Results 1 - 10 of 255
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[en] Reliable pavement prediction models are needed for pavement management systems (PMS), as they are a key component to forecast future conditions of the pavement and to prioritize maintenance, rehabilitation and reconstruction strategies. The International Roughness Index (IRI) is the most used parameter worldwide for calibrating pavement roughness and measures reasonably the ride comfort perceived by occupants of passenger cars. The Regional Government of Biscay also collects this value on the road network under its control These surveys are carried out regularly in the XXI century. Several IRI performance models have been proposed by different authors and administrations, varying greatly in their comprehensiveness, the ability to predict performance with accurancy and input data requirements. The aim of this paper is to develop a roughness performance model for Biscay's roads, based on availablbe IRI data, taking into account heavy traffic volume and the age of pavement. Local characteristics as climate conditions and average rainfall are not considered. IRI performance models have been suggested for regional two lane highways with low and medium heavy traffic constructed in the last 20 years in the province of Biscay, with no treatments during their life. They can be applied for flexible pavements, but no logical coherent results have been concluded for semi-rigid pavements. (Author)
[en] This paper presents a methodology for the dynamic estimation of traffic flows on all links of a network from observable field data assuming the first-in-first-out (FIFO) hypothesis. The traffic flow intensities recorded at the exit of the scanned links are propagated to obtain the flow waves on unscanned links. For that, the model calculates the flow-cost functions through information registered with the plate scanning technique. The model also responds to the concern about the parameter quality of flow-cost functions to replicate the real traffic flow behaviour. It includes a new algorithm for the adjustment of the parameter values to link characteristics when its quality is questionable. For that, it is necessary the a priori study of the location of the scanning devices to identify all path flows and to measure travel times in all links. A synthetic network is used to illustrate the proposed method and to prove its usefulness and feasibility. (Author)
[en] In this paper, we study the effect of moving bottlenecks on traffic flow. The full velocity difference (FVD) model is extended to the traffic flow on a two-lane highway, and new lane changing rule is proposed to reproduce the vehicular lane changing behavior. Using this model, we derive the fundamental current—density diagrams for the traffic flow with the effect of moving bottleneck. Moreover, typical time—space diagram for a two-lane highway shows the formation and dissipation of a moving bottleneck. Results demonstrate that the effect of moving bottleneck enlarges with the increase of traffic density, but the effect can be reduced by increasing the maximum velocity of heavy truck. The effects of multiple moving bottlenecks under different conditions are investigated. The effect becomes more remarkable when the coupling effect of multiple moving bottlenecks occurs. (interdisciplinary physics and related areas of science and technology)
[en] In this paper it is used the experimental design to minimize the travel time of motor vehicles, in one of the most important avenues of Celaya City in Guanajuato, Mexico, by means of optimal synchronization of existing traffic lights. In the optimization process three factors are considered: the traffic lights’ cycle times, the synchrony defined as stepped, parallel and actual, and speed limit, each one with 3 evaluation levels. The response variables to consider are: motor vehicles’ travel time, fuel consumption and greenhouse effect gas (CO2) emissions. The different experiments are performed using the simulation model developed in the PTV-VISSIM software, which represents the vehicle traffic system. The obtained results for the different proposed scenarios allow to find proper levels at which the vehicle traffic system must be operated in order to improve mobility, to reduce contamination rates and decrease the fuel consumption for the different motor vehicles that use the avenue. (Author)
[en] Road signs constitute a complex and growing communication system where different elements (pictograms, shapes, texts, etc.) are combined following different strategies. In this paper we have confronted drivers with a number of messages (congestion or road works, before, between, after location/s) developed as an adaptation of Advance Location Signs (class G, 1c in the 1968 Convention) to electronic displays. We manipulate two main factors a) the reading strategy (top-down vs. bottom-up) and the type of matrix display (hybrid, dissociating pictogram and text, vs. full matrix), in a repeated measures experimental design. The time taken to answer and the response given (correct, incorrect) was measured for each of the 24 message-blocks. Results show that the organization of the elements displayed is a key determinant for driver comprehension. Further thoughts on the need to understand the interplay between the formats adopted by static vs electronic message signs are provided. (Author)
[en] In our days we face a fundamental issue concerning road signs. We may display contents in vertical and horizontal format (static signs, variable message signs, road markings), either on a post, a gantry or a dashboard. And we foresee a coming age where the excellent matrix resolution of painted signs will be truly approached by the resolution of full matrix displays. But we also risk a babel context threatening the universal approach encouraged by international catalogues as the 1968 Convention (ECE/TRANS/196, 2007). And the fundamental risk comes from our decisions regarding how the transition from the contents and formats displayed on static message signs to the ones displayed on electronic signs (in gantries or dashboards) should be. Our work explores this issue specifically, considering the transition from Advance Direction Signs (static message signs, class G, 1 in the 1968 Convention) to what could be termed Advance Location Signs (signs concerning the location of variable events with regards to certain landmarks) developed as an adaptation of the G, 1 class to electronic traffic signs.(Author)
[en] In general terms good geometric design means providing an adequate level of mobility and appropriate land use access for the function of the roadway while maintaining high degree of safety for all roadway users. One of the most suitable techniques used to improve safety on roads is to check the consistency of geometric design. In this study, continuous real speed (operating speed) data was collected using a vehicle equipped with VBox (a GPS based device) along the selected test sections. Three test sections were selected along two-lane, two-way old alignment N-5 (Kotri- Thatta Section). The speed profiles, resulting from continuous tracking of vehicle, make it possible to measure true operating speed and detailed information of driver's behaviour such as the speed variation and maximum and minimum speed, along the tangents on selected test sections of existing old alignment. The model was developed for prediction of operating speed on tangents. Cross validation was carried out to compare predicted values with observed values. The validation of developed models shows the compatibility with the trend of experimental data. Hence the developed model can be used to predict operating speed on tangents along two-lane, two-way old alignment in Pakistan. (author )
[en] This study investigated the effect of odour on multisensory environmental evaluations of road traffic. The study aimed to answer: (1) Does odour have any effect on evaluations on noise, landscape and the overall environment? (2) How different are participants' responses to odour stimuli and are these differences influential on the evaluations? Experimental scenarios varied in three Traffic levels, three Tree screening conditions and two Odour presence conditions were designed, and presented to participants in virtual reality. Perceived Loudness, Noise Annoyance, Landscape Quality and Overall Pleasantness of each scenario were evaluated and the results were analysed. It shows that Odour presence did not have significant main effect on any of the evaluations, but has significant interactions with Traffic level on Noise Annoyance and with Tree screening on Landscape Quality, indicating the potential of odour to modulate noise and visual landscape perceptions in specific environmental content. Concerning participants' responses to odour stimuli, large differences were found in this study. However, the differences did not seem to be influential on environmental evaluations in this study. Larger samples of participants may benefit this study for more significant results of odour effect.
[en] The ideal value of the traffic stream that can pass through an intersection is known as the saturation flow rate per hour on vehicle green time. The saturation flow is important in the understanding of the traffic light cycle and from there the understanding the Level of Service. The paper wishes to evaluate through a series of applied mathematical methods the effect of different lane grouping and critical lane group concept on the saturation flow rate. The importance of this method is that it creates a base for a signalized intersections timing plan. (Author)
[en] The system of mixture of single lane and double lane is studied by a cellular automata model, which is developed by us based on the Nagel and Schreckenberg's models. We justify that the model can reach a stable states quickly. The density distributions of the stable state is presented for several cases, which illustrate the manner of the congestion. The relationship between the outflow rate and the total number of vehicles and that between the outflow rate and the density just before the bottleneck are both given. Comparing with the relationship that occurring in the granular flow, we conclude that the transition from the free traffic flow to the congested traffic flow can also be attributed to the abrupt variation through unstable flow state, which can naturally explain the discontinuities and the complex time variation behavior observed in the traffic flow experiments.