sshao45 – Georgia Transportation Institute

18-23

Title and Subtitle:

Development of Tools to Model Driver Behavior in a Cooperative and Driverless Vehicle Mixed Roadway Environment

Lead PI:

Michael Hunter

Lead Affiliate:

Georgia Institute of Technology

Co Pi:

Angshuman Guin (Georgia Institute of Technology)

Abstract:

Promising advances in autonomous vehicle (AV) technology have fueled industry and research fields to dedicate significant efforts to the study of the integration of AVs into the traffic network. While most studies anticipate a beneficial role of AVs, contributing to improved traffic efficiency and roadway safety, the underlying assumptions on the interactions between AVs and human-driven vehicles (HDVs) are often cooperative in nature. The first portion of this study investigates the impact of aggressive human-driven vehicles’ (AHDVs) merging behaviors on traffic performance in a mixed environment that includes three vehicle types: AVs, HDVs, and AHDVs. This study is undertaken in an open-source microscopic traffic simulation model, Simulation of Urban Mobility (SUMO). AHDVs have been modeled in this study to show aggressive merging behaviors at a merge section of a freeway exit ramp by targeting the farthest reachable AV for lane change as well as forcing a merge immediately in front of the AV. Results show that the travel-time gains achieved by AHDVs were at the expense of AVs and HDVs, and the interaction of aggressive HDVs with cooperative AVs could negatively impact overall capacity. The second portion of this study developed an Excel-based tool exploring the impact of AVs on departure capacity from a signalized intersection. Through both portions of this study, it was seen that critical indicators of the impact of AVs on traffic performance are: (1) Is a rise in aggressive interactions witnessed? (2) What are the headways being adopted by AVs? And (3) What are the spacing and maximum-length platooning characteristics?

NTL Report:

GDOT RP 18-23

18-02

Title and Subtitle:

Impact on Construction Loads on Steel Diaphragm Bridge Design

Lead PI:

Lauren Stewart

Lead Affiliate:

Georgia Institute of Technology

Co Pi:

Lawrence Kahn (Georgia Institute of Technology); Yang Wang (Georgia Institute of Technology); Nadine Fahed (Georgia Institute of Technology)

Abstract:

Bridges are critical structures, serving an important function that is vital to the safe and economical conveyance of people and goods throughout Georgia. They are designed with specifications to carry loads including their self-weight and a design vehicle load, among others, when they are in service. Satisfying all design specifications is crucial to the structure’s strength, stiffness, stability, and durability throughout its lifetime. In addition to the in-service dead and live load conditions, bridges are also designed to accommodate various loading conditions during the construction process. In some cases, these construction load and associated stability requirements are the governing load conditions for some of the bridges’ components. Georgia Department of Transportation (GDOT) has recently allowed the substitution of steel diaphragms for concrete diaphragms in its bridges. This substitution is gaining popularity among contractors for its ease of construction and subsequent reduction of cost. Currently, there is no standardized design for GDOT steel diaphragms, and contractors are allowed to produce their own designs based on loading scenarios currently specified in the 2018 GDOT Bridge and Structures Design Manual. These scenarios include full long-term wind loadings and are thought to be overly conservative because the actual loads to which the bridges are subjected during the construction process are poorly understood. This project seeks to provide the data and recommendations for a more efficient, yet safe, steel diaphragm design. Specifically, this project will (1) observe and measure GDOT construction practices through visual observations by experts and by electronic sensors, (2) quantify the effects of the construction practices in terms of loadings via observations and computational models, (3) assess the overall impact of construction load variations on bridge designs, and (4) make recommendations to GDOT for loading specifications and for a standardized steel diaphragm design.

NTL Report:

GDOT RP 18-02

18-01

Title and Subtitle:

Development of GDOT Ultra-High Performance Concrete for Bridge Deck Closure Pours

Lead PI:

Lauren Stewart

Lead Affiliate:

Georgia Institute of Technology

Co Pi:

Lawrence Kahn (Georgia Institute of Technology); Kimberly Kurtis (Georgia Institute of Technology); Giovanni Loreto (Georgia Institute of Technology)

Abstract:

The use of precast prestressed girders with composite precast deck panels along with the use of precast prestressed deck bulb-T girders provide for more economical bridges because of their ability to utilize accelerated bridge construction techniques. The use of concrete deck panels and deck bulb-T systems require the use of closure pours between the units. Ductal™, a proprietary ultra-high performance concrete (UHPC), has been shown to provide an outstanding link between deck segments for closure pours as narrow as 6-in, but Ductal is expensive. This research develops a concrete based on locally available materials (GDOT-UHPC), which has a direct tensile strength greater than 750 psi and ductility and toughness under tensile loads such that the concrete can develop the tensile yield stress of #5 (⅝-in. diameter) reinforcing bars within a 5-in. embedment length. Minimizing the width of the closure between deck and bulb-T units provides further economies by greatly simplifying formwork and eliminating shoring. Testing assured not only the short development length of reinforcement but also ultimate strength capacity of transverse and longitudinal closure pours. Further, best practices for formwork, closure design, UHPC mixing and placement, and quality assessment are considered.

NTL Report:

GDOT RP 18-01

ESTIMATED IMPACT OF GDOT’S HIGHWAY EXPENDITURES ON EMPLOYMENT, INCOME, AND TOTAL VALUE ADDED IN HIGHWAY DISTRICTS, LOCAL AREAS, AND THE STATE OF GEORGIA: 2009-2013

Project Description:

Well-designed transportation investments have many short-term and long-term economic benefits. They can spur economic growth, create jobs, boost labor productivity and profitability, increase efficiency and accelerate local and regional economic development. Given the anemic job growth in the US economy today, and the growing fiscal constraints imposed on public agencies, policy makers and stakeholders are increasingly demanding that impacts of infrastructure investments be quantified. This would allow scarce resources to be allocated more efficiently and effectively.

This study measures the impact of GDOT’s highway expenditures on economic activity in the State of Georgia. The study examines impacts at three levels (1) Statewide impacts; (2) Impacts within GDOT Highway Districts; and (3) County impacts. The timeframe of the analysis is January 2009 through May 2013. During this period, GDOT spent $3.6 billion on highway projects. Each project expenditure had a ripple effect on economic activity in local areas.

Posters:

GRTA/GDOT REAL-TIME TRACKING AND CHOICE DATA

Project Description:

The primary goals of this project are: 1) to demonstrate the capabilities of smart phone systems to provide more reliable freeway and arterial travel time data than currently provided by VDS spot speed measurements, and 2) to facilitate the monitoring and analysis of real-time HOT corridor and GRTA Express Bus performance data. Georgia Tech researchers will first integrate the existing Commute Warrior and Commute Viewer systems with the Flash-based data interface developed for the HOV-to-HOT monitoring project so that second-by-second travel data collected in the project can be reviewed by researchers. The team will then recruit 80 regular HOT corridor users, including express bus riders, HOT lane users, and drivers who regularly use the general purpose lanes. The team will deploy the Commute Warrior application on the Android Smart Phones of the volunteers to collect second-by-second vehicle activity data as the volunteers use the HOT corridor and major arterials. The team will compare monitored second-by-second corridor traverse travel times with travel time estimates derived from VDS spot speed data. The team will assess the potential benefits of more widespread deployment of the Commute Warrior App throughout the region. The team will also conduct focus groups with participants to gather information regarding the potential impacts of real-time data on their use of HOT lane and express bus services.

Posters:

Project Information Forms:

January 2012

VIABILITY OF CONCRETE PERFORMANCE-BASED SPECIFICATIONS FOR GEORGIA DOT PROJECTS

Project Description:

To (1) review best practices for development and implementation of performance-based specifications for concrete structures; (2) compare initial and long-term costs associated with prescriptive and performance-based designs; and (3) generate guidelines for applying performance-based specifications.

Posters:

Assessment of Type IL Cements for Transportation Applications (September 2013)

ASSESSMENT OF SAND QUALITY ON CONCRETE PERFORMANCE: EXAMINATION OF ACIDIC AND SULFATE/SULFIDE-BEARING SANDS

Project Description:

Project Objective: To evaluate early age properties, strength development; and durability of several sand sources to make recommendations for GDOT concrete aggregate specifications.

Posters:

Assessment of Sand Quality on Concrete Performance: Examination of Acidic and Sulfate/Sulfide-Bearing Sands (September 2013)

ASSESSMENT OF CRACK DEPTH IN REINFORCED CONCRETE BRIDGE ELEMENTS BY ULTRASONIC METHODS

Project Description:

The objective of this research project is to develop a simple field-ready method of assessing cracks in reinforced concrete bridge pile caps and of measuring cracks occurring through greater depths.

Posters:

Assessment of Crack Depth in Reinforced Concrete Bridge Elements by Ultrasonic Methods (September 2013)

EVALUATION OF LONG-TERM PERFORMANCE OF RUBBERIZED PAVEMENTS, PHASE II

To investigate the long-term performance of well-designed rubberized PEM and SMA mixtures.

Posters:

EFFECTIVE CAPACITY ANALYSIS AND TRAFFIC DATA COLLECTION FOR THE I-85 HOV TO HOT CONVERSION

Project Description:

To (1) perform data collection and analytical efforts that support the regional conversion of HOV lanes into high-occupancy toll (HOT) lanes, and (2) assess the impacts of HOT conversion on the I-85 corridor.

Final Report

Posters: