Claudio Roncoli

Feedback-Based Mainstream Traffic Flow Control for Multiple Bottlenecks on Motorways

Mainstream traffic flow control (MTFC) enabled via variable speed limits (VSLs) has been investigated in previous studies, utilizing various control strategies. In this paper, an extended feedback control strategy is proposed for MTFC enabled via VSLs, considering multiple-bottleneck locations. Feedback-based results are compared with optimal control results for the evaluation of the controller using a validated macroscopic model. The performance of the feedback controller is shown to approach the optimal control results, despite the fact that many practical and safety restrictions are additionally considered by the feedback controller.

Optimal control for multi-lane motorways in presence of vehicle automation and communication systems

Abstract The presence and exploitation of Vehicle Automation and Communication Systems (VACS) while defining optimal control strategies in motorway traffic flow control is addressed in this paper. VACS are supposed to act both as sensors (providing information on traffic conditions) and as actuators, allowing the application of ramp metering, variable speed limit control, and lane changing control. A quadratic programming problem is defined on the basis of a novel first-order traffic flow model for multi-lane motorways. An example is presented in order to illustrate the effectiveness of the proposed optimisation problem.

Model predictive control for multi-lane motorways in presence of VACS

A widespread use of vehicle automation and communication systems (VACS) is expected in the next years. This may lead to improvements in traffic management because of the augmented possibilities of using VACS both as sensors and as actuators. To achieve this, appropriate studies, developing potential control strategies to exploit the VACS availability, are essential. This paper describes a model predictive control framework that can be used for the integrated and coordinated control of a motorway system, considering that vehicles are equipped with specific VACS. Microscopic simulation testing demonstrates the effectiveness and the computational feasibility of the proposed approach.

An overview of a multiagent-based simulation system for dynamic management of risk related to Dangerous Goods Transport

Transportation engineering, and especially of Dangerous Goods (DG), is one of the areas in which technological development is crucial. Logistic control systems, routing and scheduling algorithms, supply chain management have been applied in this aspect so as to improve the cost-effectiveness ratio and to reduce risks. Unfortunately, most of these works remain theoretical since tests on real case scenario sometimes proves difficult to achieve especially when we are dealing with Dangerous Goods Transport (DGT). In this paper, an architecture of a visual DGT simulation system has been introduced. It provides entries for testing these works and produces results close to real experiments. Applications on serious games, financial market, engineering are evidence of success of the visual simulation system. Thus, the challenge consists on how to design a system that represents real-world systems with an appropriate degree of complexity and dynamics. Several researchers have already suggested solutions since the 50s. These solutions have been classified in three levels: microscopic, mesoscopic and macroscopic simulation. It has been decided to use a microscopic approach using an agent-based model. It allows the representation of systems at different levels of complexity, a System of Systems (SoS), through the use of autonomous, goal-driven and interacting entities. The system is implemented using the software MATSim (http://www.matsim.org/). The main actors of the system stand for the DG Carriers Operator (CO) agent that manages a fleet of DG Carriers agents, taking logistic decisions on their behalf. The COs collaborate with the National Authority (NA), which is an agent concerned by the safety shipment of goods at regional and national level. The paper focus on the Multi-Agent System (MAS) architecture and introduces its key components as well as the means on interaction.

A Risk-Based System of Systems Approach to Control the Transport Flows of Dangerous Goods by Road

A risk-based approach to control dangerous goods (DG) transport flows by roads is proposed, solving a real-time flow assignment problem. The model takes into account the planned scheduling of the DG fleets. The objective is to readapt the schedule in real time, controlling the DG flow to minimize both the risk on the network and the gap between the proposed modified delivery and the planned one. The innovative aspect of the proposed approach is to balance the social objective of a national authority, thus minimizing the risk on the road infrastructures, with the economical objective of the DG distribution companies that have to minimize the actual time, as defined by the planned deliveries. The proposed DG transport model is defined according to a system of systems view. Each subsystem (SS) represents either a regional area or, more commonly, a segment of a road. The proposed approach provides a useful tool for evaluating the optimal speed for DG vehicles in each SS and the optimal amount of DG flow that should transit from one SS to another, following the planned delivery schedule. The problem has been tackled in two different formulations. First, a nonlinear mathematical programming formulation is defined. Then, according to simplifying assumptions, the problem is solved as a discrete-time finite horizon linear quadratic optimal control problem with a state feedback control. An exemplificative case study is used to show a comparison between the two formulations, as well as the effects of a risk sudden change in the overall DG routing.

Use of Speed Measurements for Highway Traffic State Estimation

This paper presents two case studies in which a macroscopic model-based approach for the estimation of traffic conditions, which the authors have recently developed, is employed and tested. The estimation method is developed for a mixed traffic scenario, in which traffic is composed of both ordinary and connected vehicles. Only average speed measurements, which may be obtained from connected vehicle reports, and a minimal number (sufficient to guarantee observability) of spot sensor–based total flow measurements are utilized. In the first case study, NGSIM microscopic data are used to test the capability of estimating traffic conditions on the basis of aggregated information retrieved from moving vehicles and considering various penetration rates of connected vehicles. In the second case study, a longer highway stretch with internal congestion is utilized to test the capability of the proposed estimation scheme to produce appropriate estimates for varying traffic conditions on long stretches. In both cases, the performances are satisfactory and the obtained results demonstrate the effectiveness of the method in both qualitative and quantitative terms.

Freeway Traffic Management in Presence of Vehicle Automation and Communication Systems (VACS)

During the last decade, there has been a significant effort to develop a variety of Vehicle Automation and Communication Systems (VACS). These are expected to revolutionise the features and capabilities of individual vehicles within the next decades. The introduction of VACS brings along the (sometimes ignored) necessity and continuously growing opportunities for accordingly adapted or utterly new Traffic Management (TM) actions and strategies. This calls for a new era of freeway TM research and practice, which is indispensable in order to accompany, complement and exploit the evolving VACS deployment. Specifically, the development of new traffic flow modelling and control approaches should become a priority in the years to come.

Real-time risk definition in the transport of dangerous goods by road

The definition of risk in the transport of dangerous goods is an open issue. No international standard is currently defined. In addition, the definition of risk is directly related to the possibility to its control at decisional level, for example, by rerouting the traffic. In this work, a proposal to define risk at strategic, tactical, operational and realtime level is proposed. A system of systems vision of the definition at operational/realtime level is particularly promising of research aspects both from a SoSE and a technological viewpoint.

Lane-Changing Feedback Control for Efficient Lane Assignment at Motorway Bottlenecks

A feedback control strategy is proposed for lane assignment at bottleneck locations. The strategy assumes that some vehicles equipped with vehicle automation and communication systems are capable of receiving and executing specific lane-changing orders or recommendations. From a previously proposed optimal control strategy based on a simplified multilane motorway traffic flow model and formulated as a linear quadratic regulator, a feedback control problem was designed. The aim was to maximize the throughput at bottleneck locations while distributing the total density at the bottleneck area over the lanes according to a given policy by optimal lane assignment of the vehicles upstream of the bottleneck. The feedback control decisions were based on real-time measurements of the traffic state and inflow. The proposed strategy was tested on a nonlinear first-order macroscopic multilane traffic flow model, which also accounted for the capacity drop phenomenon.

Feedback-Based Integrated Motorway Traffic Flow Control With Delay Balancing

The development and deployment of simple, yet efficient, coordinated and integrated control tools for motorway traffic control remains a challenge. A generic integrated feedback-based motorway traffic flow control concept is proposed in this paper. It is based on the combination and suitable extension of control algorithms and tools proposed or deployed in other studies, such as ramp metering or variable speed limit (VSL)-enabled cascade-feedback mainstream traffic flow control, and allows for consideration of multiple bottlenecks. The new controller enables coordination of ramp metering actions at a series of on-ramps, as well as integration with VSL control actions, toward a common control goal, which is bottleneck throughput maximization. While doing this, the approach considers a pre-specified (desired) balancing of the incurred delays upstream of the employed actuators, via a suitably designed knapsack problem. Despite the multitude of the offered configurations, options, and possibilities, the generic control algorithm remains simple, efficient, and suitable for field implementation. The control algorithm is demonstrated and evaluated using a validated macroscopic traffic flow model for a number of scenarios.