Traffic Operations and Management

Proposed Asymmetric Microscopic Traffic Flow Theory

Skabardonis, Alexander
Yeo, Hwasoo
Transportation Research Board
2009

The paper presents a microscopic asymmetric traffic flow theory based on detailed analysis of individual vehicle trajectories from the Next-Generation Simulation (NGSIM) database. The findings clearly show the asymmetry in vehicle’s acceleration and deceleration and define five traffic phases: free flow, acceleration, deceleration, coasting, and stationary. The proposed theory provides detailed description and mechanism of phase transitions. Extensions of the basic theory address common driver behavioral characteristics such as maneuvering error and anticipation. The application of the...

Quantification of Weather Influences on Freeway Bottlenecks

Seeherman, Joshua
Skabardonis, Alexander
Transportation Research Board
2013

Weather is a major source of non-recurring delay on freeways within the United States. How weather affects areas of daily recurring delay, particularly freeway bottlenecks, has not been thoroughly researched. A type of freeway bottleneck in the form of a lane drop was studied across two winters at a site of daily recurring congestion. This bottleneck was located in Pittsburg, California. Queue discharge flow was compared between rainy days and clear days either one week before or after the rainy event. Discharge flows during rainy events dropped by an average of 11% and this difference was...

Progression Through a Series of Intersections with Traffic Actuated Controllers. Volume 2: User's Guide. Final Report

Skabardonis, A
Deakin, Harvey, Skabardonis, Incorporated
Federal Highway Administration
1988

Many traffic control systems on urban arterials and grid networks include signals with actuated controllers. However, commonly used computer programs for signal timing cannot directly optimize the timing of coordinated signals. Users have to apply techniques designed for pretimed signals, and then "translate" the optimized pretimed settings into settings for the actuated controllers. In addition, other signal control choices, such as whether to operate a particular signal as pretimed, semi-actuated, or fully actuated, are left entirely to the user. This report is a user's guide for...

Proof of Concept for the Trajectory-Level Validation Framework for Traffic Simulation Models

Xyntarakis, Michalis
Alexiadis, Vassili
Punzo, Vincenzo
Campbell, Robert
Skabardonis, Alex
Flanigan, Erin
Cambridge Systematics
Purdue University
Indiana Department of Transportation
Federal Highway Administration
Department of Transportation
2017

Based on current practices, traffic simulation models are calibrated and validated using macroscopic measures such as 15-minute averages of traffic counts or average point-to-point travel times. For an emerging number of applications, including connected vehicles, the realism of simulated driver dynamics at the second-by-second or subsecond trajectory level plays an important role. This report presents a Proof of Concept Application (PCA) for the Trajectory Level Validation Framework, which is presented in a separate report. The structure of this document parallels that of the Validation...

Progression Through a Series of Intersections with Traffic Actuated Controllers. Volume 1: Technical Report. Final Report

Skabardonis, A
Deakin, Harvey, Skabardonis, Incorporated
Federal Highway Administration
1988

Many traffic control systems on urban arterials and grid networks include signals with actuated controllers. However, commonly used computer programs for signal timing cannot directly optimize the timing of coordinated signals. Users have to apply techniques designed for pretimed signals, and then "translate" the optimized pretimed settings into settings for the actuated controllers. In addition, other signal control choices, such as whether to operate a particular signal as pretimed, semi-actuated, or fully actuated, are left entirely to the user. This report describes the development of...

Prediction of Arrival Profiles and Queue Lengths Along Signalized Arterials by Using a Markov Decision Process

Geroliminis, Nikolas
Skabardonis, Alexander
2005

An analytical methodology for prediction of the platoon arrival profiles and queue length along signalized arterials is proposed. Traffic between successive traffic signals is modeled as a two-step Markov decision process (MDP). Traffic dynamics are modeled with the use of the kinematic wave theory. The MDP formulation allows prediction of the arrival profiles several signals downstream from a known starting flow. This modeling approach can be used to estimate queue lengths and predict travel times, even in cases in which data from loop detectors are unknown, inaccurate, or aggregated. The...

Predicting Lane-by-Lane Flows and Speeds for Freeway Segments

Sasahara, Fabio
Staichak Carvalho, Luan Guilherme
Chowdhury, Tanay Datta
Jerome, Zachary
Elefteriadou, Lily
Skabardonis, Alexander
2020

The Highway Capacity Manual is a major reference for evaluating the capacity and quality of service of road facilities. However, it holds the assumption that lanes perform equally, which can result in inaccuracies in performance estimation. The main purpose of this research is to develop a series of models for estimating flows and speeds by lane for various types of freeway segments, including basic, merge, and diverge types. These models consider the demand-to-capacity ratio, the presence of trucks, grade, and the presence of upstream and downstream ramps. To predict lane performance...

Predicting Air Quality Effects of Traffic-Flow Improvements: Final Report and User's Guide

Dowling, R
Ireson, R
Skabardonis, A
Gillen, D
Stopher, P
Transportation Research Board
Dowling Associates Incorporated
2005

This report contains a user's guide and case studies, providing a recommended methodology to predict the long- and short-term mobile source emission impacts of traffic-flow improvement projects. Guidance is provided to evaluate the magnitude, scale, and duration of such impacts for a variety of representative urbanized areas.

Predicting the Impacts of Intelligent Transportation Systems on Freeway Queue Discharge Flow Variability

Dowling, Richard G
Skabardonis, Alexander
Reinke, David B
2008

This study focuses on the problem of measuring the queue discharge flow rates for a nonbottleneck freeway section and on developing an approach for estimating the impacts of intelligent transportation system (ITS) measures on the mean and variance of the queue discharge flow rate. The whole-year mean and variance of the queue discharge flow rates for the subject section of freeway are computed on the basis of measured 5-min congested flow rates over the course of a year. The flow data are categorized into congested and uncongested flows on the basis of a speed threshold that separates...

Person-Based Traffic Signal Optimization for Real-Time Applications

Christofa, Eleni
Papamichail, Ioannis
Skabardonis, Alexander
Transportation Research Board
2012

This paper presents a person-based traffic responsive signal control system for transit signal priority on conflicting transit routes. A mixed integer nonlinear program is formulated that minimizes the total person delay at the intersection while assigning priority to the transit vehicles based on their passenger occupancy. The mathematical formulation consists of an improvement to previous formulations in that it ensures global optimality for undersaturated traffic conditions in reasonable computational time for real-time applications. The system has been tested at a complex signalized...