1,720,963 research outputs found
A calculation code for the air pollution valuation produced by duty vehicle moving in an urban area
No full textScientific research that started three years ago and was first developed in a Ph.D., has resulted in important results in producing a calculation code in “Excel” that values the main pollutant emissions (CO, NOx, VOC and PM) produced by duty vehicles moving in an urban area. Emissions were obtained by studying data about the main geometrical and flow features of transport network in the area covered. Two mathematical models were integrated in the developed code, a flow and an emission model respectively. The flow simulation model determines, after a calibration according to the particular urban area in examination, the average vehicular speed on a single homogeneus branch of a road network. So, when the average speed is fixed, it is possible to calculate the polluting emissions through the definition of an opportune emission model integrated in the code. The emission model is based on the CORINAIR methodology, implemented in the COPERT III program (COmputer Programme to calculate Emissions from Road Transport) that, where necessary, has been modified according to experimental results, without distorting its basic philosophy. In conclusion, the calculation code allows for making choices in the transport fields considering environmental sustainabilityy aspects in the urban planning analysis, and it represents a good decision support system (DSS)
Optimization of Dynamic Ridesharing Systems
No full textInternet-enabled technologies are becoming more widespread; users are constantly connected to the network in every place and daily activity. Access to transportation-related features—mobile payment systems, Global Positioning System connections, real-time public transit timetables or traffic congestion information, and so on—is easy. This access results in new ways to plan mobility. In the innovative mobility systems implemented and developed with these technologies, the new real-time capabilities of dynamic ridesharing, an extended version of traditional ridesharing, can play a key role if the relevant performance is improved. In other words, although ridesharing is not a new idea, recent technological advances should increase its popularity. In this paper, a proposed ridesharing system considers the interactions between drivers or riders and the system manager and the interactions between drivers and riders. The positions and speeds of the shared vehicles and the traffic flows in which such vehicles travel are omitted. To optimize the performance of the ridesharing system, a discrete event, dynamic pickup and delivery model that represents the considered dynamics and an optimal matching problem that optimally allocates an empty seat in a vehicle to a rider are proposed. The dynamic model represents the behavior of the ridesharing system and computes the relevant performance; the optimization problem finds the best match and path in the considered transportation network to minimize the difference between the desired departure and arrival times. In this paper, after the introduction of the ridesharing model, the discussion of the solution to the optimal matching problem, a simulation model is described. A real world case study is then presented and discussed
OPTIMIZING DYNAMIC RIDE-SHARING SYSTEMS
No full textInternet-enabled technologies are becoming more and more used, so that users are constantly connected to the network in every place and daily activity, and can use transportation related features, such as mobile payment systems and GPS connections, or receive real-time information on public transport timetable, traffic congestion, and so on, being then able to plan their mobility at the best.
In this framework, in effect, among the innovative mobility systems implemented and developed using these technologies, the new real-time capabilities of dynamic ride-sharing, which is an extended version of the traditional ride-sharing, can play a key role if the relevant performances are improved. In other words, although ride-sharing is not a new idea, recent technological advances should increase its popularity.
In this paper, a ride-sharing system is proposed whose dynamic behavior consists of two levels: the first, disaggregate level takes into account the positions and speeds of all the drivers’ vehicles, as well as the dynamics of the traffic flows in which such vehicles “move”; the second level only considers the interactions of drivers/riders with the system manager, and the interactions between drivers and riders. Then, with the aim of optimizing the performances of the above introduced RS system only the second kind of dynamics is considered, designing a pick-up and delivery optimization model able to allocate an empty seat in a vehicle to a rider through an optimal matching problem is proposed also providing, at a time, the expected performances of the system for each user.
In particular, the optimization problem finds the best match and path in the considered transportation network that minimize the difference between the desired departure and arrival times, also providing, by means of suitably defined auxiliary variables, the generalized costs of each trip.
The paper is organized as follows. First the ride-sharing model is introduced. Then, after the statement of the optimal matching problem and the discussion on its solution and integration with modal choice models, a simulation model is described. Finally, a real-world based case study is presented and discussed
Sensitivity Analysis of Different Supply Design Alternatives: Experimental Results
No full textAbstractThe continuous increase in traffic has put into evidence the need of research and investments in more effective solutions. In this framework, the design of any transportation infrastructure or service is in general performed assuming to know the present mobility demand and to be able to forecast the future one with the best accuracy as possible.The main aim of this paper is the definition of a suitable criterion, based on a Global Sensitivity Analysis of an a-priori chosen transportation performance index, which helps in resource planning and in decision-making. In the end, the proposed methodology is evaluated by means of a real world case study in Italy
Measuring the quality of port hinterland accessibility: The Ligurian case
No full textTraditionally, distance was considered the parameter that could better reflect the economic influence of a
seaport on land. Containerisation and intermodality progressively eroded such a paradigm and currently
distance becameonly one of the factors across the overall ‘‘equation’’. In this respect, a fundamental role is
played by the effectiveness of inland connections. The better the connection of a port to the various inland
markets, the bigger the potential to enlarge its overall captive area. Furthermore, the higher the ‘‘frictions’’
(bottlenecks, delays, etc.) for reaching the hinterland, the lower the inland traffic flows.
The major purpose of the paper is to measure container traffic diversion from Ligurian ports (Genoa, La
Spezia and Savona) to the main Italian and European competitors.
The application of a gravitymodel will reveal the current role of distance in drawing hinterlandmarket
share among the selected ports. Moreover, for evaluating the unexploited potentialities of Ligurian ports,
we compared real traffic flows with the outcomes of a spatial interaction model, reassigning inland
container flows to the different sampled ports. The calculation of the traffic delta through a gap analysis,
allowed measuring the ‘‘frictions’’ thwarting the connectivity between the Ligurian ports and the sampled
hinterland regions. Finally, the paper discusses the nature and the reasons for the above traffic diversion
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