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Promet - Traffic&Transportation journal

Accelerating Discoveries in Traffic Science

Accelerating Discoveries in Traffic Science

Articles

Vol. 29 No. 2 (2017)
Published on 19.04.2017

Srđan Vujičić, Đani Mohović, Robert Mohović
2017 (Vol 29), Issue 2

The main objective of this paper proposes the model for the decision-making process with the intent of optimising the collision avoidance in the crossing situation on the open sea. Using the IMO Resolution standards for ship manoeuvrability, along with the equation for determining the required distance of the closest point of approach (CPA) and other parameters for own ship and the target ship, it can be possible to determine the distance at which to start alternation and collision avoidance. The research results that involved ship officers and captains with the aim of determining the Closest Point of Approach (CPA) showed a very subjective assessment method. The presented model obtained by the simulation method to determine the CPA between ships on the open sea is the key finding of this research and leaves room for further research and its further implementation on unmanned ships.


Doris Novak
2017 (Vol 29), Issue 2

Zongzhi Li, Hoang Dao, Harshingar Patel, Yi Liu, Bei Zhou
2017 (Vol 29), Issue 2

Traffic control and safety hardware such as traffic signs, lighting, signals, pavement markings, guardrails, barriers, and crash cushions form an important and inseparable part of highway infrastructure affecting safety performance. Significant progress has been made in recent decades to develop safety performance functions and crash modification factors for site-specific crash predictions. However, the existing models and methods lack rigorous treatments of safety impacts of time-deteriorating conditions of traffic control and safety hardware. This study introduces a refined method for computing the Safety Index (SI) as a means of crash predictions for a highway segment that incorporates traffic control and safety hardware performance functions into the analysis. The proposed method is applied in a computation experiment using five-year data on nearly two hundred rural and urban highway segments. The root-mean square error (RMSE), Chi-square, Spearman’s rank correlation, and Mann-Whitney U tests are employed for validation.


Goran Zovak, Goran Kos, Boris Huzjan
2017 (Vol 29), Issue 2

The paper presents the current research related to the speed of traffic flow on the roads of high serviceability. It analyses the speed of vehicle as one of the main causes of traffic accidents. A flat four-lane motorway section, motorway section in the tunnel and a city bypass section were chosen for this research, and several speed limit scenarios for the vehicles have been applied with the aid of variable signalling. The survey results show that few vehicles respect the speed limits in traffic in the case of a straight section of motorway or city stretch of the motorway which has good geometric elements; however, speed limits are exceptionally well respected in tunnels. Although a large number of drivers do not respect the signs, a certain group of drivers can be influenced by variable signs of limitations, and thus positive changes can be achieved in traffic flow which will result in increasing the traffic safety on the motorways. Thus, increasing the degree of respect for speed limits on the motorways directly affects the increase in the level of traffic safety. It is necessary to influence the group of drivers who do not respect the speed limits with other measures, including repressive ones.


Rongrong Fu, Shutao Wang, Shiwei Wang
2017 (Vol 29), Issue 2
The purpose of this paper was to develop a real-time alarm monitoring system that can detect the fatigue driving state through wireless communication. The drivers’ electroencephalogram (EEG) signals were recorded from occipital electrodes. Seven EEG rhythms with different frequency bands as gamma, hbeta, beta, sigma, alpha, theta and delta waves were extracted. They were simultaneously assessed using relative operating characteristic (ROC) curves and grey relational analysis to select one as the fatigue feature. The research results showed that the performance of theta wave was the best one. Therefore, theta wave was used as fatigue feature in the following alarm device. The real-time alarm monitoring system based on the result has been developed, once the threshold was settled by using the data of the first ten minutes driving period. The developed system can detect driver fatigue and give alarm to indicate the onset of fatigue automatically.

Ana Trpković, Marina Milenković, Milan Vujanić, Branimir Stanić, Draženko Glavić
2017 (Vol 29), Issue 2
The population of elderly people is rapidly growing and in terms of safety, senior pedestrians represent one of the most vulnerable group. The pedestrian crossing speed is a significant input parameter in traffic engineering, which can have effect on pedestrians’ safety, especially of older population. The objective of this study was to determine the value of the crossing speed of elderly pedestrians (65+) for different types of urban crossings. The research was conducted at ten intersections in the city of Belgrade, Serbia, using the method of direct observation and a questionnaire for collecting data. The data were analysed in the statistical software package IBM SPSS Statistics. The results showed that elderly pedestrians walk slower and the crossing type significantly influenced the speed of older population. The order of crossing types in relation to the measured speed is ranked as follows, from the lowest to the highest speed value: unsignalized, signalized, signalized with pedestrian countdown display, signalized with pedestrian island and pedestrian countdown display and finally signalized crossing with pedestrian island. According to the questionnaire results, the elderly recognize the importance of implementing pedestrian counters. This indicates the necessity to provide safe street crossing for the elderly using the corresponding engineering measures.

Laura Eboli, Giuseppe Guido, Gabriella Mazzulla, Giuseppe Pungillo, Riccardo Pungillo
2017 (Vol 29), Issue 2
Speed has been identified for a long time as a key risk factor in road traffic: inappropriate speeds contribute to a relevant part of traffic accidents. Many literature studies have focused on the relationship between speed and accident risk. Starting from this consideration this paper investigates traffic accident risk by analysing the travelling speeds recorded by real tests on the road. A survey was conducted to collect experimental speed values in a real context. A specific road segment, belonging to an Italian rural two-lane road, was repeatedly run by 27 drivers in order to collect the instantaneous speed values for each trajectory. Smartphone-equipped vehicles were used to record continuous speed data. The recorded data were used to calculate: the average speed, 50th and 85th percentile speed for each geometric element of the analysed road segment. The main result of the research is the classification of car users’ driving behaviour based on the speed values. By using the above mentioned ranges of speed, the classification provides three types of driving behaviour: safe, unsafe, and safe but potentially dangerous. It was found that only four drivers feature “safe” behaviour, driving in a safe manner on most of the road elements. However, the major part of drivers, even if they feature safe behaviour, could be dangerous for other drivers because they drive at very low speeds.

Geran-Marko Miletić, Slaven Gašparović, Tonči Carić
2017 (Vol 29), Issue 2

Starting from the fact that the transport mode choice is one of those aspects of travel behaviour that, to a great extent, affects the efficiency of the transport system, this paper analyses the factors that contribute to the use of public and car transport. The goals of the analysis were to obtain insight into the preferences for using these two modes of transport in Croatia and find out to which extent the basic demographic and socioeconomic characteristics of the respondents affect the usage of car and public transport and the possibility of taking trips by these transport modes. The paper analyses the data collected by surveys on a representative national sample. The results show that in Croatia, the number of people who frequently use public transport is far fewer than the number of frequent users of passenger car transport. However, the comparison has found that the number of frequent public transport users varies significantly among certain categories of respondents. Using binary logistic regression analysis has determined that the preferences towards the frequent use of car or public transport are significantly influenced by the age of the respondents, size of the settlement, accessibility of the destinations by public transport, the number of vehicles in the household and whether the respondent is the main car user in the household.


Serđo Kos, Luka Vukić, David Brčić
2017 (Vol 29), Issue 2

The proposed paper discusses multimodal container transport due to savings in external costs. Relevant data have been analysed by reviewing previous research and published works for making a synthesis of one’s own conclusions. The research findings showed that there is no significant difference in the share of external costs of container transport and transport of other types of cargo in great European seaports as well as in energy consumption of multimodal rail-inland ship container transport and the same transport mode of bulk cargo. Intermodal terminals have also their own external costs. In spite of a double railway operational cost, it is important to include the railway in the intermodal terminal. The inland waterway transport has much higher external costs than sea transport. Multimodal container transport does not necessarily lower external costs. The savings are more common if the location and type of intermodal terminal are selected properly, and the sea transportation is involved in the multimodal transport chain.


Chunbo Zhang, Xiucheng Guo, Zhenping Xi
2017 (Vol 29), Issue 2
Due to unbalanced speed-density observations, the one-regime traffic fundamental diagram and speed-density relationship models using least square method (LSM) cannot reflect actual conditions under congested/jam traffic. In that case, it is inevitable to adopt the weighted least square method (WLSM). This paper used freeway Georgia State Route 400 observation data and proposed 5 weight determination methods except the LSM to analyse 5 wellknown one-regime speed-density models to determine the best calibrating models. The results indicated that different one-regime speed-density models have different best calibrating models, for Greenberg, it was possible to find a specific weight using LSM, which is similar for Underwood and Northwestern Models, but different for that one known as 3PL model. An interesting case is the Newell's Model which fits well with two distinct calibration weights. This paper can make contribution to calibrating a more precise traffic fundamental diagram.

Habibollah Nassiri, Sara Tabatabaie, Sina Sahebi
2017 (Vol 29), Issue 2

Due to their different sizes and operational characteristics, vehicles other than passenger cars have a different influence on traffic operations especially at intersections. The passenger car equivalent (PCE) is the parameter that shows how many passenger cars must be substituted for a specific heavy vehicle to represent its influence on traffic operation. PCE is commonly estimated using headway-based methods that consider the excess headway utilized by heavy vehicles. In this research, the PCE was estimated based on the delay parameter at three signalized intersections in Tehran, Iran. The data collected were traffic volume, travel time for each movement, signalization, and geometric design information. These data were analysed and three different models, one for each intersection, were constructed and calibrated using TRAF-NETSIM simulation software for unsaturated traffic conditions. PCE was estimated under different scenarios and the number of approach movements at each intersection. The results showed that for approaches with only one movement, PCE varies from 1.1 to 1.65. Similarly, for approaches with two and three movements, the PCE varies from 1.07 to 1.99 and from 0.76 to 3.6, respectively. In addition, a general model was developed for predicting PCE for intersections with all of the movements considered. The results obtained from this model showed that the average PCE of 1.5 is similar to the value recommended by the HCM (Highway Capacity Manual) 1985. However, the predicted PCE value of 1.9 for saturated threshold is closer to the PCE value of 2 which was recommended by the HCM 2000 and HCM 2010.


Leonardo Jesus Valdivia, Gonzalo Solas, Javier Añorga, Saioa Arrizabalaga, Iñigo Adin, Jaizki Mendizabal
2017 (Vol 29), Issue 2

It is necessary to verify the faults tolerance of the European Train Control System (ETCS) on-board unit even if these faults are uncommon. Traditional test methods defined and used in ETCS do not allow to check this, so it is necessary to develop a new mechanism of tests. This paper presents the design and implementation of a saboteur applied to the railway sector. The main purpose of the saboteur is the fault injection in the communication interfaces. By means of a virtual laboratory it is possible to simulate actual train journeys to test the ETCS on-board unit. Making use of the saboteurs and the virtual laboratory it is possible to analyse the behaviour of the train in the presence of unexpected faults, and to verify that the decisions taken are correct to ensure the required safety level. Therefore, this work shows a testing strategy based on different kinds of train journeys when faults are injected, and the analysis of the results.


Jiangfeng Wang, Chang Gao, Zhouyuan Zhu, Xuedong Yan
2017 (Vol 29), Issue 2
Considering the impact of drivers’ psychology and behaviour, a multi-lane changing model coupling driving intention and inclination is proposed by introducing two quantitative indices of intention: strength of lane changing and risk factor. According to the psychological and behavioural characteristics of aggressive drivers and conservative drivers, the safety conditions for lane changing are designed respectively. The numerical simulations show that the proposed model is suitable for describing the traffic flow with frequent lane changing, which is more consistent with the driving behaviour of drivers in China. Compared with symmetric two-lane cellular automata (STCA) model, the proposed model can improve the average speed of vehicles by 1.04% under different traffic demands when aggressive drivers are in a higher proportion (the threshold of risk factor is 0.4). When the risk factor increases, the average speed shows the polarization phenomenon with the average speed slowing down in big traffic demand. The proposed model can reflect the relationship among density, flow, and speed, and the risk factor has a significant impact on density and flow.


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