of a detailed analysis of current types of the construction. The new technical solution was proved by means of a numerical simulation of passenger car impact and compared with the current design of culvert faces.


tanja brcko, jelenko švetak
2013 (Vol 25), Issue 6
Despite the generally high qualifications of seafarers, many maritime accidents are caused by human error; such accidents include capsizing, collision, and fire, and often result in pollution. Enough concern has been generated that researchers around the world have developed the study of the human factor into an independent scientific discipline. A great deal of progress has been made, particularly in the area of artificial intelligence. But since total autonomy is not yet expedient, the decision support systems based on soft computing are proposed to support human navigators and VTS operators in times of crisis as well as during the execution of everyday tasks as a means of reducing risk levels.
This paper considers a decision support system based on fuzzy logic integrated into an existing bridge collision avoidance system. The main goal is to determine the appropriate course of avoidance, using fuzzy reasoning.

Alireza Khademi, Nafiseh Ghorbani Renani, Maryam Mofarrahi, Alireza Rangraz Jeddi, Noordin Mohd Yusof
2013 (Vol 25), Issue 6
Speed bumps, as traffic calming devices, have been extensively used to reduce traffic speed on local streets. This study represents a unique application of experimental design methodology where the effects of some controllable factors in determining the best location for installing speed bumps before stop points (e.g. entry gates, road junctions) were investigated. Through Classical Design of Experiments (DOE), the optimum location of the speed bump was obtained based on the graphical plots of the significant effects. The speed at the stop point was treated as the response and minimum speed is desirable. Design-Expert® software was used to evaluate and analyze the results obtained. The suggested mathematical model effectively explains the performance indicators within the ranges of the factors. The car speed is the most significant factor that affects the distance-time in comparison with other factors, which provides secondary contributions.

Olli-Pekka Hilmola
2013 (Vol 25), Issue 6

The Baltic Sea shipping is at a crossroads as sulphur regulation will lead to excessive cost increases from the year 2015 onwards and CO2 emission trading is planned to be implemented for the entire shipping sector within the EU area. Therefore, shipping is going to be minimized and hinterland transportation (road and rail) will act as substitute. This research analyzes the situation on one of the highest volume general cargo transportation routes of Finland (operating between Helsinki, Finland and Tallinn, Estonia), including loading and unloading at seaports and short sea shipping activity in between. Based on the efficiency evaluation results, it seems that containers should be favoured over semi-trailers – containers could be carried efficiently either in container ships or even at currently favoured RoRo or RoPax ships. Our research illustrates that pure container shipping with larger container ships within the analyzed route is not entirely out of question, but lead time and hinterland operations should receive more attention. Alternatively, RoRo and RoPax ships can also do something to increase their competitiveness in environmental harm caused and diesel consumption – higher cargo loads and utilization levels are short-term key for continued dominance.


Ivica Skoko, Marinko Jurčević, Diana Božić
2013 (Vol 25), Issue 6

With the rapidly increasing global energy needs, offshore oil production has become an attractive source of energy. Supplying offshore oil production installations is a complex logistics problem that hinges on many factors with significant uncertainties. So, it is critical to provide the necessary supplies and services without interruption. In a typical offshore oil production effort, oil companies charter most or all drilling units as well as offshore supply vessels (OSV). The type and duration of charter contract has direct impact on the project budget as vessels market is closely correlated with the world market crude oil price which can have daily significant fluctuations. As the region of West Africa is one of the world’s busiest offshore exploration and oil production markets employing 12% of the world’s fleet, exploring its issues, was taken to study the relations between daily OSV rates and crude oil price. The research results presented in this paper show correlation between OSV daily rates and crude oil price with broader fluctuations in crude oil price.

 


Ante Galić, Tonči Carić, Juraj Fosin
2013 (Vol 25), Issue 6

Using new optimization methods and information-communications technology has become the key issue in the competition among the distributers of fast-moving consumer goods. Introducing a delivery optimization system instead of manual routing enables significant cost savings. The prerequisites for optimization are stable information system and efficient company management. The rich vehicle routing problem model is discussed and the effects of implementing the delivery optimization system are presented. For four years of continuous utilisation, the system has helped the distributer to reduce the overall distribution costs. It also made possible to close down several depots and handle more customer requests without investing in the vehicle fleet. The developed optimization system enabled the distributer to adapt to the new distribution schedule and react to first indicators of recession very fast.


Sandra Kasalica, Dragomir Mandić, Vojislav Vukadinović
2013 (Vol 25), Issue 5
Intention– Cyclic locomotive assignment planning is a specific type of organization of locomotive usage, and in fact, it means putting the complete workload to a closed chain, which is repeated periodically. The concept of cyclic locomotive assignment planning type organization in the area of train traction has proven in practice as the best one, but as it is made for in-advance defined timetable and without considering the stochastic nature of the timetable realization process, it leads to incompatibility in using locomotives. Methodology – Methodology defined in this paper contains: research of train delays on the Serbian Railways and Montenegrin Railways networks, analysis of the real system organization of locomotive usage in conditions of train delays, theoretical thesis of solving the problem of optimal cyclic locomotive assignment planning in conditions of train delays, designing of a model with algorithms, preparing the software package, testing the model and program with results, as well as the conclusions drawn from the complete research project. Results– The optimization model of cyclic locomotive assignment planning during the process of making timetable including train delays has been defined. Conclusion –The obtained results have shown as expected, that the larger delays of trains required a larger number of locomotives. However, by using this model it is possible to optimize the required number of locomotives, taking into account the real time delays of trains.

Jelena Budak
2013 (Vol 25), Issue 5

Ali Ghasemi
2013 (Vol 25), Issue 5
The problem of controlling a string of vehicles moving in one dimension is considered so that they all follow a lead vehicle with a constant spacing between successive vehicles. This paper is concerned by considering both effect of the parasitic time delays and lags and comfort specification. The Contribution of this paper is two-fold. Firstly, most physical systems often involve parasitic time delays and lags. Due to practical design and implementation, the negative effect of the parasitic time delays and lags on the string stability be taken into account Secondly, the aim here, however, is specifically to consider the restrictions which need to be imposed on the control parameters, in order to be well-suited with bounds on the dynamic variables as well as the requirement for string stability. At the end the robustness against the noise in the measurement signals factors are studied.

Senka Sekularac-Ivošević, Sanja Bauk, Mirjana Gligorijević
2013 (Vol 25), Issue 5

This paper considers the effects of combination of two different approaches in developing seaports positioning strategy. The first one is based on comparing the most important quantitative and qualitative seaports choice criteria by benchmarking method. Benchmarking has been used in creating the appropriate model for efficient marketing positioning of Aegean, Adriatic and Black Sea seaports. The criteria that describe the degree of these seaports competitiveness are chosen upon the investigation of ports customers’ preferences. The second employed approach based on matrix game concept has been used for the purpose of optimal repositioning of the ports. Though, nine selected ports’ functions are treated in a way that they are divided into two sets: one composed of the functions which are to be developed, and the other consisted of the functions for which it is expected to be suppressed in the future. According to the numerically obtained results the ports are repositioned, and corresponding explanations are given in the marketing manner. The mixture of these two concepts should contribute to the review of the state of these business systems and their images at the market, as well as to open prospective toward finding out the ways of creating and maintaining their competitive advantages.


Fang Zong, Jia Hongfei, Pan Xiang, Wu Yang
2013 (Vol 25), Issue 5
This paper presents a model system to predict the time allocation in commuters’ daily activity-travel pattern. The departure time and the arrival time are estimated with Ordered Probit model and Support Vector Regression is introduced for travel time and activity duration prediction. Applied in a real-world time allocation prediction experiment, the model system shows a satisfactory level of prediction accuracy. This study provides useful insights into commuters’ activity-travel time allocation decision by identifying the important influences, and the results are readily applied to a wide range of transportation practice, such as travel information system, by providing reliable forecast for variations in travel demand over time. By introducing the Support Vector Regression, it also makes a methodological contribution in enhancing prediction accuracy of travel time and activity duration prediction.

Đani Mohović, Robert Mohović, Igor Rudan
2013 (Vol 25), Issue 5
Ship grounding is one of the primary maritime navigation casualties and a result of an error made by the navigating officer, of a technical failure on vital ship equipment or of force majeure. In order to decrease the risk of grounding in such cases, this paper explores the ship movement during navigation when an extraordinary event occurs, such as steering system failure that affects the vessel’s direction directly and speed indirectly. One way to determine the ship movement in such circumstances is by simulating the ship movement on the navigational simulator according to the predefined scenarios, as explained in this paper. A total of 60 scenarios were researched, in the process of which ship type, ship size, ship speed and rudder deflection angle were varied. During the simulation, all relevant data concerning current movement of the ship and a graphical display of the performed simulation were recorded every 30 seconds. On the basis of the simulation results it is possible to determine the worst case scenario which can be used to define the consequence of grounding, one of the parameters necessary for the assessment of the risk of grounding.

Mian Yang, Y.J. Wang
2013 (Vol 25), Issue 5

A major problem addressed in railway network planning relates to distinguishing the role of the railway line in the network, and making a reasonable classification of the lines based on their role. Accessibility has been widely used to measure the role of transportation infrastructure in various studies, but few quantitative models for the classification of the role have been presented yet. In this paper, the line accessibility classification model is proposed, which aims to distinguish the role of railway lines in the network and to classify the lines into different grades. The practicability of the model is demonstrated through the case study of Northeast China railway network where the railway lines in Northeast China can be classified into three grades. The line accessibility classification model is supposed to be a strategic decision support tool for planners and policy makers to determine the classification of railway lines.


Tomaž Tollazzi, Goran Jovanović, Marko Renčelj
2013 (Vol 25), Issue 5
The problems of low level traffic safety on multi-lane roundabouts have been resolved in various ways in different countries, usually by using alternative types of roundabouts that reduce the number of conflict points. Alternative types of roundabouts typically differ from 'normal' or 'standard' roundabouts in one or more design elements, as their implementation purposes could also be specific. Today, several different types of roundabouts are already in use ('mini', 'double mini', 'dumb-bell', those 'with joint splitter islands' ('dog-bone'), those 'with a spiralling circular carriageway' ('turbo'), those 'with depressed lanes for right-hand turners' ('flower') etc.). This paper introduces a new type of roundabout, dual one-lane roundabouts on two levels with right-hand turning bypasses, namely the 'target roundabout'. This paper describes and analyses their design, traffic safety, and capacity characteristics, compared with the standard two–lane roundabouts.

Luoyi HUANG, Jiao YAO, Wei WU, Xiaoguang YANG
2013 (Vol 25), Issue 5

With the evolution of advanced wireless communication technologies, tremendous efforts have been invested in vehicular networking, particularly the construction of a vehicle-to-vehicle communication system that supports high speed and mobility. In vehicle-to-vehicle communication environment, vehicles constantly exchange information using wireless technology.

This paper aims to propose a vehicle-to-vehicle communication system and validate the feasibility of the system on a suburban road in China. Two vehicles were used equipped with IEEE 802.11p based DSRC (Dedicated Short Range Communications) device to construct a vehicle-to-vehicle communication platform. The system architecture consisting of hardware and software was described in details. Then, communication characteristics such as RSSI (Received Signal Strength Indicator), latency and PLR (packet loss rate) were analyzed. Additionally, GPS-related information (such as ground speed and location) was obtained through field test on a suburban road in Shanghai and Taicang City. The test results demonstrate satisfactory performance of the proposed system.

Ioan Felea, Istvan Csuzi, Eva Barla
2013 (Vol 25), Issue 5
Energy conservation is one of the key priorities of sustainable development strategy. Transport systems are responsible for about one third of energy consumption. As result, the identification of solutions to reduce energy consumption in these systems is essential for the implementation of the sustainable development strategies. The present work is dedicated to identifying the possibilities for a reduction in the consumption of electric energy in electric urban public transport systems, using the audit of their electricity system. After justifying the importance of these concerns, a mathematical model of the electrical energy balance of the electric urban public transport system and its components is presented. The analysis is applied to determine the losses in the system components and useful energy, based on the evaluation and energy consumption measurements. The measurements to reduce energy losses are identified and characterized under technical and economic aspect, optimal electrical energy balances being done on this basis.


Predrag Atanasković, Vladeta Gajić, Ivan Dadić, Svetlana Nikoličić
2013 (Vol 25), Issue 4
This paper presents research related to the choice of the criteria that can be used to perform an optimal selection of the forklift unit for warehouse operation. The analysis has been done with the aim of exploring the requirements and defining relevant criteria that are important when investment decision is made for forklift procurement, and based on the conducted research by applying multi-criteria analysis, to determine the appropriate parameters and their relative weights that form the input data and database for selection of the optimal handling unit. This paper presents an example of choosing the optimal forklift based on the selected criteria for the purpose of making the relevant investment decision.

Ann Mills, Davor Sumpor
2013 (Vol 25), Issue 4



Mauro Dell'Orco, Ozgur Baskan, Mario Marinelli
2013 (Vol 25), Issue 4

In this study, a bi-level formulation is presented for solving the Equilibrium Network Design Problem (ENDP). The optimisation of the signal timing has been carried out at the upper-level using the Harmony Search Algorithm (HSA), whilst the traffic assignment has been carried out through the Path Flow Estimator (PFE) at the lower level. The results of HSA have been first compared with those obtained using the Genetic Algorithm, and the Hill Climbing on a two-junction network for a fixed set of link flows. Secondly, the HSA with PFE has been applied to the medium-sized network to show the applicability of the proposed algorithm in solving the ENDP. Additionally, in order to test the sensitivity of perceived travel time error, we have used the HSA with PFE with various level of perceived travel time. The results showed that the proposed method is quite simple and efficient in solving the ENDP.


Pooya Najaf, Sina Famili
2013 (Vol 25), Issue 4

Road freight transportation between provinces of a country has an important effect on the traffic flow of intercity transportation networks. Therefore, an accurate estimation of the road freight transportation for provinces of a country is so crucial to improve the rural traffic operation in a large scale management. Accordingly, the focused case study database in this research is the information related to Iran’s provinces in the year 2008. Correlation between road freight transportation with variables such as transport cost and distance, population, average household income and Gross Domestic Product (GDP) of each province is calculated. Results clarify that the population is the most effective factor in the prediction of provinces’ transported freight. Linear Regression Model (LRM) is calibrated based on the population variable, and afterwards Fuzzy Regression Algorithm (FRA) is generated on the basis of the LRM. The proposed FRA is an intelligent modified algorithm with an accurate prediction and fitting ability. This methodology can be significantly useful in macro-level planning problems where decreasing prediction error values is one of the most important concerns for decision makers. In addition, Back-Propagation Neural Network (BPNN) is developed to evaluate the prediction capability of the models and to be compared with FRA. According to the final results, the modified FRA estimates road freight transportation values more accurately than the BPNN and LRM. Finally, in order to predict the road freight transportation values, the reliability of the calibrated models is analyzed using the information of the year 2009. Results show higher reliability for the proposed modified FRA.


Valentina Basarić, Jelena Mitrović, Zoran Papić
2013 (Vol 25), Issue 4

The analysis of the experiences in European cities, following the implementation of different transport policy measures, has led to a conclusion that parking policy measures have the dominant effect on the choice of private car as a mode of transport. This effect is the greatest for the commutes to work, characterized by the longest duration of parking space occupancy. Given the aforementioned experiences in developed European cities, the main aim of the study presented here was the determination of a relationship between limiting the duration of parking space occupancy in the Novi Sad city centre and the transport participants’ decision whether or not to use passenger car to commute to work. Based on the established interdependence between these parameters, we developed a mathematical model for calculating a number of expected car (commuting) journeys that terminate in the city centre as a function of limited duration of parking space occupancy.

 


Gholamali Shafabakhsh, Raheb Mirzanamadi, Mehdi Mohammadi
2013 (Vol 25), Issue 4

Since 1996 to 2006, Iran‟s population structure experienced considerable changes. During the mentioned period, the share of the population under 15 decreased from 39.6% to 28%. Considering this decrease, Iran‟s population was quickly guided to oldness which will have irreversible social and economical repercussions on the country‟s future progress. The main objective of this study is to estimate the effects of the elderly on the moving stream of the other pedestrians in Iran‟s sidewalks, which is done for the first time in Iran using the Micro-Simulation method. The Micro-Simulation model of pedestrians is a computerized simulation procedure in which the moving behavior of each pedestrian such as speed, path, and the direction is considered separately. According to the obtained results from this study, an increase in the percentage of the elderly population can lower the sidewalk's level of service. Also, the decrease of the average motion speed and the free walking space for wider paths is not necessarily less than that of narrow paths; in a way that by increasing the width of a sidewalk, pedestrians‟ total average speed and the average walking space decrease up to a specific width and then, start to increase. This decrease in wider sidewalks is more than that in more narrow ones.


Mohammad Hossain Jalal Kamali, Mohammad Saeed Monajjem, Mohammad Sadegh Ayubirad
2013 (Vol 25), Issue 4

Safety in highways is one of the most important subjects in Transportation Engineering. Increasing rate of vehicles and the needs to design or geometrically modifying the highways, emphasized on the safe-designing of the roadways more than before. Between the constructive components of the highway, horizontal curves due to the more occurrences of accidents are of great importance. The American ministry of highway and transportation introduced the software IHSDM, with variant capabilities, to predict accidents. In this research, five types of curves (simple circle curve and clothoid-circle-clothoid) at different intersection angles were designed, and accident rates based on the standard specifications on each curve was predicted by using the IHSDM, and the results are compared with each other. Finally, by processing the curves of accident rates versus the curves types and intersection angle, and comparing them with each other, the necessity of using spiral curves in the highway design is emphasized.


Deniz Türsel Eliiyi, Gamze Mat, Burcu Ozmen
2013 (Vol 25), Issue 4
In this study, we consider a real-life export container storage problem at an important container terminal in the Port of Izmir, Turkey. Currently, the container storage decisions at the port are taken by operators manually, which leads to continuous unnecessary re-handling movements of the containers. High transportation costs, waste of time, and inefficient capacity utilization in the container storage area are the consequences of non-optimal decisions. The main goal of this study is to minimize the transportation costs and the number of re-handling moves while storing the export containers at the terminal yard. We formulate the problem in two stages. While the first stage assigns the containers of the same vessel to a group of yard bays via an optimization model, the second stage decides on the exact location of each container with the help of an efficient heuristic approach. The experimental results with real data are presented and discussed.

Branislav M Ćorović, Petar Djurovic
2013 (Vol 25), Issue 4
We are aware of a large number of marine accidents that result in numerous casualties and even deaths and substantial negative environmental effects. The objective of this paper is to indicate factors that contribute to human errors which is identified as the most frequent cause to marine accidents. Despite rapid technological development and safety legislation, this paper identifies the human factor as the waekest link in maritime safety system. This analysis could lead to decrease of vessel accidents. In addition, starting from the European Maritime Safety Agency data and by linear regression model application, we have obtained the trend of number of ships involved in marine accidents as well as the trend of lives lost in marine accidents  in and around European Union waters.

Aleksandar Nikolic, Emilija Nikolic
2013 (Vol 25), Issue 4

Environmental and occupational noise is common nuisance that affects the health of employees. Performed health checks of employees engaged by Company “Pomorski Saobraćaj” showed that 5% of examined sailors had hearing loss. The results were a trigger for starting experiment on noise risk assessment with objective to discover possibilities of noise pollution presence, precise significant noise sources and describe solutions for eliminating negative effects.

Several measurements on five positions were performed on ferry boat “KAMENARI”, according to EC Physical Agents Directive and Merchant Shipping and Fishing Vessels Regulations 2007.

Noise on selected positions exceeded the limit for about 1-5dB. Noise exposure level was 84.5dB. Diesel engine, exhaust system and structural noise were main sources of excessive noise.

Experiment shows noise presence as nuisance that affects sailors. Noise presents a serious threat for sailor’s health. It interferes with crew communication and jeopardizes navigation safety. Technical measures, crew health checks and noise monitoring could prevent all negative effects.


Pančo Ristov
2013 (Vol 25), Issue 4
The quality of Vessel Traffic Management and Information Systems depends on the quality of all subsystems, in particular the quality of control centers. The most commonly used quantitative indicators of the control centers' quality are: reliability, availability, safety, and system failure. Therefore, a block diagram of reliability and the model for reliability / availability (Markov model) have been created in this paper and a detailed analysis and calculation of the quantitative indicators of critical components (servers) of the control center have been performed. The quality functioning of the control centers will enable gathering, processing, storing and dissemination of timely, safe, and reliable data and information to the services in charge of monitoring and management of maritime traffic.

Dubravko Tomašić, Dragan Peraković, Marinko Jurčević
2013 (Vol 25), Issue 3

The study determines the correlation between the application of advanced models and methods of inventory optimisation in the supply chain in relation to the satisfaction of employees who are responsible for managing the inventory optimisation processes. The previous studies confirm that the optimisation of inventory management in the supply chain insures competitive advantages on the market. There is space for further research of impact of the achieved inventory optimisation in the supply chain on the change of the employees’ satisfaction. The paper establishes the interrelation of the interdependence of the achieved inventory optimisations on the satisfaction of the employees and the related synergy effects of acquiring added value of the companies on the market oriented to the satisfaction of the buyers and service users. The research has defined new knowledge in interdependence of inventory management optimisation on the change of indicators of employees’ satisfaction. Based on the performed research an assumption has been created for the design of an application package (so-called XaaS-based services) for the management of interaction processes of inventory optimization in the supply chain, satisfaction of service users and employees.


Juraj Fosin, Davor Davidović, Tonči Carić
2013 (Vol 25), Issue 3

The Travelling Salesman Problem (TSP) is one of the most studied combinatorial optimization problem which is significant in many practical applications in transportation problems. The TSP problem is NP-hard problem and requires large computation power to be solved by the exact algorithms. In the past few years, fast development of general-purpose Graphics Processing Units (GPUs) has brought huge improvement in decreasing the applications’ execution time. In this paper, we implement 2-opt and 3-opt local search operators for solving the TSP on the GPU using CUDA. The novelty presented in this paper is a new parallel iterated local search approach with 2-opt and 3-opt operators for symmetric TSP, optimized for the execution on GPUs. With our implementation large TSP problems (up to 85,900 cities) can be solved using the GPU. We will show that our GPU implementation can be up to 20x faster without losing quality for all TSPlib problems as well as for our CRO TSP problem.


Jasmina Pašagić Škrinjar, Miroslav Drljača, Zvonko Kavran
2013 (Vol 25), Issue 3
The paper studies the relations between logistics of international express shipments and air traffic analysing the basic characteristics of international express shipments that are carried by combined transport, usually road vehicles and aircraft. The paper indicates the possibility of optimising individual technological processes in the logistic chain of express shipments distribution. It analyses the forms for the calculation of time slots in single logistic chain hubs of collecting and delivery of express shipments. It has been shown that the international distribution chains in the air express sector, related to the globalisation process, change the traditional functions of combined ground-air transport. Here, the increased investment into automation plays the crucial role in the development strategies of companies and in the operationalization of the quality policy of numerous carriers of express shipments by air.

Sadko Mandžuka, Marijan Žura, Božica Horvat, Davor Bićanić, Evangelos Mitsakis
2013 (Vol 25), Issue 3
The paper analyzes the current guidelines of the European Union on deployment of Intelligent Transport System, as well as their importance for the development of the Croatian transportation system. The crucial problems of modern transport and traffic are indicated as: congestions and congestion costs, harmful emissions in road transport, fatalities, etc. The current state of Intelligent Transport System development in Croatia is presented based on the transport infrastructure, modern road telematic industry, and other supporting activities (including scientific research, educational activities, standardization system, etc.). The final part of the paper deals with the need and potentials for the development of South East European regional ITS architecture.

Marko Matulin, Štefica Mrvelj
2013 (Vol 25), Issue 3
Continuous monitoring of achieved level of service quality in packet-switched networks represents an activity of major importance for network and service providers. This is paramount for network resources provisioning which have to satisfy expectations of fickle customers. However, providing enough resources to specific user does not automatically increase their Quality of Experience (QoE), hence understanding of the relationship between these two is crucial in the network management process. Essentially, this requires subjective testing of service quality which is usually done in controlled environments such as laboratories. Nevertheless, the most accurate subjective evaluation of QoE includes real-life experiments in the environments where the services are actually used. Therefore, the aim of this paper is to provide a review of the current state-of-the-practice in evaluating QoE in real-life environments.

Xuecai Xu, Ahmad Kouhpanejade, Željko Šarić
2013 (Vol 25), Issue 3

The objective of this study is to identify the influencing factors of crash rates from the perspective of access management techniques in urban areas. The target areas are located in the Las Vegas Metropolitan area, and 19 arterials are selected. In order to address the interdependency between crash rates and travel speeds, and left-censored issue, a tobit model with endogenous variable is presented. The structure of the tobit model addresses the left-censored issue for the segments meanwhile the endogeneity issue between crash rates and travel speeds is explained. The results indicate that there is a strong interdependency between crash rates and travel speeds. The segment length, driveway density, median opening density, posted speed limit and AADT per lane are statistically significant factors that influence crash rates on segments, moreover, crash rates are significantly influenced by two-directional median opening density. 


Danijela Barić, Goran Zovak, Marko Periša
2013 (Vol 25), Issue 3
Sustainable mobility is the basic and long-term goal of the traffic policy. Eco-driving represents one of 40 measures that should by 2050 contribute to 60% of traffic-generated emission reduction. The paper presents the significance of educating the drivers about eco-driving as well as eco-drive training with the aim of reducing fuel consumption and CO2 emission. During research the drivers were tested in three cycles, prior to education, immediately following the education and eco-training and three months after the eco-training. The analysis of the results shows that driving according to eco rules allows fast and efficient reduction of fuel consumption and CO2 emissions, which means at the same time also the need to systemically educate the drivers about the eco-driving at specialized educational centres which is for the moment absent in the Republic of Croatia.

Tatiana Molkova, Ivo Hruban
2013 (Vol 25), Issue 3

The contribution deals with the customers’ claims on provided services during train delay in personal railway transport. There is comparison between the situation in the Czech Republic (Brno main station) and Austria (Wien Westbahnhof) in the contribution. Development of the compensation policy cannot be based only on customer requirements. If the railway company focuses on providing compensation for delays, it must follow its economic balance. However, as the passengers' opinion survey showed, the negative impact of delays can be reduced by providing adequate information to passengers. Based on the passengers' opinion survey, it is necessary to consider the Regulation 1371/2007/ES as the minimum of the possible and on the basis of this reasoning to compile a compensation policy. The costs associated with compensation for the delay should be divided according to the causes of the delay among the individual culprits, so that railway undertakings bear the responsibility even for delays arising from reasons that are beyond the control of the railway undertaking itself.

 


Fenling Feng, Liuen Yang, Dan Lan
2013 (Vol 25), Issue 3
We investigate the synergetic nature and complexity of the railway freight system and select 13 parameters (railway fixed asset investment, GDP, railway’s revenue kilometers, etc.) as the system’s state variables. By using method of least square and method of external function, we build an order-parameter model for synergetic theory-based railway freight system, which will potentially support the studies on the railway freight system’s evolution. Our result shows that railway fixed asset investment is the order-parameter that governs the evolution of railway freight system: the average random fluctuation parameter  is 0.7060, which means that the mean fluctuation period of railway freight system is 9 years. Evolution of the railway freight system is a gradual process with abrupt changes from time to time.

Vladislav Krivda
2013 (Vol 25), Issue 3

The wrong behavior of the road traffic participants is a permanently discussed issue in many countries with advanced road transport. Such behavior doesn’t always result in traffic accident, but only in restriction or danger of the culprit or other participants. For monitoring the behavior problems we can for example use the video-analysis of the conflict situations.

The methodology of the conflict situations monitoring with the video-apparatus application is described in the paper presented. There are also results of the conflict situations analysis on the selected roundabouts in the Czech Republic.

The paper refers to suitability of the conflict situations video-analysis application not only for monitoring the wrong behavior of drivers and other participants of road traffic, but also for monitoring the inappropriately designed building elements (this hypothesis is confirmed by results of research, which are shown this article).


Veronique Van Acker, Begga Van Cauwenberge, Frank Witlox
2013 (Vol 25), Issue 3

There is need for better understanding of how mobility management interventions work and how they affect the individuals’ modal choice decisions, as well as need for robust evaluation techniques allowing any behavioural changes to be observed. Changing individual’s behaviour is not a one-step process and any evaluation methodology should account for this. A new standardized expert evaluation resource MaxSUMO takes this step-wise process into account. MaxSUMO is based on a new theoretical behavioural change model MaxSEM which measures individuals’ stage positions (their susceptibility to change behaviour) and stage movement (progression towards actual behavioural change). This paper illustrates the use of MaxSUMO by the evaluation of the mobility campaign “I keep moving, even without my car” undertaken by the City of Ghent.


Karel Greiner
2013 (Vol 25), Issue 2
The article describes a possibility of generating train calendar text for the needs of compiling the annual timetable in the conditions of the Czech Republic. Based on the analysis of the types of texts of calendars that appear in various print outputs, a heuristic algorithm was designed to generate a text from a set of calendar days. The algorithm is a part of an application that also provides a tool to define the text of the calendar by using a mask of sub-periods and calendars to be displayed in them. The algorithm was tested on real data of the timetable. In most cases, the algorithm shows the same or better results than the previously used tools. In several cases, however, a better result can be obtained by the user. The described algorithm to generate the text of the calendar is a part of a program that is used for compiling the timetable for trains in the Czech Republic.

Xin Wang, Hai-Jun Huang
2013 (Vol 25), Issue 2
For an elastic demand transportation network with continuously distributed value of time, the system disutility can be measured either in time units or in cost units. The user equilibrium model and the system optimization model are each formulated in two different criteria. The conditions required for making the system optimum link flow pattern equivalent to the user equilibrium link flow pattern are derived. Furthermore, a bi-objective model has been developed which minimizes simultaneously the system travel time and the system travel cost. The existence of a pricing scheme with anonymous link tolls which can decentralize a Pareto system optimum into the user equilibrium has been investigated.

Efendi Nasibov, Uğur Eliiyi, Mefharet Özkilçik Ertaç, Ümit Kuvvetli
2013 (Vol 25), Issue 2
The quality of public transportation services is one of the most important performance indicators of modern urban policies for both planning and implementation aspects. Therefore, along with the size of the city, the significance of appropriate cost evaluation and optimization of all related transportation activities increases as well. One of the most important cost factors for the public transport agencies is naturally the fuel consumption of the vehicles. In this study, the attention is focused on the metropolitan bus transport service. The specific aim is to minimize a significant portion of total fuel utilization that occurs due to the so called deadhead trip or dead mileage, which is defined as the idle distance covered by the vehicle between the garage and the route terminal stops without carrying any passengers. In this study, the results of four mathematical models for minimizing the total deadhead trip distance covered in city bus services of Izmir are presented. The models vary due to the inclusion of garage capacity restrictions or operator distinction for supporting both operational and strategical decisions. All models are applied to the recent bus schedule data, which consist of 293 routes, 1,424 buses and 10 garages, for obtaining the optimal route bus-garage allocations and garage capacities. The results of the Decentralized-Capacitated model, which is appropriate for quick implementation, promise a 7.8% reduction in total dead mileage. While on the other hand, if all garage capacities can be expanded and the bus service is maintained only by one operator as modelled in the Centralized-Uncapacitated case, even a 31.4% improvement is possible in the long term. The environmental gains as well as the financial benefits to be achieved when the solutions are actually implemented, justify the practical contribution of the study.

Marina Zanne, Aleš Groznik, Elen Twrdy
2013 (Vol 25), Issue 2
The probability that an individual will be involved in a car accident is relatively high. Traffic safety is a global problem, and Slovenia is no exception. Despite the large improvement in traffic safety records, Slovenia still ranks very low on the European level with 63 fatalities per million inhabitants. The paper analyses the official data on traffic accidents in Slovenia in the period from 1999 to 2011. The paper presents an overview of road safety in Slovenia with emphasis on the participation of young people in severe accidents. It has been examined whether young people in Slovenia are the most dangerous and at the same time the most vulnerable category of road users and the causes of road accidents involving young people have been compared with the causes of accidents involving overall population.

Slađana Janković, Snežana Mladenović, Krsto Lipovac, Dušan Mladenović, Slavko Vesković
2013 (Vol 25), Issue 2
One class of methods for black spots identification is based on the analysis of: traffic accidents (TA), road parameters, and traffic intensity. The data used in the analysis can be grouped into the information about: roads, persons participating in TA, vehicles participating in TA, traffic accidents and their consequences, and traffic. These categories of data are usually under the jurisdiction of different traffic and non-traffic subjects. Therefore, it is necessary to exchange traffic safety data among the following sources: traffic police, road manager, and health and judicial sector. This paper proposes a model for the exchange and integration of traffic safety data into a single database, which allows the calculation of risks for road sections, as well as the classification and ranking of the sections. The model is based on B2B integration of service-oriented applications. This paper describes a practical example that demonstrates the proposed integration model.

Tomislav Mihetec, Sanja Steiner, Denis Odić
2013 (Vol 25), Issue 2
With increasing air traffic demand in the Pan-European airspace there is a need for optimizing the use of the airspace structure (civilian and military) in a manner that would satisfy the requirements of civil and military users. In the area of Europe with the highest levels of air traffic (Core area) 32% of the volume of airspace above FL 195 is shared by both civil and military users. Until the introduction of the concept of flexible use of airspace, flexible airspace structures were 24 hours per day unavailable for commercial air transport. Flexible use of airspace concept provides a substantial level of dynamic airspace management by the usage of conditional routes. This paper analyses underutilization of resources, flexible airspace structures in the Pan-European airspace, especially in the south-eastern part of the traffic flows (East South Axis), reducing the efficiency of flight operations, as result of delegating the flexible structures to military users. Based on previous analysis, utilization model for flexible use of airspace is developed (scenarios) with defined airspace structure. The model is based on the temporal, vertical, and modular airspace sectorisation parameters in order to optimize flight efficiency. The presented model brings significant improvement in flight efficiency (in terms of reduced flight distance) for air carriers that planned to fly through the selected flexible airspace structure (LI_RST-49).

Tomas Apeltauer, Jiri Macur, Petr Holcner, Michal Radimsky
2013 (Vol 25), Issue 2
A necessary stage in the development of traffic models is model validation, where the developed model is verified by comparing its outputs with observed data. The most frequently used variables are average value of speed, flow intensity and flow density (during a selected period).It is possible to use these values for the calibration of macroscopic models, but one cannot always obtain a relevant microscopic dynamic model in this way. A typical use of the microsimulation models is the capacity assessment, where this sort of data (flow, speed and queues) is considered to be standard and sufficient. However microsimulation is also increasingly being used for other assessments (e.g. noise and emissions) where the correct representation of each vehicle’s acceleration and deceleration plays a crucial role. Another emerging area is the use of microsimulation to predict near-miss situations and conflicts to identify dangerous and accident prone locations. In such assessments the vehicle trajectory, distance from other vehicles as well as velocity and acceleration are very important.Additional source of data, which can be used to validate vehicle dynamics in microsimulation models, is the Global Positioning System (GPS) that is able to determine vehicle position with centimeter accuracy.In this article we discuss validation of selected microscopic traffic models, based on the comparison of simulated vehicle dynamics with observed dynamic characteristics of vehicles recorded by the precise geodetic GPS equipment.

Francisco Campuzano-Bolarín, Antonio Guillamón Frutos, Ma Del Carmen Ruiz Abellón, Andrej Lisec
2013 (Vol 25), Issue 2
The research of the Bullwhip effect has given rise to many papers, aimed at both analysing its causes and correcting it by means of various management strategies because it has been considered as one of the critical problems in a supply chain. This study is dealing with one of its principal causes, demand forecasting. Using different simulated demand patterns, alternative forecasting methods are proposed, that can reduce the Bullwhip effect in a supply chain in comparison to the traditional forecasting techniques (moving average, simple exponential smoothing, and ARMA processes). Our main findings show that kernel regression is a good alternative in order to improve important features in the supply chain, such as the Bullwhip, NSAmp, and FillRate.

Aliasghar Sadeghi, Esmaeel Ayati, Mohammadali Pirayesh Neghab
2013 (Vol 25), Issue 2
The aim of the present study is the representation of a method to identify and prioritize accident-prone sections (APSs) based upon efficiency concept to emphasize accidents with regard to traffic, geometric and environmental circumstances of road which can consider the interaction of accidents as well as their casual factors. This study incorporates the segmentation procedure into data envelopment analysis (DEA) technique which has no requirement of distribution function and special assumptions, unlike the regression models. A case study has been done on 144.4km length of Iran roads to describe the approach. Eleven accident-prone sections were identified among 154 sections obtained from the segmentation process and their prioritization was made based on the inefficiency values coming from DEA method. The comparisons demonstrated that the frequency and severity of accidents would not be only considered as the main factors for black-spots identification but proper rating can be possible by obtaining inefficiency values from this method for the road sections. This approach could applicably offer decision-making units for identifying accident-prone sections and their prioritizations. Also, it can be used to prioritize intersections, roundabouts or the total roads of the safety organization domain.

Borna Abramović
2013 (Vol 25), Issue 2

Ivan Markežić
2013 (Vol 25), Issue 2

Erdinç Öner
2013 (Vol 25), Issue 1
Cumulative interarrival time (IAT) distributions for signalized and non-signalized freeway entrance ramps were developed to be used in digital computer traffic simulation models. The data from four different non-signalized entrance ramps (three ramps with a single lane, one ramp with two lanes) and two different signalized entrance ramps (both with a single lane) were used for developing the cumulative IAT distributions. The cumulative IAT distributions for the signalized and non-signalized entrance ramps were compared with each other and with the cumulative IAT distributions of the lanes for freeways. The comparative results showed that the cumulative IAT distributions for non-signalized entrance ramps are very close to the leftmost lane of a 3-lane freeway where the maximum absolute difference between the cumulative IAT distribution of the leftmost lane of a 3-lane freeway and the entrance ramps cumulative IAT distribution was 3%. The cumulative IAT distribution for the signalized entrance ramps was found to be different from the non-signalized entrance ramp cumulative IAT distribution. The approximated cumulative IAT distributions for signalized and non-signalized entrance ramp traffic for any hourly traffic volume from a few vehicles/hour up to 2,500 vehicles/hour can be obtained at http://www.ohio.edu/orite/research/uitds.cfm.

Hualing Ren, Haoxiang Liu, Jiancheng Long, Ziyou Gao
2013 (Vol 25), Issue 1
This paper presents a proposal of novel signal design problem at isolated intersections, which assumes that the effective green times assigned to each signal phase follow dynamic user optimal (DUO) principle. At the DUO state, the average delays of vehicles using the signal phases with positive additional green times (the assigned effective green times minus the minimum effective green times) are equal and maximum. The proposed signal design problem is formulated as a variational inequality (VI) problem. The point queue (PQ) model is applied to represent traffic dynamics and to generate the cumulative traffic flows, which is further used to estimate the average delay of each signal phase. The existence of the solution of the proposed VI problem is proved and a solution algorithm based on the method of successive averages (MSA) is developed to solve the proposed signal design problem. Finally, a sample intersection is used to illustrate the application of the proposed model and the solution algorithm.

Yonggang Wang, Guomiao Xu, Han Bai
2013 (Vol 25), Issue 1
Geometric design consistency refers to the conformance of a proposed or existing freeway’s geometry with the driver’s expectancy. Considerable efforts have been undertaken to develop potential quantitative consistency measures and models to estimate them. However, little work has been focused on the facts of freeways in China, especially in mountainous areas. The primary objective of this study is to examine and quantify the design consistency of a freeway, using an interactive driving simulator, so as to identify any inconsistency on the roadway geometry and improve its overall safety performance. More specifically, the techniques to evaluate the consistency of a geometric design depend on three criteria: design consistency, operating speed consistency, and consistency in driving dynamics, as well as three levels of consistency: good, acceptable and poor. In the case of Taigan Freeway, a part of G45 Daguang Freeway in Jiangxi, China, a 21km long segment has been divided into 38 sections including 22 curves and 16 tangents, and transferred into the graphics models in the simulator system. There were 42 drivers required to take part in the simulation experiment and the speed, location of vehicle, and other real time data were recorded as well. The findings have shown that these proposed measures and standards can identify a geometric inconsistency more effectively when there is a large rate of change in the alignment elements for a successive roadway segment.

Vuk Bogdanović, Nenad Ruškić, Zoran Papić, Milan Simeunović
2013 (Vol 25), Issue 1
Vehicle acceleration is an important parameter used in planning various road elements, traffic signalization, geometric elements of an intersection, signal plans of traffic lights, etc. The knowledge of vehicle acceleration values is also necessary in using simulation softwares for more accurate analysis of the total situation at an intersection, on a road section or in a traffic network. In a lot of earlier studies, acceleration values were analysed and defined, mostly in optimal conditions for traffic functioning. However, values of almost all traffic flow parameters have been changed over time, due to changes in driving-dynamic vehicle characteristics, pneumatic tyres, material used for building road surface, etc. Besides, local environment influence and changes in drivers’ behaviour also significantly affect values of this parameter. According to HCM, it is advisable to perform local research for all values of the parameters recommended within the framework of this handbook, and to adapt their values to local conditions as well. The results of measuring the values of vehicles acceleration at signalized intersections in Novi Sad, Serbia, have been shown in this paper, using the procedure based on video recording processing.

António Luís Pimentel Vasconcelos, Álvaro Jorge Maia Seco, Ana Maria César Bastos Silva
2013 (Vol 25), Issue 1
The capacity analysis of roundabouts in Portugal is mostly done using the UK regression method. Due to its empirical and non-explanatory nature, this method has some limitations, particularly for studying innovative layouts, which has recently motivated research in Portugal into the use of capacity methods based on gap-acceptance theory. This paper describes the results of a related project: the estimation of critical headways and follow-up times at Portuguese roundabouts. For this study, gap-acceptance data were collected at six roundabouts, in two cities, and used to estimate the parameters at each entry, for the left and right entry lanes independently. Several estimation methods were used (Siegloch, Raff, Wu, Maximum Likelihood and Logit). The results have revealed important specificities of the methods that have significant effects on the results and therefore on the capacity estimate exercises. The comparison of the estimates with reference values from several countries indicates significant differences, suggesting the existence of relevant driving style differences, which implies that locally calibrated, country-specific, parameters are required for capacity calculations.

Darija Rugelj, Marija Tomšič, France Sevšek
2013 (Vol 25), Issue 1
Elderly people are the most vulnerable group in urban traffic and a large proportion of them are as pedestrians victims of traffic accidents. The majority of these happen while crossing the road. Crossing a busy road at an intersection with traffic lights or without them is a typical dual task condition requiring a motor task i.e. walking and a cognitive task such as monitoring traffic. The purpose of present study was to compare the walking speed and the related spatio-temporal gait variables of fallers and non-fallers in three walking conditions against the speeds required by regulations in Slovenia for safe street crossing. To assess the spatio-temporal characteristics of gait we used a 7m instrumented walkway.
The general results showed that the spatio-temporal gait parameters did not differ between the two groups at the self-selected speed. But as soon as a constraint, such as fast walking speed, was imposed on the subjects the differences between the groups became evident. Fallers demonstrated a significantly slower mean gait velocity and shorter stride length while the cadence and the base of support did not differ between the two groups. In dual task conditions the difference between the two groups reached 25 percent. The fallers group gait velocity dropped to 0.99 m/s. The observed walking speed was slower than considered by the guidelines for the design of traffic light equipped road crossing.
In conclusion, the results of walking speed under dual task conditions could be a useful parameter for planning of optimal pedestrian crossing in urban areas. These results will serve for the design of a population based study in Ljubljana.

Robert Rijavec, Jure Zakovšek, Tomaž Maher
2013 (Vol 25), Issue 1
There are different factors that affect driver’s behaviour at an urban signalized intersection. Complementary countdown signal heads can be used to inform the driver about the traffic light phase status. In the research presented in this paper, we explored how a countdown signal affects the driver’s reaction. We focused on the analysis of red/amber, red and amber running violations. We also observed and measured traffic flow start-up lost time and headway per cycle. Measurements took place in Ljubljana at a four-way intersection where two countdown signal heads are installed that face different directions. We used the “on-off-on” approach, using video surveillance and detection technology. According to the results of the investigative questionnaire, more than 84% of the surveyed drivers expressed positive opinion about the device. Analyses of field-test results have shown that the red and/or amber running violation rate is higher when the device is turned off. The results of the paper suggest that the countdown device had very little effect on the capacity of an urban signalized intersection.

Izabela Kotowska
2013 (Vol 25), Issue 1
The paper attempts to identify the social costs and benefits of marine container terminal operations regarding feeder vessels services. It presents a method of valuation which takes into account the external costs of additional factors: the nature and direction of the shipping lines operated by the terminals and the size of port hinterland. Based on the proposed method, the impact of container terminals to reduce the external costs of transport has been assessed.

Csongor Máthé, Erika Tamási, Géza Schubert
2013 (Vol 25), Issue 1
The present study focuses on the Central Development Region in Romania and attempts to highlight the deficiencies of the regional railway network, as well as to scientifically analyse the impact of new lines designed in the region. The current regional rail network is greatly determined by the historical development process of the railway, and therefore, in the first section, the most notable causes, milestones, and historical factors have been summarized. The goal of this paper has been to evaluate the current situation of the Central Region’s rail network and investigate the potential processes entailed by the line designed between Tîrgu Mureş and Sighişoara. For this, at first, some quantitative and qualitative analyses as well, including traffic and travel speed measurements have been carried out. Finally, using the analysis capabilities offered by the application of graph theory, we had the opportunity to perform a simulation with the planned rail line. Our conclusion is that the improvement of the Tîrgu Mureş rail accessibility toward Braşov could be considered as a real option, especially, as in the near feature, the motorway connection between these two important Transylvanian cities will be built, which will represent a huge challenge for the rail transport on this axis.

Published by
University of Zagreb, Faculty of Transport and Traffic Sciences
Online ISSN
1848-4069
Print ISSN
0353-532
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