Neeraj Saxena

Deployment and Calibration Considerations for Large-Scale Regional Dynamic Traffic Assignment: Case Study for Sydney, Australia

Dynamic traffic assignment (DTA) has received increasing attention in recent years, and there are numerous examples of practical implementations. This work adds to the literature by describing the ongoing experience of building the first large-scale simulation-based DTA model in Australia. The input data for the model are summarized, and an in-depth discussion and an analysis of model output and the calibration process are presented. Current results put 80% of the 322 calibration points spread across the network within an acceptable bound of error, but the project found that alternative metrics of network performance also must be considered so that other aspects of model realism are not neglected. The described DTA model could be used for evaluating important policy decisions and infrastructural development in the context of the macro- and mesoscale network operation. Additionally, this project is a proof of concept for the Australian region and may provide insight to practitioners interested in emerging areas of transport planning and traffic modeling.

Effect of number of stop-&-gos experienced on the route choice behaviour of car drivers

ABSTRACT Stop-&-go (S&G) waves are prevalent in congested traffic conditions and are characterised by cyclic patterns of forced deceleration followed by acceleration. These waves lead to an escalated level of frustration among drivers which further influences their physiological characteristics. This study tests the hypothesis that an increase in the number of S&Gs on a route increases its disutility for the driver. A stated choice experiment was designed to study the route choice behaviour of participants who drive regularly by car. A random parameter error component logit model is used to evaluate the willingness to pay (WTP) measures among the presented attributes. Results show a statistically significant WTP measure for the trade-off between travel time and the number of S&Gs. This study expands the literature on the route choice behaviour of drivers to aid the decision-making of transportation planners, in particular on problems relating to network design, management, operation and planning.

Consistency Between Convergence of Dynamic Assignment and Stochasticity of Microsimulation: Implication for Number of Runs

Dynamic transportation models route vehicles by using the principles of dynamic user equilibrium. These models include a dynamic network loading (DNL) module that is used to evaluate link costs. However, an element of stochasticity creeps into the modeling framework when the analytical dynamic assignment (DA) procedure is used along with a stochastic microscopic DNL. A methodologically correct way of approaching this problem is by solving the entire DA with a microscopic DNL (DA-microDNL) model until convergence for a given random seed and then repeating the process with different seed values. This paper proposes an approach to determine the minimum number of replications of the DA-microDNL model to determine a statistically valid estimate of the measure of effectiveness (MOE). The approach was tested on a small and medium-size network having different demand and network characteristics. Results show that running the integrated DA-microDNL framework for a minimum number of replications provides a statistically significant MOE at much lower computation time. The consistent estimates obtained by using this approach would provide robust information to transportation planners and practitioners in evaluating the impacts of several policy decisions on network performance.

Evaluating the Perception Index for Cyclists’ Safety Using Structural Equation Modelling

Transportation authorities across the globe are encouraging people to take up cycling for their daily activities. Even though individuals are aware about the advantages of cycling, there are a few barriers, which restrict them to use bicycles for their everyday commute. One of them, is the risk of getting hit from the rear by a motor vehicle travelling in the same direction. This study proposes a measure called perception index towards cyclist safety (PICS), to represent the level of insecurity among individual road users travelling on a corridor. A structural equation modeling framework is applied to express the perception index towards cyclist safety in terms of observed variables like road, road user, and environmental characteristics. This value is further used to predict an individual specific behavior and a preferred minimum overtaking distance. The contribution of this study is towards providing traffic planners, with a tool to forecast the reasonable minimum overtaking distance, based on the observed data that serves both safe cycling and smooth traffic conditions.

Large-Scale Dynamic Traffic Assignment: Practical Lessons from an Application in Sydney, Australia

Traditional static traffic assignment models no longer meet the strategic planning needs of most major metropolitan areas, especially in regard to evaluating major infrastructure projects. One promising possibility is dynamic traffic assignment (DTA), which has been receiving greater attention in the research community for the last ten years. This work describes the ongoing experience of building the first large-scale DTA model in Australia. We divide our experiences into categories regarding data, implementation, and visualization, and we discuss the challenges faced as well as our methods for overcoming those challenges. Finally, we discuss initial model results and the calibration process. In the future, the DTA model described here could aid in evaluating important policy decisions and infrastructural development in the context of the macro/meso-scale network operation. This project serves as a proof of concept for the Australia region and may provide valuable insight to other practitioners interested in emerging areas of transport planning and traffic modeling.