1,721,089 research outputs found
Traffic Modeling of a Cooperative Charge While Driving System in a Freight Transport Scenario
Full text linkThe aim of this paper is to present a research study on a traffic model developed for analysing the performance of the wireless inductive systems for charging while driving (CWD) fully electric vehicles (FEVs) from both traffic and energy points of view. The design assumptions of the developed traffic model are aimed to simulate in particular a freight distribution service in a fully cooperative traffic environment. In this case, the CWD service could be used to guarantee the minimum state of charge (SOC) of the batteries at the arrival to the depot that allows the vehicles to shortly start with further activities. In this way, the fleet manager could avoid wasting time for the stationary recharge, thus increasing the level of service of the freight distribution. The CWD system is applied to a multilane ring road with several intermediate on-ramp entrances, where the slowest lane is reserved for the charging activities, when authorized vehicles are present. A specific traffic model has been developed and implemented adopting a mesoscopic approach, where vehicle energy needs and charging opportunities affect drivers' behavior. Overtaking maneuvers, as well as new entries in the CWD lane of vehicles which need to charge, have been modeled by taking into account a fully cooperative driving system among vehicles which manages an adequate gap between consecutive vehicles. Finally, a speed control strategy in which vehicles can be delayed to create an empty time-space slot in the CWD lane, is simulated at a defined node. This type of control, though is simulated to allow extraordinary maintenance operations, which may require a free charging zone for a given time slot, could also be applied to support merging maneuvers for on ramp vehicle
Simulation of railroad terminal operations and traffic control strategies in critical scenarios
Full text linkRailroad terminals contribute to the competitiveness of intermodal transport and play an important role in the transport chain to achieve seamless cross-modal processes, because they must guarantee a fast, safe, and efficient transfer of intermodal loading units. The equipment required, such as gantry and mobile cranes can be critical to the terminal process. However, numerous cranes cannot be designated to guarantee a high level of redundancy, because of their relevant cost.
This paper presents a micro-simulation approach for evaluating the resilience of typical railroad terminals in a critical scenario, such as the temporary unavailability of a gantry crane. Resilience can be defined as the capability of the system to recover its functionality despite a disruption and a gating strategy is proposed in this case to maintain the desired level of service inside the terminal. Therefore, this traffic control strategy is investigated to ascertain its ability in enhancing the terminal resilience when a disruption occurs in a process.
The proposed simulation method is not only used for performing a typical sensitivity analysis under disturbed conditions, but also for assessing the flexibility of the simulated terminal. A comparison is performed for a baseline traffic scenario in equilibrium conditions by setting equal average values for the arrival and service rates, thereby exploring the operation of the infrastructure near its capacity.
In the simulation tool, the relevant features of the typical phases of the internal process are represented, and the traffic flow data of truck arrivals are disaggregated based on specific operations using dedicated service lines. To compare the modeled scenarios, some quantitative key performance indicators (KPIs) are selected and quantified in terms of quality and energy impacts
Safety systems and vehicle generations: Analysis of accident and travel data collected using event data recorders
Full text linkThe current paper proposes a data analysis method to evaluate the impact of vehicle-technology evolution on road safety based on a recent and extensive accident dataset (1.3 million vehicles in 2017 and 1.7 million in 2018, Italy). Seventeen models of vehicles equipped with an event data recorder were selected for acquiring data, including the distances travelled by the vehicles during the year, and were aggregated by their year of initial registration and model. This unique information in conjunction with the accident datasets enabled a consistent estimation of risk exposure and accident rates for various subsets of vehicles. Thereafter, the comparative analysis of accident rates revealed an improvement in the road safety along with a significant variation between various vehicle models that approximately ranged from 5–10 accidents per million kilometres. Moreover, the accident rate reduced after the electronic stability control system was mandated for vehicles in the market, exhibiting variations in the range of 15–30% for serious accidents that were dependent on the vehicle model. Further safety improvements were identified for the latest generation of vehicles equipped with more advanced technologies such as the autonomous emergency braking that can reduce the accident rate up to 38%
Evaluation of a reactive dynamic route guidance strategy
No full textThe aim of the paper is to evaluate the performance of a new strategy which is able to control dynamic route guidance (DRG) systems, mainly in urban road networks. The purpose of this strategy is to achieve dynamic user equilibrium in the network, even in abnormal network conditions, for example when there is an unexpected increase in traffic volume. It is based on feedback concept and it reacts to the traffic conditions observed in real time by adopting a decentralized structure. A series of experiments was performed, by means of a traffic micro-simulator, in a section of an urban road network. In the situations examined, the results seem to be quite positive. The analyses of the link level show that all of the various travel alternatives to reach the destination become more advantageous for users if DRG devices become more widespread among vehicles. In some cases we observe that the strategy succeeds in maintaining the possible alternatives in equilibrium conditions, by distributing users among the feasible turns. At no point in our investigations do we observe an unstable behaviour of the system, even when the number of vehicles fitted with a DRG device increases
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