Neila Bhouri

An agent-based computational approach for urban traffic regulation

This paper proposes a bimodal urban traffic control strategy based on a multi-agent model. We call bimodal traffic, a traffic which takes into account both private vehicles and public vehicles such as buses. The objective of this research is to improve global traffic, to reduce bus delays and to improve bus regularity in congested areas of the network. In our agent-based approach, traffic regulation is obtained thanks to communication, collaboration and negotiation between heterogeneous agents. An important feature of our system is that it allows regulation at two levels: macroscopic and microscopic levels. To model in depth regulation procedures, we have introduced special features such as priority levels for buses, computation and update of traffic signal plans, urgency index of intersection stages depending on the level of congestion on the arcs. We have tested our strategy on a small network of six intersections, using the JADE platform. The simulation is described and preliminary results are presented. They show that our MAS strategy improves bus travel time while improving also private vehicles’ travel time, decreases bus delays and improves its regularity compared to a classical strategy called fixed-time control strategy.

Effectiveness of travel time reliability indicators in the light of the assessment of dynamic managed lane strategy

ABSTRACT The aim of traffic management is to ensure a high quality of service for a maximum number of users by decreasing congestion and increasing safety. Uncertainty of travel times decreases the quality of service and leads end users to modify their plans regardless of the average travel time. Indicators describing travel time reliability are being developed and should be used in the future both for the optimization and for the assessment of active traffic management operations. This article discusses the efficiency of certain reliability indicators in an ex-post assessment of a traffic management strategy. Ex-post assessment is based on an observational before–after study. As some factors other than the studied management strategy may intervene between the two periods, and as most reliability indicators require knowledge of the full travel time distribution and not only its average, a methodology is developed for the identification of the impact of these exogenous factors on the whole distribution. Many reliability indicators are split into different parts allowing the identification of the part due to the management strategy impact. The methodology is tested numerically on a managed lane operation consisting of Hard Shoulder Running (HSR) at rush hour on a section of a French motorway. The variation of some reliability indicators appears misleading, whereas the splitting of the indicators increases our understanding of the strategy and highlights its impact. The paper gives the reliability assessment of the HSR field test and discusses different reliability indicators to identify their potential performances and shortcomings.

Development of Coordinated Ramp-Metering Based on Multi-objective Nonlinear Optimization Functions: Traffic and Safety

This paper is focused on the extension of the OASIS (Optimal Advanced System for Integrated Strategies) in order to take into account the multi-objective nonlinear optimization technique for coordinated ramp metering. The multi-objective function includes two costs functions: traffic and safety (Risk model) indices. OASIS is revisited and off-line simulation studies are conducted on real test site corresponding to A6W France motorway located in the south part of “Ile de France” Motorway networks. Five consecutive on-ramps are considered for the control. The obtained results are very promising.

Power and Exponential Functions Relating Accidents to Traffic and Rain. Calibration on a French Network

Relations between the occurrence of road accidents, traffic and rainfall conditions are valuable in setting safety objectives for traffic management, and in assessing the safety impacts of new traffic management systems, prior to their implementation. Based on traffic, road accidents and rain data collected over one year, on a French urban motorway network, a set of safety performance functions were estimated; each of them provides the accident risk per vehicle-kilometer for a certain type of accident, according to the occurrence of rain, and to the level of a traffic variable (average speed, occupancy, percentage of tailgating…). Analyses were carried out separately by lane and for two types of accidents: single-vehicle accidents and multiple-vehicle accidents. The relationships, although statistically significant, have yet to be validated by the treatment of another set of accidents.

A simulation-based model for dynamic traffic assignment on guided vehicles

This article presents a simulation-based model to dynamic assignment of guided vehicles over a parallel network. The simulation was constructed while following a routing game model and has been implemented on the multiagent simulation platform JADE. The model follows an integrated assignment simulation framework which assigns guided vehicles, that communicate with a coordinator agent related to the infrastructure, on the network in order to minimize the total travel time of each vehicle while keeping the network in an equilibrated or near-equilibrated state.