1,721,031 research outputs found
Equity measures for the identification of public transport needs
No full textThe present paper deals with the identification of the PT needs taking into account not only effectiveness and efficiency of the PT services but also equity issues. The PT needs refer to the identification of the possible spatial development of corridors, connecting areas of the urban agglomeration, in which there is the need of upgrading the overall performance of the PT services. The main novelties of the paper concern with the determination of the zones with a low “quality” of PT supply and the assessment of priorities and areas of upgrading of the PT system, so supporting the transport planning decisions. This paper focuses on measuring the equity in terms of “quality” of PT system using a new approach based on the computation of the GINI index and the Lorenz curve. In this context, the equity is related with the fair allocation of transport resources. The procedure proposed has been applied in a real-size context of the city of Rome. The case study shows promising results about the robustness of the proposed approach from the methodological point of view and the capability to assess effective measures in a real context. The results of the validation phase of the methodology and the results of the different phases of zone classification underline the strength of the choices made to represent the quality of public transport services and the GINI index approach. Specifically, taking into account the results by the point of view of equity, the GINI index shows a changes of about 7%, that is a promising result considering the few zones selected for the identification of public transport needs
Assessing the impact of Autonomous Vehicles on urban noise pollution
Full text linkThis paper presents the results of a noise emission study of Autonomous Vehicles (AVs) and their impact on the road network. By comparing the current situation with a future hypothetical scenario (100% AVs penetration), this study highlights the positive effect, in terms of noise pollution, of the adoption of AVs on a real road network (city of Rome). For this scope, a traffic simulation-based approach was used to investigate the effects of AVs on the network congestion. Results show that the full AVs penetration scenario leads to an improvement in the network performances in terms of travel time and average network speed. Moreover, the amount of Vehicle Kilometre Travelled (VKT) shows an 8% increase on longer extra-urban routes, due to the higher capacity impact of AVs on highways, with a consequent load reduction for intra-urban shortcutting routes. These results are also reflected in terms of noise emission. In fact, the central area would benefit from lower noise emission, whereas an increase in traffic volume and speed lead to worsened conditions for some specific highway links of the network. Overall, it was shown that a 100% AVs fleet would have a beneficial effect for the noise pollution, leading to a general reduction of noise emissions, which is more pronounced for intra-urban roads
The value of en-route information on the accessibility to concurrent transit system services
No full textMotorway Traffic Emissions Estimation through Stochastic Fundamental Diagram
No full textTravel time, or, more generally, level of service, has always been considered the main parameter with which to design roads, particularly in extra-urban areas where geometries and policies, such as speed limits, play a key role in the performance achieved. Unfortunately, this type of approach does not consider the impact on emissions that is obtained when only performance-based goals are pursued. The paper deals with the analysis of the impact on emissions and fuel consumption under different traffic conditions, and we present a new methodology for emission estimation based on the stochastic formulation of the fundamental diagram in a highway environment. The proposed methodology estimates the emissions using a stochastic adaptation of the CORINAIR methodology based on COPERT software on both specific vehicle types and the average Italian vehicle fleet. As expected, due to the convexity of the emission function, accounting for speed dispersion leads to an increase in energy consumption and emissions. Tests show that the stochastic component can lead to an increase in the emission estimation up to 5.5% and, therefore, it should be considered. The methodology has been applied by means of real trajectories, and the results of the application show that performance optimization strategies can contrast with sustainability and emission reduction policies. Results show that for some vehicular classes, emissions or fuel consumption are highly dependent on speed, with different proportionalities. In all cases, the minimum consumption is obtained at speeds ranging from 70 to 90 km/h. The analysis of the curves shows that an increase in speeds, even to reach low speeds, generally leads to an increase in energy consumption and emissions per kilometer traveled and, therefore, is independent of the decrease in travel time
Applying UAVs for indoor emergency risk evaluation
No full textThis study deals with the adoption of UAVs in the case of indoor fires. UAVs map the indoor space before the rescue team arrival in order to minimize the risk of exposure to firefighters, maximize the effectiveness of their intervention and provide information to the evacuees. We develop a framework in which first we compute the drone trajectory that minimizes the number of sacrificed detection points; next, we derive the value of risk associated with each monitored point, evaluated through the main dangerous products of a fire (i.e. smoke, temperature and carbon monoxide). After that, we match the pedestrian path with the environment risk analysis and finally, the lowest risk pedestrian paths are generated both for evacuees and rescue operators, respectively toward the exits and the ignition point(s). Preliminary results are shown for a real-case indoor space, simulated using a synthetic environment generator
Integrated Variable Speed Limits and User Information Strategy
No full textThis paper deals with the study of variable speed limits (VSLs) for traffic control and their integration with user information strategies. As few studies have addressed the integrated VSL and user information strategy, we focus on comparing the adoption of the latter with the VSL alone strategy application and the no-control case, highlighting the benefits the integration brings. The integrated strategy is able to smooth the severity of congestion, shifting its occurrence in a section of the mainstream mostly suited to vehicle accumulation. An application on a real network is carried out. The traffic congestion conditions along the real highway are simulated by means of Dynameq simulation software and the METANET macroscopic model. The VSLs are applied in a control area aiming to evaluate the potential and the limitations of the strategy on a real network as well as the integration of variable speed limits and user information strategies. Two different cases of road congestion caused by the presence of on-ramps are studied. Results show that the integration of the two strategies leads to a redistribution of flows, achieving a reduction in the total travel time spent in the network and an increase in the traveled distances, i.e., reducing the overall network time despite the increase in assigned flows. However, an integrated strategy requires adequate transportation supply and mainly crossing demand
Integration between activity-based demand models and multimodal assignment: Some empirical evidences
No full textAiming at supporting decision makers in transport policy choices, transport models used for decades the trip-based approach for travel demand forecasts. This approach, despite suited to peak hours modelling where systematic trips are predominant, suffers the limits of not being related to the sequence of activities usually undertaken in real day-life. Differently, in the Activity Based Models (ABM) the travel demand is explicitly modelled as the result of individuals’ involvement in different activities in different times and locations. The use of such models is recommended when complex trip chains connected to the multiple daily activities that characterise today's life have to be taken into account, even if the integration with other sub-models (particularly with the assignment) within the whole transport modelling procedure has to be carefully considered. For this reason, this paper focuses on the integration between ABM and transport assignment by investigating the multimodal demand-supply interaction. Specifically, the consistency between ABM and assignment models is studied proposing a methodology that can be applied to large real size networks. It is based on a multimodal static equilibrium assignment, which is easy-to-use and less time consuming with respect to a Dynamic Traffic Assignment (DTA), allowing a better estimation of the modal splits between alternative transport modes. Such a model also considers (road) congestion and (transit) crowding phenomena, as well as the multimodal network performances are estimated by taking into account the interaction between different modes sharing the same network facilities. The goodness of the proposed approach is investigated through the convergence analysis of both the entire integration procedure and its individual components (ABM and assignment) for a better transport simulation in urban areas. The application to an urban multimodal network of real-size dimensions (Rome) is presented to show the promising results of this research
Traffic demand estimation using path information from Bluetooth data
No full textRecent advances in technology have made available numerous new monitoring systems that collect updated traffic measurements both in fixed locations and over specific corridors or paths. Such recent technological developments point to challenging and promising opportunities for Origin-Destination (OD) traffic demand estimation and forecast. Therefore, the aim of this paper is to study how to exploit available information detected by new monitoring devices in the estimation of traffic demand. Starting from the formulation proposed by Spiess (1987, 1990), in this paper a new method to estimate the traffic demand by means of Bluetooth data is proposed. It explores inherent properties of this information in an off-line (and static) context, where mathematical formulation of the estimation problem can be derived. The effectiveness of the proposed method has been investigated in an extensive plan of experiments carried out both on test networks and on a study network consisting in a part of the city of Rome, Italy, obtaining promising results in both application
Case studies of integration between activity-based demand models and multimodal assignment
No full textAiming at supporting decision makers in transport policy choices in an increasingly complex sequence of activities of our real day-life, this paper investigates the integration between Activity Based Model (ABM) and transport assignment by focusing on the multimodal demand-supply interaction to be used in more advanced simulation models. The consistency between ABM and assignment models is studied proposing a methodology that can be applied to large real size networks. A new formalization of integration of ABM with multimodal assignment is proposed, oriented to an easy-to-use and computationally faster application. The interaction between different modes sharing the same network facilities is considered, as well as crowding (public transport) and congestion (road) phenomena. The application to different real case studies in Qatar and in Rome are presented to show the promising results of the proposed approach for a better transport simulation in urban areas
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