EAR PROGRAM—RESEARCH ASSOCIATES PROGRAM  |  a

Exploratory Advanced 

Research Program 

Research Associates 

Program 2018 
b  |  EAR PROGRAM—RESEARCH ASSOCIATES PROGRAM 

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Cover photos 

Left: A simulation input illustrates EAR Program research associate Nopadon 

Kronprasert s work on alternative intersection and interchange designs (see page 23). 

Right: Image showing the nucleation of ettringite mineral in the interfacial transition 

zone, part of a research objective to develop inorganic curing compounds for 

addressing the shortcomings of current organic membrane-forming curing compounds 

in pavement construction (see page 12). 
Contents

The Research Associateship Program 3 

Breakthrough Concepts in Materials Science 4 

Ultra-High Performance Concrete: A Pathway to Resilient Infrastructure 

Systems through Material Characterization and Structural Design 4 

Modeling of Pavement Response Under Trafc Speed Defection 

Providing a Performance-Based Asphalt Mixture Design Framework 

Tensile Response of Ultra-High Performance Concrete: 

Comprehension and Development of Nano-Additives to Judicially 

Devices for Pavement Management Application 5 

through Fatigue and Thermal Cracking Index Parameters 7 

Developing Frameworks of Performance-Based Asphalt Mix Design 9 

Validation of Characterization Methods 10 

Performance of Geosynthetic-Reinforced Soils at the Service Limit State 11 

Use of Inorganic Coatings as Curing Compounds 12 

Developing New Vehicle–Tire and Contact Friction Models 13 

Improve the Interfacial Region in Concrete and Asphalt 15 

Connected Highway and Vehicle System Concepts 16 

Cost-Beneft Analysis of Connected and Automated Vehicle Operations 16 

Knowledge-Based Signal Timing and Optimization Expert System 

for Advanced Urban Signal Control 17 

Development of an Eco-Cooperative Adaptive Cruise Control to 

Optimize Vehicle Performance for Environment and Mobility Benefts 18 

Developing and Implementing Dynamic Junction Control System 

in the United States 19 

Human Behavior and Travel Choices 20 

Efectiveness of High-Visibility Crosswalks in Improving 

Pedestrian Safety 20 

Data-Driven Space-Time Dependent Trafc Condition Estimation 

and Management 21 

Operational and Safety Analyses of Alternative Intersection/ 

Interchange Designs 23 

Integrating Driving Simulation and Other Behavioral Data: 

Assessment of Driver Behavior and Performance 25 

Operational and Safety Analyses of Alternative Intersection/ 

Interchange Designs 26 

Utilizing Naturalistic Driving Data and Highway Safety Information 

System to Advance Highway Crash Data Modeling Concepts 

and Methods 28 

Technology for Assessing Performance 30 

Air-Coupled Acoustic and Ultrasonic Arrays for Concrete 

Non-Destructive Test Methods 30 

Prediction of Pavement Temperature Profles Using Surface 

Temperatures: An Analytical Approach With Model Validation 

Based on Long-Term Pavement Performance Data 31 

EAR PROGRAM—RESEARCH ASSOCIATES PROGRAM  |  1

The Research Associateship Program 

Since 1954, the National Research Council (NRC) has conducted the Research Associateship 

Program (RAP) in cooperation with sponsoring Federal laboratories and other approved 

participating research organizations. RAP provides highly skilled and exceedingly promising 

postdoctoral and senior scientists and engineers with opportunities to research problems that are 

compatible with the interests of sponsoring laboratories. RAP ofers recent doctoral graduates 

opportunities for concentrated research with selected members of permanent, professional, 

laboratory staf and allows them to contribute to the overall eforts of the laboratories. 

The Federal Highway Administration (FHWA) has participated in RAP since 1992. To supplement the 

expertise of permanent staf, FHWA’s Turner–Fairbank Highway Research Center (TFHRC), through its 

Exploratory Advanced Research (EAR) Program, invites researchers with appropriate backgrounds to 

investigate specifc problems on a short-term basis across a wide range of topics and disciplines. 

NRC provides a process for selecting candidates on a competitive merit basis and, subsequently, for 

administration of the resident fellows during their tenures at FHWA. The process begins with a 

prospective FHWA adviser developing a proposed research opportunity. The adviser then coordinates 

with FHWA leadership to approve the opportunity and forward the proposed research to NRC. All 

research opportunities require an abstract that relates to exploratory advanced research and is of 

specifc relevance to the FHWA research program. One of the signifcant benefts of this process is that 

it encourages interaction between government researchers and new researchers who are using 

cutting-edge approaches and research tools in their work. 

RAP provides opportunities for FHWA’s EAR Program to advance research methods used at TFHRC. 

Over the years, associates have researched topics as diverse as cost-beneft analysis of connected 

and automated vehicle operations, nano-additives for concrete and asphalt, alternative intersection 

and interchange design, and modeling to predict collisions based on driver behavior and 

environmental conditions. 

The following pages contain summary descriptions of some of the research projects that the resident 

fellows have been involved in during their respective tenures at FHWA. 

The EAR Program addresses the need for longer term, higher risk research with the potential for 

long-term improvements to transportation systems. The EAR Program seeks to leverage 

advances in science and engineering that could lead to breakthroughs for critical, current, and 

emerging issues in highway transportation by experts from diferent disciplines who have the 

talent and interest in researching solutions and might not do so without EAR Program funding. 

EAR PROGRAM—RESEARCH ASSOCIATES PROGRAM  |  3
Breakthrough Concepts in Materials Science 

PROJECT: Ultra-High Performance Concrete: A Pathway to Resilient Infrastructure Systems through Material Characterization 

and Structural Design 

ASSOCIATE: Rafc El-Helou 

SCHOOL: Virginia Polytechnic Institute and State University 

PERIOD: December 2016– 

OBJECTIVE: To develop material testing standards, construction practices, and design methodologies for ultra-high performance 

concrete (UHPC), and to advance innovative structural applications that fully use UHPC’s durability and 

performance characteristics. 

ADVISER: Ben Graybeal, FHWA Ofce of Infrastructure 

Research and Development 

SUMMARY: UHPC has many advantages over conventional 

concrete, including greater strength, ductility, and resistance to 

corrosion, chemicals, and severe environmental conditions. Rafc 

El-Helou’s research aims to standardize material testing protocols, 

establish design models, and explore the best construction 

practices for UHPC. The nature of UHPC requires detailed 

standards to assess material behaviors like frst cracking, postcracking behavior in tension, compression, and ductility. This 

standardization will minimize variations in material data and 

foster the development of characteristic design models for UHPC. 

To pursue those goals, El-Helou is building a national database of 

UHPC material testing procedures and experimental data, 

performing material tests that explore UHPC characteristics, 

assessing the applicability of current testing methods to UHPC, 

and developing design guides and codes that include material 

models and structural design methods for UHPC. Prototyping of 

pretensioned bridge girders built with UHPC is also part of ElHelou’s project. This efort is intended to validate that increasing 

the span range of concrete bridges can be achieved with UHPC. 

IMPACT: El-Helou is taking part in FHWA efforts to develop and 

deliver a draft on UHPC for the AASHTO LRFD Bridge Design and 

Construction Guide Specifcations. (LRFD is short for load and 

resistance factor design.) This work will support the American 

Association of State Highway and Transportation Ofcials’ 

(AASHTO) interest in producing a national UHPC standard through 

its Committee on Bridges and Structures, Subcommittee T-10. ElHelou’s research on material testing standards, design 

methodologies, and construction practices will encourage 

simplicity, speed, and creativity in designing and implementing 

UHPC. His investigation also provides suggestions on optimal use 

of UHPC in innovative highway applications. 

ONGOING RESEARCH: El-Helou continues to assess the reliability 

of the current design approaches, as well as develop new design 

methodologies to recommend for the AASHTO draft. El-Helou is 

helping prepare for large-scale tests of UHPC girders that are 

planned for execution at FHWA’s TFHRC, and he is using the 

fndings to validate his proposed design methodologies. 

These images illustrate the process for developing and evaluating UHPC bridge 

design methods. 

RESOURCES: Several publications and papers resulted from this 

RAP research. They are outlined below. 

Haber, Z. B., De La Varga, I., Graybeal, B. A., Nakashoji, B., & El-Helou, R. 

(2018). Properties and behavior of UHPC-class materials, Report No. 

FHWA-HRT-18-036, Federal Highway Administration, Washington, DC. 

Graybeal, B., & El-Helou, R. G. (2018). AASHTO LRFD design and 

construction guide specifcation for ultra-high performance concrete, 

FHWA-TFHRC plan towards development and delivery. Presented at 

the AASHTO Committee on Bridges and Structures (CBS) T-10 

Committee Meeting, Burlington, VT. 

El-Helou, R. G., & Graybeal, B. (2018). Towards ultra-high performance 

concrete design guidance in the United States. Presented at the 

American Concrete Institute Spring 2018 Convention, Salt Lake City, UT. 

El-Helou, R. G., & Graybeal, B. (2017). AASHTO LRFD design and 

construction guide specifcation for ultra-high performance concrete, 

models and design concepts: Compression, tension, fexure, and 300 ft 

pretensioned girder. Presented at the Transportation Pooled Fund 

Solicitation TFP-5(366) Kickof Meeting, Ames, IA. 

Graybeal, B., & El-Helou, R. G. (2017). AASHTO LRFD design and 

construction guide specifcation for ultra-high performance concrete, 

FHWA-TFHRC plan towards development and delivery. Presented at 

the AASHTO Subcommittee on Bridges and Structures (SCOBS) T-10 

Committee Meeting, Cleveland, OH. 

4  |  EAR PROGRAM—RESEARCH ASSOCIATES PROGRAM 
Breakthrough Concepts in Materials Science 

PROJECT: Modeling of Pavement Response Under Trafc Speed Defection Devices for Pavement Management Application 

ASSOCIATE: Seyyedmahdi Nasimifar 

SCHOOL: University of Nevada–Reno 

PERIOD: April 2016– 

OBJECTIVE: To develop robust methods to relate trafc speed defection device (TSDD) measurements to pavement structural 

responses for assessing pavement structural condition and rate of deterioration. 

ADVISER: Nadarajah Sivaneswaran, FHWA Ofce of Infrastructure Research and Development 

SUMMARY: Seyyedmahdi “Mahdi” Nasimifar developed an 

analytical approach that is designed to advance the incorporation 

of TSDDs, specifcally the Rolling Wheel Defectometer (RWD) 

and the Trafc Sp eed De fectometer (T SD), in to pa vement 

management applications. To help achieve his research objective, 

he used 3D-Move, a software tool developed under an FHWA 

research efort, w hich m odels l oads a s t hey m ove a cross 

pavements and computes the resulting pavement responses. 

Nasimifar’s current project is an outgrowth of his previous work 

with 3D-Move as a member of a team that carried out an FHWAsponsored project evaluating the RWD and TSD through feld 

trials at the Minnesota Road Research Facility and analytical 

modeling. Nasimifar used data collected at the feld trials and TSD 

data collected on pavement sections in several States that 

participated in an FHWA-led transportation pooled-fund study to 

calibrate his analytical model. With the calibrated model, he 

developed correlations that related critical pavement responses 

such as tensile strains at the bottom of the asphalt layer (fatigue) 

and compressive strains at the top of subgrade (rutting) to TSDD 

measurements and pavement layer properties. He also conducted 

sensitivity analyses to identify the best correlations between 

TSDD measurements and pavement responses. The fnal step was 

validating the results from the new model against the feld 

measurements to illustrate that it can be applied at a system-wide 

level. Nasimifar thoroughly investigated all parameters that could 

afect the analytical model, from the viscoelastic properties of the 

asphalt-concrete layer to moving-load properties and unbound 

pavement layer properties. In addition, he developed a robust and 

practical method to adjust the surface curvature index from TSD 

data to a reference temperature and proposed a method to use 

TSD data to estimate the effective structural number. This can be 

used to determine remaining structural life and rank pavement 

sections for improvements, maintenance, and rehabilitation. 

IMPACT: Building upon previous FHWA-sponsored research into 

TSDDs, Nasimifar is working toward better methods for 

evaluating pavement structural condition and the rate at which 

it deteriorates. Studies have shown that incorporating pavement 

structural condition into the decisionmaking process for 

pavement management leads to better-informed decisions and 

more cost-effective pavement rehabilitation and preservation 

strategies. Nasimifar’s effort will enable State highway agencies 

to incorporate pavement structural condition into their pavement 

management systems to predict how traffic and environmental 

loads will affect their pavement networks over time and better 

plan treatment types and timing to optimize investment 

decisions. The Virginia Tech Transportation Institute, the research 

team for a new transportation pooled-fund study, is using a tool 

that incorporates Nasimifar’s research for analyzing the TSD 

data collected as part of the project. 

ONGOING RESEARCH: With the development of TSDDs, networklevel assessment of pavement structural condition has become 

practical. The application of structural condition data in pavement 

management systems can increase the robustness of structural 

deterioration models. A comprehensive study on improving the 

pavement deterioration models that include structural condition 

The Trafc Speed 

Defectometer is 

a trailer truck that 

measures pavement 

dynamic responses 

while traveling at 

trafc speed. 

EAR PROGRAM—RESEARCH ASSOCIATES PROGRAM  |  5
Breakthrough Concepts in Materials Science 

is under investigation. The results of this study will enable State 

highway agencies to use enhanced pavement deterioration 

models that will foster more informed treatment selections and 

timing and will maximize the benefts from the investments being 

made. 

RESOURCES: Several publications and papers resulted from 

this RAP research. They are outlined below. 

Nasimifar, M., Thyagarajan, S., & Sivaneswaran, N. (2018). Computation of 

pavement vertical surface defections from trafc speed defectometer 

data—Evaluation of current methods. Journal of Transportation 

Engineering, Part B: Pavements, 144(1), 04018001. 

Nasimifar, M., Thyagarajan, S., & Sivaneswaran, N. (2017). Backcalculation 

of fexible pavement layer moduli from trafc speed defectometer 

data. Transportation Research Record: Journal of the Transportation 

Research Board, 2641, 66–74. 

Nasimifar, M., Thyagarajan, S., & Sivaneswaran, N. (2017). Comparison of 

the methodologies to compute pavement surface defections from 

trafc speed defectometer data. Presented at the World Conference 

on Pavement and Asset Management, Milan, Italy. 

Internal pavement 

response measure 

instrumentation of 

the Trafc Speed 

Defectometer. 

Nasimifar, M., Thyagarajan, S., Chaudhari, S., & Sivaneswaran, N. (2018). 

Evaluation of temperature correction models for defection index from 

falling weight defectometer and trafc speed defectometer. Presented 

at the 97th Transportation Research Board Annual Meeting, 

Washington, DC. 

Nasimifar, M., Thyagarajan, S., & Sivaneswaran, N. (2017). Backcalculation 

of fexible pavement layer moduli from trafc speed defectometer 

data. Presented at the 96th Transportation Research Board Annual 

Meeting, Washington, DC. 

Nasimifar, M. (2016). Using trafc speed defectometer data to backcalculate pavement layer moduli. Presented at the Falling Weight 

Defectometer Users Group, San Jose, CA. 

6  |  EAR PROGRAM—RESEARCH ASSOCIATES PROGRAM 
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Breakthrough Concepts in Materials Science 

PROJECT: Providing a Performance-Based Asphalt Mixture Design Framework through Fatigue and Thermal Cracking 

Index Parameters 

ASSOCIATE: David Mensching 

SCHOOL: University of New Hampshire 

PERIOD: May 2015–August 2016 

OBJECTIVE: To develop index parameters to relate material and structural parameters, identifying whether a mixture is prone to 

fatigue or thermal cracking. 

ADVISER: Nelson Gibson, FHWA Ofce of Infrastructure Research and Development 

SUMMARY: The premature distress and failure of highways cost 

money in the form of repairs and time in the form of increased 

congestion while repairs are being made. One way to alleviate 

these efects is to improve the science behind pavement design, 

including the proportion of asphalt, additives, and aggregates for 

creating performance-based mixtures. David Mensching’s research 

explored ways to revise, enhance, and expand the index parameters 

for informing the design decisions of highway departments and 

contractors. An index parameter compares a specialized value (or 

index) to a critical threshold for failure of a material. In this case, 

Mensching used index parameters to gauge the impact of content, 

gradation, and air voids on asphalt mixtures, with an eye toward 

impeding thermal and fatigue cracking. The project consisted of 

testing various asphalts in the feld and developing a database to 

monitor degradation and volumetric changes in pavement over 

time. The feld methods included dynamic modulus testing to 

develop a framework for creating Black Space diagrams, a physics 

tool for evaluating the elasticity and stifness o f m aterials, a nd 

direct tension fatigue tests using the simplifed viscoelastic 

continuum damage model. Mensching used FHWA’s Accelerated 

Loading Facility at the TFHRC and the Asphalt Mixture Performance 

Tester to monitor performance. To develop a materials database 

that could refect regional diferences in pavement materials and 

predict their performance, he collected information from WesTrack 

in Nevada and from departments of transportation. 

IMPACT: Mensching’s research is expected to beneft FHWA’s 

initiative on performance-based asphalt designs in multiple ways. 

The work will show how diferent a sphalts p erform b ased o n 

temperature changes and fatigue stresses; it will expand national 

data about asphalt materials and soil structures for future research; 

it will expand the usefulness of Black Space diagrams to gauge the 

performance of asphalt mixtures and monitor pavement degradation; 

and it will generate a report to help highway departments and 

contractors adjust asphalt designs based on temperature, fatigue, 

and rutting performance. 

ONGOING RESEARCH: Using continuum damage theory, 

the WesTrack study of regional differences in pavement 

materials continues to characterize the impact that 

volumetrics have on predicted asphalt performance. The 

Black Space diagram analysis of both binder and mixture 

with respect to the FHWA Accelerated Loading Facility 

sections is continuing, with high levels of reclaimed asphalt 

pavement and shingles. 

This beta-gamma plot compares conventional, short-term oven 

aging (STOA) for asphalt with loose-mix, long-term oven aging 

(LTOA) and extended, high-temperature oven aging (EHTOA). 

Varying amounts of re-refned engine oil bottoms (REOB) are 

used. Cracking resistance is expected to decrease as beta/ 

gamma decreases and gamma increases. The plot shows that 

EHTOA is more extreme than LTOA and that 15 percent REOB is 

in a less crack-resistant location than the other mixtures. 

EAR PROGRAM—RESEARCH ASSOCIATES PROGRAM  |  7
Breakthrough Concepts in Materials Science 

RESOURCES: Several publications and papers resulted from 

this RAP research. They are outlined below. 

Mensching, D. J. (2016). Testing for fatigue cracking in the asphalt mixture 

performance tester, Report No. FHWA-HIF-16-027, Federal Highway 

Administration, Ofce of Asset Management, Pavement, and 

Construction, Washington, DC.

 Mensching, D. J., Rahbar-Rastegar, R., Underwood, B. S., & Daniel, J. S. 

(2016). Identifying indicators for fatigue cracking in hot mix asphalt 

pavements using viscoelastic continuum damage principles. 

Transportation Research Record: Journal of the Transportation 

Research Board, 2576, DOI: 10.3141/2576-04.

 Jeong, M. M., & Mensching, D. J. (2017). Testing and acceptance procedures 

for as-constructed asphalt mixtures related to thermal fracture. Journal 

of Transportation Engineering: Part B, Pavements, 143(4).

 Mensching, D. J., Andriescu, A., DeCarlo, C., Li, X., & Youtchef, J. S. (2017). 

Efect of extended aging on asphalt materials containing re-refned 

engine oil bottoms. Transportation Research Record: Journal of the 

Transportation Research Board, 2632, DOI: 10.3141/2632-07. 

 Li, X., Mensching, D. J., & Gibson, N. H. (2017). A practical method to 

determine the strain level for cyclic direct tension fatigue testing in the 

AMPT. Transportation Research Record: Journal of the Transportation 

Research Board, 2631, DOI: 10.3141/2631-15. 

Mensching, D. J., Jeong, M. M., & McCarthy, L. M. (2016). Relative 

comparison of complex dynamic modulus predictive models for nonconventional asphalt concrete mixes. Journal of Testing and Evaluation, 46(1).

 Mensching, D. J., Gibson, N. H., Andriescu, A., Rowe, G. M., & Daniel, J. S. 

(2016). Assessing the applicability of rheological parameters to 

evaluate modifed binders. Presented at the International Society for 

Asphalt Pavements Symposium, Jackson Hole, WY.

 Mensching, D. J., Gibson, N. H., Rowe, G. M., & Daniel, J. S. (2016). Using 

mixture-based rheology to evaluate cracking performance of modifed 

asphalt pavements. Presented at the International Society for Asphalt 

Pavements Symposium, Jackson Hole, WY. 

8  |  EAR PROGRAM—RESEARCH ASSOCIATES PROGRAM 
Breakthrough Concepts in Materials Science 

PROJECT: Developing Frameworks of Performance-Based Asphalt Mix Design 

ASSOCIATE: Jong-Sub Lee 

SCHOOL: North Carolina State University 

PERIOD: September 2014–April 2016 

OBJECTIVE: To investigate use of mechanistic models to evaluate voids in mineral aggregate (VMA), design air void content, and 

in-place air void content as parameters for reliably predicting feld performance of various asphalt mix designs. 

ADVISER: Katherine Petros, FHWA Ofce of Infrastructure Research and Development 

SUMMARY: Performance-related specifcations (PRS) will offer 

engineers, contractors, and funding agencies a way to assess 

future performance, maintenance requirements, and lifecycle 

costs for highway construction projects. PRS can be thought of as 

a set of quality assurance specifcations that describe the desired 

levels of key materials and construction-acceptance quality 

characteristics that correlate with fundamental engineering 

properties that predict performance. PRS will rely on models that 

objectively assess performance based on observed constructionquality characteristics related to fundamental engineering 

properties and will: 

• Utilize testing that focuses on key measureable characteristics

related to performance.

• Use pavement design assumptions as a basis for construction

performance.

• Incorporate incentives and disincentives based on modeled

performance.

• Allow contractors to innovate and be competitive.

• Reduce long-term monitoring and management.

When fully developed, PRS will employ the quantifed relationships 

containing the characteristics to predict as-constructed pavement 

performance. Thus, PRS will provide the basis for rational 

acceptance and pay-adjustment decisions related to highway 

construction projects. 

Jong-Sub Lee’s research helped develop a testing and modeling 

framework for performance-based asphalt mix design. The goal 

was to identify the efect of volumetric mix design targets (design 

VMA and design air void) and compaction level (in-place air 

density) on fatigue characteristics and performance. The project 

investigated asphalt mixtures based on the Superpave® mix design 

system (developed through the Strategic Highway Research 

Program) using mechanistic analyses based on the viscoelastic 

continuum damage (VECD) analyses and mechanistic–empirical 

pavement analysis using the AASHTOWare Pavement ME Design® 

program. The analyses included the simplifed VECD model at the 

material level and two structural models: (a) layered viscoelastic 

analysis and (b) layered viscoelastic pavement analysis for critical 

distresses. 

Key performance-related fndings of the research include: 

• The damage state at failure is increased (i.e., better fatigue

performance) with an increase in the design VMA and a decrease 

in the in-place air void and design air void content. The design

VMA is more sensitive than the others.

• Fatigue life was found to improve when the value of the design

VMA was increased and the in-place air void content and design 

air void content was decreased in rank of sensitivity.

• Superpave® mix design parameter of design VMA was the most

sensitive parameter that signifcantly afected the linear

viscoelastic property, damage characteristic, and fatigue life in

the mechanistic analysis.

• The efect of the design air void on mechanistic fatigue life was

diminished as the pavement thickness increased.

• Increasing the design VMA content caused the least amount of

fatigue cracking area at the thin pavement.

IMPACT: Data gathered through this research will contribute to 

the development of testing and modeling protocols that can be 

used to develop PRS for asphalt mix design. 

RESOURCES: The following reports resulted from this RAP 

research and are outlined below. 

Lee, J., Norouzi, A., & Kim, Y. R. (2016). Determining specimen geometry of 

cylindrical specimens for direct tension fatigue testing of asphalt 

concrete. Journal of Testing and Evaluation, 45(2). 

Lee, J-S., Gibson, N., & Kim, Y. R. (2015). Use of mechanistic models to 

investigate fatigue performance of asphalt mixtures: efects of asphalt 

mix design targets and compaction. Transportation Research Record, 

Journal of the Transportation Research Board, 2507. 

Lee, J-S., & Kim, Y. (2014). Performance-based moisture susceptibility 

evaluation of warm-mix asphalt concrete through laboratory tests. 

Transportation Research Record, Journal of the Transportation 

Research Board, 2446. 

Balis, J., & Platte, K. (n.d.). Performance specifcations to speed 

construction, reduce oversight, and encourage innovative approaches: 

Performance specifcations for rapid renewal (R07). SHRP2 Solutions. 

EAR PROGRAM—RESEARCH ASSOCIATES PROGRAM  |  9
Breakthrough Concepts in Materials Science 

PROJECT: Tensile Response of Ultra-High Performance Concrete: Validation of Characterization Methods 

ASSOCIATE: Luis Felipe Maya Duque 

SCHOOL: Polytechnic University of Madrid 

PERIOD: June 2013–April 2016 

OBJECTIVE: To critically assess the applicability of a recently proposed tensile-test method for ultra-high performance, fberreinforced concrete. 

ADVISER: Ben Graybeal, FHWA Ofce of Infrastructure Research and Development 

SUMMARY: Concrete is the most widely used construction 

material and has played a fundamental role in the development 

of infrastructure since the Romans. Advances in fber-reinforced 

concretes over the last 50 years have enabled the development of 

an entirely new generation of cement-based composite materials. 

Ultra-high performance concrete (UHPC) represents a class of 

cement composites with high compressive strength and whose 

tensile response is characterized by high-strain capacity 

accompanied by multiple microcracking. To take full advantage of 

the tensile behavior of these UHPC materials, it is necessary to 

develop tensile-test methods and guidelines to be incorporated 

into codes and recommendations. Luis Felipe Maya Duque’s 

research project focused on the assessment of proposed test 

methods designed to provide a reliable assessment of UHPC 

tensile behavior, not only in a research environment, but also for 

quality-control purposes in a production environment. Maya 

Duque assessed a singular direct tensile-test method that has 

already been the subject of FHWA research to establish 

advantages and drawbacks compared with existing methods. 

Maya Duque also conducted a critical review of the state of the art 

in tensile-test methods for UHPC. The research project included 

an extensive experimental campaign to properly assess the 

performance of the proposed tensile-test method. Furthermore, 

Maya Duque also considered the suitability of the direct tension 

test method to accurately refect the infuence of the fber 

distribution and orientation in structural elements. 

IMPACT: This research allows for the development 

and implementation of a quality control test method for 

UHPC in a production environment. Broader use of UHPC could 

lead to more durable and longer lasting highway structures, 

reducing the cost and risks associated with reconstruction. 

ONGOING RESEARCH: FHWA conducted over 120 direct tension 

tests on both mold-cast and sawed specimens to assess the 

infuence of fow conditions, as well as fber orientation and fber 

distribution on the tensile response of UHPC. FHWA also 

performed fexural tests on UHPC strips and slabs to correlate the 

results from the material characterization tests with the mechanical 

Casting of beam splice connection. Full-scale fexural test of a beam splice 

connection made of UHPC. 

response of structural elements. Those results will contribute to 

assessing the reliability of the current design approaches as well 

as to improving understanding of the main mechanisms and 

variables to be considered in the development of design codes 

and recommendations. Maya Duque continues to complete the 

assessment of the structural efciency of fber reinforcement in 

UHPC structures through an experimental and analytical validation 

process at FHWA. FHWA plans to conduct two full-scale beam 

tests at the TFHRC Structures Laboratory. The results of these 

tests will provide insight for the development of continuity 

connection using UHPC as an alternative to increase the span 

range currently covered by conventional, precast, prestressed 

concrete girders. 

RESOURCES: Several publications and papers resulted from this 

RAP research. They are outlined below. 

Graybeal, B., & Baby, F. (2013). Development of a direct tension test 

method for ultra-high-performance fber-reinforced concrete. ACI 

Materials Journal, 110(2), 177–186. 

Maya, L. F., Zanuy, C., Albajar, L., Lopez, C., & Portabella, J. (2013). 

Experimental assessment of connections for precast concrete frames 

using ultra high performance fber reinforced concrete. Construction 

and Building Materials, 48(11), 173–186. 

Maya, L. F., Ruiz, M., Muttonni, A., & Foster, S. J. (2012). Punching shear 

strength of steel fber reinforced concrete slabs. Engineering Structures, 

40, 83–94. 

The following website provides insight on the FHWA UHPC research 

portfolio: http://www.fhwa.dot.gov/research/resources/uhpc/ 

10  |  EAR PROGRAM—RESEARCH ASSOCIATES PROGRAM 
Breakthrough Concepts in Materials Science 

PROJECT: Performance of Geosynthetic-Reinforced Soils at the Service Limit State 

ASSOCIATE: Danial Esmaili 

SCHOOL: University of Oklahoma 

PERIOD: December 2014–October 2015 

OBJECTIVE: To analyze large-scale performance test results to evaluate the efect of tensile strength, vertical reinforcement 

spacing, facing elements, and backfll properties on deformations of geosynthetic-reinforced soil under typical 

bridge support service pressures. 

ADVISER: Jennifer E. Nicks, FHWA Ofce of Infrastructure Research and Development 

SUMMARY: Geosynthetic-reinforced soil (GRS) technology 

consists of closely spaced layers of geosynthetic reinforcement 

and compacted granular fll material. This method of using 

geosynthetics to reinforce foundations is a proven alternative to 

the construction of deep foundations, depending on the site 

conditions. GRS is widely used for a variety of earthwork projects, 

particularly in GRS-integrated bridge system (IBS) applications. 

GRS-IBSs are economical and easy to design; they can be built in 

a variety of weather conditions and can be modifed to 

accommodate characteristics of varying site conditions. An 

important geotechnical feature of any bridge foundation, 

including GRS bridge elements, is the service limit state (SLS), 

which ensures the durability and serviceability of a bridge and its 

structural components under everyday loads for the design life. 

The SLS for GRS abutments primarily includes vertical settlement, 

lateral deformation, and reinforcement strain. Notwithstanding 

their widespread use in construction, the SLSs of GRS abutments 

have not been well defned. 

Danial Esmaili’s research project involved analyzing the results of 

a series of 13 large-scale column experiments (also called 

performance tests or minipier tests) conducted to help quantify 

both the SLS and ultimate limit state for GRS. The experiments 

were conducted on GRS piers consisting of different backfll 

materials, geosynthetic reinforcement strengths, and 

reinforcement spacing (the thickness of backfll between 

reinforcement layers). Some test piers were constructed with 

concrete masonry facing; others had no facing. All GRS 

confgurations were tested to failure, with the focus of this study 

on the performance at loads of 200 kPa (recommended allowable 

GRS bearing pressure) and 400 kPa (to test performance at 

extreme service loading). Key research fndings of these 

experiments are that: 

• GRS piers built with higher strength backfll undergo less lateral 

and vertical deformation.

• Settlement and lateral displacement at 200 kPa, depending on

composition of test columns, ranged from 8.3 mm to 33.9 mm

and 3.0 mm to 10.1 mm, respectively.

• Reinforcement spacing plays a larger role than does

reinforcement strength in lateral and vertical deformation.

• Lateral movement of pier walls is greatest in the top third of

the composite.

• Limiting-bearing pressure to 10 percent of the estimated

bearing resistance of the GRS abutment will limit axial strains to 

within 0.5 percent of the abutment.

IMPACT: Data gathered through these experiments will help 

engineers more reliably design GRS-IBS projects without having 

to conduct complex and expensive laboratory testing. 

RESOURCES: Several publications and papers resulted from this 

RAP research. They are outlined below. 

Nicks, J. E., Esmaili, D., & Adams, M. T. (2016). Deformations of geosynthetic 

reinforced soil under bridge service loads. Geotextiles and 

Geomembranes, 44(4), 641–653. 

Adams, M. T., Ooi, P. S. K., & Nicks, J. E. (2014). Mini-pier testing to estimate 

performance of full-scale geosynthetic reinforced soil bridge 

abutments. Geotechnical Testing Journal, 37(5). 

Minipier tests helped quantify SLS for GRS with (left photo) and without (right 

photo) concrete masonry facing. 

EAR PROGRAM—RESEARCH ASSOCIATES PROGRAM  |  11
Breakthrough Concepts in Materials Science 

PROJECT: Use of Inorganic Coatings as Curing Compounds 

ASSOCIATE: Jessica Silva 

SCHOOL: University of Wisconsin–Madison 

PERIOD: September 2012–December 2013 

OBJECTIVE: To develop inorganic curing compounds to address the shortcomings of current organic membrane-forming 

curing compounds. 

ADVISER: Jack S. Youtchef, FHWA Ofce of Infrastructure Research and Development 

SUMMARY: Proper curing is a vital post-treatment process when 

constructing durable concrete pavements. This is because water 

loss by evaporation through exposed surfaces can result in 

mechanical or chemical defciencies in the fnal surface of the 

concrete product. Existing membrane-forming curing compounds 

are widely used to form a physical barrier to prevent the migration 

of water during the frst few hours of concrete placement; 

however, these membranes do not always form a continuous 

coating, may degrade after environmental exposure, and provide 

little protection of the concrete section at later stages of the 

pavement’s service life. Jessica Silva’s research project examined 

the use of inorganic curing compounds to address the 

shortcomings of current organic compounds. These inorganic 

curing compounds, prepared from metal-oxide materials, can 

react with the concrete surface to form durable coatings and 

hydration products. The compounds may also impart benefcial 

characteristics to the roadway and provide improvements to the 

pavement long after traditional membranes. Silva examined 

changes occurring to the air and mortar and mortar and aggregate 

interface, in addition to the porosity, density, and chemical 

makeup of the cement paste. Silva also ensured that the inorganic 

curing compounds under development would not adversely 

afect the concrete material. As part of this research project, Silva 

used a traceable element to better understand the efect of the 

compound as it penetrates the concrete. 

IMPACT: This research could represent a paradigm shift in 

the world of curing compounds. In addition, if the material 

developed as a result of this research is not ultimately useful 

as a curing compound, it may still prove useful to enhance 

general concrete characteristics. 

RESOURCES: Several publications and papers resulted from this 

RAP research. They are outlined below. 

Silva, J. M. S., Youtchef, J., & Arnold, T. (2013). Utilizing sol-gel nanoparticles 

in concrete curing to improve surfaces. National Research Council 

Research Associateship Programs Newsletter, 14–16. 

Munoz, J. F., Silva, J. M. S., Perry, L., Youtchef, Y., & Sobolev, K. (2014). 

Interaction of amorphous nano-aluminosilicates with cement pore 

solution and the efect on the early hydration reaction of portland 

cement. Proceedings of the Fifth International Symposium on 

Nanotechnology in Construction. 

12  |  EAR PROGRAM—RESEARCH ASSOCIATES PROGRAM 

Nucleation of ettringite mineral in the interfacial transition zone. 
Breakthrough Concepts in Materials Science 

PROJECT: Developing New Vehicle–Tire and Contact Friction Models 

ASSOCIATE: Emmanuel Bolarinwa 

SCHOOL: University of Birmingham 

PERIOD: September 2013–September 2015 

OBJECTIVE: To use a model-based approach for investigating the efect of tire–pavement contact friction on the safety 

performance of vehicles. 

ADVISER: James A. Sherwood, FHWA Ofce of Infrastructure Research and Development 

SUMMARY: The effective management of critical pavement 

surface characteristics, such as friction and texture, has been 

shown to help prevent or reduce the consequences of rear-end 

and run-off-the-road crashes. Although high-friction surfaces 

can lead to increased numbers of dry pavement rollovers, they 

also lead to fewer wet pavement run-off-the-road crashes and 

tend to have fewer crashes involving fatalities and serious 

injuries. For his research project, Emmanuel Bolarinwa 

implemented a model-based approach to investigate the effect 

of variations in vehicle– and tire–pavement friction on vehicle 

safety performance, such as stopping distances during braking. 

He considered the interactions among key crash causative 

factors and predicted vehicle performance and stability metrics. 

Bolarinwa examined a vehicle simulation package containing 

various values for pavement friction and texture inputs. For 

model verifcation, Bolarinwa obtained vehicle data and crash 

information from the Highway Safety Information System (HSIS) 

and the second Strategic Highway Research Program’s 

naturalistic driving study. He then used the model to develop 

theoretical thresholds for pavement friction and texture inputs 

(i.e., the minimum values when crash rates have been found to 

increase at a signifcantly higher rate). Bolarinwa analyzed 

results from the simulation to extract vehicle performance and 

safety metrics as possible indicators of the onset of vehicle 

crashes for different vehicle types and a variety of road sections 

and geometries. 

IMPACT: This research should lead to enhanced road safety, 

ensuring signifcant savings in cost and human lives by managing 

pavement friction. The research directly contributes to FHWA’s 

strategic safety improvement program by predicting friction 

threshold values to determine conditions when a pavement 

should be investigated for maintenance intervention. Bolarinwa’s 

research will lead to better characterization of the efects o f a 

broad range of human, vehicle, and environmental factors on 

crash outcomes. It will also provide a basis for evaluating practices 

related to pavement surface material parameters and roadway 

geometry. FHWA will ultimately use the results of this research to 

develop new vehicle crash models, which will be of value to safety 

engineers working on State highway safety improvement 

programs. In addition, the results could be used to change 

pavement design standards to select the best pavements in terms 

of safety. 

ONGOING RESEARCH: Bolarinwa continues research into 

the development of theoretical threshold values for pavement 

friction and development of procedures for predicting stopping 

distances based on the friction of the pavement surface. The 

long-term goal is to reduce fatal and severe (incapacitating 

injury) crashes, by prescribing levels of pavement friction and 

macrotexture. 

A simulation model for 

investigating vehicle 

behavior on a sloped 

terrain surface. 

EAR PROGRAM—RESEARCH ASSOCIATES PROGRAM  |  13
Breakthrough Concepts in Materials Science 

RESOURCES: Several publications and papers resulted from 

this RAP research. They are outlined below. 

Uzunsoy, E., Bolarinwa, E., Olatunbosun, O., & He, R. (2014). Investigating 

vehicle behavior on a sloped terrain surface. SAE Technical Paper 2014-

01-0857. 

Yang, X., Olatunbosun, O., Ramos, D. G. P., & Bolarinwa, E. (2013). 

Experimental investigation of tire dynamic strain characteristics for 

developing strain-based intelligent tire system. SAE International 

Journal of Passenger Cars–Mechanical Systems, 6(1), 97–108. 

Bolarinwa, E. O., Mahadevaiah, U., Marzougui, D., & Opiela, K. S. (2012). The 

development of an enhanced fnite element tire model for roadside safety 

hardware assessment. Proceedings of the Institution of Mechanical 

Engineers, Part K: Journal of Multi-Body Dynamics, 226(3), 206–219. 

Bolarinwa, E. O. (2014). Material and geometrical characterization for FE 

tire modeling and simulation. Paper presented at the 2014 Tire 

Technology Expo Conference, Cologne, Germany. 

Bolarinwa, E. O. (2013). Development of an FE tire model for vehicle crash 

simulations. Paper presented at the 2013 Tire Technology Expo 

Conference, Cologne, Germany. 

Bolarinwa, E. O. (2013). Experimental investigation of vehicle behavior on a 

sloped-terrain surface. Paper presented during the SAE 2013 World 

Congress and Exhibition, Detroit, MI. 

Bolarinwa, E. O. (2012). Role of tire testing in eforts to develop improved 

fnite element models to support crash simulation. Workshop on 

Improving the Modeling of Tire, Steering and Suspension Systems in Angular 

Crashes, FHWA Turner–Fairbank Highway Research Center, McLean, VA. 

Bolarinwa, E. O. (2011). The development of an enhanced fnite element tire 

model for vehicle crash simulations. Paper presented at the 30th 

Annual Conference on Tire Science and Technology, Akron, OH. 

Bolarinwa, E. O. (2011). Role of tire testing in eforts to develop improved 

fnite element vehicle models to support crash simulations. Paper 

presented at the 2011 Tire Technology Expo Conference, Cologne, Germany. 

14  |  EAR PROGRAM—RESEARCH ASSOCIATES PROGRAM 
Breakthrough Concepts in Materials Science 

PROJECT: Comprehension and Development of Nano-Additives to Judicially Improve the Interfacial Region in Concrete and Asphalt 

ASSOCIATE: Jose Muñoz 

SCHOOL: University of Wisconsin–Madison 

PERIOD: April 2010–April 2013 

OBJECTIVE: To investigate how judicially applied coatings on the surface of the aggregates of diferent nano-additives 

can improve the interfacial region in concrete and asphalt. 

ADVISER: Jack S. Youtchef, FHWA Ofce of Infrastructure Research and Development 

SUMMARY: Jose Muñoz examined a method to enhance the area 

of contact between cement-paste aggregates and asphalt 

aggregates, known as the interfacial region. This is one of the 

most vulnerable areas of concrete and asphalt, potentially 

afecting the overall performance of pavement. The durability of 

concrete is highly infuenced by its pore structure, specifcally a 

highly porous area known as the interfacial transition zone (ITZ). 

Large fractions of the microcracks occurring in concrete are 

associated with the ITZ; therefore, improving the strength of the 

ITZ could signifcantly improve concrete durability. Traditional 

approaches to the problem, involving the successive addition of 

diferent s ilicon o r a luminum-based m aterials, h ave b een 

inefcient and costly. Mu ñoz based his research on the theory that 

nanoparticles added as nanoporous flms, and when judiciously 

placed on the aggregate surface, can greatly improve the ITZ and 

thereby the performance of the concrete. He investigated changes 

triggered by nanoporous thin flms in the chemistry and 

morphology of the hydration products located at the aggregate– 

cement-paste interface. Muñoz developed a model to determine 

two-dimensional spatial distribution of cement hydration phases 

and to study the aggregate–cement-paste interface in concrete. 

In addition, Muñoz developed a new sol-gel synthesis (a method 

for producing solid materials from small molecules) to produce 

“nano-aluminosilicate” gels with a controlled silicon-to-aluminum 

ratio. Muñoz also studied the efect of these nano-aluminosilicate 

gels with diferent s ilicon-to-aluminum r atios o n t he h ydration 

reaction of portland cement. 

IMPACT: The development of new nano-additives, together with 

a new method for applying them in concrete, is expected to 

help create materials with less water and chloride 

penetrability and higher mechanical strength and resistance 

to cracking. This is expected to lead to the creation of 

construction materials with improved characteristics and less 

energy demand for maintenance operations. The application of 

nanoparticles in concrete and asphalt, using dip- or spray-coating 

methods, offers several advantages when compared with the 

traditional addition of nanoparticles as powder additives. It is 

an easier and safer application method— fewer additives are 

required, which reduces costs—and the technology is 

already available. In addition, this technology can have a positive 

Backscattered 

electron images 

of a potassium 

sulfate crystal 

formed inside 

of a silica gel in 

the interfacial 

transition zone. 

aggregate sources. For example, these nano-additives can be used 

to improve performance of currently marginal aggregates, such as 

natural aggregate with signifcant contents of clay minerals strongly 

adhered to their surface. 

ONGOING RESEARCH: Muñoz continues to study the effect of the 

nanoparticles in concrete pore solution at early stages of 

hydration. In addition, he also performed research with the U.S. 

Army Engineer Research and Development Center to characterize 

the ITZ modifed with nanoparticles. 

RESOURCES: Several publications and papers resulted from this 

RAP research. They are outlined below. 

Mu ñoz, J. F., Meininger, R. C., & Youtchef, J. (2010). New possibilities and 

future pathways of nanoporous thin flm technology to improve 

concrete performance. Transportation Research Record, Journal of the 

Transportation Research Board, 2142, 34–41. 

Muñoz, J. F., Yao, Y., Youtchef, J., & Arnold, T. (2011). Nanotechnology to 

improve aggregate performance. National Research Council, Research 

Associateship Program Newsletter. 

Muñoz, J. F., Yao, Y., Arnold, T., & Youtchef, J. (2013). Mixtures of silicon 

and aluminum oxides to optimize the performance of nanoporous thin 

flms in concrete. Cement and Concrete Composites, 48. 

Munoz, J. F., Silva, J. M. S., Perry, L., Youtchef, Y., & Sobolev, K. (2014). 

Interaction of amorphous nano-aluminosilicates with cement pore 

solution and the efect on the early hydration reaction of Portland 

cement. Proceedings of the Fifth International Symposium on Nanotechnology in Construction. 

Balachandran, C., Muñoz, J. F., Arnold, T., & Youtchef, J. (2014). Potential 

application of surface enhanced Raman spectroscopy as a tool to 

study cementitious materials. Proceedings of the Fifth International 

Symposium on Nanotechnology in Construction. 

impact in locations with limited or marginal-quality EAR PROGRAM—RESEARCH ASSOCIATES PROGRAM  |  15
-------------------------------------------------~ ----

-- --­ .. ...._.._ 

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PROJECT: Cost-Beneft Analysis of Connected and Automated Vehicle Operations 

ASSOCIATE: Mehdi Zamanipour 

SCHOOL: University of Arizona 

PERIOD: September 2016– 

OBJECTIVE: To study the costs and benefts of deploying connected and automated vehicle (CAV) technology along signalized 

corridors and develop a tool to analyze the mobility and environmental benefts of deploying systems. 

ADVISER: Govindarajan Vadakpat, FHWA Ofce of Safety Research and Development 

Information Administration timelines, and emissions 

The proposed integrated signal and trajectory control optimization framework. 

© Mehdi Zamanipour. 

based on U.S. Environmental Protection Agency guidelines. 

IMPACT: Although the simulation environment in this project was 

created to analyze MMITSS and GlidePath, it could be used to 

study other dynamic mobility applications such as cooperative 

adaptive cruise control. State and local transportation agencies 

could incorporate the tool into a larger, overall analysis framework 

to justify investments into CAVs. The results of the research also 

can help demonstrate the relationship between CAV market 

penetration and lower fuel consumption. 

ONGOING RESEARCH: Zamanipour continues to develop and test 

the integrated signal and trajectory optimization model in the 

simulation environment. In addition, he will implement his model 

in testing intersections at FHWA’s TFHRC and evaluate the 

benefts of the model. 

RESOURCES: Several publications and papers resulted from this 

RAP research. They are outlined below. 

Beak, B., Zamanipour, M., Head, L., & Leonard, B. (2018). Peer-to-peer 

priority signal control strategy in a connected vehicle environment. 

Transportation Research Record: Journal of the Transportation Research 

Board. Available online: https://doi.org/10.1177/0361198118773567. 

Zamanipour, M., Head, K. L., Feng, Y., & Khoshmagham, S. (2016). Efcient 

priority control model for multimodal trafc signals. Transportation 

Research Record: Journal of the Transportation Research Board, 2557, 

86–99. Available online: http://dx.doi.org/10.3141/2557-09. 

Feng, Y., Zamanipour, M., Head, K. L., & Khoshmagham, S. (2016). 

Connected vehicle-based adaptive signal control and applications. 

Transportation Research Record: Journal of the Transportation Research 

Board, 2558, 1–13. Available online: http://dx.doi.org/10.3141/2558-02. 

Khoshmagham, S., Head, K. L., Feng, Y., & Zamanipour, M. (2016). 

Multimodal data analytics comparative visualization tool: Case study 

of pedestrian crossing design. Transportation Research Record: Journal 

of the Transportation Research Board, 2557, 44–54. Available online: 

http://dx.doi.org/10.3141/2557-05. 

Feng, Y., Head, L., Khoshmagham, S., & Zamanipour, M. (2015). A real-time 

adaptive signal phase allocation algorithm in a connected vehicle 

environment. Transportation Research Part C: Emerging Technologies, 

55, 460–473. 

Zamanipour, M., Hu, J., Vadakpat, G., Bared, J., & Curtis, D. (2018). A design 

of cooperation between trafc signal and connected automated 

vehicle. Presented at the 97th Transportation Research Board Annual 

Meeting, Washington, DC. 

Beak, B., Zamanipour, M., Head, L., & Leonard, B. (2018). Peer-to-peer 

priority signal control strategy in connected vehicle environment. 

Presented at the 97th Transportation Research Board Annual Meeting, 

Washington, DC. 16  |  EAR PROGRAM—RESEARCH ASSOCIATES PROGRAM 

Connected Highway and Vehicle System Concepts 

SUMMARY: Mehdi Zamanipour is evaluating the costs and benefits 

of deploying CAV technologies along signalized traffic corridors. 

His research examines two specific w ireless c ommunications 

applications—Multi-Modal Intelligent Traffic Si gnal Sy stems 

(MMITSS) and GlidePath. Developed under U.S. Department of 

Transportation (DOT) programs, both systems get technologically 

advanced vehicles “talking” to each other and to computerized 

roadside infrastructure. MMITSS uses the data generated in such 

communications to optimize the movements of transit and freight 

traffic, em ergency ve hicles, an d pe destrians, wh ile Gl idePath is 

designed to maximize fuel efficiency as vehicles move through 

traffic signals. Zamanipour developed a simulation environment 

for analyzing these technologies. The elements of the

simulator include an application called CAV Message Distributor, 

containerization technology to run MMITSS and GlidePath, and 

traffic flow software. This package collects information from CAVs,

broadcasts messages to roadside infrastructure, sets an emission 

model, and controls driving behaviors like speed and acceleration 

for each vehicle. Zamanipour is using the DOT-sponsored Research 

Data Exchange to calibrate baseline software models for traffic 

demand, signal t
PROJECT: Knowledge-Based Signal Timing and Optimization Expert System for Advanced Urban Signal Control 

ASSOCIATE: Yi Zhao 

SCHOOL: Beijing Jiaotong University 

PERIOD: December 2015–June 2018 

OBJECTIVE: To develop a knowledge-based signal timing and optimization expert system and employ a robust evaluation 

methodology to test its applicability. 

ADVISER: Peter Huang, FHWA Ofce of Safety Research and Development 

SUMMARY: The limitations of adaptive traffic control systems as 

a tool to optimize signal timing posed an opportunity for Yi 

Zhao to develop a knowledge-based expert system to improve 

existing signal-control systems. Knowledge-based expert 

systems are an artifcial intelligence (AI) technique to help 

people analyze and solve problems. Zhao also applied artifcial 

neural network technology for trafc-demand prediction. 

His project consisted of fve major tasks: 

• Designing a system framework.

• Developing a hybrid origin–destination (OD) model to estimate 

trafc demand.

• Developing a system to generate plans and select the appropriate 

options from the plans, based on real-time trafc data.

• Optimizing the signal timing plan by using this system.

For his hybrid OD estimation model, Zhao integrated diferent 

types of trafc data (time of day, day of week, and average daily 

trafc count), pulling data from various sources (wireless trafc 

sensors, link-based trafc sensors, and national survey data). He 

used AI to estimate each small-area OD, which can be used to 

generate any size of scalable ODs to support advanced signal 

operations. A unique feature of Zhao’s work is assembling an OD 

table from many small-area ODs, which is just like assembling a 

puzzle from small pieces. In this way, a scalable OD can be made 

to provide much improved, timely demand data for more 

effective signal timing. 

IMPACT: Traffic engineers will beneft from Zhao’s research as 

they work to improve the efciency of U.S. trafc signals. The 

software package he developed will help them optimize signal 

timing practices based on AI technology. This advanced system 

is working on the basis of more accurate trafc-demand data, 

and it can become “smarter over time” on the basis of 

accumulated knowledge in the expert system and machinelearning technique. 

RESOURCES: One publication and several papers resulted from 

this RAP research. They are outlined below. 

Zhao, Y., James, R., Xiao, L., & Bared, J. (2018). A capacity estimation 

model for a contrafow left-turn pocket lane at signalized intersections. 

Transportation Research Record: Journal of the Transportation Research Board. 

Available online: http://journals.sagepub.com/ 

doi/10.1177/0361198118787978. 

Zhao, Y., Huang, P., Xiao, L., Ma, J., Hu, J., & Wang, Y. (2017). A scalable 

short-term origin-destination estimation approach based on modularized 

network with connected vehicle technology. Presented at the 

96th Transportation Research Board Annual Meeting, Washington, DC. 

Wolfgram, J., Huang, P., Zhao, Y., & Christofa, E. (2018). A quick and reliable 

traffic incident detection methodology using connected vehicle data. 

Presented at the 97th Transportation Research Board Annual 

Meeting, Washington, DC. 

Wang, Y., Zhao, Y., Zhang, W., Bared, J., & Huang, P. (2017). Signal timing 

strategies for Georgia’s frst in-house designed DDI, 5th Urban Street 

Symposium, Raleigh, NC. 

Xiao, L., Wang, Y., Hu, J., & Zhao, Y. (2017). Responsive signal control with 

active connected vehicles. Presented at the 96th Transportation 

Research Board Annual Meeting, Washington, DC. 

Zhao, Y., James, R., Xiao, L., & Bared, J. (2018). A capacity estimation 

model for a contrafow left-turn lane at signalized intersections. Presented 

at the 97th Transportation Research Board Annual Meeting, Washington, 

DC. 

Wang, Y., Zhao, Y., Zhang, W., Bared, J., & Huang, P. (2017). Signal timing 

strategies for Georgia’s frst in-house designed DDI. Presented at the 5th 

Urban Street Symposium, Raleigh, NC. 

Zhao, Y., James, R., Xiao, L., & Bared, J. (2017). A capacity estimation 

model for a contrafow left-turn lane at signalized intersections. Presented 

at the 5th Urban Street Symposium, Raleigh, NC. 

EAR PROGRAM—RESEARCH ASSOCIATES PROGRAM  |  17

Connected Highway and Vehicle System Concepts 
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PROJECT: Development of an Eco-Cooperative Adaptive Cruise Control to Optimize Vehicle Performance for Environment 

and Mobility Benefts 

ASSOCIATE: Jia Hu 

SCHOOL: University of Virginia 

PERIOD: October 2014–July 2017 

OBJECTIVE: To develop an algorithm for eco-cooperative adaptive cruise control (ECACC) that accounts for road topography 

to minimize fuel consumption and emissions while maximizing mobility. 

ADVISER: Joe Bared, FHWA Ofce of Operations Research and Development 

SUMMARY: Eco-driving systems improve fuel efficiency by 

keeping equipped vehicles within a range of speeds in 

mountainous terrain rather than at a fxed speed like 

conventional cruise control. However, the algorithms that these 

systems use do not gauge their impact on mobility. Jia Hu 

sought to develop a framework for ECACC that could minimize a 

vehicle’s fuel consumption while maximizing its mobility. His 

research also evaluated how speed changes within the ECACC 

framework could affect vehicle safety performance. Hu reviewed 

literature on three topics—state-of-the-art ECACC, fuelconsumption models that consider variables like vehicle speed 

and roadway grade, and car-following models. In the next phase 

of work, he developed an algorithm for ECACC in three stages. 

Using simulation tools, Hu initially designed the algorithm to 

optimize both fuel economy and mobility for a single vehicle. 

Next, he expanded the algorithm to traffic scenarios that mixed 

one ECACC-equipped vehicle with human-driven vehicles. The 

third phase of algorithm development envisioned multiple 

vehicles using ECACC. Hu fnished the project by testing the 

algorithm and evaluating the results. This required identifying 

several stretches of highways with different topographies to 

serve as the prototype for a simulation test bed. The tests took 

into account average grade and grade changes in the road, 

vehicle weight, target speed range, and other factors when 

gauging the performance of the algorithm. Hu compared the fuel 

efficiency, emissions, speed, vehicle spacing, throughput, and 

number of conficts that occurred in multiple ECACC simulations. 

IMPACT: Hu’s project is expected to generate an ECACC 

framework that can maximize fuel efficiency and minimize the 

technology’s impact on mobility, regardless of the road 

topography the vehicle is traveling. The framework should work 

for either a lone ECACC-equipped vehicle or a platoon of them. 

As a secondary beneft, the research could demonstrate 

improved safety performance for vehicles with ECACC. 

ONGOING RESEARCH: Hu continues to develop a number of CACC 

controllers at this moment, including one that is robust against 

cyber attacks, one that cooperates with multiple signal 

controllers on a corridor, and one that includes humans in the 

control loop in order to improve the driving experience and 

Hu’s research shows that an eco-CACC with a connected powertrain can 

bring additional fuel savings of 15 to 25 percent, compared with mere speed 

optimization. 

reduce the hardware cost of enabling CACC. In addition, Hu is 

also developing a generic simulation platform incorporating 

vehicle dynamics for a more realistic evaluation of CACC’s 

impact on traffic fow. 

RESOURCES: Several publications and papers resulted from 

this RAP research. They are outlined below. 

Hu, J., Shao, Y., Sun, Z., & Bared, J. (2017). Integrated vehicle and powertrain 

optimization for passenger vehicles with vehicle-infrastructure 

communication. Transportation Research Part C: Emerging 

Technologies, 79, 85–102. 

Jiang, H., Hu, J., An, S., Wang, M., & Park, B. B. (2017). Eco approach at an 

isolated signalized intersection under partially connected and 

automated vehicle environment. Transportation Research Part C: 

Emerging Technologies, 79, 290–307. 

Zhang, L., Zhang, L., Hale, D., Hu, J., & Huang, Z. (2017). A cycle-based 

variable speed limit methodology for improved freeway merging. IET 

Intelligent Transport Systems, 11, DOI: 10.1049/iet-its.2017.0017. 

Hu, J., Shao, Y., Sun, Z., Wang, M., Bared, J., & Huang, P. (2016). Integrated 

optimal eco-driving on rolling terrain for hybrid electric vehicle with 

vehicle-infrastructure communication. Transportation Research Part C: 

Emerging Technologies, 68, 228–244. 

Ma, J., Hu, J., Hale, D., & Bared, J. (2016). Dynamic hard shoulder running 

for trafc incident management. Transportation Research Record: 

Journal of the Transportation Research Board, 2554, 120–128. 

18  |  EAR PROGRAM—RESEARCH ASSOCIATES PROGRAM 

Connected Highway and Vehicle System Concepts 
--------------------------------------------------------------------~ --------

2ml •1 I+-- 1000 ft ---+ 

PROJECT: Developing and Implementing Dynamic Junction Control System in the United States 

ASSOCIATE: Ximiao Jiang 

SCHOOL: University of Tennessee, Knoxville 

PERIOD: October 2013–May 2015 

OBJECTIVE: To investigate the efciency of dynamic merge control (DMC) strategy at freeway merge areas. 

ADVISER: Joe Bared, FHWA Ofce of Operations Research and Development 

SUMMARY: DMC is a traffic management strategy that can be 

used to dynamically monitor and control trafc fow at freeway 

on- or of-ramps or where multiple-lane freeways merge—for 

example, where a 2-lane freeway merges with a 3-lane freeway 

into 4 lanes. DMC minimizes disruption that can occur, for 

example, when trafc vo lume on an on-ramp is signifcantly 

higher than on the freeway. In this case, ramp trafc must fnd 

gaps in lower volume freeway trafc, resulting in hesitation and 

delay and increasing the possibility of rear-end collisions. DMC 

strategy, now being used in Germany and the Netherlands, 

assigns priority to the high-volume trafc stream. In the example 

above, DMC could close the right lane of the main freeway and 

allow ramp trafc free access at the merge. DMC has not been 

implemented anywhere in the United States, and knowledge of 

the strategy is still experimental here. 

Ximiao Jiang’s research project used an analytical technique 

called microsimulation to examine the efectiveness of DMC on 

several road and trafc co nfgurations. Microsimulation can 

efectively model the behavior of many individual vehicles within 

specifed trafc environments, including merge queuing and 

congested road networks, to the point of gridlock. Jiang 

simulated DMC lane-closing strategy on two trafc confgurations: 

the frst, two 2-lane freeways merging into 3 lanes, and the 

second, a 3-lane freeway merging with a 2-lane freeway into 4 

lanes. Simulations included trafc demands ranging from 1,000 

vehicles per hour (vph) to 4,600 vph on 3 lanes and 2,500 vph 

to 6,500 vph on 2 lanes. In the simulations, signals notify drivers 

of lane closure 2,500 ft upstream of the lane closing and close 

the lane 1,000 ft upstream of the merge. The simulation assumed 

that drivers would be 100-percent compliant with lane closure. 

Fifteen runs were simulated for each scenario. Key fndings of 

the simulations are: 

• Implementing DMC strategy produced benefts in vehicle

delay and speed at almost all demand combinations.

• When trafc demand on the minor roadway reached 1,900

vph per lane, DMC benefts became statistically and practically 

signifcant.

• DMC reduced lane changing in the merge area, thereby

increasing capacity and delaying the formation of bottlenecks. 

Microsimulation studies evaluated dynamic merge control in confgurations such as a 2-

lane freeway merging with a 3-lane freeway to form four traffic lanes. 

From Jiang, X., J. Bared, M. Maness, and D. Hale. Traffic Performance Analysis of 

Dynamic Merge Control Using Microsimulation. Transportation Research Record: Journal 

of the Transportation Research Board, No. 2484, Figure 1, p. 24, 2015. Reproduced with 

permission of the Transportation Research Board. 

IMPACT: This research represents an important frst step in 

evaluating the DMC strategy as an effective approach to reducing 

delays and congestion at freeway merge areas. 

ONGOING RESEARCH: The next phase of DMC microsimulation 

will investigate varying closing locations and varying distances 

at which drivers are warned. The next phase also will investigate 

various closed-lane compliance ratios. 

RESOURCES: Several publications resulted from this RAP 

research. They are outlined below. 

Jiang, X., Gan, Q., Bared, J., Mannes, M., & Hale, D. (2015). Traffic 

performance analysis of dynamic merge control using microsimulation. Transportation Research Record, Journal of the 

Transportation Research Board, 2484. 

Zhang, Y., Jiang, X., Haghani, A., & Huang, B. (2015). Exploring nonlinear 

efects of trafc crash determinants using a novel poisson-mixed 

multivariate adaptive regression splines model. Transportation 

Research Record, Journal of the Transportation Research Board, 2515. 

EAR PROGRAM—RESEARCH ASSOCIATES PROGRAM  |  19

Connected Highway and Vehicle System Concepts 
Human Behavior and Travel Choices 

PROJECT: Efectiveness of High-Visibility Crosswalks in Improving Pedestrian Safety 

ASSOCIATE: Tawfq Sarwar 

SCHOOL: State University of New York–University at Bufalo 

PERIOD: November 2016–September 2018 

OBJECTIVE: To analyze crashes and near-crashes using Strategic Highway Research Program 2 (SHRP 2) naturalistic driving 

study (NDS) data and evaluate the efectiveness of high-visibility crosswalks (HVCs) in improving pedestrian safety. 

ADVISER: Carol Tan, FHWA Ofce of Safety Research and Development 

SUMMARY: Tawfq Sarwar’s exploration of HVCs as a potential 

tool to improve pedestrian safety is an extension of research 

conducted under SHRP 2. The researchers for the initial project 

analyzed video data of driver behavior that was collected in two 

SHRP 2 projects—NDS and the roadway information database. 

The researchers used the data to develop statistical models for 

gauging the effectiveness of HVCs at three uncontrolled 

intersections in Erie County, NY, one of six NDS test sites. They 

defned benchmark points before each intersection based on 

predictions of when drivers could see and react to the HVCs. 

Then they examined changes in speed, acceleration, and throttle 

pedal actuation as drivers passed through the intersections, both 

before and after HVCs were installed. Sarwar took that research 

to the next level by developing similar statistical models to 

analyze data from all six NDS test sites. The other fve sites are in 

Florida, Indiana, North Carolina, Pennsylvania, and Washington. 

For more efficient and unbiased estimates of speed, acceleration, 

and throttle pedal actuation, Sarwar will develop statistical 

models that take into account correlations for each factor at the 

benchmark and crosswalk points. He plans to develop models for 

gauging the distance from a driver’s frst application of the 

brakes to an HVC and the time it takes for the vehicle to slow to 

a minimum speed value. 

IMPACT: By incorporating data from all six SHRP 2 test 

sites, Sarwar will create advanced statistical models for 

gauging how different HVC marking types and placements 

could improve pedestrian safety. The broader sampling of 

data also makes it possible to evaluate HVCs based on 

regional differences in driving behavior. Finally, Sarwar’s 

models can be used to pinpoint how far from HVCs to 

place warning signs as a prompt for drivers to slow their speed. 

ONGOING RESEARCH: Sarwar is currently continuing his research 

at the University of Buffalo. 

RESOURCES: Several publications and papers resulted from 

this RAP research. They are outlined below. 

Sarwar, M. T., Fountas, G., & Anastasopoulos, P. C. (2017). Simultaneous 

estimation of discrete outcome and continuous dependent variable 

equations: A bivariate random efects modeling approach with 

unrestricted instruments. Analytic Methods in Accident Research, 16, 

23–34. 

Sarwar, M. T., Anastasopoulos, P. C., Golshani, N., & Hulme, K. (2017). 

Grouped random parameters bivariate probit analysis of perceived 

and observed aggressive driving behavior: A driving simulation study. 

Analytic Methods in Accident Research, 13, 52–64. 

Anastasopoulos, P. C., Fountas, G., Sarwar, M. T., Karlaftis, M., & Sadek, A. 

(2017). Transport habits of travelers using new energy type modes: A 

random parameters hazard-based approach of travel distance. 

Transportation Research Part C: Emerging Technologies, 77, 516–528. 

Nahidi, S., Fountas, G., Sarvani, S., Sarwar, M. T., & Anastasopoulos, P. C. 

(2017). Project discrepancies in roadway construction and preservation: 

A statistical analysis of public–private partnership contract types in the 

US. Frontiers in Built Environment, 3, 15, DOI: 10.3389/fbuil.2017.00015. 

Sarwar, M. T., Fountas, G., Bentley, C., Anastasopoulos, P. C., Blatt, A., 

Pierowicz, J., Majka, K., & Limoges, R. (2017). Preliminary investigation 

of the efectiveness of high-visibility crosswalks on pedestrian safety 

using crash surrogates. Transportation Research Record: Journal of the 

Transportation Research Board, 2659, DOI:10.3141/2659-20. 

Sarwar, M. T., Fountas, G., & Anastasopoulos, P. C. (2017). Analysis of 

stationary and dynamic factors afecting highway accident occurrence: 

A dynamic correlated grouped random parameters binary logit 

approach. Accident Analysis and Prevention, 113, 330–340. 

Sarwar, M. T., Fountas, G., Bentley, C., Anastasopoulos, P. C., Blatt, A., 

Pierowicz, J., Majka, K., & Limoges, R. (2017). Preliminary investigation 

of the efectiveness of high-visibility crosswalks on pedestrian safety 

using crash surrogates. Presented at the 96th Transportation Research 

Board Annual Meeting, Washington, DC. 

Fountas, G., Sarwar, M. T., & Anastasopoulos, P. C. (2017). Analysis of 

stationary and dynamic factors afecting highway accident occurrence. 

Presented at the 96th Transportation Research Board Annual Meeting, 

Washington, DC. 

Golshani, N., Sarwar, M. T., & Anastasopoulos, P. C. (2017). Exploratory 

empirical analysis of measured and perceived aggressive driving 

behavior in a driving simulation environment. Presented at the 96th 

Transportation Research Board Annual Meeting, Washington, DC. 

20  |  EAR PROGRAM—RESEARCH ASSOCIATES PROGRAM 
Human Behavior and Travel Choices 

PROJECT: Data-Driven Space-Time Dependent Trafc Condition Estimation and Management 

ASSOCIATE: Lin Xiao 

SCHOOL: Hong Kong University of Science & Technology 

PERIOD: October 2015–June 2018 

OBJECTIVE: To analyze the Strategic Highway Research Program 2 (SHRP 2) and other datasets to gain critical insights into the 

spatial, temporal, and causation patterns of trafc crashes; perform targeted analyses to uncover the underlying 

relationships between crashes and level of services in diferent types of land-use environments; and develop datamining tools for identifying high-crash locations and extracting relevant crash record data for detailed further analysis. 

ADVISER: Wei Zhang, FHWA Ofce of Safety Research and 

Development 

SUMMARY: Lin Xiao conducted multi-dimensional analyses of 

datasets from SHRP 2, including the Roadway Information 

Database (RID), the Safety Pilot Dataset from Ann Arbor, MI, and 

statewide crash data from Virginia and Texas. The data he analyzed 

from the RID were primarily the geocoded statewide crash data 

from Florida, Indiana, New York, North Carolina, Pennsylvania, and 

Washington. Xiao developed tools for viewing, analyzing, and 

visualizing the large datasets. The most important tool he 

developed is 2-STEP, which reads in statewide crash data. In Step 

1, an entire State is partitioned into grids of 10 mi2

. The grids are 

ranked by crash frequency and crash cost. In Step 2, the selected 

grids are further partitioned into grids of 0.5 mi2

, and the ranking 

process is repeated. The highlighted smaller grids are the ones 

with the highest number or highest cost of crashes. Based on the 

codes written for this tool, Xiao developed over a half-dozen other 

tools. These tools can analyze diferent types of geolocated data 

(crash, trafc fo w, sp eed, et c.) an d ma ke va rious pr edictions. 

These additional tools can be used to: 

• Identify trafc bottleneck locations and the peak periods.

• Identify the dates on which weather and other large-scale

events caused signifcant changes to the daily crash frequency.

• Predict the annual crash frequency of any location based on

historic, multi-year crash data.

• Merge naturalistic driving data from the Safety Pilot data

collected in the Ann Arbor, MI, area with crash data to investigate 

the delays caused by diferent severities of crashes.

• Merge crash data with data from permanent trafc-counting

stations, and assess the impacts of crashes to speed distribution 

(further refnement of this tool can lead to efective crashdetection algorithms).

• Predict time series trends.

An illustration of the 2-STEP tool at work, counterclockwise from top: Divide the 

entire region, the State of Virginia in this case, into a grid of 10 mi2 and pick one for 

further analysis (Step 1); subdivide the highlighted grid in Step 1 into a grid of 0.5 

mi2

 (Step 2); and identify a high-crash location. 

Xiao contributed to the investigation of the relationship between 

crash severity and the level of trafc service using a neural network/ 

machine-learning approach. He collaborated with other associates 

on research into connected vehicles and artifcial intelligence. 

IMPACT: Xiao’s research makes it easier for practitioners to 

identify and extract useful information from large SHRP 2 and 

other datasets. These tools can provide the precise where, when, 

and why of trafc crashes in the identifed high-crash areas, 

which provide actionable information for decisionmakers. Safety 

projects initiated based on the above information can increase 

the return on investment signifcantly and improve systemwide 

safety. His work produced the following mathematical and 

technological tools to help achieve those goals: 

EAR PROGRAM—RESEARCH ASSOCIATES PROGRAM  |  21
Human Behavior and Travel Choices 

• 2-STEP, a tool for identifying high-crash locations based on

multi-year, statewide (or other types of regional) crash data.

• A big data approach to predicting trafc crashes for any

location in a State.

• An interactive tool for identifying trafc bottlenecks.

• An interactive tool for identifying the dates of large-scale

events that signifcantly altered daily crash patterns.

• A methodology for assessing the relationship between crash

severity and levels of trafc fow.

• Algorithms for identifying crash events based on permanent

trafc counter data.

ONGOING RESEARCH: Xiao developed a series of software 

packages for data fusion, data analysis, and data mining that 

could have applications beyond his immediate research project. 

RESOURCES: Several publications and papers resulted from this 

RAP research. They are outlined below. 

Pan, D., Silverstein, C., Xiao, L., Caamaño, A., Zhang, W., & Hamdar, S. 

(2018). Investigating the relationship between collision characteristics 

and trafc level of service through big data analytics: A case study in 

the State of Virginia. Presented at the American Society of Civil 

Engineers’ Transportation and Development International Conference, 

Pittsburg, PA. 

Zhang, W., & Xiao, L. (2018). Vulnerable road user crash patterns in Orlando. 

Presented at the 18th Chinese Overseas Transportation Association’s 

International Conference of Transportation Professionals, Beijing, 

China. 

Zhang, W., Xiao, L., Wang, Y., & Kelarestaghi, K. (2018). Big data approach 

of crash prediction. Presented at the 97th Transportation Research 

Board Annual Meeting, Washington, DC. 

Wang, P., Wu, W., Wang, L., Xiao, L., Deng, X., & Li, M. (2017). A novel 

cooperative collision avoidance model for connected vehicles. 

Transportation Research Record: Journal of the Transportation 

Research Board, 2645, DOI: 10.3141/2645-16. 

Kelarestaghi, K., Zhang, W., Wang, Y., Xiao, L., Hancock, K., & Heaslip, K. 

(2017). Impacts to crash severity outcome due to adverse weather and 

other causation factors. Advances in Transportation Studies, 43, 31–42. 

Wang, P., Yu, H., Xiao, L., & Wang, L. (2017). Online trafc condition 

evaluation method for connected vehicles based on multisource data 

fusion. Journal of Sensors, 2017, Article ID 7248189, 11 pages. 

Qu, X., Wang, S., Wang, T., Xiao, L., Yi, W., & Liu, Z. (2017). Mixed-integer 

linear programming models for teaching assistant assignment and 

extensions. Scientifc Programming, 2017, Article ID 9057947, 7 pages. 

Ren, Y., Wang, Y., Yu, G., Liu, H., & Xiao, L. (2016). An adaptive signal control 

scheme to prevent intersection trafc blockage. IEEE Transactions on 

Intelligent Transportation Systems, 18(6), 1519–1528. 

Zhao, Y., Huang, P., Xiao, L., Ma, J., Hu, J., & Wang, Y. (2017). A scalable 

short-term origin-destination estimation approach based on 

modularized network with connected vehicle technology. Presented at 

the 96th Transportation Research Board Annual Meeting, Washington, 

DC. 

Xiao, L., Wang, Y., Hu, J., & Zhao, Y. (2017). Responsive signal control with 

active connected vehicles. Presented at the 96th Transportation 

Research Board Annual Meeting, Washington, DC. 

22  |  EAR PROGRAM—RESEARCH ASSOCIATES PROGRAM 
Human Behavior and Travel Choices 

PROJECT: Operational and Safety Analyses of Alternative Intersection/Interchange Designs 

ASSOCIATE: Nopadon Kronprasert 

SCHOOL: Virginia Polytechnic Institute and State University 

PERIOD: November 2012–April 2014 

OBJECTIVE: To evaluate operational and safety impacts when implementing alternative intersection and interchange designs. 

ADVISER: Wei Zhang, FHWA Ofce of Safety Research and Development 

SUMMARY: Transportation and traffic professionals working on 

today’s highway improvement projects face daunting pressures 

from the needs of diferent stakeholders to provide safe, 

efcient, and co st-efective int ersections and int erchanges. 

FHWA recently proposed several alternative intersection and 

interchange designs to improve the safety- and mobility-related 

issues across the Nation. These new intersections and interchanges 

include displaced left-turn, median U-turn, and restricted-crossing 

U-turn intersections, as well as the double-crossover diamond

interchange. It is important to evaluate how efcient the new

designs will be and to identify the trafc co nditions th at wi ll

deliver the best cost–beneft performance. In accordance with this 

objective, Nopadon Kronprasert’s research project investigated

operational and safety measures and evaluation procedures,

analyzed proposed designs at diferent e valuation s ites, a nd

developed mathematical models for evaluating operational and

safety measures for diferent intersection and interchange designs. 

Kronprasert used microscopic trafc simulation to model

characteristics and behaviors of trafc systems and to evaluate

the performance of alternative designs. This is a cost-efective

method to compare diferent designs, predict potential impacts,

replicate real-world phenomena, and provide valuable insights

into the efects on operational and safety performance. Kronprasert 

conducted his research based on problems derived from real

projects. As part of the technical support to State departments

of transportation, he performed trafc simulation st udies of

three double-crossover diamond interchanges, three restrictedcrossing U-turn intersections, and six miniroundabout projects.

IMPACT: As of October 2014, at least one restricted-crossing Uturn and three miniroundabouts Kronprasert worked on have 

been constructed and opened to trafc. Many of the performance 

predictions stated in his research are being verifed in the feld. 

The results will help analysts understand the relationships 

between the features of alternative designs and their operational 

and safety benefts. The research will ultimately help practitioners 

to fnd the best course of action when implementing alternate 

designs and also will help highway engineers and the public 

understand the benefts and impacts. 

A screen capture of an intersection based on Nopadon Kronprasert’s 

simulation input. 

An aerial view of a two-cloverleaf highway interchange from a simulation video 

created by Nopadon Kronprasert. 

EAR PROGRAM—RESEARCH ASSOCIATES PROGRAM  |  23
Human Behavior and Travel Choices 

ONGOING RESEARCH: Wei Zhang is continuing to conduct research 

on alternative intersection and interchange designs, building on 

Kronprasert’s work. Zhang and Kronprasert are also collaborating 

on at least two more research papers. 

RESOURCES: Several publications and papers resulted from this 

RAP research. They are outlined below. 

Krause, C., Kronpraset, N., Bared, J., & Zhang, W. (2015). Operational 

advantages of dynamic reversible left-lane control of existing signalized 

diamond interchanges. Journal of Transportation Engineering, 141(5). 

Zhang, W., & Kronprasert, N. (2014). The ABCs of designing RCUTs. Public 

Roads, 78(2), 9–13. 

Zhang, W., & Kronprasert, N. (2014). Unlock DDI’s capacity potential by 

implementing relaxed bowtie, superstreet, and quadrant road design at 

adjacent signal intersections. Presented at the Second International 

Conference on Access Management, Shanghai, China. 

Zhang, W., & Kronprasert, N. (2014). Unlock diverging diamond interchange’s 

capacity potential using relaxed bowtie design at adjacent signalized 

intersection. Presented at the Transportation Research Board’s 

Alternative Intersections and Interchanges Symposium, Salt Lake City, UT. 

Zhang, W., & Kronprasert, N. (2014). Crash prediction models for rural 

restricted crossing U-turn intersections. Presented at the Transportation 

Research Board’s Alternative Intersections and Interchanges 

Symposium, Salt Lake City, UT. 

Zhang, W., & Kronprasert, N. (2014). Mini-roundabout case studies. 

Presented at the Transportation Research Board’s International 

Roundabout Conference, Seattle, WA. 

Zhang, W., Kronprasert, N., & Gustafson, J. (2014). Unclog local network 

congestion using high-capacity mini-roundabouts: A feasibility study. 

Presented at the Transportation Research Board’s 93rd Annual 

Meeting, Washington, DC. 

Lochrane, T., Kronprasert, N., Bared, J., Dailey, D., & Zhang, W. (2014). 

Determination of mini-roundabout capacity in the United States. 

Journal of Transportation Engineering, 140(10). 

Zhang, W., & Kronprasert, N. (2016). System intersections—Concepts, 

simulation studies, and potential applications. Presented at the 

International Conference on Transportation and Development 2016, 

Houston, TX. Available online: https://ascelibrary.org/doi/10.1061/ 

9780784479926.020. 

Zhang, W., & Kronprasert, N. (2014). Unlock DDI’s capacity by re-routing 

left-turns at nearby intersections. Presented at the Conference on 

Access Management Theories and Practices, Shanghai, China. Available 

online: https://ascelibrary.org/doi/10.1061/9780784413869.020. 

24  |  EAR PROGRAM—RESEARCH ASSOCIATES PROGRAM 
.... I 

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Human Behavior and Travel Choices 

PROJECT: Integrating Driving Simulation and Other Behavioral Data: Assessment of Driver Behavior and Performance 

ASSOCIATE: Alicia Romo 

SCHOOL: The University of Texas at El Paso 

PERIOD: September 2013–July 2015 

OBJECTIVE: To develop methods that will use data from various sources, such as driving simulator experiments, crash 

databases, and naturalistic driving studies, to gain comprehensive understanding about road-user behaviors. 

ADVISER: C. Y. David Yang, FHWA Ofce of Safety Research and Development

SUMMARY: A high percentage of transportation incidents and 

vehicle crashes are caused by human errors. As a result, it is 

important to continue investing in research resources to gain a 

comprehensive understanding of human errors and to try to 

answer the question, “Why do drivers and travelers do what they 

do?” A number of diferent d atasets h ave r ecently b ecome 

available to analyze human errors; however, these datasets point 

in diferent directions within diferent areas of interaction. Alicia 

Romo’s research project is focused on fnding methods to combine 

data from diferent sources to gain better understanding about 

road-user behavior. During the frst year, Romo conducted a 

comprehensive literature review and summarized information 

from more than 100 technical journals and reports about various 

methods to study road-user behavior and types of available 

behavioral data. Based on the information from this literature 

review, Romo has since developed a framework to categorize 

The relationship between research methods and impacting factors. Note: There 

are fve empirical factors that can be used to evaluate the quality of data and 

the analysis performed. The fve factors are: driving states, risk, level of control, 

measurements, and validity. The fve factors presented in this fgure explain the 

similarities, diferences, advantages, and disadvantages among the diferent 

research methods. 

behavior data from various sources, such as crash databases, 

driving simulator experiments, feld test vehicle studies, and 

naturalistic driving studies. Romo’s research will show the beneft 

of using information from multiple data sources to study 

behavioral issues instead of relying on just one data source. 

IMPACT: This research project is expected to demonstrate one 

or more methods of using data from various sources to better 

understand road-user behavior. The concept of combining and 

using behavioral data from multiple sources is relatively new, 

and this work will pave the way for others to follow. Results from 

this project will clearly show many benefts of combining data to 

better understand behavior issues. Integration of human 

behavior collected using diferent methods could lead to faster 

design and testing of safety countermeasures and new geometric 

designs, resulting in fewer crashes and potentially saved lives. 

The integration of diferent human behavior data also could 

provide safe and efective methods for studying and testing 

emerging connected-vehicle and automation technologies. 

ONGOING RESEARCH: The second year of Romo’s 

research concentrated on demonstrating applicability of 

fusing data from sources, such as driving simulator 

experiments and naturalistic driving studies, to gain an indepth understanding about certain behaviors. 

RESOURCES: Several publications resulted from this 

RAP research. They are outlined below. 

Romo, A., Mejia, B., & Yang, C. Y. D. (2014). Utilizing various data sources for 

surface transportation human factors research: workshop summary 

report (Publication No. FHWA-HRT-14-077). FHWA Turner–Fairbank 

Highway Research Center, McLean, VA. Available online: 

http://www.fhwa.dot.gov/advancedresearch/pubs/14077/index.cfm. 

Romo, A., Yang, C. Y. D. (2015). The science and art of putting drivers 

under the microscope. Public Roads, 78(5). Federal Highway 

Administration Pub. No. FHWA-HRT-15-003. Available online: 

https://www.fhwa.dot.gov/publications/publicroads/15marapr/04.cfm. 

EAR PROGRAM—RESEARCH ASSOCIATES PROGRAM  |  25
Human Behavior and Travel Choices 

PROJECT: Operational and Safety Analyses of Alternative Intersection/Interchange Designs 

ASSOCIATE: Yubian Wang 

SCHOOL: University of Texas at El Paso 

PERIOD: October 2014–September 2017 

OBJECTIVE: To conduct analytical and simulation studies to fnd suitable and implementable methods of analyzing innovative 

alternative intersection and interchange designs. 

ADVISER: Wei Zhang, FHWA Ofce of Safety Research and Development 

SUMMARY: Researchers and practitioners in the United States 

are exploring ways to improve highway safety and address 

traffic capacity issues in part by implementing innovative 

designs at intersections and interchanges. Yubian Wang spent 3 

years at the TFHRC researching alternative intersection designs, 

including diverging diamond interchanges (DDIs), continuous 

fow intersections (CFIs), and restricted crossing U-turn 

intersections (RCUTs). Alternative intersections/interchanges are 

designs aimed at reducing congestion and improving safety by 

reducing traffic conficts rather than adding lanes. These designs 

take advantage of site-specifc traffic demand patterns by 

introducing auxiliary intersections at strategic locations and 

rerouting certain traffic movements. The traffic conficts at the 

primary intersection can be reduced by 50 percent or more, and 

some previously conficting movements become compatible and 

can move simultaneously. Alternative designs typically eliminate 

the protected left-turn phase and increase effective green-light 

time for other traffic movements, which usually translate into 

more capacity with minimal or no increases in the intersections’ 

right-of-way. In fully developed areas, alternative designs are 

often the only effective and fscally viable solution to congestion 

and safety problems that plague the Nation’s roadway network. 

Wang’s work flled some critical gaps in this area and has been 

applied to solve real work problems. She reviewed relevant 

literature to synthesize best practices for DDI, CFI, and RCUT 

designs. The review covered operational and safety performance 

of the designs, their challenges and limitations, and lessons 

learned from building and operating them. She also traveled to 

alternative intersection sites in Haymarket, Norfolk, and Vienna in 

Virginia to see frsthand how diferent t ypes o f f eld d ata a re 

collected and used to assess diferent p erformance a spects o f 

alternative designs. Wang expanded the research work of a 

previous postdoctoral fellow and helped deliver critical technical 

assistance to many State and local agencies. In 2015, the Georgia 

Department of Transportation (GDOT) decided to design a future 

DDI at I 285 and Camp Creek Parkway in Atlanta. Wang took a 

leading role in performing the simulation analysis to evaluate the 

impacts of diferent a lternative d esigns a nd s ignal-timing 

strategies. Over 4 months, the research team (including Wang) 

presented the simulation results in multiple Web conferences, 

GDOT staf provided feedback, and the simulation models were 

refned to make the simulated conditions closer to feld conditions. 

Wang thoroughly analyzed the before- and after-crash data of 

more than 150 modern roundabouts in 6 States, and she developed 

crash-modifcation factors for single-lane and multi-lane 

roundabouts converted from previous stop- or signal-controlled 

intersections. This is one of the largest number of roundabouts 

included in a single study. Wang manually examined the satellite 

images of each site by year to verify if the previous type of trafc 

control device was coded correctly, sorted through the crash 

records and organized them into unifed formats, and analyzed 

the data using various statistical models. 

Wang also contributed to big data research in which she helped 

develop models to predict the frequency and economic cost of 

traffic crashes in a region. 

IMPACT: DDIs, CFIs, and RCUTs can reduce the number of traffic 

signal phases and confict points, but these designs are still relatively 

new to most trafc en gineers. Wa ng’s wo rk he lped co nvince 

practitioners to implement alternative intersection designs at 

more suitable locations. Her work with GDOT provides insight into 

how diferent geometric designs and signal-timing strategies could 

26  |  EAR PROGRAM—RESEARCH ASSOCIATES PROGRAM 
Human Behavior and Travel Choices 

improve the level of service. A congested signal intersection 

sitting next to a high-capacity DDI would limit the capacity 

utilization of the DDI. Wang helped advance the state of the art in 

solving this class of problem. Her analysis of roundabouts flled a 

critical gap in safety impacts of converting existing stop- or 

signal-controlled intersections into yield-controlled modern 

roundabouts. 

RESOURCES: Several publications and papers resulted from this 

RAP research. They are outlined below. 

Zhang, W., Xiao, L., Wang, Y., & Kelarestaghi, K. (2018). Big data approach 

of crash prediction. Presented at the 97th Transportation Research 

Board Annual Meeting, Washington, DC. 

Kelarestaghi, K., Zhang, W., Wang, Y., Xiao, L., Hancock, K., & Heaslip, K. 

(2017). Impacts to crash severity outcome due to adverse weather and 

other causation factors. Advances in Transportation Studies, 43, 31–42. 

Wang, Y., Zhao, Y., Zhang, W., Bared, J., & Huang, P. (2017). Signal timing 

strategies for Georgia’s frst in-house designed DDI. Proceedings for 

the 5th Urban Street Symposium. 

Wang, Y., & Cheu, R. L. (2016). Operational impacts of implementing 

auxiliary lanes at isolated freeway of-ramps. ITE Journal, 86, 36–41. 

Wang, Y., & Zhang, W. (2016). Analysis of roadway and environmental 

factors afecting trafc crash severities. Transportation Research 

Procedia, 25, 2124–2130. 

Hancock, K., Zhang, W., Sardar, H., & Wang, Y. (2016). A two-step geo-grid 

screening process to identify locations for safety improvements. Advances 

in Transportation Studies: An International Journal, special issue, 2, 89–102. 

Zhang, W., Hancock, K., Wang, Y., & Sardar, H. (2015). Estimate economic 

losses due to roadway crashes. Proceedings of the 2015 Road Safety 

and Simulation International Conference. 

Zhang, W., Hancock, K., Wang, Y., & Sardar, H. (2016). Prioritize safety 

projects with confdence using two-step spatial screening. Proceedings 

for ASCE International Conference on Transportation & Development. 

EAR PROGRAM—RESEARCH ASSOCIATES PROGRAM  |  27
 

Human Behavior and Travel Choices 

PROJECT: Utilizing Naturalistic Driving Data and Highway Safety Information System to Advance Highway Crash Data 

Modeling Concepts and Methods 

ASSOCIATE: Kun-Feng Wu 

SCHOOL: Pennsylvania State University 

PERIOD: July 2012–June 2013 

OBJECTIVE: To advance safety analysis using surrogate safety measures and improve the evaluation of 

intervention efectiveness. 

ADVISER: Craig P. Thor, FHWA Ofce of Safety Research and Development 

SUMMARY: Kun-Feng Wu’s research project builds on 40 years of 

research concerning the development of crash surrogates for 

assessing trafc safety. The term crash surrogate refers to a crash 

or near-crash event, defned in this project by a set of driver or 

event attributes, driving environment, and kinematic variables. 

Researchers use crash surrogates because crashes are rare events, 

making it hard to draw statistically valid conclusions about 

contributing factors. Surrogate event counts can be used to predict 

the expected number of crashes and identify sites with promise for 

improvement by knowing the number of surrogate events at each 

intersection. Wu investigated a sequence of statistical tests with 

the overall goal of validating surrogate events and facilitating their 

use in enhanced safety analyses. Wu used raw naturalistic driving 

data, including vehicle kinematic, video, and location information, 

to produce sets of specifc conditions that identify crashes and 

near crashes (i.e., surrogate events). Wu tested the procedure on a 

small, 100-car naturalistic driving study dataset, conducted by the 

Virginia Tech Transportation Institute, with successful results. A 

second validation procedure compared these results with the 

number of crashes observed in HSIS data, a multistate database 

that contains crash, roadway inventory, and trafc volume data for 

a select group of States. Wu’s research extends research already 

completed in the joint use of crash events and surrogate events in 

a structured framework. His research project specifcally compared 

surrogate analyses of countermeasure efectiveness and sites with 

improvement potential to comparable HSIS studies. Wu applied 

the same methods to evaluate the Integrated Vehicle-Based Safety 

System dataset (an initiative designed to develop and feld test an 

integrated safety system on light vehicles and commercial trucks). 

In addition, Wu expanded the procedures to include diagnostic 

analytical techniques borrowed from medical science. These 

statistical methods allow for a more accurate assessment of the 

presence of surrogate events. 

IMPACT: Specifc conditions for defning surrogate events could 

be further tested and studied through driving performance 

assessment and may ultimately lead to improved understanding of 

inappropriate driving behaviors, driver responses, roadway design, 

and operational defciencies. In addition, crash surrogate studies 

could ultimately reduce the time needed to develop a sufcient 

sample size for analysis. These studies would enable researchers to 

develop models with greater prediction precision and understand 

the factors that contribute to crashes. Decreasing the time and 

increasing the precision of factors that contribute to crashes allow 

faster development and implementation of better countermeasures, 

thereby reducing crashes and potentially saving lives. 

Safety-related 

Event 

Surrogate Event/ 

Crash Symptom 

Crash 

© Kun-Feng Wu 

Near Crash 

Disease 

Begins 

Start of 

Etiology Process 

Clinical 

Symptoms 

Outcome of 

Disease 

Induction Promotion Expression 

A schematic that relates the crash progression process to the etiological process of disease progression. 

28  |  EAR PROGRAM—RESEARCH ASSOCIATES PROGRAM 
-· 

■ ■ ■ ■ ■ ■ ■ ■ ■ ■ 

■ ■ ■ ■ ■ ■ ■ ■ ■ ■ 

Human Behavior and Travel Choices 

Case 23 (Crash=0) Case 34 (Crash=1) 

-100 

Symp. A 

Measurement Duration (Unit 0.1 Seconds) 

Symp. D Symp. E Symp. F Symp. B 

-50 0 50 100 150 200 -100

Symp. A 

Measurement Duration (Unit 0.1 Seconds) 

Symp. D Symp. E Symp. F Symp. B 

-50 0 50 100 150 200 

© Kun-Feng Wu 

Case 49 (Crash=0) Case 52 (Crash=0) 

-100 -50 0 50 100 150 200 -100 -50 0 50 100 150 200 

Measurement Duration (Unit 0.1 Seconds) Measurement Duration (Unit 0.1 Seconds) 

Symp. A Symp. D Symp. E Symp. F Symp. B Symp. A Symp. D Symp. E Symp. F Symp. B 

The crash symptoms (horizontal lines) as they compare to manual identifcation of a crash-related event (vertical red lines). This exhibits the potential of 

surrogate measures to predict safety-related events based on kinematic and environmental factors. 

RESOURCES: The papers that resulted from this RAP research are Wu, K. F., & Thor, C. (2015). Method for the use of naturalistic driving study 

data to analyze rear-end crash sequences. Transportation Research outlined below. 

Record, Journal of the Transportation Research Board, 2518(2518):27– Wu, K. F., Thor, C., & Ardiansyah, M. N. (2016). Identify sequence of events 36. likely to result in severe crash outcomes. Accident; Analysis and 

Prevention, 96:198–207. 

EAR PROGRAM—RESEARCH ASSOCIATES PROGRAM  |  29
Technology for Assessing Performance 

PROJECT: Air-Coupled Acoustic and Ultrasonic Arrays for Concrete Non-Destructive Test Methods 

ASSOCIATE: Hajin Choi 

SCHOOL: University of Illinois 

PERIOD: January 2017–February 2018 

OBJECTIVE: To develop air-coupled acoustic and ultrasonic arrays for non-destructive evaluation of concrete damage or property. 

ADVISER: Hoda Azari, FHWA Ofce of Infrastructure Research and Development 

SUMMARY: The large size of concrete structures, the time 

required to adequately inspect them, and the rough texture of 

the material pose challenges to the use of acoustic nondestructive test (NDT) methods for condition assessment of 

highway infrastructure. This research project by Hajin Choi 

aimed to develop an air-coupled acoustic and ultrasonic array 

as a contact-free NDT alternative to the conventional acoustic 

technology. Air-coupled sensors measure leaky Rayleigh 

waves without physical contact on the concrete being tested. 

The research encompassed four tasks. First, Choi developed 

an air-coupled acoustic array for two testing methods, impactecho (IE) and ultrasonic waves (USW). Both methods generate 

stress waves and measure how they refect of the concrete to 

identify faws in the material. After developing the air-coupled 

system, Choi evaluated the system by collecting signal data 

from a test sample in FHWA’s specimen library. He evaluated 

the speed of data collection, the signal-to-noise ratio, and the 

accuracy of test results. Next, Choi analyzed USW from the 

hybrid test setup and used the data to develop a linear formula 

for predicting various types of concrete damages. For the fnal 

task of the project, Choi applied the new air-coupled acoustic 

array and NDT parameters to a robotic platform for inspecting 

bridge decks to evaluate their practical use, and he described 

the tests, results, and analysis in a fnal report. 

IMPACT: The research illustrates the potential of air-coupled 

acoustic arrays to increase the speed of conventional NDT for 

condition assessment of highway infrastructure. The possible 

feld uses include IE and USW testing. 

RESOURCES: Several publications and papers resulted from this 

RAP research. They are outlined below. 

Choi, H., & Azari, H. (2017). Guided wave analysis of air-coupled impact-echo 

in concrete slab. Computers and Concrete, 20(3), 257–262. 

Choi, H., Sadegh, S., & Azari, H. (2017). The improvement of impact-echo 

method using hybrid system and guided wave analysis. Proceedings in 

International Conference on Maintenance and Rehabilitation of 

Constructed Infrastructure Facilities. 

Choi, H., Sadegh, S., & Azari, H. (2017). NDE application of air-coupled array 

for thickness of concrete slab. Proceedings in International Ultrasonics 

Symposium. 

Choi, H., Sadegh, S., & Azari, H. (2017). Application of air-coupled ultrasonic 

array system and f-k domain analysis for delamination-like defect 

detection in bridge deck. Presented at the IEEE International Ultrasonic 

Symposium, Washington, DC. 

Choi, H., Sadegh, S., & Azari, H. (2017). The improvement of impact-echo 

method using hybrid system and guided wave analysis. Presented at the 

International Conference on Maintenance and Rehabilitation of 

Constructed Infrastructure Facilities, Seoul, Korea. 

30  |  EAR PROGRAM—RESEARCH ASSOCIATES PROGRAM 
Technology for Assessing Performance 

2SO 

O __ -•. 1 I 1111... . ... ~ ; ~ ; ; 

PROJECT: Prediction of Pavement Temperature Profles Using Surface Temperatures: An Analytical Approach With Model 

Validation Based on Long-Term Pavement Performance Data 

ASSOCIATE: Dong Wang 

SCHOOL: University of Illinois at Urbana–Champaign 

PERIOD: June 2011–May 2013 

OBJECTIVE: To derive and feld-validate an easily implementable algorithm for predicting temperature profles in paving 

materials. 

ADVISER: Yan “Jane” Jiang, FHWA Ofce of Infrastructure 

Research and Development 

SUMMARY: The mechanical properties of paving materials are 

usually temperature-dependent, but to accurately back-calculate 

the elastic moduli of pavement layers (i.e., the pavement’s 

resistance to being deformed elastically when a force is applied to 

it), time-dependent pavement temperature must be known. 

Knowing the temperature profle allows researchers to better 

characterize the properties of paving materials and predict 

pavement responses under trafc an d en vironmental lo adings. 

Dong Wang’s research project investigated a new method for 

predicting time-dependent pavement temperature profles with 

limited inputs. There are currently three main methods for 

predicting temperature profles: statistics-based models, 

numerical, and analytical approaches. These existing methods 

require large databases of climatic, meteorological, and 

geographical data and several other inputs to predict temperatures 

for the algorithms to operate efectively. Current pavement-testing 

methods do not easily obtain the required climatic data; thus, 

these algorithms are subsequently limited in their ability to predict 

pavement temperature profles. Wang focused his research efort 

on infrared pavement surface temperature data that can be easily 

obtained during pavement testing. This improved approach makes 

it possible to develop an entirely new algorithm for predicting a 

time-dependent pavement temperature profle that requires very 

limited inputs when compared with previous algorithms. The only 

inputs needed for this new method are infrared surface 

temperatures, initial pavement temperature profle, pavement 

geometry, and thermal properties of layer materials. Most 

Histogram of asphalt pavement subsurface temperature diference (predicted 

(Tp

)-measured (Tm) temperature diference). 

important, unlike previous methods, no climatic data are required. 

To validate the new algorithm, when there are so many diferent 

types of pavement structures across regions with varied climatic 

conditions, an extremely large temperature dataset is required. To 

meet this requirement, Wang used data from the Long-Term Pavement 

Performance (LTPP) Program database for model validation. 

IMPACT: Wang’s research is expected to greatly beneft feld 

engineers in characterizing pavement temperature for the purpose 

of analyzing and interpreting testing data. In addition, it could lead 

to high savings on pavement evaluation costs. 

RESOURCES: Several publications and papers resulted from 

this RAP research. They are outlined below. 

Wang, D. (2013). Prediction of asphalt pavement temperature profle during 

FWD testing: A simplifed analytical solution with model validation 

based on LTPP data. Journal of Transportation Engineering, 139(1), 109–113. 

Wang, D. (2012). Analytical approach to predict temperature profle in a 

multilayered pavement system based on measured surface temperature 

data. Journal of Transportation Engineering, 138(5), 674–679. 

Wang, D. (2013). Simplifed analytical approach to predict asphalt pavement 

temperature. Journal of Materials in Civil Engineering, 27(12). 

Wang, D. (2013). Prediction of asphalt pavement temperature profle 

during FWD testing: simplifed analytical solution with model validation 

based on LTPP data. Journal of Transportation Engineering, 139(1). 

Wang, D. (2012, July 5–7). Prediction of time-dependent temperature 

profle in a slab. Paper presented at the Third Advanced Workshop on 

Innovations and Modeling for Sustainable and Resilient Concrete 

Pavements, Quebec, Canada. 

Wang, D. (2013, January 13–17). Assessing BELLS3 equation in predicting 

asphalt layer temperature profle based on the latest LTPP FWD 

temperature data. Paper presented at the 92nd Transportation Research 

Board Annual Meeting, Washington, DC. 

Wang, D. (2013, January 13–17). Simplifed analytical approach to predict 

temperature profle within a PCC slab during FWD testing. Paper 

presented at the 92nd Transportation Research Board Annual Meeting, 

Washington, DC. 

Wang, D. (2012, January 22–26). Model validation based on LTPP data to 

predict asphalt temperature profle. Paper presented at the 91st 

Transportation Research Board Annual Meeting, Washington, DC. 

Wang, D. (2012, January 22–26). Prediction of temperature profle in a 

multilayered pavement system using measured surface temperature 

data: An analytical approach. Paper presented at the 91st Transportation 

Research Board Annual Meeting, Washington, DC. 

EAR PROGRAM—RESEARCH ASSOCIATES PROGRAM  |  31
32  |  EAR PROGRAM—RESEARCH ASSOCIATES PROGRAM 
EAR PROGRAM—RESEARCH ASSOCIATES PROGRAM  |  33

Getting Involved with the EAR Program 

To take advantage of a broad variety of scientifc and engineering discoveries, the EAR 

Program involves both traditional stakeholders (State department of transportation 

researchers, University Transportation Center researchers, and Transportation Research 

Board committee and panel members) and nontraditional stakeholders (investigators 

from private industry, related disciplines in academia, and research programs in other 

countries) throughout the research process. 

Learn More 

For more information, see the EAR Program website at https://highways.dot.gov/ 

research/exploratory advanced research. The site features information on research 

solicitations, updates on ongoing research, links to published materials, summaries of 

past EAR Program events, and details on upcoming events. 
34  |  EAR PROGRAM—RESEARCH ASSOCIATES PROGRAM 

U.S. Department 

of Transportation 

Federal Highway 

Administration 

EAR Program Results 

The EAR Program strives to develop partnerships with the public and private 

sectors because the very nature of the EAR Program is to apply ideas across 

traditional felds of research and stimulate new approaches to problemsolving. 

The program bridges basic research (e.g., academic work funded by National 

Science Foundation grants) and applied research (e.g., studies funded by State 

departments of transportation). In addition to sponsoring EAR Program 

projects that advance the development of highway infrastructure and 

operations, the EAR Program is committed to promoting cross-fertilization 

with other technical felds, furthering promising lines of research, and 

deepening vital research capacity. 

EXPLORATORY ADVANCED RESEARCH

FHWA-HRT 18-061 

HRTM-30/01-19(1M)E