PUBLIC ROADS

www.fhwa.dot.gov Summer 2021

Michigan DOT’s Unmanned 

Surface Vehicles for 

Monitoring Bridge Scour

Also in this issue: 

Using Technology Transfer to Improve SuperpaveTM Design

Launching Careers with the Research Associateship Program

Improving Pavement Sustainability Through Aggregates Research 
Summer 2021 | Vol. 85, No. 2

The Michigan Department of 

Transportation’s Unmanned Surface 

Vehicles for Monitoring Bridge Scour 

PAGE 7

FEATURES

4 Tech Transfer Success: How the DAV 

Improved SuperpaveTM Design

by Mary Huie, Thomas Harman, and Eileen S. Nelson

The Dynamic Angle Validation (DAV) kit ensures 

uniformity and consistency between gyratory compactors 

in asphalt testing. Here’s how it came about.

7 Monitoring Scour Using Unmanned Vehicle Technology

by Ralph Pauly and Chad Skrocki

Michigan DOT researched the use of unmanned surface vehicles 

for bridge scour observation to improve the safety of inspectors 

and transportation systems users during and after flood events.

10 CARMASM: Maritime Administration CDA 

Development and Testing 

by Hyungjun Park, Kirk Claussen, Lindsey Grooms, 

Katie Blizzard Piskai, and Ed Leslie

Can applying cooperative driving automation (CDA) systems 

increase efficiency and safety and decrease emissions in a port 

environment? The CARMA Program’s testing aims to find out.

13 How 10 States Use, Evaluate, and Implement 

Nondestructive Evaluation Technology 

by Hoda Azari

State DOTs are adopting nondestructive evaluation 

(NDE) techniques to manage pavement and 

bridge deck maintenance and repairs. 

23 Former Research Associates Find Success

by Jim Shurbutt

FHWA’s Research Associateship Program helps participants 

launch their careers—sometimes with FHWA itself.

26 Looking to Aggregates to Improve Pavement Sustainability

by Richard Meininger, Heather Dylla, and Jack Youtcheff

FHWA is conducting research, developing tools, and gathering 

data to improve how aggregate materials are sourced, planned, and 

used in sustainable pavement construction and maintenance.

PAGE 13 

© Colorado DOT.

DEPARTMENTS

Guest Editorial ..................................................1

Innovation Corner ..........................................2

Hot Topic ..........................................................3

Along the Road ..............................................34

Internet Watch ..............................................36

Training Update .............................................37

Communication Product Updates ..............38

COVERS and ABOVE—Michigan DOT is using an unmanned 

surface vessel to supplement its scour inspections on bridges.

© 2021 Michigan Department of Transportation Photo Unit.
WWW.FHWA.DOT.GOV | 1

U.S. Department of Transportation

Federal Highway Administration

U.S. Department of Transportation

Pete Buttigieg, Secretary

Federal Highway Administration

Stephanie Pollack, Acting Administrator

Office of Research, Development, and Technology

Kelly Regal, Associate Administrator 

Shana Baker, Director, Office of Corporate Research, 

Technology, and Innovation Management

Maria Romstedt, Editor-in-Chief

Lisa A. Shuler, Distribution Manager

Editorial Board: 

T. Everett, T. Hess, H. Kalla, M. Knopp, A. Lucero, 

G. Shepherd, C. Walker 

Editorial Contractor:

Arch Street Communications (ASC), 

Publication Management 

N. Madonick, A. Martinez, K. Vangani, C. Ibarra

Editorial Subcontractor:

ICF, Editorial 

C. Boris, A. Kozicharow

Design Contractor:

Schatz Strategy Group, Layout and Design 

M. Mitchell, R. Nemec, C. Williams

Public Roads (ISSN 0033-3735; USPS 516-690) is published 

quarterly by the Office of Research, Development, and 

Technology, Federal Highway Administration (FHWA), 6300 

Georgetown Pike, McLean, VA 22101-2296. The business and 

editorial office of Public Roads is located at the McLean address 

above. Phone: 202–493–3375. Fax: 202–493–3475. Email: 

lisa.a.shuler@dot.gov. Periodicals postage paid at McLean, VA, 

and additional mailing offices (if applicable).

POSTMASTER: Send address changes to 

Public Roads, HRTM-20, FHWA, 

6300 Georgetown Pike, McLean, VA 22101-2296.

Public Roads is sold by the Superintendent of Documents, U.S. 

Government Printing Office, Washington, DC 20402. Requests 

for subscriptions should be sent directly to New Orders, 

Superintendent of Documents, P.O. Box 979050, St. Louis, MO 

63197-9000. Subscriptions are available for 1-year periods. Paid 

subscribers should send change of address notices to the U.S. 

Government Printing Office, Claims Office, Washington, DC 

20402.

The electronic version of Public Roads can be accessed through 

the Turner-Fairbank Highway Research Center home page 

(https://highways.dot.gov/research).

The Secretary of Transportation has determined that the 

publication of this periodical is necessary in the transaction of 

the public business required by law of this department.

All articles are advisory or informational in nature and should not 

be construed as having regulatory effect.

Articles written by private individuals contain the personal views 

of the author and do not necessarily reflect those of FHWA.

All photographs are provided by FHWA unless otherwise 

credited.

Contents of this publication may be reprinted, provided credit is 

given to Public Roads and the authors.

For more information, representatives of the news media should 

contact FHWA’s Office of Public Affairs at 202–366–0660.

Recommended citation: Federal Highway Administration, 

Public Roads, Summer 2021 (Washington, DC: 2021) 

https://doi.org/10.21949/1521635

NOTICE

This document is disseminated under the sponsorship of the 

U.S. Department of Transportation in the interest of information 

exchange. The U.S. Government assumes no liability for the use 

of the information contained in this document. This document 

does not constitute a standard, specification, or regulation. 

The U.S. Government does not endorse products or manufac

turers. Trademarks or manufacturers’ names appear in this 

document only because they are considered essential to the 

objective of the document; they are included for informational 

purposes only and are not intended to reflect a preference, 

approval, or endorsement of any one product or entity. 

-

GUEST EDITORIAL

The Road to Technology Transfer

Source: FHWA.

We’ve been in the innovation and technology transfer game for more than 70 years at the 

Turner-Fairbank Highway Research Center. Over 

that time, we’ve turned scientific discoveries and 

technological breakthroughs into products that 

transform entire industries. One example of tech

nology transfer (T2) success is how the Dynamic 

Angle Validation (DAV) kit improved SuperpaveTM 

design. The gyratory compactor dynamic angle 

measuring device was developed by the Federal 

Highway Administration in partnership with its 

equipment partners.

-

The creation of the angle measuring device 

spurred competitors to develop similar devices. 

The invention of the dynamic angle measuring device has dramatically changed 

the practice of asphalt testing by producing more consistent test results between 

laboratories. Most transportation departments and asphalt suppliers are now using 

gyratory compactors to verify the volumetric data and compaction consistency. For 

more information, see “Tech Transfer Success: How the DAV Improved Superpave 

Design” on page 4 of this issue of Public Roads.

FHWA’s T2 activities include direct technical and financial assistance, training, 

peer exchanges, collaboration with industry groups to disseminate knowledge and 

information, and evaluation of deployment methods to determine effectiveness, 

assess needed improvements, and document outcomes. FHWA uses a series of 

successful T2 venues including Every Day Counts (EDC), the Accelerated Inno

vation Deployment Demonstration program, the Accelerating Market Readiness 

program, and the State Transportation Innovation Councils, a State-based innova

tion deployment approach. EDC is a State-based model that identifies and rapidly 

deploys proven, yet underutilized innovations to shorten the project delivery 

process, enhance roadway safety, reduce traffic congestion, and integrate automa

tion. The EDC program has made a significant positive impact in accelerating 

the deployment of innovations and in building a culture of innovation within the 

transportation community.

-

-

-

Key T2 stakeholders include State departments of transportation and local agen

cies, Federal land management agencies, Tribal governments, and industry groups. 

These stakeholders are often the intended audiences for the research deployment 

outputs. The Local and Tribal Technical Assistance Program centers and other 

deployment programs play a critical role in T2 activities with these stakeholders. 

FHWA markets products and demonstrates to these stakeholders that the FHWA 

research products (such as ultra-high performance concrete and diverging diamond 

interchanges) are valuable, practical, and constitute best practices. For example, the 

FHWA-patented in-situ scour testing device (ISTD) was piloted in 19 States and 

is now being improved based on the lessons learned from the pilots. The ISTD is a 

field testing device used to determine the scour-depth potential of soils relied upon 

to support structural foundations placed in flowing water.

-

As I mentioned, we’ve been in the business of innovation and T2 for a long 

time, and we’re still at it today. To paraphrase Acting Administrator Stephanie 

Pollack’s statement in the Spring issue of Public Roads, FHWA has some of the 

world’s most innovative road and bridge engineering and planning expertise, and 

access to important and actionable data. It is the perfect place to lead in solving 

some of the most difficult transportation challenges. Thus, the mission of FHWA’s 

T2 program is to ensure that innovations developed for the U.S. transportation 

system are broadly available to all levels of the government and the general public—

maximizing the benefit to the Nation.

Dr. Kelly Regal

Associate Administrator for Research, 

Development, and Technology

Director, Turner-Fairbank Highway Research Center

Federal Highway Administration
2 | PUBLIC ROADS | SUMMER 2021

INNOVATION CORNER 

The New FHWA Office Is a HIT!

by AMY LUCERO

Source: FHWA.

I

t is my great pleasure to introduce you to the new Office of 

Transportation Workforce Development and Technology Deploy

ment. If you’re wondering what this has to do with innovation, the 

answer is A LOT!

-

The Office of Transportation Workforce Development and 

Technology Deployment will be the Federal Highway Administra

tion’s conduit to a broad network of external partners. It provides 

the highway transportation community with world-class subject 

matter experts, resources, and innovative technologies and practices 

all under one organization. It leverages external relationships 

with other government agencies, industry, foreign partners, and 

academia to provide FHWA partners access to innovative transpor

tation solutions.

-

-

While the new office name is a mouthful, we refer to the new 

team internally as HIT—a nod to Innovation and Technology. 

This new organization brings together two offices that have tradi

tionally been leaders in workforce development, innovation, and 

technology deployment: the Office of Technical Services and the 

Office of Innovative Program Delivery. Together, this team will 

achieve several outcomes: (1) create efficiencies and enhance inno

vation and collaboration; (2) centralize formal technical assistance, 

training, workforce development, and implementation support for 

transportation practitioners; and (3) develop and manage work

force opportunities for the practitioners of the future.

-

-

-

Creating efficiencies. In HIT, the development and delivery 

of training courses will happen under one roof, fostering closer 

collaboration across the training and delivery aspects. The new 

structure adds efficiency and cohesiveness and ensures that the 

needs of all audiences—States, localities, Tribes, Federal lands 

management agencies, and industry partners—are met. HIT 

also brings together the two key teams behind the Every Day 

Counts program and other innovation initiatives, so that innova

tion program development and implementation are more closely 

linked. The new structure centralizes all primary innovation and 

technology deployment functions and maximizes the opportunity 

for collaboration and better coordination. Internally, HIT supports 

the FHWA workforce with training and technical assistance on 

essential collaboration tools and techniques, technical topics, and 

key FHWA initiatives.

-

Centralizing support. The new office merges all training, 

workforce development, technical assistance, and implementation 

support, regardless of the customer. This is particularly supportive 

when a transportation partner needs a solution that incorporates 

several of these activities. An initial call for technical assistance on 

a safety issue may evolve into assistance with deploying a proven 

safety countermeasure, and then lead to training on Road Safety 

Fundamentals. Now, customers can access their needed technical 

assistance, technology deployment, and training with one phone 

call. Within HIT, staff are well-positioned to respond to iterative 

and evolving partner requests.

Developing and managing workforce opportunities. The new 

structure facilitates closer connections and shared goals. Programs 

such as the Highway Construction Workforce Program can be 

developed in parallel with State and local partners (through the 

Local Technical Assistance Program) who provide essential input 

into future skillset needs. And these activities will be enhanced 

through their tie to the National Highway Institute. This connec

tivity results in programs that can best address the needs of the 

future highway workforce.

-

I’m excited about our new organization, and I hope you are too. 

We’re better together, and our customers will see the fruits of this 

great collaboration. All of us in the new FHWA Office of Trans

portation Workforce Development and Technology Deployment 

(the HIT Team) look forward to partnering with you on your 

workforce development, technology deployment, and innovation 

needs. You’ll still find the same great staff that you’ve worked with 

before, and now our combined resources are positioned to serve 

you even more effectively. Please reach out to us and let us know 

how we can support you.

-

AMY LUCERO is FHWA’s Associate Administrator for the Office of Transporta

tion Workforce Development and Technology Deployment.

-

The lobby of the EDC Virtual Summit gave attendees access to a range of content, 

including panel presentations, online posters, and office hours sessions. 

Source: FHWA.
WWW.FHWA.DOT.GOV | 3

Managing Curbside Productivity

by JEFF A. PRICE

I

ncreasing use of curb space offers challenges in considering acces

sibility for all users, accommodating increased delivery access, 

and optimizing curb productivity.

-

The Nation’s roadways now serve an ever-growing set of users: 

vehicular traffic, pedestrians, public transportation riders, trans

portation network services, freight and delivery drivers, and various 

micromobility riders, including cyclists. Many areas require mixed 

usage of curb space for both motorized and nonmotorized traffic 

and must adapt to unanticipated uses such as outdoor restaurant 

space, temporary shelter for homeless populations, and emer

gencies. Local jurisdictions are constantly challenged to develop 

creative ways to manage the demand from the various functions of 

the street. 

-

-

The Federal Highway Administration recognizes the need for 

strategic curbside management approaches to the street network. 

State and metropolitan partners need tools and knowledge to 

understand and react to this developing practice. Curbside 

management project goals and objectives need to support the 

overall efficiency of the surface transportation system. It will take 

a continuing, cooperative, and comprehensive transportation 

planning process to foster and improve a systems-based approach 

to making the street network deliver benefits to all users. 

In partnership with State and local governments, public trans

portation agencies, and other interested parties, FHWA has under

taken research to identify challenges faced by the growing demands 

for curb space and infrastructure. There is a consensus that research 

needs to include: (1) a summary of best practices, (2) a report on 

curb data to understand what is happening, and (3) an exploration 

of the co-benefits of curbside management.

-

-

In collaboration with the Institute of Transportation Engineers, 

FHWA has developed a new resource on curbside management 

that will support communities in managing curb space consid

erations for accessibility, delivery access, and mobility innova

tions such as emerging micromobility options and autonomous 

vehicle technology.

-

-

FHWA has explored potential solutions to optimize curb 

productivity for the transportation network that address challenges 

in the following main areas: increased freight traffic and deliveries, 

transit priority, shared mobility and micromobility, pedestrians, 

accessibility and compliance with the Americans with Disabilities 

Act, parking management, electric and autonomous vehicles, and 

curbside retail. 

FHWA is preparing the Curbside Implementation Report to 

convey current practices and emerging specifications in the area of 

curbside management. The study aims to provide practitioners of 

all levels of experience with information on how to assess, gather, 

and analyze data to understand available information on curbside 

management inventories. The research provides practitioners with 

suggested criteria to weigh tradeoffs to better assess, prioritize, and 

optimize curb uses and to synthesize data to create a strategic, datadriven approach to curbside management projects.

The Curbside Implementation Report will provide an indepth 

technical study pertaining to the collection, inventories, and 

processing of information relevant to existing conditions, curbside 

activity, and performance measurement. The analysis will provide 

the practitioner with the tools needed to establish modal priori

ties within a jurisdiction, paving the way for the pursuit of new 

projects and strategies. The study will cover identifying appropriate 

measures of effectiveness to understand project needs, selecting 

appropriate data to evaluate the measures and project alternatives, 

and obtaining selected data. It will include a discussion of meth

odologies for collecting new data relevant to curbside management 

projects through both manual, in-person observations and auto

mated data collection equipment.

-

-

-

For more information on FHWA’s curbside management 

program, visit www.fhwa.dot.gov/livability/fact_sheets/curbside_fact 

_sheet.cfm.

JEFF A. PRICE is a transportation specialist in FHWA’s Office of Planning, 

Environment, and Realty. 

Curbside management can include considerations for pedestrians, micromobility 

(like this bikeshare dock), parking, and access to businesses.

Source: FHWA.

In 2020, some towns and cities expanded outdoor dining onto sidewalks or along the 

curb on the roadway.

Source: FHWA.

HOT TOPIC
4 | PUBLIC ROADS | SUMMER 2021

TECH TRANSFER SUCCESS:

How the DAV Improved 

SuperpaveTM Design

The Dynamic Angle Validation (DAV) kit ensures uniformity and consistency 

between gyratory compactors in asphalt testing. Here’s how it came about.

by MARY HUIE, THOMAS HARMAN, and EILEEN S. NELSON

Mixing asphalt can be tricky business. To use the analogy of baking chocolate 

chip cookies, it is essential to balance the 

ingredients to get the desired taste. To make 

the cookie analogy work, think of a recipe 

as having three components: the fine (flour, 

baking soda, salt, sugar), the coarse (choco

late chips, brown sugar), and the sticky stuff 

(egg, vanilla, butter). Similarly, in asphalt 

mixes, there is the fine (sand or aggregate 

typically less than 2.36 millimeters, or that 

can pass through a number 8 sieve), the 

coarse (typically rocks or aggregate retained 

on a number 8 sieve), and the sticky stuff 

(asphalt binder, which can include modifiers 

and additives). In asphalt, the desired taste is 

a long-life pavement.

-

How these ingredients are proportioned 

together requires a meticulous baker and 

state-of-the-art utensils. In an asphalt labo

ratory, ingredients are combined, mixed, 

and then compacted using a SuperpaveTM

(SUperior PERforming asphalt PAVEment) 

gyratory compactor. The gyratory presses 

the mix into its cookie shape, which is a 

cylindrical specimen 115 millimeters high 

with a diameter of 150 millimeters. During 

mix design, where the baker develops the 

recipe for production, the asphalt cookies 

are evaluated volumetrically and undergo 

additional performance testing. Dry 

“cookie” recipes can lead to cracking on the 

roadway and recipes that are too soft can 

lead to rutting.

-

The Superpave asphalt mixture design 

system requires gyratory compactors to 

provide a uniform compaction effort. This 

effort is based on the downward pressure 

inside the compaction mold, the speed and 

number of rotations, and the tilt or angle 

of the model. The most important compo

nent is the angle, which creates the shearing 

action. Today, the angle of gyration is set 

and verified internally to 1.16 °±0.02° under 

American Association of State Highway 

and Transportation Officials specifications. 

However, there was a time when internal 

angles could not be measured, and there was 

no way to ensure uniformity from machine 

to machine or manufacturer to manufac

turer. The issue became a major hurdle in 

-

-
WWW.FHWA.DOT.GOV | 5

the 1990s during the national implementa

tion of the Superpave system.

-

Enter the Dynamic Angle Validation 

kits, or DAVs. DAVs are used for ensuring 

consistency and volumetric quality between 

gyratory compactors. Asphalt “cookie” 

specimens from gyratory compactors are 

not only used for developing tasty recipes, 

but are also used during field production in 

quality assurance testing.

FHWA’s Dynamic Angle Validation kit enables 

highway engineers to verify the required angle 

of any manufacturer’s gyratory compaction 

equipment, required for Superpave asphalt. 

© i-Stockr / iStock.com. 

The Dynamic Angle Validation Kit is 

designed to ensure uniformity between 

gyratory compactors. This secondgeneration DAV 2.0 includes 

an added eccentric 

ring to create an 

internal movement 

to simulate 

asphalt mix. 

Source: FHWA. 

Initial Development

The original prototype gyratory compactor, 

developed during the Strategic Highway 

Research Program (SHRP), called for an 

external angle of gyration set to 1.25°. An 

external angle does not account for some

thing called “machine compliance.” As 

a gyratory compactor presses an asphalt 

specimen into shape, the asphalt specimen 

pushes back on the load frame, which causes 

it to comply (deform slightly). This issue of 

machine compliance was not realized during 

the initial technology transfer effort for the 

Superpave system in the early 1990s.

-

Under a pooled fund procurement, the 

Federal Highway Administration solic

ited manufacturers to produce a gyratory 

compactor that could meet an external angle 

of 1.25°. FHWA selected two companies as 

successful bidders for this procurement and 

asked them to provide “first article” units 

to FHWA for evaluation. Upon receipt of 

these units, FHWA, along with the Asphalt 

Institute, performed extensive evaluations 

on each unit and conducted extensive 

discussions with SHRP researchers and the 

manufacturers. After a slight redesign of one 

of the units, FHWA ultimately approved 

both units, enabling a pooled fund purchase 

to proceed for all State highway agencies.

-

As time went on, more equipment manu

facturers became involved with producing 

Superpave gyratory compactors. However, 

each production model employed a unique 

method of setting, inducing, and main

taining the angle of gyration. Unfortunately, 

this meant that no single manufacturer’s cali

bration system could be universally applied 

to all the different models that were commer

cially available.

-

-

-

-

Creating a Universal 

Angle Validator

Recognizing the need for a way to validate 

the angle of gyration on any device, a team 

of three researchers at FHWA began to 

brainstorm. Tom Harman, then the lead 

for the Asphalt Pavement Team at FHWA’s 

Turner-Fairbank Highway Research Center; 

Tom Brovold, who, at the time, sold his own 

version of a portable gyratory compactor; 

and Paul Fuchs, who had been an onsite 

contractor under FHWA’s Nondestructive 

Evaluation Validation Center, sketched out a 

rough idea of what a universal fixture might 

look like that could dynamically measure the 

angle of gyration internally and work with 

any device.

Using this idea to produce a single, 

small conceptual device, the team worked 

to demonstrate consistent calibration with 

the same uniformity of compaction between 

two different devices. As with all eventual 

successful technologies, the first few attempts 

failed, and there were many design iterations. 

However, over the course of several years, the 

team developed and validated a functional 

internal device, which is now known as 

the DAV.

The team realized it had something novel, 

and they had the added advantage of using 

Brovold’s private gyratory company to fully 

realize the technology. At the time, FHWA’s 

device was the only proven technology. The 

creation of the DAV spurred competitors 

to develop similar devices. Other compa

nies designed at least two devices—and 

even produced the same results—but their 

approaches were different.

-

FHWA aimed to get the internal cali

bration technology into the hands of State 

departments of transportation and asphalt 

suppliers. To do so, the DAV kits needed to 

be commercially available. In addition, the 

inventors wanted to secure the intellectual 

property rights. The next step was to file for 

a patent, which was successfully awarded 

in 2002.

-

The successful patent led to an exclusive 

license agreement between FHWA and 

Brovold, who already owned a company that 

manufactured and sold gyratory compactors. 

A royalty arrangement for the use of the 
6 | PUBLIC ROADS | SUMMER 2021

technology was established, with a nominal 

licensing fee with the intent of giving 

recognition back to the laboratory and 

researchers while also making the use of the 

technology affordable and attractive at all 

levels of industry.

Improving Asphalt Testing

The invention of the dynamic angle 

measuring device has dramatically 

changed the practice of asphalt testing. 

Most transportation departments and 

asphalt suppliers are now using gyratory 

compactors to verify the volumetric data 

and compaction consistency. A version 

of the DAV, or a similar device, is used to 

calibrate gyratory compactors used in the 

United States.

The Nebraska Department of 

Transportation (NDOT) has been using 

the DAV technology for more than a 

decade. Two of the main advantages are 

convenience and consistency. Because the 

DAV acts as a mix inside the mold, it does 

not need existing hot mix. In other words, 

no mix has to be continually hauled to 

various branch labs. Further, says Jody Paul, 

the highway quality assurance manager at 

NDOT’s Bituminous Aggregate Laboratory, 

“The DAV gives you your true angle 

reading. Consistently. From my gyratory to 

the branch lab to the next branch lab, it is 

all consistent.”

Robert Rea, NDOT’s assistant materials 

and research engineer, says, “The DAV 

allows contractors and Nebraska labs to 

tighten up their verification testing toler

ance and precision between laboratories, 

which means producing more consistent test 

results. Therefore, it reduces the amount of 

test variability on a paving project.”

-

FHWA’s Technology 

Transfer program played 

an important role in the 

process of getting the 

DAV kits patented, 

licensed, and commer

cialized. The Tech

nology Transfer 

program is designed 

to provide support 

services in moving 

research from laboratory to market and 

ensures that the technologies produced are 

developed and disseminated with the user 

and adopter needs guiding the process. In 

addition, the program seeks to market 

products and demonstrate to State and 

local highway agencies that the FHWA 

research products are valuable, practical, 

and constitute best practices.

-

-

“The overall impact of 

the DAV technology and its 

successful adoption by the 

industry are a Technology 

Transfer success story,” says 

Jack Jernigan, the director of 

FHWA’s Research and Tech

nology Program Development 

and Partnership Team.

-

MARY HUIE is the manager of the 

Technology Transfer program at 

FHWA’s Turner-Fairbank Highway 

Research Center. She holds a 

B.S. in civil engineering from the 

Catholic University of America in 

Washington, D.C.

THOMAS HARMAN serves as the 

director of FHWA’s National Highway 

Institute and was the Director of the 

Center for Accelerating Innovation. 

He has a bachelor’s degree in civil 

engineering from the University of 

Maryland and a master’s in civil 

engineering from the University 

of Illinois.

EILEEN S. NELSON is a program manager 

working as a contractor with FHWA's 

Technology Transfer program. She holds 

a B.A. in history and curricular studies, as 

well as a minor in women’s studies, from 

the former Randolph-Macon Woman’s 

College in Lynchburg, VA.

For more information, contact 

Mary Huie at 202–493–3460 or 

Mary.Huie@dot.gov.

The DAV, shown here, is 

a Technology Transfer 

program success story. 

© 2021 Troxler Electronic 

Laboratories, Inc. 
MONITORING SCOUR 

USING UNMANNED 

VEHICLE TECHNOLOGY

WWW.FHWA.DOT.GOV | 7

The Michigan Department of Transportation tested unmanned surface 

vehicles (USV) to aid in inspections of bridges and other assets. 

The selected USV is shown here with the associated running gear. 

© Chad Skrocki, Michigan Department of Transportation.

Michigan DOT researched the use of unmanned surface vehicles for bridge scour observation to 

improve the safety of inspectors and transportation systems users during and after flood events.

by RALPH PAULY and CHAD SKROCKI

During and after flood events, inspectors monitor scour at bridges to ensure that 

public safety is not compromised. The effect 

of scour on structure stability is difficult to 

assess during events as the extent of scour 

is not visible and cannot be easily verified 

by probing. Thus, inspectors make stability 

determinations based on experience, visual 

cues, flow rates, and other factors that hint 

at potentially unsafe conditions.

To help, the Michigan Department of 

Transportation (MDOT) researched several 

platforms for collecting scour-related data 

during and after flood events. To meet 

MDOT’s needs, the platforms needed to be 

stable in swift-moving water, able to collect 

data using sonar technology, and easily and 

safely deployable throughout the State.

The platforms researched included 

monohull and catamaran (multihull) 

unmanned surface vessels (tethered and 

untethered) as well as stationary and 

fixed-position systems. MDOT evaluated 

both multibeam and single beam sonars for 

use with the platforms.

Assessing Vessel Design

Early on, the research team dismissed 

tethered and stationary or fixed-position 

systems as viable alternatives because of 

their inherent limitations. Tethered systems 

prove hard to deploy when there is limited 

clearance, or freeboard, between the water

line and a structure’s low chord—the lowest 

portion of the superstructure (bottom of the 

lowest beam or girder)—which hinders the 

inspector’s ability to collect scour-related 

data. Stationary or fixed-position systems 

are difficult to use when flood events create 

unsteady or irregular flows and are unable 

to collect data rapidly at multiple locations 

(such as structures and substructure units).

-

A catamaran hull design provides a stable 

platform; however, keeping the vessel as 

small as possible means limited internal hull 

storage, requiring more of the instrumen

tation and equipment to be mounted on 

the exterior of the hull. Exterior mounting 

exposes the equipment to environmental 

hazards and snagging by trees or debris 

within the waterway or channel.

-

MDOT chose a monohull design 

because it offers protection for instrumen

tation and equipment within the enclosed 

-
8 | PUBLIC ROADS | SUMMER 2021

hull, reduces the potential for hooking 

obstructions within the waterway or 

channel, and is durable enough to be 

deployed from riverbanks during flood 

events. The untethered vessel may be safely 

operated from shore, ensuring that the 

inspector is out of harm’s way.

MDOT selected a vessel 50 inches (130 

centimeters) in length, weighing 37 pounds 

(17 kilograms), and capable of achieving 

speeds of 18 miles (29 kilometers) per hour.

MDOT’s USV performs a scour inspection.

© Chad Skrocki, Michigan Department of Transportation.

Sonar imagery showing a pier footing displays in real time on the USV operator’s equipment in the field.

© Chad Skrocki, Michigan Department of Transportation.

Selecting Sonar

The research for appropriate sonar equip

ment focused on an inspector’s ability to 

collect, interpret, and evaluate the sonar 

data to aid the decisionmaking process while 

on site.

-

Multibeam sonar provided more 

accurate data than single beam sonar; 

however, the multibeam sonar equipment 

was cost prohibitive and required extensive 

knowledge to obtain and process the data. 

Researchers also expressed concern about 

maintaining the GPS signal lock adjacent 

to or below structures to provide correct 

spatial orientation.

Single beam sonar has its own limita

tions. Sonar imagery is collected and 

displayed relative to the position of the 

vessel and the fixed markers (such as piers 

and abutments), requiring the operator 

to maintain a relatively straight parallel 

path to the fixed marker to ensure data 

quality. The heaving, swaying, or surging 

motion caused by whirlpools and eddies 

formed during an event also affects data 

quality. As translational motion increases, 

data quality is reduced, and images may 

become distorted.

-

Despite these limitations, by testing 

the capabilities of single beam sonar, the 

research team found it to be advantageous 

for field use during flood events. Data can 

be collected and interpreted quickly by 

inspectors with varying levels of experience, 

ensuring that safety-related decisions are 

sound and data driven.

Proof of Principle

MDOT verified the sonar capabilities of the 

recommended unmanned surface vehicle 

(USV) platform (monohull vessel with 

single beam sonar) using underwater diver 

inspection data collected during a scour 

inspection on Michigan’s Upper Peninsula. 

The researchers first plotted the inspection 

data on a drawing of the plan and the eleva

tion of the submerged pier, then overlaid 

sonar imagery on the drawing using known 

points of reference. The results from sonar 

imagery proved comparable to inspec

tion findings.

-

-

During and after the spring storms 

experienced throughout mid-Michigan in 

2020, MDOT used the platform to monitor 

and assess conditions at scour-susceptible 

structures. The results further confirmed the 

capabilities of the selected platform.

“MDOT’s USV platforms are an 

excellent tool for bridge inspectors to safely 

assess the condition of underwater elements 

and monitor scour sensitive issues safely, 

without putting inspectors at risk in the 

waterway itself,” says Matt Chynoweth, 

the director of MDOT’s Bureau of Bridges 

and Structures. “The platform was used 

extensively immediately following the 

flooding from the dam breaches along the 

Tittabawassee and Tobacco Rivers in May 

2020 on many trunkline and local agencyowned structures to ensure safety and 

stability prior to reopening.”

Additional Value

Rising water levels throughout Michigan 

have reduced the available distance between 

the waterline and a structure’s low chord, 

limiting inspector access to the underside 

The research team compared sonar imagery 

collected using MDOT’s USV to the underwater 

inspection streambed performed by divers, overlaid 

on a drawing of the elevation of the pier.

© Chad Skrocki, Michigan Department of Transportation.
WWW.FHWA.DOT.GOV | 9

of the structures. USVs, when outfitted 

with video cameras and advanced imaging 

equipment, can gather photos and data to 

supplement routine visual inspections when 

access may be difficult or unsafe.

USVs can also be used to verify probing 

(wade and probe or boat and probe) and 

waterway information gathered during 

routine and construction inspection, which 

is crucial for managing long-term risks 

associated with scour. Information gath

ered before, during, and after construction 

of scour countermeasures ensures that 

measures are installed in accordance with 

design specifications and plans and will 

provide adequate protection during the 

design flood event. 

-

The USV platform has also proven to be 

a valuable tool when performing underwater 

inspections. The detailed imagery can be 

used to identify underwater hazards and to 

verify inspection findings when underwater 

visibility is limited.

“We have integrated the use of this USV 

platform into our routine and high-risk dive 

operations to identify hazards, to monitor 

and assist divers during the dives, and 

for additional data that are not attainable 

during the dive,” says Casey Collings, a 

project manager with a private engineering 

group. “The platform has made our higher 

risk dives safer.”

Use of the USV platform for scour 

monitoring is crucial to improving inspector 

safety and ensuring that the transportation 

systems remain safe for all users during and 

after flood events. Information gathered by 

USVs during flood events or during routine 

inspections will assist owner agencies with 

managing these assets in a more effective 

and efficient manner.

RALPH PAULY, P.E., is the assistant structures 

engineer for FHWA’s Michigan Division. He 

provides oversight of State compliance with the 

National Bridge Inspection Standards; technical 

guidance to ensure that regulatory mandated 

requirements are met; leadership on Federal-aid 

eligibility; structural asset management and 

structural preservation; and technical support 

as requested to Division staff on structural, 

geotechnical, and hydraulic issues. He earned 

both a B.S. and an M.S. in civil engineering from 

Michigan State University.

CHAD SKROCKI, P.E., is the assistant region 

bridge engineer for MDOT’s North Region. He 

serves as a regionwide resource and is involved 

in the routine bridge inspection program, annual 

bridge call for projects, bridge maintenance and 

construction, and many other tasks associ

ated with managing the North Region’s bridge 

inventory. He served as the project manager 

for the recent research project titled Unmanned 

Surface Vessels for Bridge Scour Monitoring. He 

earned a B.S. in civil engineering from Michigan 

Technological University.

-

For more information, see www.michigan 

.gov/mdot/0,4616,7-151-9622_11045_24249 

-487023--,00.html or contact Chad Skrocki 

at skrockic@michigan.gov or Ralph Pauly at 

ralph.pauly@dot.gov.

Before (top) and after (bottom) sonar imagery collected 

as part of a construction inspection for placing riprap.

© Chad Skrocki, Michigan Department of Transportation.

Here, MDOT’s USV is being used to aid visual inspections of bridges and culverts with 

reduced freeboard both with (left) and without (right) the canvas boat cover.

© Chad Skrocki, Michigan Department of Transportation.
10 | PUBLIC ROADS | SUMMER 2021

CARMASM: MARITIME ADMINISTRATION 

CDA DEVELOPMENT AND TESTING 

Can applying cooperative driving automation (CDA) systems 

increase efficiency and safety and decrease emissions in a port 

environment? The CARMA Program’s testing aims to find out.

by HYUNGJUN PARK, KIRK CLAUSSEN, LINDSEY GROOMS, KATIE BLIZZARD PISKAI, and ED LESLIE

Urban streets, commuter corridors, work zones—all of these environments 

can benefit from the implementation of 

cooperative driving automation (CDA) 

technologies. But the benefits of CDA are 

not only for passenger travel. The Maritime 

Administration, the Federal Motor Carrier 

Safety Administration (FMCSA), and the 

Intelligent Transportation Systems Joint 

Program Office (ITS JPO) have partnered 

with the Federal Highway Administration’s 

Saxton Lab to explore CDA applications 

to port drayage and commercial motor 

vehicle operations.

This multifaceted project began in 2019 

and will be completed in 2022. Its primary 

goal is to use CDA to improve the perfor

mance of maritime ports and terminals 

along with the larger freight network. The 

project aims to develop and test use cases for 

port drayage and commercial motor vehicle 

operations that leverage CDA-equipped 

commercial vehicles to increase efficiency 

and safety and decrease emissions.

-

This port drayage testing has two 

primary objectives: (1) to support the adop

tion of connected automated vehicle and 

CDA technologies in U.S. ports, and (2) to 

study the costs and benefits of automated 

truck movement in queues at ports and 

staging areas. By building on past research, 

the testing should provide some indica

tion of possible benefits to port authorities 

and stakeholders.

-

-

“CDA technology offers the potential 

to significantly improve port operations,” 

says Kevin Dopart, the program manager 

for vehicle and safety automation with 

the ITS JPO. “However, further use case 

development is necessary to demonstrate 

the concept to stakeholders, and data-driven 

analyses are needed to refine the technology 

to operate in the most beneficial way.”

This project aims to fill these gaps by 

developing and testing proof-of-concept 

use cases for a test track, initially with a real 

CDA-enabled Class 8 tractor and trailer and 

later with CDA-enabled, automated, smallscale model trucks.

FHWA and its partners are developing 

the CDA-enabled model trucks as part 

of the CARMA 1Tenth program. The 

program is inspired by the F1TENTH 

program, an effort founded by the Univer

sity of Pennsylvania that now partners with 

dozens of universities and organizations 

worldwide. F1TENTH holds regular 

racing competitions focused on advancing 

automated driving system education on 

scaled-down autonomous vehicles. CARMA 

1Tenth works to incorporate CDA into 

F1TENTH’s efforts.

-

Researchers are using a test fleet of four CARMA-equipped commercial motor vehicles 

to explore CDA technology for freight, including at maritime ports. 

Source: FHWA.

This research builds on FHWA’s 

CARMA PlatformSM, which provides 

open-source software for the research and 

development of CDA capabilities. The port 
WWW.FHWA.DOT.GOV | 11

drayage use cases will extend the CARMA 

ecosystem to explore the benefits of CDA 

for the Nation’s ports and their stakeholders. 

Proof-of-Concept Testing

The team developed a high-level concept 

of operations for using CDA to improve 

drayage operations at ports, as well as a 

proof-of-concept test plan for demon

strating this concept using CDA-equipped 

commercial motor vehicles. In the demon

stration, the trucks will self-navigate 

around a loop, starting and ending in a 

mock staging area lot for the loading and 

unloading of containers. Along this loop, 

each vehicle will enter a mock port (on a 

test track), get a container loaded onto its 

chassis, and stop at a virtual inspection 

point where vehicles “passing” inspection 

will continue onward and vehicles “failing” 

inspection will navigate to a holding area for 

further inspection. Passing vehicles will then 

traverse gate passage and emulate a shorthaul drayage before returning to the starting 

location. The CARMA ecosystem’s cloud 

capabilities (CARMA CloudSM) will be used 

to manage the rules of this fleet as it drives 

through each of the activities.

-

-

The project will use commercial motor 

vehicles equipped with automation tech

nologies, including CARMA, for this 

testing. The U.S. Department of Transpor

tation currently maintains a fleet of four 

CDA-enabled commercial vehicles—three 

from FMCSA’s Automated Commercial 

Motor Vehicle Evaluation (ACE) program 

and one from the FHWA CARMA 

Program. The FMCSA ACE program 

supports this project and several related 

efforts to promote the safe deployment of 

commercial vehicles with connected and 

automated vehicle technology.

-

-

The demonstration will use FMCSA 

and FHWA’s combined fleet of CDA- and 

CARMA-equipped Class 8 tractor trailers 

at a test track. Researchers are considering 

the Aberdeen Test Center in Aberdeen, 

MD, and SunTrax in Auburndale, FL, for 

the testing.

Key trends indicate the need for greater 

operational efficiencies in ports where 

port drayage automation could help 

offset or overcome some limitations. The 

current atmosphere includes increased costs 

because of increasing port traffic, fluctua

tion in demand, larger vessels deployed by 

ocean carriers, rigid capacity limitations, 

and diverging needs of truck and marine 

terminal operators.

-

CARMA-equipped vehicles like this truck are helping FHWA, MARAD, and FMCSA discover 

how CDA technologies can improve safety and efficiency for commercial freight. 

Source: FMCSA.
12 | PUBLIC ROADS | SUMMER 2021

This map shows a proposed use case test route for port drayage at a test track. The commercial motor 

vehicle enters, is directed to one of three loading points (1, 2, 3), goes through a virtual inspection 

point (4), and then exits if it passes inspection or proceeds to a holding area (5) if it does not. 

Original image © Google Earth. Overlay source: FHWA.

Looking Ahead

The next step after the proof-of-concept 

demonstration will be to develop and test a 

more enhanced port drayage automation use 

case customized for an actual port. The team 

is in the process of selecting a port by identi

fying and reaching out to candidate ports 

that show an interest in collaborating on 

this testing and meet the use case require

ments. Once a port is selected, the team will 

develop a customized port drayage automa

tion use case, and two demonstrations will 

take place sequentially. The first demonstra

tion will use CARMA 1Tenth trucks and a 

model of the configuration of the selected 

real port. The second demonstration will 

use real CDA-enabled commercial motor 

vehicles at the selected port.

-

-

-

-

“This project is an exciting part of our 

multiyear research program that addresses 

critical freight movement and ITS infra

structure gaps,” says Travis Black, the team 

lead for Port Development and Intermodal 

Planning for the Maritime Administration’s 

Office of Ports & Waterways Planning.

-

For more information, see “CARMASM: 

Enabling Collaboration and Ensuring Safety 

in Freight Operations” in the Summer 2020 

issue of Public Roads. The CARMA opensource software is available on GitHub at 

https://github.com/usdot-fhwa-stol.

FMCSA’s ACE program uses CARMA-equipped freight trucks. 

Source: FMCSA.

HYUNGJUN PARK is a technical program manager 

of the CARMA Freight program in FHWA’s Office 

of Operations Research and Development. He 

manages various CDA activities, focusing on 

commercial motor vehicles and freight. He earned 

a B.S. in city planning from Hanyang University 

in South Korea, and an M.S. and a Ph.D. in civil 

engineering from the University of Virginia.

KIRK CLAUSSEN serves in the Maritime 

Administration’s Office of Ports & Waterways as 

a port finance agent and leads port innovation 

activities. He provides guidance to ports on 

infrastructure investment and leads the intelligent 

transportation systems program, focusing on 

increasing cargo capacity and the reliability of 

freight moving through ports.

LINDSEY GROOMS is a contracted junior 

communications specialist who supports 

communications and outreach activities at FHWA’s 

Saxton Lab. She earned her B.A. in public relations 

from Virginia Tech.

KATIE BLIZZARD PISKAI is a contracted research 

and development project manager for connected 

and automated vehicles. She supports CARMA 

and connected and automated vehicle projects 

at the Saxton Lab, and is the contracted project 

manager for the CARMA Freight project. She 

earned her master’s degree in city planning from 

the Massachusetts Institute of Technology and a 

bachelor’s degree from Bowdoin College.

ED LESLIE is a contracted senior electrical 

engineer who supports CARMA and connected 

and automated vehicle projects at the Saxton 

Lab. He is the contracted principal investigator 

for the CARMA Freight project. He earned his 

M.S. in electrical engineering from San José 

State University and a B.S. from the University 

of Maryland.
WWW.FHWA.DOT.GOV | 13

How 10 States Use, Evaluate, and Implement Nondestructive Evaluation Technology 

State DOTs are adopting NDE techniques 

to manage pavement and bridge deck 

maintenance and repairs. 

A bridge inspector uses the chain dragging technique to 

help identify delamination. While some States continue 

to prefer traditional methods like chain dragging, others 

are beginning to employ advanced nondestructive 

evaluation (NDE) technologies instead or in addition to 

these methods. FHWA spoke with 10 States about their 

use of NDE methods for assessing bridges and tunnels.

© Oregon DOT.

by HODA AZARI

Historically, State departments of transportation have relied primarily upon visual inspections to evaluate the condition of 

bridge decks. For suspect areas identified during the visual inspection, 

engineers use hammer sounding or “chain dragging” to further eval

uate potential subsurface damage, such as delamination. Delamina

tion occurs when deicing materials and water penetrate the concrete 

bridge deck down to the steel reinforcing bar. The steel corrodes until 

the force from the buildup of corrosion product cracks the concrete 

along the rebar mat, resulting in spalls and similar damage.

-

-

Advances in nondestructive evaluation (NDE) technology have 

enabled States to save inspection time and better assess the actual 

condition of bridge decks. The Federal Highway Administration 

NDE Program, in collaboration with the U.S. Department of 

Transportation’s Technology Transfer program, recently conducted a 

comprehensive review of current practices and policies of those States 

that are using NDE technologies to complement visual inspections. 

FHWA researched published papers and conference presentations and 

also conducted interviews with key State asset owners.

The FHWA review primarily addressed bridge deck inspection 

and presented highlights of how bridge owners use NDE technolo

gies to assist in managing bridges more effectively. The most common 

NDE methods used by States, primarily on bridge decks, pavement, 

and tunnels, are ground-penetrating radar (GPR), infrared thermog

raphy (IR), and impact echo. As part of the research process, each 

State also answered the question: “How can FHWA help with NDE 

knowledge and implementation?” 

-

-

NDE Method Description of Physical Principle

GroundPenetrating 

Radar (GPR)

Ground-penetrating radar uses electromagnetic 

wave pulses in the microwave band of the radio 

spectrum to image the subsurface features in 

bridge decks or pavement. Radar reflections 

from inside the material are then imaged for 

evaluation. GPR can be deployed by hand or on 

push carts (“ground coupled”) for a slow, more 

detailed inspection, or attached to a vehicle at 

traffic speeds (“air coupled”), but with some lost 

resolution in exchange for speed.

Infrared 

Thermography 

(IR)

Infrared thermography uses a camera that 

images the temperature of an object in lieu of 

inspecting the visual appearance of the object. 

Flaws in the bridge deck, pavement, or tunnel 

liner heat and cool at a different rate, providing a 

surface image of the location of the flaw. 

Impact Echo

Impact echo is an acoustic or stress wave-based 

method in which stress waves are transmitted 

into the material and then reflected from 

features and flaws in the material. 

Common NDE Methods.
14 | PUBLIC ROADS | SUMMER 2021

The States discussed in this article also 

participated in at least one of the second 

Strategic Highway Research Program 

(SHRP2) projects by the American Associ

ation of State Highway and Transportation 

Officials (AASHTO): Nondestructive 

Testing for Concrete Bridge Decks and 

Nondestructive Testing for Tunnel Linings. 

Details of each State’s participation, 

results, and reports can be found on the 

AASHTO SHRP2 program website 

at 

-

http://shrp2.transportation.org/Pages 

/R06_NondestructiveTesting.aspx.

While it is difficult to call any one State 

a lead NDE adopter because different States 

have different needs, examples of successful 

applications and case studies are provided in 

the following summaries and tables.

CALIFORNIA

While the California Department of 

Transportation (Caltrans) is researching and 

starting to implement newer NDE technol

ogies, the agency’s bridge deck inspections 

remain primarily visual. Like most State 

DOTs, Caltrans supplements and enhances 

its visual inspections with spotting scopes 

and similar visual aids. As a followup to 

the visual bridge deck inspections, hammer 

sounding and chain dragging continue to 

be the primary methods to further evaluate 

suspect areas.

-

Caltrans has some high-speed inspection 

programs in place for pavement inspection 

and crack detection. Cameras collect images 

of pavement and bridge decks and apply 

artificial intelligence technology to identify 

and determine details like crack locations, 

widths, and density. The program has 

proved highly effective, especially in urban 

areas where it is difficult to close lanes for 

conventional visual inspection.

As a result of its participation in the 

SHRP2 program, Caltrans is deploying 

some NDE techniques such as IR cameras 

and GPR.

Caltrans reported that air-coupled GPR 

enables an increased data acquisition speed 

of up to 50 miles (80 kilometers) per hour; 

however, this rate is not appropriate for 

every investigation. The agency also inves

tigated automated hammer sounding. This 

technique can be done faster than walking 

speed and is yielding similar results to chain 

dragging. The main advantage of this tech

nique is that it uses a rolling closure at about 

20 miles (30 kilometers) per hour in lieu of 

complete lane closures.

-

-

In terms of barriers to additional imple

mentation of advanced NDE techniques, 

Caltrans indicated that the primary limiting 

factor is resources. With the number of 

bridge decks in California, current appli

cations of advanced NDE technologies are 

better focused on specific project-level inves

tigations responding to known or antici

pated problems. Caltrans is not yet routinely 

using GPR, IR, or any other common NDE 

technologies for bridge deck evaluations.

-

-

-

-

The agency indicated that GPR is a 

good tool, but it 

requires signifi

cant training and 

experience to use 

it effectively. It 

is not clear how 

to make GPR 

simpler or more 

accessible, but it 

is a valuable tool, 

and Caltrans 

says it should be 

pushed forward to become a more routine, 

turnkey-type inspection. Similarly, IR is also 

helpful and complementary to GPR, but it 

needs some continued internal development 

to deploy. Other NDE techniques, such as 

impact echo, are waiting in the wings but 

not quite ready for broad implementation. 

These techniques should continue to be 

researched and moved ahead as a comple

ment to GPR and IR.

-

-

“Caltrans would like to see improve

ments and enhancements in existing NDE 

techniques,” says Erol Kaslan, the State 

bridge maintenance engineer in the Divi

sion of Maintenance at Caltrans. “More 

research is required to make NDE methods 

more economical to use and less subjec

tive, so that the advanced NDE methods 

can be routinely used. Cheaper versions 

of technology with little or simplified 

postprocessing of data would be the goal in 

that alternative.”

-

-

-

Caltrans performs return-on-investment 

calculations to decide when and where to 

use NDE and to determine if it is worth 

implementing additional NDE technologies.

How Can FHWA Help?

When asked how FHWA can help Caltrans 

with NDE knowledge transfer and imple

mentation in California, the agency noted 

that there seems to be a core group of States 

implementing these technologies. On a 

Federal level, it would be good to bring 

States together and share results so that they 

can hear about lessons learned, develop core 

experiences, apply certain best practices, 

transfer knowledge, and implement group 

training. Improved dissemination of infor

mation among the States would be benefi

cial so that they can keep in touch with each 

other to share experiences.

-

-

-

Caltrans also feels more work needs to be 

done in validating and evaluating the effec

tiveness of the various NDE methods. An 

unbiased assessment of the advantages and 

limitations of the methods would be more 

useful than relying on assessments from 

consultants and equipment manufacturers.

-

Caltrans uses GPR data 

overlaid on maps to 

help identify service line 

locations and depths 

prior to roadway milling. 

Original image © Google 

Earth. Overlay © Caltrans.

COLORADO

The Colorado Department of Transpor

tation (CDOT) applied NDE techniques 

as part of its SHRP2 tunnel inspection 

program. CDOT employed both IR and 

LiDAR (light detection and ranging) 

methods in the initial scans of some tunnels.

-

“CDOT ran the IR and LiDAR system 

at traffic speed (up to 35 miles per hour, or 

56 kilometers per hour) so that the tunnel 

could initially be inspected much faster 
WWW.FHWA.DOT.GOV | 15

than through manual inspections,” says 

Tyler Weldon, a maintenance engineer with 

CDOT. “Where IR identified potential 

problems, CDOT manually investigated the 

areas with the conventional tunnel lining 

inspection techniques of visual inspection 

and tapping.”

The agency found that the time 

required to collect, correlate, and analyze 

the data was not necessarily 

cost-effective relative to the 

information obtained from 

the inspections, and noted 

some data analysis repeatability 

issues. Correlating the images 

to the correct locations proved 

to be particularly cumbersome 

and time-consuming.

For bridge deck inspections, 

CDOT starts with a visual 

inspection and uses chain drag

ging to further investigate any 

suspect areas. Because NDE 

inspections provide the bridge 

inspectors with more detailed 

information about the condi

tion of a bridge, CDOT looks 

at the NDE results when rating 

the bridge. For bridge decks 

with overlays, the agency brings 

in maintenance personnel for 

more examination and repair if 

the visual inspection identifies any suspected 

membrane problems. For inspections prior 

to a bridge deck rehabilitation, CDOT 

employs chain dragging and GPR to help 

with rehab quantity estimates.

-

-

In addition, CDOT applies various 

monitoring technologies, including acceler

ometers, tilt meters, and water flow meters, 

when the agency has particular concerns 

about a bridge or wall—often because of 

scour impacts.

-

-

State Chain 

Dragging

Ground-Penetrating 

Radar (GPR)

Infrared 

Thermography (IR)

Impact 

Echo

California

• Evaluating suspect 

areas on bridge decks 

• Investigating 

automated sounding

• Inspecting pavement

• Estimating recycled volumes for 

asphalt milling 

• Determining asphalt thicknesses 

for concrete overlay

• Detecting delamination in 

suspect areas on bridge decks 

and in tunnel liners 

• Locating subsurface utilities

• Measuring cover depth prior 

to milling operations to avoid 

equipment damage

• Identifying clear areas for coring

• Using in conjunction 

with GPR

• Detecting moisture in 

tunnel liner

• Detecting 

delamination in 

suspect areas on 

bridge decks and 

tunnel liners

Colorado

• Evaluating suspect 

areas on bridge decks

• Hammer sounding 

tunnel liners

• Evaluating suspect areas on 

bridge decks

• Inspecting tunnel 

liners

• Using in trial 

evaluations of suspect 

areas in tunnels

While CDOT does not have any new 

NDE technology investigations in its plans, 

it keeps up with the latest NDE develop

ments through vendors, other States, and 

the Transportation Research Board to help 

identify potential applications. The agency 

has investigated drone use, but because of 

CDOT used this truck-mounted 

high-speed IR and LiDAR 

system in tunnel inspections. 

© Colorado DOT.

Summary of NDE Technology Applications in California and Colorado.
16 | PUBLIC ROADS | SUMMER 2021

the involvement required (such as trained 

pilots) and high costs, CDOT does not 

anticipate a broad implementation of drones 

for its inspections.

How Can FHWA Help?

When asked about what else FHWA can 

do to help CDOT with NDE knowledge 

and implementation in Colorado, the 

agency responded that it always seeks to 

keep up to date on new NDE technology. 

Peer exchanges are particularly valuable for 

this effort. CDOT noted that the Western 

Bridge Preservation Partnership may be a 

group to further investigate for partnership 

or information exchange opportunities 

because NDE fits into part of its objectives.

CDOT cautioned that while new NDE 

technology offers some useful applications, 

it is not always a cost-effective solution, 

and forcing new technology on the States 

should be avoided. While FHWA guidance 

helps, States should determine if and when 

new NDE technology would be useful 

and cost-effective for a particular project 

or program.

State Chain 

Dragging

Ground-Penetrating 

Radar (GPR)

Infrared 

Thermography (IR)

Impact 

Echo

Indiana

• Detecting debonding 

in overlays

• Detecting where chlorides have 

migrated into bridge deck using 

high-speed GPR

• Predicting when and where 

problems can occur

• Evaluated to identify 

suspect areas, but not 

currently implemented

• Detecting debonding 

in overlays

Iowa

• Using manual and 

automated sounding 

on bridge decks to 

evaluate suspect areas

• Not applicable (high salt buildup 

in concrete, due to Iowa’s 

climate, precludes the use of 

GPR)

• Evaluated, but 

found polished rock 

aggregate causes 

reflection problems

• Uses cart-based 

system on bridge deck 

overlays

Louisiana

• Evaluating automated 

sounding to better plan 

hydro demolition

• Inspecting decks and deck joints 

using high-speed GPR

• Inspecting bridge 

decks and deck joints

• Assessing fire damage 

to bridge decks

• Measuring pile depths 

for scour evaluations

Summary of NDE Technology Applications in Indiana, Iowa, and Louisiana.

INDIANA

The Indiana Department of Transporta

tion (INDOT) participated in the SHRP2 

study and scanned over 200 decks using 

air-coupled GPR. The agency used the 

results to assist engineers with program

ming decisions. INDOT viewed the 

SHRP2 meetings as helpful to better learn 

what other States have been doing with 

their evaluations and implementations of 

NDE technology.

-

-

“Bridge NDE inspection is becoming a 

larger part of INDOT’s program to manage 

bridges. The NDE data are used to predict 

when and where problems can occur and to 

define deteriorated areas, including delam

ination,” says Anne Rearick, the director of 

bridge management at INDOT.

-

While INDOT does have the ability 

to conduct NDE itself, it has found that 

consultants bring much more experience 

and sometimes apply proprietary software 

that does a good job. The agency enters the 

results into a database, and bridge inspec

tors may then use that information as part 

of their condition rating process. While 

INDOT does not perform return-oninvestment calculations for NDE technol

ogies, it does use the NDE data to develop 

bridge degradation curves and to make 

decisions about whether to repair or replace 

a bridge deck.

-

-

For future plans, INDOT came away 

from the SHRP2 study with questions 

about when and how to use GPR. As a 

result, the State is conducting further studies 

with IR, aerial IR, pole-mounted IR, and 

impact echo technologies with the intention 

of developing both project- and networklevel NDE programs.

How Can FHWA Help?

When asked how FHWA can help further 

NDE knowledge and implementation in 

Indiana, INDOT noted that more emphasis 

should be given to support practitioners 

on how to best apply the various NDE 

technologies, including the collection, 

interpretation, and management of the data 

produced. Different recommendations are 

needed to address variables such as State 

geographies, weather, road treatments, and 

aggregates. INDOT is always looking to 

keep abreast of what is new in NDE tech

nology and how it may help Indiana.

-

A bridge inspector uses a cart-based impact 

echo system on a bridge deck in Iowa. 

© 2020 Iowa Department of Transportation. 

IOWA

For bridge deck inspections, the Iowa 

Department of Transportation (Iowa DOT) 

employs sounding as their most widely used 

and trusted technique, with repeatable and 

readily understood results. While almost 

all inspections are done manually, Iowa 

DOT has also investigated some automated 

hammer sounding systems to speed up the 
WWW.FHWA.DOT.GOV | 17

inspections. The agency concluded that 

while it does not necessarily save money 

performing automated inspections, inspec

tions are completed much faster. Iowa 

DOT carried out validation tests and found 

that automated system results reasonably 

match the manual sounding results. In 

addition, the agency found the impact echo 

method—typically a cart-based system—to 

be the most reliable to inspect through 

concrete overlay bridge decks.

-

“The agency found that validation 

testing is the key to determine if an NDE 

technique does what consultants and 

equipment manufacturers claim,” says 

Mike Todsen, a special projects engineer for 

Iowa DOT.

In one study, Iowa DOT compared the 

results from an automated system scan to 

their manual sounding results, with almost 

no correlation. “Without physical validation 

of the actual condition when using methods 

such as coring, the NDE results cannot be 

relied on,” says Todsen.

Iowa DOT believes NDE can help in 

planning and decisionmaking, but has not 

done formal return-on-investment calcula

tions to quantify the added value of NDE.

-

How Can FHWA Help?

Iowa DOT reported that it would like to see 

more work done by FHWA to evaluate the 

effectiveness and validation of the various 

NDE methods. An unbiased assessment 

of the advantages and limitations of the 

methods would be more useful than relying 

on consultants and equipment manufac

turers. The agency would also welcome 

having advice available to pick the best 

NDE system and solution for a particular 

inspection problem.

-

LOUISIANA

The Louisiana Department of Transpor

tation and Development (LADOTD) has 

experienced a culture shift toward the use 

of NDE technology. The agency believes 

chain dragging to be an aging technology, 

and typically only the more experienced 

inspectors still use it. The new generation of 

inspectors does not view chain dragging as 

the best technique.

-

The agency has employed high-speed 

GPR and IR to minimize or eliminate the 

need for lane closures, and as a way to prior

itize which bridge decks need work.

-

“LADOTD has the third-highest bridge 

deck area in the country, and with such 

long bridges—some more than 17 miles 

[27 kilometers] long—it is not practical 

to chain drag all the decks,” says Haylye 

Brown, an assistant bridge maintenance 

engineer for LADOTD Section 51. 

“LADOTD is proactive in the use of NDE 

and relies heavily on NDE techniques to 

help identify potential problems areas.”

LADOTD noted that its NDE applica

tions are working well. Program managers 

use the NDE data to plan repairs to bridge 

decks. Currently, LADOTD does not use 

NDE results as part of the bridge condition 

rating; however, it would like to pursue this 

capability and is investigating the possibility.

-

Regarding the use of other advanced 

NDE technology in the State, LADOTD is 

evaluating unmanned aerial vehicle (drone) 

technology and plans to provide a drone 

to every district for bridge inspection. The 

agency also noted that NDE technology 

is improving. High-speed GPR deck 

inspection used to be limited to around 

34 miles (55 kilometers) per hour, and now, 

inspections are performed at up to 60 miles 

(96 kilometers) per hour.

How Can FHWA Help?

LADOTD indicated that FHWA could 

increase NDE knowledge and implemen

tation in Louisiana by working to define 

what NDE personnel requirements should 

be specified and how to correlate NDE data 

to bridge element conditions. The agency 

would also appreciate ways to keep abreast 

of advances in NDE technology, including 

knowledge sharing about what is new and 

where best to use it.

-

LADOTD used this truck-mounted, high-speed 

impact echo system as part of its SHRP2 project. 

© LADOTD. 
18 | PUBLIC ROADS | SUMMER 2021

The Nebraska Department of Transportation uses a truck-mounted, air-coupled GPR system to evaluate bridge decks.

© Nebraska DOT.

NEBRASKA

The Nebraska Department of Transporta

tion (NDOT) reported that it conducted 

university-level research in NDE and 

completed some field implementations. 

NDOT inspectors routinely use visual 

inspection. If visual inspections indicate a 

concern, NDOT performs chain dragging 

or a more indepth inspection.

-

NDOT performs advanced NDE only 

at the project level and does not own its 

equipment for advanced NDE methods. 

The agency hires outside consultants for all 

advanced NDE. Under SHRP2, the consul

tants, along with a team from the University 

of Nebraska and Brigham Young Univer

sity, carried out GPR and IR imaging on a 

variety of bridge decks. Because NDOT uses 

asphalt overlays extensively when rehabili

tating bridge decks, it primarily wanted to 

determine how the NDE methods worked 

on overlaid decks.

-

-

-

“NDOT wants to apply NDE to help 

with estimating quantities for its rehabil

itations,” says Fouad Jaber, an assistant 

State bridge engineer for NDOT. “Overall, 

NDOT was satisfied with the technology’s 

performance at estimating quantities on 

asphalt overlays.”

-

While no specific return-on-investment 

calculations have been performed, NDOT 

believes these scoping inspections will save 

money by more accurately estimating the 

range of work.

“NDOT now has 2 years of preconstruction deck evaluation data that could 

be analyzed to see if 1) they correlate with 

lower unit cost for repairs, 2) they have been 

accurate when compared to paid quantities, 

and 3) there have been cases when repairs 

were not cost-effective because they were 

too extensive,” says Kent Miller, a data 

management engineer at NDOT.

NDOT’s university partners are also 

working on a traffic speed platform with 

several NDE methods.

How Can FHWA Help?

When asked how FHWA can help with 

NDE knowledge and implementation in 

Nebraska, NDOT noted that some NDE 

methods are easy to comprehend and 

interpret and some are more challenging. 

The agency does not have the training to 

interpret NDE data, so assistance in that 

area would be helpful. The agency must rely 

on the consultant and cannot, as the owner, 

do a good job on the quality control of the 

inspection process.

“The top NDE need for NDOT would 

be a way to determine when membranes are 

breached,” says Miller.

The implementation of the SHRP2 

project went well because NDOT received 

funding to apply new technologies, rather 

than having to fund the work internally. 

NDOT would like to see more of these 

kinds of projects to try new or proven 

technologies. It would be helpful if compet

itive funding were available that could 

be requested to evaluate and enable new 

NDE research, similar to the programs for 

evaluating ultra-high performance concrete. 

An FHWA program would enable the States 

to implement some of the new ideas they 

would like to see to fruition.

-

NDOT indicated that the Midwest 

Bridge Preservation Partnership would be a 

good forum to help spread any NDE news. 

There are also annual bridge preservation 

partnership meetings at which NDE news 

could be shared.

A student researcher performs a GPR evaluation 

of a bridge deck in New Mexico. 

© New Mexico DOT. 

NEW MEXICO

The New Mexico Department of Transpor

tation (NMDOT) primarily uses NDE to 

follow up on suspected areas identified in 

visual inspections. NMDOT reported that 

it employs NDE methods to help manage 

bridges on a project level, as well as to find 

problems that need repair, and then to 

establish projects to fix the problems. The 

agency also uses NDE results to help guide 

decisions on whether to preserve, repair, or 

replace bridge sections.

-

NMDOT identified a number of factors 

as barriers to implementing more advanced 

NDE techniques, including: 1) difficulty 

accessing all areas on elements other than 

bridge decks, 2) traffic control, 3) resistance 

from users because of the uncertainty of the 

data’s usefulness, and 4) variability of results 

between inspectors. However, NMDOT 

indicated some successful NDE applica

tions, in which NDE resulted in more 

precise results than chain dragging. For 

instance, the agency used ultrasonic testing 

to detect voids on bridge diaphragms and to 

inspect steel bridge pins to ensure that they 

were free of cracks.

-

“GPR is not a magic bullet, but it offers 

value when applied appropriately,” says 

Kathy Crowell, a bridge design section 

manager for NMDOT’s Bridge Bureau. 

“GPR can help determine whether a 

deck is a candidate for preservation 

versus replacement.”

NMDOT found that GPR works well 

as a first pass, but a second, more indepth 

scan is necessary to produce the more 

detailed results critical to decisionmaking. 

For overlay inspections, NMDOT indicated 

that chain dragging is the most reliable 

technique it has used to detect debonded 

overlays. GPR seems to work in seeing 

through asphalt and epoxy overlay, but does 

not appear to work with some overlay mate

rials such as latex-modified concrete.

-
WWW.FHWA.DOT.GOV | 19

How Can FHWA Help?

NMDOT indicated that FHWA could 

contribute to NDE training and educa

tion opportunities—particularly because 

of turnover in NMDOT staff. FHWA 

could also assist with a better way to keep 

apprised of advances in NDE technology, 

including webinars, NDE-focused videos, 

and peer exchange meetings. NMDOT 

indicated that it will be important to keep 

expectations reasonable when comparing 

NDE lab performance and real-world 

NDE performance.

-

OREGON

The Oregon Department of Transporta

tion (ODOT) reported that it extensively 

employs chain dragging on concrete 

decks, and regularly uses magnetic particle 

inspection and ultrasonic inspection on steel 

bridge elements.

-

After performing some experimental 

projects using advanced NDE methods on 

concrete, the agency concluded that chain 

dragging will perform the same inspection 

as the more advanced NDE methods—and 

do it faster and cheaper. ODOT also felt 

that manufacturers oversold the capabilities 

of some of the advanced NDE technology, 

and the techniques did not necessarily do a 

good job at detecting delamination.

ODOT noted that it has had some 

successes in the area of structural health 

monitoring. “The agency monitored 

13 bridges because of known, existing 

problems,” says Steven Lovejoy, a senior 

mechanical engineer with ODOT. “ODOT 

monitored some bridges for just a few 

months and others for approximately 

20 years, generally using strain gages or 

displacement transducers.”

ODOT also noted that NDE results do 

not directly tie into the condition rating 

of bridges because the NDE results were 

difficult to correlate to an actual bridge 

condition, primarily because of issues in 

interpreting NDE data.

ODOT did not present any recent exam

ples of the value of NDE being quantified 

for any projects. The agency discussed 

future plans to assess the cost of hiring an 

NDE consultant to scan a bridge deck to 

help estimate the extent of required repairs. 

This cost would then be compared to the 

cost of material overruns.

-

How Can FHWA Help?

When asked to highlight gaps between 

NDE technology that is available and 

potential future implementations in 

Oregon, ODOT responded that the proce

dure to take large amounts of raw NDE 

data and process these data to a point where 

they could be used to manage an asset (such 

as a bridge) is too difficult and inconsis

tent between operators. Despite ASTM 

standards to help regulate the process and 

make it more consistent than chain drag

ging, the data post-processing seems to add 

inconsistency. ODOT feels that it would be 

valuable if universal references and stan

dards could be created to make the tests 

more repeatable.

-

-

-

-

State Chain 

Dragging

Ground-Penetrating 

Radar (GPR)

Infrared 

Thermography (IR)

Impact 

Echo

Nebraska

• Evaluating suspect 

areas on bridge decks

• Developing automated 

system with local 

universities

• Evaluating bridge decks to help 

estimate repair work

• Evaluating bridge 

decks

• Used infrequently

New Mexico

• Detecting debonding 

in overlay

• Checking for correct rebar 

placement when unexpected 

cracking occurs

• Detecting delamination in bridge 

decks (used infrequently)

• Used infrequently • Used infrequently

Oregon

• Evaluating bridge 

decks with high-speed 

automated sounding

• Inspecting bridge decks at 

higher speeds

• Checking for correct rebar 

location and depth

• Supporting identification of 

coring locations for concrete 

chloride testing

• Locating subsurface utilities

• Evaluating bridge 

decks

• Performing 

experimental projects 

using high-speed 

impact echo system

• Assessing bridge deck 

condition

Summary of NDE Technology Applications in Nebraska, New Mexico, and Oregon.

PENNSYLVANIA

The Pennsylvania Department of Trans

portation (PennDOT) reported that it 

primarily uses visual inspection on bridge 

decks. However, it has used NDE data, 

such as GPR and IR, to manage bridges 

and tunnels on a limited basis on specific 

projects to help with decisionmaking.

-

Pennsylvania also participated in the 

SHRP2 program for bridge decks and 

considered it a success. The program 

familiarized the State with some of the 

advanced NDE equipment and tech

nology. PennDOT has used the GPR unit 

it purchased as part of the SHRP2 project 

to scan bridge decks and help plan the type 

and amount of needed rehabilitation or 

repair work.

-

PennDOT concluded that GPR can 

be effective, but only on certain bridge 

decks and in certain circumstances, because 

getting bridge deck deterioration informa

tion takes a lot of analysis after the scanning.

-

“Uncertain accuracy in the NDE results 

and the time and cost involved to get the 
20 | PUBLIC ROADS | SUMMER 2021

final NDE results are the main barriers 

to implementing NDE on bridge decks,” 

says Tom Macioce, the chief bridge engi

neer in the Bridge Design and Technology 

Division of PennDOT’s Bureau of Project 

Delivery. “PennDOT would like to see a 

standard GPR procedure or solution for 

data analysis and reporting, including 

detailed settings of equipment, better 

accuracy in the rebar identification aspect of 

the software and process, and more cooper

ation between academia and NDE equip

ment manufacturers.”

-

-

-

PennDOT also performed some tunnel 

inspections as part of the SHRP2 program. 

The goal was to demonstrate and evaluate 

the ability of hand-held NDE methods 

and high-speed mobile scanning NDE 

methods, such as air-coupled GPR and 

vehicle-mounted IR, to detect deteriora

tion and defects in concrete tunnel linings. 

The agency also tested traditional physical 

inspection techniques, including hammer 

sounding and coring, in some limited areas 

to evaluate the high-speed NDE results.

-

PennDOT concluded that no single 

technology by itself can provide all informa

tion needed to ascertain the condition of the 

tunnel lining. The agency believes that the 

best application for the NDE technology is 

to use one or two NDE methods in combi

nation with traditional hammer soundings. 

PennDOT determined that while GPR 

correlated reasonably well with hammer 

soundings, GPR does not seem to be a 

practical solution over traditional physical 

methods for biennial inspections because 

of the cost and time required for data 

processing. However, cost and time may 

be reduced significantly during subsequent 

NDE inspections because test procedures 

would already be established.

-

-

In the tunnel IR testing, PennDOT 

found it difficult to obtain reliable and 

useful results for tunnel liners because the 

surface of the liner is not directly exposed to 

the sun for more active heating and cooling 

cycles. IR may be better suited to detect 

moisture-related anomalies in which the 

evaporative cooling is detectable.

PennDOT indicated several obstacles to 

greater highway application of NDE tech

nologies. The cost and uncertain accuracy of 

NDE results are concerns, and sounding is 

still required. The software used to process 

and analyze the large amounts of collected 

data is not user-friendly and an experienced 

operator is required to run the software. For 

example, PennDOT received an estimate of 

2,500 man-hours to convert digital photo

grammetry data to drawings. Typically, the 

agency receives final NDE results within 

about a month of an inspection. In one case, 

it took 7 months to get a final NDE report.

-

-

How Can FHWA Help?

When asked how FHWA might better 

contribute to PennDOT’s applications, 

the agency indicated that it would like to 

receive more updates about the general 

state of infrastructure NDE and to learn 

what NDE technologies and vendors have 

been evaluated by FHWA. FHWA could 

also help by continuing to share through 

the SHRP2 program what other States are 

doing. PennDOT would be interested in 

obtaining FHWA sponsorship every few 

years to participate in the updates.

State Chain 

Dragging

Ground-Penetrating 

Radar (GPR)

Infrared 

Thermography (IR)

Impact 

Echo

Pennsylvania

• Evaluating bridge 

decks and tunnel 

liners using hammer 

sounding

• Evaluating bridge decks to 

estimate repair work

• Detecting deterioration 

under asphalt

• Measuring asphalt thickness

• Measuring rebar cover depth

• Performing quality assurance 

inspections of the rebar cover 

depth on new bridge decks 

• Evaluating tunnel liners

• Evaluating 

bridge decks

• Detecting moisture in 

tunnel liners

• Used infrequently

Virginia

• Detecting 

delamination and 

overlay debonding in 

concrete decks

• Evaluating bridge decks 

• Checking rebar placement on 

new decks

• Evaluating suspect tunnel 

liner areas

• Evaluating tunnel roadway

• Evaluating 

bridge decks

• Inspecting tunnel liners 

using combination of 

IR and high-resolution 

videos 

• Checking for water 

intrusion in tunnel 

liners and culverts

• Evaluating suspect 

areas in tunnel liners

PennDOT used this van-mounted GPR 

system to inspect tunnel walls. 

© PennDOT.

Summary of NDE Technology Applications in Pennsylvania and Virginia.
WWW.FHWA.DOT.GOV | 21

VIRGINIA

The Virginia Department of Transporta

tion’s (VDOT’s) bridge deck inspections are 

primarily visual and tactile in nature. When 

preliminary inspections indicate significant 

corrosion deterioration, the agency deploys 

more indepth methods such as chain 

dragging, sounding, and half-cell potentials. 

VDOT has used advanced NDE techniques 

like GPR, IR, impact echo, and ultrasonic 

tomography if the need arises.

-

VDOT’s work on evaluating advanced 

NDE techniques concentrates on two 

areas. The first area of interest is the rapid 

screening of a bridge deck to quickly assess 

its condition without the need to close 

lanes. Lane closures not only interfere with 

normal traffic flow, but also are hazardous 

for highway workers on the bridge deck. 

The second area of interest is in using NDE 

methods to help determine the extent of 

damage to a bridge deck. This information 

becomes valuable in making repair deci

sions, estimating damage progression rates, 

and better estimating and planning repair 

material quantities.

-

“Virginia’s bridge deck NDE research 

under the SHRP2 program evaluated GPR, 

IR, and high-resolution digital imaging 

NDE technologies on 25 bridges,” says 

Soundar Balakumaran, the associate director 

at the Virginia Transportation Research 

Council, which is part of VDOT. “The 

inspections did not yield any significant new 

information when compared to conven

tional manual inspections. The tunnel lining 

interfered with IR, which did not appear to 

provide enough image contrast.”

-

VDOT inspected a few of the suspect 

areas with a more thorough hand-held GPR 

scan and with impact echo. Those results 

correlated well with routine inspections.

VDOT also performed NDE research 

in several other areas such as time-lapse 

thermography and magnetic flux leakage 

inspections. Magnetic flux leakage is a 

method where a magnetic field is introduced 

in a steel cable or tendon and then magnetic 

field sensors are used to look for leakage 

fields that identify potential underlying 

damage. These are not routine inspec

tions, and were used only for a few special 

investigations. VDOT employed a magnetic 

flux leakage NDE system to inspect some 

post-tensioned tendons with good results 

and verified the technology in the lab on a 

few mock-up tendons with prebuilt defects 

and found excellent correlation.

-

-

-

VDOT used this magnetic flux leakage NDE technique to scan a post-tensioned tendon inside a segmental box girder of a Virginia bridge. 

© Virginia DOT.

VDOT reported that its approach is to 

conduct research first, perform some trial 

projects on the more promising technolo

gies, and then look for the best potential 

applications of the technology. The agency 

usually performs the initial implementation 

of new technologies with consulting compa

nies. VDOT wants to implement the new 
22 | PUBLIC ROADS | SUMMER 2021

technologies to reduce lane closures and 

save money, but first needs to validate each 

technology’s performance.

There were many cases in which NDE 

methods saved VDOT money. In one 

example, initial tests showed that there may 

have been an issue with the cover depth of 

the reinforcing bar on a new bridge deck. 

A more detailed scan with GPR revealed 

that the entire top rebar mat had sunk due 

to misplacement and left a thick, unrein

forced layer of concrete at the surface. The 

contractor replaced the entire deck before 

the bridge was put in service, avoiding the 

problems and resulting repairs that the issue 

would have caused.

-

How Can FHWA Help?

When asked how FHWA could better 

support VDOT’s NDE applications, the 

agency stated that open communication, 

such as the discussions and demonstrations 

in the SHRP2 meetings, helps States to keep 

up with which NDE technologies are being 

used and which new ones are emerging for 

potential future applications.

SUMMARY

The FHWA review provides a snapshot of 

how 10 States use, evaluate, and implement 

both basic and advanced NDE methods 

as part of their bridge deck inspection and 

management programs. All States have 

applied NDE techniques at some level. 

Several of the sample States have successfully 

established advanced NDE technology. For 

example, Indiana and Louisiana have both 

improved their ability to efficiently manage 

bridge deck maintenance and repair through 

new NDE processes. While traditional 

chain dragging techniques remain the choice 

of some States, NDE technologies such as 

at-traffic speed GPR and IR have enabled 

some States to dramatically improve the 

value of their NDE information and inspec

tion efficiency.

-

FHWA provided States with an oppor

tunity to identify where they saw gaps 

between NDE knowledge and NDE 

implementation, and where FHWA can 

focus its support to close those gaps. FHWA 

is thoroughly evaluating and prioritizing 

these recommendations to ensure that the 

goals of the FHWA NDE program are 

addressing the needs of the States. The 

latest FHWA NDE Program Strategic Plan 

has incorporated these States’ needs as the 

primary focus.

-

HODA AZARI is the manager of the NDE Research 

Program and FAST NDE Laboratory at FHWA’s 

Turner-Fairbank Highway Research Center. She 

holds a Ph.D. in civil engineering from the University 

of Texas at El Paso.

The strategic plan for FHWA’s NDE Program includes strategic goals and objectives for stakeholders, technologies, and implementation.

Source: FHWA.
WWW.FHWA.DOT.GOV | 23

The Research Associateship Program at FHWA provides mentorship and career-building opportunities for participants in facilities 

like the Structures Lab at Turner-Fairbank Highway Research Center and sometimes results in talented new hires for FHWA.

Source: FHWA.

FORMER RESEARCH ASSOCIATES 

FIND SUCCESS

FHWA’s Research Associateship Program helps participants launch their careers—sometimes with FHWA itself.

by JIM SHURBUTT

Postdoctoral candidates who apply for positions as research associates with the Federal Highway Administration do so to continue 

their research, make connections in their fields, and launch their 

careers. For some, career success is found right at the facility where 

they started as associates.

-

FHWA’s Exploratory Advanced Research 

(EAR) Program funds research associates 

through the Research Associateship Program of 

the National Academy of Sciences. The EAR 

Program seeks qualified candidates to work 

on real-world transportation problems largely 

of their own choosing, provided the topics are 

compatible with FHWA’s research interests. 

Associates work with FHWA advisers who 

mentor them throughout their tenure, which 

usually lasts for 2 or 3 years.

From 1992 through 2019, FHWA hosted 

50 research associates at its Turner-Fairbank 

Highway Research Center (TFHRC) and its 

Headquarters office. Former associates have 

gone on to work in academia, government, and 

industry, as well as to work as consultants.

Four former research associates currently work at TFHRC, either 

as FHWA staff or as contractors. They have each gone directly from 

the program to positions that have enabled them to continue their 

research while expanding their professional expertise and developing 

their careers.

Where Did They Go?

Former Research Associateship Program participants go on to work in a variety of fields.
24 | PUBLIC ROADS | SUMMER 2021

Jose Munoz prepares fine aggregates for chemical analysis in the Chemistry Lab at TFHRC.

© Jose Munoz, SES & Associates.

Jose Munoz, Ph.D.

As an associate, Jose Munoz focused on the development of 

specific nanoadditives to improve the mechanical performance of 

the cement paste-aggregate interface in concrete—specifically, the 

fundamental aspects of the interaction between nanosilica coatings 

and concrete-based materials. Munoz worked under the guidance 

of Jack Youtcheff in the Office of Infrastructure Research and 

Development from April 2010 to April 2013.

Munoz then was hired to work as a contract researcher in the 

TFHRC Chemistry Laboratory, where today he is the contracted 

laboratory manager.

“My main motivation to accept the job offer at TFHRC was 

my passion for research. TFHRC is probably one of the few places 

in the United States that offers such a unique opportunity to do 

research on concrete-related materials,” says Munoz. “Another 

important factor was the balance between fundamental and applied 

research that could be done at TFHRC.”

Munoz currently works on two proj

ects. One is to develop a new screening 

test to assess the alkali-silica reactivity of 

aggregates used in concrete. The other is 

a collaboration between the Chemistry 

Laboratory and the Structure Laboratory 

at TFHRC, which is a continuation of the 

work he did as an associate. It is a project 

to develop nanosilica-based thin films to 

improve the bond in prefabricated bridge 

element connections.

-

Munoz cites several benefits he received 

from his participation in the Research Asso

ciateship Program, including strengthening 

his resume because of the prestige of the 

program, conducting research and publishing manuscripts, and 

networking with colleagues at TFHRC and other institutions.

-

“Thanks to the program, I had the unique opportunity to join 

the TFHRC team as a contractor and pursue both fundamental 

and applied research,” he says.

David Mensching, Ph.D., P.E.

David Mensching served as a research associate from May 2015 

to August 2016, working with former FHWA employee Nelson 

Gibson in the Office of Infrastructure Research and Development. 

As an associate, Mensching researched performance-based mixture 

design and rheological parameters for asphalt mixture and binder 

characterization. After his tenure as an associate, he was hired as 

an asphalt pavement engineer at TFHRC. Today, he is FHWA’s 

asphalt materials research program manager and serves as an 

adviser to current associates. 

“My time as an associate was for exploration and network 

building,” says Mensching. “The associateship was my first chance 

to lead research from conception to completion. That’s invaluable 

experience that can’t be had in many places and in many postdoc

toral positions.”

-

As an associate, Mensching published extensively, which he 

says built national expertise. He also took advantage of the travel 

budget he was given to present on his research and improve 

his work.

Given the opportunity to stay on at TFHRC, he took it. 

“You have so many possibilities for cross-cutting transportation 

research, and the people here are welcoming, bright, and moti

vated. TFHRC’s leaders have research backgrounds and expertise 

themselves, which allows for deeper cultivation of thought and 

creativity,” he says. “It’s really an unparalleled location for intellec

tual growth.”

-

-

Mensching’s career path has taken him from his associateship 

to managing a program of 11 other researchers, including one 

associate. He has gone from narrowly focusing on one project as an 

associate to managing a program with a broad portfolio of original 

research covering topic areas such as reclaimed asphalt pavement, 

performance specifications, long-life wearing courses, asphalt 

binder specifications, artificial intelligence, connected pavements, 

and resilience.

David Mensching sets up a dynamic modulus test 

in the Asphalt Mixture Performance Tester.

Source: FHWA.
WWW.FHWA.DOT.GOV | 25

Pavle Bujanović, Ph.D.

Pavle Bujanović spent 2 years at TFHRC as 

a graduate research fellow under FHWA’s 

Eisenhower Transportation Fellowship 

Program before serving as a research associate 

from August 2018 to August 2019. Under 

the guidance of his adviser, Taylor Lochrane 

in FHWA’s Office of Operations Research 

and Development, Bujanović worked on 

developing cooperative driving automation 

(CDA) algorithms, specifically localization 

and platooning algorithms. He also worked 

on adding the CARMA PlatformSM to one of 

the vehicles in FHWA’s CARMA fleet. 

FHWA hired Bujanović to join the staff of the Office of Opera

tions Research and Development as a highway research engineer at 

the end of his associateship.

-

“I work to increase the safety and efficiency of our Nation’s 

infrastructure through CDA strategies that are designed and tested 

in the CARMA ecosystem,” says Bujanović. “I also help promote 

CARMA and invest in relationships with different people and 

organizations that are interested in CDA research. I’m still involved 

in technical design, as I was before, but now I’m also contributing 

to the direction of the entire CARMA Program.”

Bujanović praised the Research Associateship Program as a valu

able research experience with excellent resources and opportunities 

to help recent doctoral graduates pursue their research, in part 

because of the freedom and flexibility the FHWA mentors provide 

associates in their choice of projects.

-

As a staff member with FHWA’s CARMA Program, Pavle Bujanović has 

continued and expanded the work he started as an associate.

Source: FHWA.

Rafic El-Helou installs sensors to measure the deformation 

of a UHPC beam in FHWA’s Structures Laboratory.

Source: FHWA.

Rafic El-Helou, Ph.D.

As a research associate, Rafic El-Helou worked on the structural 

behavior of prestressed ultra-high performance concrete (UHPC) 

girders and on the development of structural design guidance for 

UHPC bridge components. He worked with adviser Benjamin 

Graybeal in FHWA’s Office of Infrastructure Research and Devel

opment from December 2016 to October 2019.

-

A private firm hired El-Helou directly out of the program to 

work as a contracted structural research engineer at TFHRC.

“I am passionate about the research I started during my tenure 

as an associate and wanted to continue the work after my tenure 

ended,” says El-Helou. “I also enjoy the work environment and the 

collaborative research experience at TFHRC.”

El-Helou’s current research is a continuation of his work as an 

associate. “I am part of the TFHRC team that supports FHWA’s 

efforts to develop structural design guidance for UHPC,” he says. 

“I also research various UHPC applications in the highway sector.”

Like other alumni of the associateship program, El-Helou 

would recommend it to others. “The program connected me with 

experts in my field and provided me with mentorship to kick off 

my career. It also provided the means for numerous professional 

development opportunities,” he says. “It’s a great start to your 

career in a reputable laboratory.”

Become a Research Associate

The EAR Program actively seeks qualified postdoctoral candidates 

to participate in the Research Associateship Program, where they 

will work with leading researchers, have access to state-of-the-art 

laboratories and equipment, and expand their career possibili

ties. To learn more about RAP opportunities through the EAR 

Program, visit 

-

https://highways.dot.gov/research/research-programs

/exploratory-advanced-research/nrc-research-associates-help-ear-program

-solve-transportation-issues and click on the Apply link to view the 

list of current opportunities available at FHWA.

JIM SHURBUTT is the program coordinator for FHWA’s EAR Program. One of his 

primary responsibilities is the management of the Research Associateship 

Program. He holds a Ph.D. in applied behavior analysis from Western 

Michigan University, where his research focused on both pedestrian safety 

and organizational management.
26 | PUBLIC ROADS | SUMMER 2021

FHWA and its partners are aiming to make the 

use of aggregates in pavement more sustainable. 

Here, crushed stone is processed and shipped 

from a plant at a granite quarry in Virginia.

Source: FHWA.

Looking to AGGREGATES to Improve Pavement Sustainability

FHWA is conducting research, developing tools, and gathering data to improve how aggregate 

materials are sourced, planned, and used in sustainable pavement construction and maintenance.

by RICHARD MEININGER, HEATHER DYLLA, and JACK YOUTCHEFF

Aggregate is a critical element in the construction, maintenance, and repair 

of roadways and concrete structures. 

However, the aggregate resources needed 

for the construction and maintenance of 

highways, local roads, and streets, as well 

as for basic materials for concrete struc

tures and drainage applications, often are 

not given sufficient consideration early in 

the planning and design process. Planners 

and engineers need to consider: What are 

the local natural and recycled aggregate 

resources and are they of the quality needed 

for anticipated pavement layer construction, 

overlays, and preservation treatments?

-

Natural aggregate availability depends on 

the regional geologic resources and whether 

those resources can be mined and trans

ported in a long-term, sustainable way to 

the major construction markets. There are 

significant challenges to managing resources 

for the reuse or recycling of reclaimed 

asphalt pavement (RAP) and recycled 

concrete aggregate (RCA). In rural areas, 

the reclaiming and recycling of aggregates 

can be done on a project-by-project basis, 

ensuring more consistent quality, but it 

is expensive and inefficient to move these 

low-value materials long distances to other 

projects. Combined RAP stockpiles and 

-
WWW.FHWA.DOT.GOV | 27

urban rubble recycling of concrete, brick, 

and stone are common in many metropol

itan areas, but create more variable quality 

for these resources.

-

To help address these challenges, 

researchers at the Federal Highway Adminis

tration’s Turner-Fairbank Highway Research 

Center (TFHRC), along with other 

partners, have been researching the physical 

and chemical factors necessary to effectively 

deploy both natural aggregates and recycled 

materials in the major components of pave

ment construction and maintenance. These 

components include aggregate base courses 

for pavement foundation layers, compacted 

asphalt mixtures for bases and surface 

courses, and concrete pavements used 

extensively for heavy traffic and mainline 

highway pavements.

-

-

In addition to this research, FHWA 

has expanded its Sustainable Pavements 

Program, offering educational resources 

and tools to help project planners and 

highway engineers consider the impacts 

and costs of choosing pavement options 

in a holistic way. The program’s vision is 

to increase the knowledge and practice of 

designing, constructing, and maintaining 

more sustainable pavements. To accom

plish this vision, the Sustainable Pavements 

Program strives to educate and support 

stakeholder needs by producing technical 

resources, creating training opportunities, 

developing tools, and facilitating conversa

tions through stakeholder meetings.

-

-

In particular, over the past 20 years, 

FHWA has partnered with the Interna

tional Center for Aggregates Research and 

committees of the Transportation Research 

Board and the American Association of 

State Highway and Transportation Offi

cials in shaping research and engaging with 

stakeholders to gather information and ideas 

on technical priorities and needed research 

approaches to improve the performance 

of pavements and materials, resulting in 

the Aggregate Research Roadmap. The 

roadmap is revisited and updated regularly 

to keep it current and match priorities to 

research needs.

-

-

Sustainability and the Triple Bottom Line

Sustainability is a quality that reflects the 

balance of three primary components: 

economic, environmental, and social 

impacts, which are often collectively referred 

to as the triple bottom line. Considering 

sustainability during the transportation 

decisionmaking process is not new. Typi

cally, the environmental and social impacts 

are quantified during the conceptual design 

phases as part of the environmental review 

process, while cost-effectiveness is a consid

eration in pavement design. However, there 

is growing recognition in the industry that 

the pavement design, material selection, and 

construction phases, including aggregate 

mine sources, transportation, and aggre

gate recycling, contribute significantly to 

all three pillars, and thus opportunities for 

improvement exist.

-

-

-

Source: FHWA.

The relative importance and consid

eration of each of the economic, social, 

and environmental impacts factors are 

context-sensitive and driven by the project 

goals and performance demands, character

istics, location, materials, and constraints 

of a given project, as well as the over

arching goals of the sponsoring agency. 

By designing, constructing, restoring, 

preserving, and maintaining pavements 

that consider the triple bottom line over the 

project’s life cycle, transportation agencies 

can develop a more resilient infrastructure 

system with increased performance and 

a high return on investment despite the 

growing constraints on economic and 

material resources, such as availability of 

local crushed stone, sand, and gravel.

-

-

-

“Aggregates are the most predom

inant material in highway and other 

transportation applications,” says 

Matthew Beeson, Director of Mate

rials and Tests, Indiana Department 

of Transportation and Chair of the 

Aggregates Technical Subcommittee of the 

AASHTO Committee on Materials and 

Pavements. “Improving the performance of 

aggregates used in current applications and 

expanding the use of and sources of natural 

and recycled aggregates for new applica

tions will make a significant contribution 

toward creating a sustainable society and 

extending the performance of infrastructure 

containing aggregates.”

-

-

-

Some areas and regions of the country 

have experienced aggregate shortages for 

certain highway pavement applications 

that have necessitated longer transportation 

distances for aggregates that meet project 

requirements. Some of these inefficient and 

unsustainable practices have been prompted 

by method (rather than performance) 

specifications or pavement design practices 

that have not considered the best uses of 

certain local natural aggregate characteris

tics, nor considered whether local recycled 

or reclaimed aggregate products can be used 

instead to construct or rehabilitate quality, 

long-lasting pavement layers.

-

An aggregate stockpile in Estes Park, CO.

Source: FHWA.

A Roadmap to Research Success

For more than 20 years, FHWA has 

participated with highway agency 

and industry stakeholders, as well as 

university researchers and the TRB 

Aggregates Committee (AKM80), 

in developing and maintaining an 

Aggregate Research Roadmap. The 

Aggregate Research Roadmap 

was originally developed by an 

FHWA technical working 

group that included 
28 | PUBLIC ROADS | SUMMER 2021

university researchers, State departments 

of transportation, and aggregate industry 

representatives. In cooperation with 

the International Center for Aggregates 

Research, and later, in collaboration with 

TRB and AASHTO aggregate committees 

and subcommittees, these stakeholders 

helped shape aggregate research conducted 

over the past two decades.

Discussions about the needs for pave

ment technology research and the periodic 

review of the roadmap have resulted in 

many research needs statements, such as 

those vetted by TRB and AASHTO, and 

aggregate research projects funded by the 

States, industry, and FHWA. Roadmap 

priorities have led to completed research 

projects and syntheses recommended 

through TRB and conducted by the 

National Cooperative Highway Research 

Program, universities, and agencies. 

These include completed projects on 

compacted aggregate base course proper

ties and aggregate-specific gravity research, 

and syntheses on granular base course 

construction and on aggregate 

quality criteria.

-

-

Source: FHWA.

Resources for Sustainable 

Pavement Systems

FHWA’s Sustainable Pavements 

Program provides webinars, 

tools, and resources developed 

and presented to the pavement 

community that consider the 

elements of the triple bottom 

line of sustainability that are 

impacted by pavement design, 

aggregate choices, and pavement 

life cycle performance. Through 

the program, FHWA has devel

oped tools to aid in choosing 

sustainable options for aggregate 

sources, transportation, and 

recycling, as well as showing how 

better performance and timely 

preservation are significant 

inputs into life-cycle analysis and 

pavement management concepts.

-

In 2015, the Sustain

able Pavements Program 

published Towards Sustainable 

Pavement Systems: A Reference Document

(FHWA-HIF-15-002), which walks through 

the pavement life cycle and highlights 

potential strategies for improvement. The 

publication identifies context-specific, 

potential strategies for sustainability 

improvements, including strategies for 

aggregate production and use. Strategies for 

aggregates include reducing virgin aggre

gate use by using recycled waste materials, 

using more durable aggregates to maximize 

pavement life, reducing hauling distances 

by selecting local materials, and improving 

aggregate acquisition and processing. 

Building on the publication, FHWA offered 

a 10-part webinar series in 2019 and 2020 

on the key concepts and practices related to 

pavement sustainability to help engineers 

begin identifying potential environmental, 

economic, and social impacts of decisions. 

The webinar recordings are available at 

-

-

www.fhwa.dot.gov/pavement/sustainability

/webinars.cfm.

Tools exist to quantify and assess the 

sustainability performance and to help 

agencies review sustainability strategies and 

take a holistic life cycle approach to balance 

tradeoffs. For example, FHWA’s RealCost 

tool, available at www.fhwa.dot.gov

/infrastructure/asstmgmt/lccasoft.cfm, can help 

with life-cycle cost analysis. For pavements, 

life-cycle cost analysis provides a way of 

measuring the economic consequences of 

choices in design, materials, construction 

techniques, construction windows, mainte

nance schemes, and end-of-life treatments 

over a prescribed analysis period. Many 

State agencies have life-cycle cost analysis 

policies and procedures in place.

-

Life-cycle assessment (LCA) is a meth

odology used to evaluate a range of envi

ronmental impacts, such as potential for 

climate change, ozone depletion, acidifica

tion, eutrophication, and smog formation. 

Over the last decade, FHWA, along with 

its partners from transportation agencies 

and industry, have conducted substantial 

work to incorporate LCA into the pavement 

investment decisionmaking process. One 

resource is FHWA’s LCAPave, a new tool 

that is currently going through FHWA’s 

publication process after a successful beta 

test, which can help agencies understand 

the environmental impacts of material 

and design choices. LCAPave can incor

porate aggregate producers’ specific data, 

via environmental product declarations, 

or can help make generic assessments of 

different mixture and pavement designs, 

such as inverted pavements compared to 

conventional designs. FHWA has a pooled 

fund project for States interested in trying 

LCAPave in a demonstration project; for 

more information, visit 

-

-

-

-

www.pooledfund.org

/Details/Solicitation/1542.

Social indicators are an important pillar 

of sustainability, but harder to assess. Social 

impacts from pavement and material deci

sions can include both short-term construc

tion and long-term operations factors, such 

as noise, traffic, safety, materials hauling, 

resource conservation, and ride quality. To 

stay abreast on the latest topics of pavement 

sustainability, join the FHWA Sustainable 

Pavements Friends list by signing up at 

-

-

https://public.govdelivery.com/accounts

/USDOTFHWA/subscriber

/new?topic_id=USDOTFHWA_146.

Source: FHWA.

Pavement Sustainability Sectors

Recently, FHWA refined and restated the 

core objectives of the pavement program to 

emphasize the importance of constructing 

and managing quality pavements through 

the full life cycle, while also meeting 

community objectives. These objectives 

and categories were developed through the 

collaboration of the pavement and materials 

team leaders within FHWA’s Office of Infra

structure, Office of Infrastructure Research 

and Development, and Resource Center.

-

All phases of the life cycle are important 

in meeting the core sustainability mission, 

and since aggregates are the predominant 

constituent both by volume and mass in 
WWW.FHWA.DOT.GOV | 29

the various pavement materials and layers 

(bases, asphalt, and concrete), the selection 

and quality assurance of aggregates play a 

major role in all segments of the pavement 

life cycle. These sustainability sectors are 

pavement design, materials, quality assur

ance, pavement construction, pavement 

management, and pavement preservation 

and rehabilitation.

-

Because aggregates are the predominant constituent, 

both by volume and mass in the various pavement 

materials and layers (bases, asphalt, and 

concrete), the selection and quality assurance 

of aggregates play a major role in all segments 

of the pavement life cycle wheel.

Source: FHWA.

Pavement design and pavement type 

are often influenced by local and regional 

aggregate sources and quality, as 

well as by the properties of the 

subgrade soil.

Materials used in pavements 

and structures can be much more 

successful and durable when spec

ifications and test methods for the 

individual aggregates, and for the 

performance of mixtures containing 

aggregates, have been developed to 

properly characterize materials in the 

laboratory and in mixture designs that will 

be durable in service, and to facilitate effi

cient production and placement in the field.

-

-

Quality assurance is the backbone 

for durable, long-lasting highways and 

pavements. Owners and engineers have 

the responsibility to provide inspection, 

sampling, testing, and verification that 

construction using aggregates is in confor

mance with the plans, specifications, and 

materials designs. This includes ensuring 

that laboratory and field quality assurance 

personnel are qualified in the specialized 

sampling techniques for aggregate from 

stockpiles, bins, and roadway placements.

-

Pavement construction involving the 

placement and optimum compaction of 

granular aggregate bases can be challenging 

in that segregation needs to be avoided in all 

phases of recovery from stockpiles and bins, 

truck delivery, and spreading aggregate on 

the grade.

Pavement management depends on the 

acquisition of periodic data on rideability, 

friction, rutting, cracking, and profile and 

drainage issues. Aggregates exposed at the 

wearing surface contribute to the duration 

of sufficient macro- and micro-texture to 

provide needed traction in wet weather. 

Aggregate selection and performance can 

also contribute to the likelihood of rutting, 

drainage, and durability problems causing 

spalling, raveling, and water accumulation.

Pavement preservation and rehabilita

tion treatments and methods often require 

special attention to aggregate grading and 

quality. Even for pavements that have 

deteriorated, the aggregate bases can often 

be considered a valuable asset that can be 

reshaped, rehabilitated, or stabilized through 

processes such as full-depth reclamation and 

drainage improvements to provide a quality 

foundation for new pavement layers, over

lays, and wearing course treatments.

-

-

Photomicrograph of thin sections of recycled concrete aggregate particles for analysis, viewed through a petrographic microscope. The 

top images use cross-polarized light for mineral identification. The bottom images use fluorescent light to study porosity.

Source: FHWA.

Relative Supplies of Natural 

Aggregates by State

To help highway agencies understand the 
30 | PUBLIC ROADS | SUMMER 2021

available supply of natural aggregates 

(crushed stone, sand, and gravel) in 

each State, FHWA recently compiled 

key statistical indicators relating annual 

natural aggregate production expressed 

as a ratio to lane-miles of pavement in 

each State for 2017. This was done to 

normalize potential resources based on 

the total amount of constructed and 

managed lane-miles of roadways in 

each State. Total aggregate production 

includes current United States Geolog

ical Survey (USGS) data of annual 

supplies of construction crushed stone 

and sand and gravel available in each 

State. Natural aggregate availability 

regions for sand and gravel, and for the 

different types of crushed stone, often 

do not follow State boundaries, but are 

important considerations in local pave

ment material selection.

-

-

Some States and regions, such as the 

High Plains and the Gulf Coast, have 

limited availability of quality natural 

aggregates. Therefore, aggregates have 

to be transported long distances at 

greater economic and environmental 

costs. Alternatively, project planners 

may consider other options, such as 

tailoring pavement base and pavement 

layer construction methods to available 

local or marginal materials, greater use 

of stabilized local soils and materials for 

subbases and bases, and more aggressive 

pavement preservation techniques using 

surface treatments and thin overlays to 

maintain pavement serviceability.

Many States east of the continental 

divide and along the Gulf Coast have 

lesser amounts of natural aggregates 

(sand, gravel, and crushed stone) 

available. Rocky Mountain and Appa

lachian States, and those closer to the 

mountains, tend to have more natural 

aggregate resources as a ratio per lane 

mile in these roadway systems. States in 

the upper Midwest also typically have 

higher amounts of resources per lane 

mile because of glacial sand and gravel 

deposits, as well as ample limestone and 

dolomite bedrock sources in the region.

-

The top States for carbonate crushed 

stone as a percentage of the total natural 

aggregate resources include West 

Virginia, Kentucky, Missouri, Iowa, 

Tennessee, Florida, Texas, Indiana, 

Ohio, Michigan, and Illinois. States like 

these with high percentages of carbonate 

crushed stone, which is relatively 

soft, may face challenges in locating 

hard mineral aggregates for pavement 

wearing surfaces and surface treatments 

that provide required friction and 

texture performance.

“Understanding the local availability 

of various natural aggregates can help 

project planners determine the best 

methods and solutions to meet the 

needs of each project,” says Bob Younie, 

Director of Maintenance for the Iowa 

Department of Transportation.

-

Total Annual Natural Aggregate Resources, Ratio of 

Tons of Production per Lane-Mile of Roadways

Annual Sand and Gravel Resources, Ratio of Tons 

of Production per Lane-Mile of Roadways

Annual Crushed Stone Resources, Ratio of Tons 

of Production per Lane-Mile of Roadways

ABOVE: Amounts of annual aggregate resources expressed 

as a ratio of tons of production per lane-mile of roadways 

in each State, including total natural construction 

aggregates, sand and gravel, and crushed stone.

BELOW: This chart shows the percent of annual 

crushed stone production that is carbonate aggregates 

(limestone, dolomite, and marble) in each State. 

Carbonate aggregates are relatively soft, limiting use 

in pavement surfaces because they can polish under 

traffic, creating slippery-when-wet conditions.

Source: FHWA.

Percent of Crushed Stone that is Carbonate Aggregate

Recent FHWA Aggregates Research

FHWA’s research has helped to advance 

the understanding of aggregates and 

pavement materials.

For example, an ongoing TFHRC 

study using FHWA’s Pavement Test 

Facility (PTF) examined different 

percentages of RAP and recycled asphalt 

shingles in both conventional and 

warm-mix asphalt (WMA) pavements to 

quantify the cracking resistance of high 

RAP mixtures and the effect of lower 

WMA mixing and compaction tempera

tures on RAP performance. Lanes 

containing recycled shingles and high 

RAP using the stiffer binder were more 

susceptible to fatigue damage. The warm 

mix and hot mix materials provided 

similar performance. While this study 
WWW.FHWA.DOT.GOV | 31

focused on binder issues, the research 

advanced a method for determining the 

workability of loose hot mix based on defor

mation conducted at a fixed deformation 

rate. This can be used as a quality control 

test for RAP mixes and RAP materials.

-

An earlier study at the PTF looked at the 

use of a 4.75-millimeter nominal maximum 

aggregate size mixture containing 20 percent 

RAP to study effects on delaying top-down 

cracking. This was a less permeable mix 

and provided good performance prior to 

its aging.

FHWA plans additional research at 

the PTF to include research topics such as 

recycled materials and the development of 

data on performance of asphalt mixtures 

and overlays as well as the incorporation 

of preservation strategies, which ultimately 

affects pavement life-cycle cost analysis 

and performance.

Other research from FHWA’s Chemistry, 

Concrete, and Petrographic Laboratories 

has explored aggregate durability and 

performance issues, as well as character

izing the variability and quality of recycled 

concrete aggregates. FHWA developed a 

chemistry test called T-FAST to identify 

the potential alkali silica reactivity of coarse 

and fine aggregates. The test specification 

for coarse aggregates was recently approved 

by AASHTO. Research to date has shown 

that this test gives 100 percent agreement 

with block farm data and can be run quite 

rapidly and more efficiently than tradi

tional methods.

-

-

FHWA has also conducted a field study 

to research the concept of inverted pave

ment in cooperation with the Virginia 

Department of Transportation and the 

aggregates industry. An inverted pavement 

uses the same materials as a conventional 

pavement, but the layers are arranged differ

ently. In conventional designs, the layer 

above protects the layer below (stiffer layers 

higher up). The inverted pavement uses a 

stiff base and essentially flips the middle 

layer. The field study found that the perfor

mance of the inverted pavement sections 

was comparable to standard Virginia pave

ment sections.

-

-

-

-

FHWA’s Pavement Test Facility at TFHRC.

Source: FHWA.

Looking to the Future: 

Aggregate Research Needs

FHWA and its partners continue to 

update the Aggregates Research Roadmap. 

Currently, the roadmap indicates research 

needs for aggregate granular bases, aggre

gates in asphalt paving mixtures and in 

concrete, and designs and methods of using 

recycled aggregates and excess supplies of 

some natural aggregate sizes.

-

For aggregate granular bases, inverted 

pavements provide one option for road 

foundations based on compaction of quality 

crushed aggregate base against a more rigid 

treated subbase. Research needs include 

achieving more uniform quality compac

tion of granular aggregate layers that will 

provide stiffer, long-lasting foundations for 

roads that will resist permanent deformation 

under heavy truck traffic.

-

Ongoing research is examining the 

quality of RAP and how much can be used 

in asphalt mixtures, as well as exploring 

how well a coating of aged asphalt on the 

RAP blends with the new materials. FHWA 

has also initiated research to assess the role 

that aggregate gradation plays in pavement 

macrotexture. Other research needs indi

cated by the roadmap are finding methods 

for balanced design of performance asphalt 

mixtures, including aggregate grading 

-

Total Annual Construction Aggregate Resources Available in the U.S.

• Crushed stone—1,510,000,000 tons

– Carbonate crushed stone (includes limestone, dolomite, and marble)—

1,040,000,000 tons

• Sand and Gravel—969,000,000 tons

• RAP (includes aggregate and binder)—102,000,000 tons

– Use as aggregate—10,300,000 tons

– Use in manufactured product—91,800,000 tons

– Use in asphalt mixtures—estimated 82,200,000 tons

• RCA (includes aggregate, mortar, and adhering cement paste)—

334,000,000 tons

– Use as aggregate—301,000,000 tons

– Use in manufactured product—32,800,000 tons

• Slag aggregate (blast furnace and steel furnace)—14,200,000 tons
32 | PUBLIC ROADS | SUMMER 2021

optimization and the interaction of binder 

types with aggregate surface properties to 

resist moisture and freezing exposures and to 

provide longer-lasting ride quality.

FHWA and its partners are devel

oping and refining test methods for use 

with the new AASHTO standard for 

performance-engineered mixtures for 

concrete pavements. These methods address 

both the workability and placeability of the 

mixture for slip-form paving, but also the 

important durability criteria for aggregates 

in concrete to resist freeze-thaw, deicing 

chemical, and alkali aggregate reaction 

exposures that can shorten concrete pave

ment service.

-

-

All pavements require aggregates at the 

wearing surface with hard, wear-resistant 

minerals that provide consistent friction 

and texture. Research related to improving 

the measurement of friction and texture 

on pavements at traffic speeds on a more 

continuous basis is ongoing, so that these 

performance data can improve traction and 

safety during wet weather.

The roadmap indicates that research is 

needed to better characterize recycled and 

reclaimed aggregates and develop pave

ment designs for using and blending these 

materials in new pavement layers, as well as 

to determine treatments to extend or renew 

service life. In addition, in many areas, 

crushed stone quarries have high demand 

for clean coarse aggregate sizes, but that 

leads to the challenge of how to best use the 

excess crushed fine aggregate and oversize 

rock materials on a sustainable basis so 

that aggregate resources can be used more 

effectively locally for highway construction 

and improvements.

-

“Achieving sustainable pavements isn’t 

simply a matter of maximizing the use 

of recycled and locally available aggre

gates,” says Dr. Cheryl Richter, Director of 

FHWA’s Office of Infrastructure Research 

and Development. “To be sustainable, the 

pavement must be durable. FHWA research 

is providing information and guidelines 

needed to support use of RAP, reclaimed 

asphalt shingles, and other materials 

to achieve long-lasting, truly sustain

able pavements.”

-

-

RICHARD MEININGER is the manager of FHWA’s 

Aggregates and Petrography Lab at TFHRC and 

has been an FHWA highway materials researcher 

at TFHRC for 20 years. He holds a B.S. and an M.S. 

in civil engineering from the University of Maryland 

and is a registered professional engineer.

HEATHER DYLLA is the program manager for 

FHWA’s Pavement Sustainability Program. She 

holds a Ph.D. and an M.S. in engineering science 

from Louisiana State University and a B.S. in civil 

engineering from Bradley University.

JACK YOUTCHEFF is the leader of FHWA’s 

Infrastructure Materials Team in the Office of 

Infrastructure Research and Development at 

TFHRC. He has a Ph.D. in fuel science and a 

bachelor’s degree in chemistry from Pennsylvania 

State University.

For more information, see https://highways

.dot.gov/research/turner-fairbank-highway

-research-center/laboratories/laboratories

-overview, and www.fhwa.dot.gov/pavement

/sustainability, or contact Richard Meininger 

at 202–493–3191 or Richard.Meininger@dot

.gov, Heather Dylla at 202–366–0120 or 

Heather.Dylla@dot.gov, or Jack Youtcheff at 

202–493–3090 or Jack.Youtcheff@dot.gov.

A large power shovel loads blasted granite rock from a crushed-stone quarry in Virginia into 

a hauling vehicle for transportation to the crushing and screening plant nearby.

Source: FHWA.
FHWA’

s State-of-the-Art 

NDE Research

Non-destructive evaluation (NDE) is a means 

of analyzing and assessing the condition 

of structural components of highway 

infrastructure including pavement, 

bridges, and tunnels without 

damaging them.

Source: FHWA.

Capabilities include:

• Ground Penetrating 

Radar Testing

• Infrared Thermography 

Testing

• Impact Echo Testing

• Surface Wave Testing

• Structural Health 

Monitoring Systems

• Numerical Simulation

• Automated Data 

Collection, Analysis, 

Interpretation, 

Visualization, and Fusion

• Conventional/Phased 

Array/Full Matrix Capture 

Ultrasonic Testing

• Conventional/Advanced 

Eddy Current Testing

• Acoustic Emission

• Noncontact and 

FHWA Remote Sensing ’s Advanced

Sensing Technology (FAST) 

NDE Laboratory conducts state-of-the-art 

research, development, and implementation 

of nondestructive testing systems and technologies to 

improve the Nation’s highway infrastructure assets.

The lab also developed the NDE Web Manual (available on the 

InfoTechnology website, starting July 2021) to assist bridge practitioners 

in selecting appropriate NDE technologies for their projects.

For more information, visit http://bit.ly/2vup7F9.
34 | PUBLIC ROADS | SUMMER 2021

ALONG THE ROAD

Colorado’s Highway of Legends is one of 49 additions to America’s Byways®.

© Tim Roberts Photography / Shutterstock.com.

Along the Road is the place to look for information about current and upcoming activities, developments, trends, and items of general interest to the 

highway community. This information comes from U.S. Department of Transportation sources unless otherwise indicated. Your suggestions and input 

are welcome. Let’s meet along the road.

Personnel

USDOT Appoints Chief Science Officer

The U.S. Department of Transportation recently announced that it is appointing a Chief Science Officer for the entire Depart

ment for the first time in more than four decades. 

-

U.S. Secretary of Transportation Pete Buttigieg has desig

nated the Assistant Secretary for Research and Technology as 

the Department’s Chief Science Officer. Robert C. Hampshire, 

Ph.D. is currently acting in this role. In his role as Chief Science 

Officer, Dr. Hampshire will serve as the principal advisor to 

Secretary Buttigieg on science and technology issues. He is charged 

with ensuring that USDOT’s research, development, and tech

nology programs are scientifically and technologically well-founded 

and conducted with integrity. 

-

-

Dr. Hampshire was previously an associate professor at the 

Gerald R. Ford School of Public Policy at the University of Mich

igan (U-M) and at both the U-M’s Michigan Institute for Data 

Science and the Human Factors group of the U-M Transportation 

Research Institute. He holds a Ph.D. from Princeton University.

-

“The reintroduction of a Chief Science Officer underscores 

transportation’s key role in addressing the complexity and crit

icality of our dynamically changing climate. I look forward to 

working across all modes of transportation to address the imme

diate concerns, and to ensure our future transportation system is 

sustainable,” said Dr. Hampshire in a press release. “It is important 

that USDOT incorporate scientific research to advance climate 

change initiatives that are fair and equitable to all.”

-

-

Public Information and Information Exchange

FHWA Announces New America’s Byways® Designations

I

n February, Federal Highway Administration officials announced 

49 new designations to the America’s Byways® collection, 

including 15 All-American Roads and 34 National Scenic Byways 

in 28 States. This increases the number of America’s Byways to 184 

in 48 States. Created in 1991, the program is a collaborative effort 

to help recognize, preserve, and enhance selected roads throughout 

the United States. The USDOT recognizes certain roads based on 

one or more archeological, cultural, historic, natural, recreational, 

and scenic qualities.

The Reviving America’s Scenic Byways Act of 2019 required 

the U.S. Secretary of Transportation to solicit nominations for the 

designation of All-American Roads and National Scenic Byways, 

resulting in 63 nominations. Each application was reviewed by 

subject-matter experts on historic preservation, design, cultural 

resources, visual impacts, tourism and economic development, 

highway safety, Federal lands, and Native American history and 

culture. The U.S. Departments of Agriculture and Commerce also 

provided input.

USDOT urges all Americans to follow CDC guidance and local 

regulations on safe travel during the COVID-19 public health 

emergency. The public is encouraged to explore these newly desig

nated distinct and diverse roads once it is safe to do so. The full list 

of 2021 All-American Roads and National Scenic Byways designa

tions is available at 

-

-

https://highways.dot.gov/newsroom

/usdot-announces-new-americas-bywaysr-designations.

USDOT Implements Efforts to Promote Scientific Integrity

In addition to appointing a Chief Science Officer, USDOT 

has taken several additional steps to act on the Biden-Harris 
WWW.FHWA.DOT.GOV | 35

Administration’s commitment to address climate change. The 

Department announced that it has begun work to reestablish 

its Climate Change Center and has made significant strides to 

improve public access to climate-related reports, program informa

tion, and other scientific and technical information.

-

The Department’s actions stem from the President’s Executive 

Order on Protecting Public Health and the Environment and 

Restoring Science to Tackle the Climate Crisis, as well as from the 

Presidential Memorandum on Restoring Trust in Government 

Through Scientific Integrity and Evidence-Based Policymaking. 

The Climate Change Center will help coordinate the Depart

ment’s related research, policies, and actions and support the 

transportation sector in moving toward net-zero carbon emissions. 

Originally established in 1999 to serve as the multimodal focal 

point for information and technical expertise on transportation 

and climate change, coordinating climate-related research, policies, 

and actions, the center has been dormant since early 2017.

-

The Department has also assessed public websites and informa

tion repositories, including the National Transportation Library, 

to ensure the public has access to comprehensive climate-related 

reports, program information, and other scientific and tech

nical information.

-

-

The Department will also designate a Scientific Integrity 

Officer, responsible for research policy implementation, who 

reports directly to the Chief Science Officer.

The transportation sector is the number one producer of green

house gases in the United States, which underscores the ability of 

the transportation industry and the Department to quickly and 

meaningfully reduce greenhouse gases and address the environ

mental concerns. These actions are the first steps in establishing the 

Department as a leader in addressing climate change and environ

mental justice.

-

-

-

NHTSA has initiated two studies on bicycle and pedestrian safety.

© connel / Shutterstock.com

FHWA Publishes Pedestrian and Bicycle Case Studies

Pedestrian fatalities have been on the rise throughout the United 

States, and as more Americans are walking and bicycling, many 

agencies have been working to improve safety for these vulnerable 

road users. 

A new report from FHWA highlights the work of transporta

tion agencies at the Federal, State, and local levels to improve safety 

for pedestrians and bicyclists. Case Studies for FHWA Pedestrian and 

Bicycle Focus States and Cities (FHWA-SA-21-021) provides infor

mation on agency efforts through FHWA’s Pedestrian and Bicyclist 

Safety Focused Approach Program. The case studies include the 

city of Austin, TX, and Arizona, California, Florida, Georgia, 

New Mexico, and New York. The case studies describe the lessons 

learned from processes related to implementing safety initiatives 

and countermeasures. The document is available at: 

-

-

https://safety.fhwa.dot.gov/ped_bike/ped_focus/docs/FHWA

_FocusApproach_CaseStudies_508.pdf.

For more information, visit https://safety.fhwa.dot.gov/ped_bike

/ped_focus.

Work Zone Fatalities at Highest Level Since 2006

During April’s Work Zone Awareness Week, FHWA joined State 

departments of transportation and other organizations nationwide 

to urge drivers to keep highway workers and the traveling public 

safe as construction activities increase. In 2019, the most recent 

year for which data are available, 842 people died in highway 

work-zone crashes, compared to 757 the year before. The 11.2-

percent increase is the largest percentage increase of highway work 

zone fatalities since 2006.

Crashes in highway work zones happen most frequently when 

drivers are not paying attention to changing road conditions. 

Distracted driving is a key element of many crashes, leading many 

drivers to crash into other vehicles, highway equipment, or safety 

barriers. 

Though highway workers are often among the victims of work 

zone crashes, the dangers of reckless driving more often affect those 

behind the wheel and their passengers. Four out of five work zone 

fatalities were drivers or passengers, according to FHWA data.

FHWA has supported work zone safety efforts for more than 

20 years and, since 2005, has awarded more than $40 million in 

grants to States for specialized work zone safety training. To date, 

nearly 4,300 courses have been provided to over 120,000 State and 

local DOT personnel or other transportation agency staff.

NHTSA Announces New Projects on 

Pedestrian and Bicyclist Safety

The National Highway Traffic Safety Administration (NHTSA) 

recently initiated two new projects focusing on pedestrian and 

bicyclist safety.

A 3-year project will focus on identifying and developing 

educational materials and products on pedestrian and bicyclist 

safety for drivers’ education and training courses. A second 2-year 

study will conduct a comparative analysis between States and cities 

with low percentages of pedestrian fatalities and those that have 

made improvements yet continue to have higher percentages of 

pedestrian fatalities. The team will identify common strategies or 

characteristics that result in better safety outcomes to inform new 

approaches for places with high pedestrian fatalities. 

For more information, contact Ruth Esteban-Muir, the 

NHTSA project manager, at Ruth.Esteban-Muir@dot.gov.
36 | PUBLIC ROADS | SUMMER 2021

INTERNET WATCH

The web-based IPaC tool helps users determine if a transportation project 

will impact protected habitats or wildlife, like this marbled murrelet.

Source: USFWS National Conservation Training Center Image Library.

by DANIEL BUFORD, VICTORIA FOSTER and CHELLBY KILHEFFER

Transportation planners always need to be aware of potential impacts from their projects to federally listed endangered 

species and designated critical habitats. If a project may impact 

these wildlife populations or habitats, Section 7 of the Endangered 

Species Act requires planners to create a biological assessment 

and complete a consultation with the U.S. Fish and Wildlife 

Service (USFWS). To assist with Section 7, USFWS developed the 

web-based application Information for Planning and Consultation 

(IPaC) that helps users determine if a project will impact protected 

wildlife or habitats. 

In December 2020, USFWS launched an expansion of IPaC—

the Consultation Package Builder (CPB). The CPB provides the 

information, tools, and guidance necessary to submit biological 

assessments to USFWS in compliance with the Endangered Species 

Act. It also helps project planners identify conservation measures 

designed to avoid or minimize effects to listed species.

Improving Information and Accuracy

As a decision-support tool, IPaC, including the CPB, improves the 

consultation process by informing more accurate and consistent 

determinations. The CPB is an interactive, step-by-step process 

that helps IPaC users prepare full consultation packages while 

leveraging USFWS data and recommendations. The CPB results 

in better, more complete consultation packages, thereby saving 

time and resources while reducing the workload for all consulting 

parties. It provides enhanced functionality to existing IPaC tools, 

including official species lists and determination keys.

Determination keys are logically structured sets of questions 

that assist users in determining if a project qualifies for a stream

lined, programmatic consultation outcome. Qualifying projects 

can generate USFWS concurrence letters instantly through IPaC. 

Determination keys provide consistent and transparent outcomes, 

and significantly reduce the time to complete consultation for 

qualifying projects. 

-

“One benefit to IPaC is having a central location to obtain 

a project Official Species List for species to be addressed 

during Section 7 review. Prior to IPaC, [the process] was 

time-consuming,” says Amy Golden with the Virginia Department 

of Transportation (VDOT). “VDOT typically updates Section 7 

and threatened and endangered species reviews every 6 months or 

at project development milestones...It [is] easy to go to IPaC to 

obtain an updated Official Species List for projects.”

Streamlining Consultations

Determination keys and the CPB assist users in conducting more 

thorough analyses and determining what effects their projects may 

have on federally listed species and critical habitats. Benefits of 

using the CPB include:

• Producing consistently formatted and more complete 

consultation packages ready for submission to USFWS

• Saving time and resources while drafting a 

biological assessment

• Prepopulating USFWS information into the biological 

assessment for consideration during the analysis

• Receiving fewer requests for additional information 

during consultation

• Reducing workloads by streamlining the overall 

consultation process

“Using IPaC has definitely streamlined the endangered species 

coordination process,” says Betty Ketchum with the New York 

State Department of Transportation. “It is straightforward and easy 

to use.”

For more information, visit https://ecos.fws.gov/ipac or contact 

FWHQ_IPaC@fws.gov. 

DANIEL BUFORD is an ecologist with FHWA’s Office of Project Development 

and Environmental Review.

VICTORIA FOSTER is USFWS’s national IPaC program coordinator.

CHELLBY KILHEFFER is a biologist on the USFWS Headquarters’ IPaC team.
WWW.FHWA.DOT.GOV | 37

TRAINING UPDATE

NHI now offers some of its structures courses 

in a virtual instructor-led format.

NHI’s Commitment to Virtual Training for Engineers © one photo / Shutterstock.com

by MIGNON WHITTED and AMBER CLARK

Despite the shift in how to meet the needs of today’s workforce, the National Highway Institute (NHI) prides itself on its 

commitment to provide quality training to engineers. To continue 

to do so, NHI now offers some of its structures courses in an 

online, instructor-led format.

With this new training format, engineers can learn current 

information on key topics such as bridge and tunnel inspection, 

fracture-critical inspection techniques for steel bridges, and load 

rating of concrete and steel superstructures from the comfort of 

their home or office. The virtual environment offers engineers 

access to expert instructors worldwide while earning continuing 

education units.

Virtual Structures Courses

The following courses are, or will soon be, available in an online, 

instructor-led format.

Bridge Inspection Refresher Training (FHWA-NHI-130053V/

FHWA-NHI-130053A). This virtual training teaches learners how 

to effectively inspect and manage bridge inspection programs. 

Individuals will refresh their skills and knowledge on conducting 

bridge inspections and learn information on other related topics 

through various techniques and tools.

Load and Resistance Factor Rating of Highway Bridges (FHWANHI-130092V) (coming soon). The Load and Resistance Factor 

Rating of Highway Bridges course offers both novice and expe

rienced bridge engineers the fundamental knowledge necessary 

to apply the most recent American Association of State Highway 

and Transportation Officials Load and Resistance Factor Design 

specifications to bridge ratings. Participants are introduced to 

applications of these specifications that can be used to enhance 

bridge safety and to identify and discuss the steps needed to ensure 

a successful transition for this new state-of-the-art methodology.

-

Tunnel Safety Inspection Refresher (FHWA-NHI-130125V). 

The Tunnel Safety Inspection Refresher course provides learners 

with the foundation needed to successfully manage and execute a 

tunnel inspection. This highly interactive virtual training enhances 

participants’ prior knowledge of bridge and/or tunnel inspec

tions. Prior to taking this training, participants must complete the 

FHWA-NHI-130110 and FHWA-NHI-130124 courses.

-

Strut-and-Tie Modeling (STM) for Concrete Structures (FHWANHI-130126V) (coming soon). This online course provides 

engineers with a straightforward analysis and design tool for deep 

concrete bridge elements and disturbed regions that would other

wise require a rigorous refined analysis.

-

How to Attend or Host a Course

NHI invites professionals interested in earning continuing educa

tion units or professional development hours to visit 

-

http://bit.ly/NHIHome and browse the complete digital course 

catalog, which encompasses more than 400 courses spanning 18 

program areas. To sign up for alerts when a course session is sched

uled, visit the individual course’s description page and select the 

“Sign Up for Session Alerts” link.

-

Interested hosts can submit a Host Request Form or find more 

information about hosting NHI courses by visiting 

www.nhi.fhwa.dot.gov/training/host.aspx.

NHI is an approved Accredited Provider by the International 

Association for Continuing Education and Training (IACET). As 

an IACET Accredited Provider, NHI offers continuing education 

units for its programs that qualify under the American National 

Standards Institute/IACET Standard. 

MIGNON WHITTED is an acting NHI training program manager.

AMBER CLARK is a contracted marketing analyst for NHI.
38 | PUBLIC ROADS | SUMMER 2021

COMMUNICATION PRODUCT UPDATES

Below are brief descriptions of communications products recently developed by the Federal Highway Administration’s Office of Research, 

Development, and Technology. All of the reports are or will soon be available from the National Technical Information Service (NTIS). In some cases, 

limited copies of the communications products are available from FHWA’s Research and Technology (R&T) Product Distribution Center (PDC).

Compiled by LISA A. SHULER of FHWA’s Office of Corporate Research, Technology, and Innovation Management 

When ordering from NTIS, include the NTIS publication number 

(PB number) and the publication title. You also may visit the 

NTIS website at www.ntis.gov to order publications online. Call 

NTIS for current prices. For customers outside the United States, 

Canada, and Mexico, the cost is usually double the listed price. 

Address requests to:

National Technical Information Service 

5301 Shawnee Road 

Alexandria, VA 22312

Telephone: 703–605–6050 

Toll-free number: 1–888–584–8332 

Website: www.ntis.gov 

Email: customerservice@ntis.gov

Requests for items available from the R&T Product Distribution 

Center should be addressed to:

R&T Product Distribution Center 

Szanca Solutions/FHWA PDC 

700 North 3rd Avenue 

Altoona, PA 16601 

Telephone: 814–239–1160 

Fax: 814–239–2156 

Email: report.center@dot.gov

For more information on R&T communications products available 

from FHWA, visit FHWA’s website at www.fhwa.dot.gov, the FHWA 

Research Library at https://highways.dot.gov/research/resources

/research-library/federal-highway-administration-research-library

(or email fhwalibrary@dot.gov), or the National Transportation 

Library at ntl.bts.gov (or email library@dot.gov).

Contributing Factors for 

Focus Crash and Facility 

Types 

Publication Number: FHWAHRT-20-052

Identifying and implementing 

systemic safety improvements 

leads not only to the reduc

tion of crashes, but also to the 

reduction of the severity of 

crash incidents. Safety improve

ments are also bolstered by the 

identification of focus crash 

and facility types (FCFTs) and 

crash-contributing factors.

-

-

A study by FHWA explored FCFTs and contributing factors 

and how improvements can directly impact incidents that are 

deemed prevalent but are somewhat disperse in their occurrence.

This report details several key goals of the study, which included 

identifying FCFTs, contributing factors, and possible low-cost 

safety measures to support systemic improvements, as well as 

identifying and applying quality data, statistical methodologies, the 

analysis process, and tools.

The publication is available at www.fhwa.dot.gov/publications

/research/safety/20052/20052.pdf.

High-Level Concept of Operations: Examination of the 

Relationships Between Transportation Systems Management 

and Operations Strategies and Cooperative Driving 

Automation 

Publication Number: FHWA-HRT-20-063

The convergence of transpor

tation systems management 

and operations (TSMO) and 

cooperative driving automation 

(CDA) continues to advance 

FHWA’s CARMA PlatformSM. 

This report explores the highlevel concept of operations, its 

support of CARMA, and the 

ties between TSMO and CDA.

-

The research team exam

ined several factors integral 

to the TSMO/CDA relation

ship, including traditional 

TSMO strategies relevant to 

transportation infrastructure; 

identification of key criteria 

that would likely be affected by implementation of CDA; and 

consideration of four groups of use cases, including basic travel, 

traffic incident management, road weather management, and work 

zone management.

-

-

The report also explores what technologies and processes may 

need to be modified or introduced to accommodate new roles and 

functions for TMSO, while examining the challenges associated 

with traditional vehicles and CDA-equipped vehicles sharing the 

Nation’s roads.

The publication is available at www.fhwa.dot.gov/publications

/research/operations/20063/index.cfm.
WWW.FHWA.DOT.GOV | 39

Novel Highway Signs to Support Infrastructure-Based 

Motorcycle-Crash Countermeasures: Phase II 

Publication Number: FHWA-HRT-21-009 (TechBrief)

Publication Number: FHWA-HRT-21-010 (Final Report)

Identifying safety countermea

sures to prevent motorcycle 

crashes on the Nation’s road

ways remains a top priority 

for FHWA.

-

-

To improve motorcycle 

safety, FHWA recently con

ducted a human factors study 

on highway signage for motor

cyclists. The research consisted 

of reviewing existing highway 

signs, developing an initial 

group of signs targeting motor

cyclists, and advancing sample 

signs into a review phase. To 

ensure the clarity of messaging 

on the signs, FHWA also included nonmotorcyclists in its review 

phase. The research resulted in the identification of five novel signs 

that could significantly reduce motorcycle crashes.

-

-

-

The TechBrief is available at www.fhwa.dot.gov/publications

/research/safety/21009/21099.pdf.

The final report is available at www.fhwa.dot.gov/publications

/research/safety/21010/index.cfm.

Impacts of Automated Vehicles on Highway Infrastructure 

Publication Number: FHWA-HRT-21-015

Infrastructure owner-operators 

and highway agency policymak

ers have become increasingly 

interested in the impact of 

automated vehicles (AV) on 

roadways now and in the future.

-

A recent FHWA study 

explored the rise in interest in 

AV, and how that interest could 

impact infrastructure owneroperators as they begin inte

grating AV into their own 

transportation systems. The 

study included the examination 

of several factors that pertain to 

roadway infrastructure, includ

ing traffic control devices, intelligent transportation system devices, 

pavement and bridge structural mandatories, multimodal impacts, 

and additional roadside infrastructure, like guardrails.

-

-

This report also details AV and infrastructure deployment from 

a stakeholder perspective, providing recommendations and strate

gies for infrastructure owner-operators to implement in the future.

-

The publication is available at www.fhwa.dot.gov/publications

/research/operations/21015/index.cfm.

Nondestructive Evaluation of Concrete Bridge Decks 

with Overlays 

Publication Number: FHWA-HRT-21-023

For decades, highway agencies 

have used concrete bridge deck 

overlays to repair bridges and 

extend their service life. How

ever, concrete overlays deterio

rate in different ways over time, 

making evaluations of underly

ing decks challenging.

-

-

-

A study by FHWA evaluated 

use of nine nondestructive eval

uation technologies on seven 

varying types of overlays to 

identify defects in the concrete 

deck and debonding between 

deck and overlay.

-

This report documents and 

details the capabilities and limitations of each technique to detect 

certain types of defects in concrete decks with overlay.

The publication is available at www.fhwa.dot.gov/publications 

/research/infrastructure/structures/bridge/21023/21023.pdf.

Developing Analysis, Modeling, and Simulation Tools for 

Connected Automated Vehicle Applications: A Case Study 

on SR–99 in California 

Publication Number: FHWA-HRT-21-039

A recent study conducted by 

FHWA examined the use of 

automation technology in a 

real-world setting—a 13-mile 

(21-kilometer) portion of 

SR–99 near Sacramento, 

CA—that is a heavily traveled 

commuter corridor. The traffic 

simulation study examined how 

the implementation of vehicles 

equipped with cooperative 

adaptive cruise control (CACC) 

could impact traffic flow, con

gestion, and fuel consumption.

-

The research team examined 

scenarios with heavy traffic 

congestion during morning peak travel, 6:30 a.m. to 9 a.m., with 

several on-ramp bottleneck locations also included in the case 

study parameters. One of several key findings from the research 

shows that when CACC penetration was 100 percent, the busy 

commuter corridor enabled approximately 30 percent more traffic 

to enter the facility, with no drop in travel time.

The publication is available at www.fhwa.dot.gov/publications

/research/operations/21039/index.cfm.
© MTJ Roundabout 

Engineering.

CELEBRATE NATIONAL 

ROUNDABOUTS WEEK!

September 20–24, 2021

When the third week of September comes ’round, 

it’s time for National Roundabouts Week!

Modern roundabouts are a proven safety countermeasure. There are 

more than 6,000 modern roundabouts in the United States. From 

minis in Michigan and multi-laners in Massachusetts to interchanges 

with freeways and gateways into national parks, modern roundabouts 

are improving safety in many different communities and contexts.

Modern roundabouts:

• Reduce severe crashes by about 80 percent

• Decrease conflicts between users

• Reduce speeds to 15–25 miles/hour

• Provide benefits for pedestrians and bicyclists

• Reduce congestion and delay

• Provide a Safe System solution

Share your roundabout success story on social media using #RoundaboutsWeek.

#RoundaboutsWeek

For more information, tips, and facts, visit 

https://safety.fhwa.dot.gov/nrw and 

https://safety.fhwa.dot.gov

/provencountermeasures/roundabouts.
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