Articles
Vol. 25 No. 6 (2013)
Published on 16.12.2013
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.
Borna Abramović
2013 (Vol 25), Issue 6
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.
