PUBLIC ROADS

www.fhwa.dot.gov Autumn 2021

Rehabilitating the 

Historic Arlington Memorial Bridge

Also in this issue: 

 Implementing Nature-Based Solutions 

for Coastal Highway Resilience

Establishing Uniform Standards 

for Safer Ice Roads

Recognizing 50 Years of National 

Bridge Inspection Standards
Autumn 2021 | Vol. 85, No. 3

The National Park Service and the Federal 

Highway Administration partnered to 

restore the Arlington Memorial Bridge. 

PAGE 28

FEATURES

4 CARMASM: Boosting Safety, Efficiency, and 

Reliability on the Nation’s Highways

by Taylor Lochrane, Govind Vadakpat, and Nicole Paladeau

The CARMASM Program navigates advancements in 

transportation systems management and operations through 

emerging cooperative vehicle and infrastructure technology.

9 Nature-Based Solutions for Coastal Highway Resilience

by Katherine Buckingham and Jessica Torossian

Natural strategies for efficient, cost-effective, and ecologically 

friendly protection for coastal roads can help transportation 

agencies address the effects of extreme weather events. 

14 Confronting the Storm: Arizona’s Innovative 

Dust Detection and Warning System

by Tony Coventry and Kevin Duby

The ADOT Dust Storm Warning System offers the 

promise of intelligent transportation solutions to decrease 

the impact of hazardous weather occurrences.

18 Safety on Ice

by Adam Larsen and Billy Connor

Ice roads are critical to seasonal transportation in the North. FHWA 

and its partners are working to improve safety and establish uniform 

standards for their design, construction, operation, and use.

23 Bolstering the Safety of America’s Bridges for Half a Century

by Joey Hartmann

FHWA’s national bridge inspection program 

marks 50 years of improving safety.

28 Rehabilitating the Historic Arlington Memorial Bridge

by Sandy Sinclair

The National Park Service and the Federal Highway Administration 

partnered successfully to restore the iconic bridge. 

PAGE 14 

© Arizona Department of Transportation.

DEPARTMENTS

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

Hot Topic ..........................................................2

Innovation Corner ...........................................3

Along the Road ..............................................32

Training Update .............................................35

Communication Product Updates ..............36

FRONT COVER and ABOVE—The project team used 

floating barges to help with the rehabilitation 

of the Arlington Memorial Bridge.

BACK COVER—The rehabilitation project considered historic 

architectural details, like the decorative fascia shown being 

removed, to be important features to preserve and restore.

Source: FHWA.
WWW.FHWA.DOT.GOV | 1

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

TaMara McCrae, 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 

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The Secretary of Transportation has determined that the 

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All articles are advisory or informational in nature and should not 

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Articles written by private individuals contain the personal views 

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Contents of this publication may be reprinted, provided credit is 

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For more information, representatives of the news media should 

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Recommended citation: Federal Highway Administration, 

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

https://doi.org/10.21949/1521676

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 

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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

Challenges and 

Opportunities

Source: FHWA.

2021 has been a busy year at the Federal Highway Administration. We are 

all excited about the new opportunities 

created by new leadership at the White 

House and throughout the Department of 

Transportation, as well as by congressional 

interest both in reauthorizing surface 

transportation funding and enacting a 

bipartisan infrastructure bill. Even though 

I’ve only been with FHWA for several 

months, it’s been a busy and exciting time.

This issue of Public Roads spotlights 

bridge safety—from the history, decline, 

and recent recovery of the century-old 

Arlington Memorial Bridge in Washington, DC, to an article about the 50th 

anniversary of the National Bridge Inventory System, which has kept all public 

bridges safe since the tragic collapse of the Silver Bridge in West Virginia in 

1967. Shining a light on the importance of bridge inspections is especially timely, 

given the fracture discovered in May on the Hernando DeSoto Bridge over the 

Mississippi River between Tennessee and Arkansas. 

This year featured many historic milestones, including the Interstate system’s 

65th birthday on June 29. Such occasions prompt many to look back and reminisce 

about the difficulties of travel before the age of the superhighway. While we all 

can and should learn lessons from the past, we also must look to the future. How 

will the Nation be better because of the decisions and investments we make today? 

When others look back 65 years from now, how will they judge the work we are 

doing in 2021?

For me, one topic that raises those very questions is our response to the climate 

crisis. The recent report by the Intergovernmental Panel on Climate Change is 

a stark reminder that no matter how much we work to reduce greenhouse gas 

emissions, we must also make our transportation infrastructure more resilient to the 

heat, precipitation, and sea level rise already locked in by climate change. Weather 

has been a significant factor in the safety of the traveling public this year—from 

a week of extreme heat over the Pacific Northwest that caused roads to buckle, 

to the flash floods and mudslides that closed I–70 through Glenwood Canyon 

in Colorado. This issue of Public Roads focuses on strategies used to respond to 

unusual weather, as well as coastal resilience and Arizona’s massive dust storms. 

Making the Nation’s roads safer and more resilient to a changing climate are 

only two of the challenges we face as we work to Build Back Better. We seek a 

transportation system that is safe, reliable, equitable, sustainable, and resilient—

but with each challenge comes opportunity. Each problem invites creative 

new solutions.

While new to the job, it’s already clear to me that FHWA is a problemsolving agency that is up to these challenges and eager to take advantage of new 

opportunities. It’s also clear that we will not succeed alone but by collaborating 

with our State and local partners, advocates, and stakeholders. Indeed, I believe that 

facing the challenges ahead together will prove to be the greatest opportunity of all.

Stephanie Pollack 

Acting Administrator 

Federal Highway Administration
2 | PUBLIC ROADS | AUTUMN 2021

HOT TOPIC

Source: FHWA.

Simplifying Environmental Reviews 

and Collaboration with INPCT

by MEGAN COGBURN and DAVID WILLIAMS

The Federal Highway Administration is on the cutting edge of efforts to accelerate project delivery. To help save time 

and simplify the environmental documentation required by the 

National Environmental Policy Act (NEPA), FHWA created the 

Interagency NEPA & Permitting Collaboration Tool (INPCT). A 

rebranded and improved version of FHWA’s eNEPA, INPCT is a 

web-based collaboration tool designed to aid NEPA practitioners 

in efficiently managing the environmental review and permitting 

processes for all types of transportation projects, from simple Cate

gorical Exclusions to more complex Environmental Assessments 

and Environmental Impact Statements. 

-

More than 400 participants attended the webinars launching 

INPCT, hosted by FHWA’s Office of Project Development and 

Environmental Review in May and June 2021. Attendees included 

representatives from 37 State departments of transportation, 

33 FHWA division offices, other USDOT modal administrations, 

6 other Federal agencies, and multiple metropolitan 

planning organizations and consulting firms.

Housed behind FHWA’s firewall, INPCT 

provides a secure web-based platform. The tool 

can help strengthen interagency collaboration 

during the NEPA process by making it easier for 

project managers, environmental planners, and 

resource and regulatory agency staff to exchange 

documents and collect and share comments in 

real time. INPCT centralizes the many elements 

of a NEPA review to help seamlessly manage 

the decisionmaking process. Through its userfriendly interface, users can track project and 

permitting schedules and key milestones, send 

meeting invites, manage documents, and even 

track mitigation commitments. 

INPCT’s integration with FHWA’s Project and Program 

Action Information System means data can now be sent to the 

Federal Permitting Dashboard. Users only enter information once, 

eliminating redundant data entry. These time-saving features can 

help reduce the time it takes to complete environmental reviews 

and permit applications in line with the new regulations from the 

Council on Environmental Quality for implementing NEPA. 

INPCT is available at https://inpct.fhwa.dot.gov. For more 

information about the tool, see FHWA’s Environmental Toolkit at 

www.environment.fhwa.dot.gov/pubs_resources_tools/env_tools/INPCT

/default.aspx. 

MEGAN COGBURN (Megan.Cogburn@dot.gov) and DAVID WILLIAMS

(David.Williams@dot.gov) are FHWA’s INPCT system administrators. 

Source: FHWA.

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

INNOVATION CORNER

Source: FHWA.

Building a Better Mousetrap 

Improves Communities

by TRINETTE BALLARD

I

n transportation, building a better mousetrap means solving 

problems by going outside the box. Each year, FHWA and Local 

Technical Assistance Program Centers recognize government agen

cies that build a better mousetrap to creatively solve problems and 

improve transportation in their communities. FHWA honors four 

organizations with 2021 Build a Better Mousetrap Awards.

-

Building Better Mousetraps in Local Communities

Smart Transformation Award

A mobile app increased 

data accessibility and 

improved ADA inspections.

© Seminole County, FL.

Seminole County, FL, received this 

year’s Smart Transformation Award. Its 

developers built a mobile application 

to improve Americans with Disabilities 

Act (ADA) accessibility throughout 

the county. This solution reduced the 

county’s reliance on paper, increased 

data accessibility, improved how ADA 

field inspections are conducted, and 

increased productivity.

Jose Salas with the Seminole County 

Public Works Department is proud of 

the solution. “We continue to discuss 

ways to improve the application and 

have received feedback for improve

ments from users,” he says.

-

Innovative Project Award 

Jones County’s hopper improved 

shoulder maintenance.

© Jones County, IA.

FHWA named the Jones County, IA, 

Secondary Roads Department recipient 

of the 2021 Innovative Project Award

for its development of a hopper, a 

dump truck attachment that saves time 

and money when conducting shoulder 

maintenance along the roadways. 

The hopper results in fewer materials 

wasted and reduced labor and equip

ment costs while increasing lane miles 

covered. The county currently has two 

hoppers, with a third in production.

-

 “Shoulder edge dropoff is a major 

safety issue that our Secondary Roads 

Department continually mitigates with 

our shoulder replacement program,” says Todd Postel, the Jones 

County assistant to the engineer.

Pioneer Award

Thermoplastic centerline markings 

improve visibility and safety.

© Independent Highway District.

A Pioneer Award recipient is among 

the first to solve a maintenance 

problem with a homegrown solution. 

The Independent Highway District in 

Sandpoint, ID, did just that by devel

oping a new process to extend the life 

of centerline markings on a roadway 

that sees a lot of wear and tear from 

residents, commercial truck drivers, 

and heavy snowfall.

-

“Schweitzer Mountain Road leads 

to the local ski area,...receives 100 

to 300 inches [254-762 centimeters] 

of snow annually, and has 2,000 to 

5,000 vehicles traveling up and down 

the mountain daily,” says Mel Bailey, the agency’s board chair.

The district developed a process to make indentations, or 

divots, along the roadway’s centerline using metal plates and then 

cover them with thermoplastic markings that can remain visible 

for up to 10 years. The solution saved time and money, and also 

improved roadway safety.

Bold Steps Award

Models of roadway electrical 

equipment make training 

safer and more efficient.

© Illinois Tollway.

The recipient of the 2021 Bold Steps 

Award, the Illinois Tollway, took a bold 

move toward improving safety. With 

many veteran roadway electric workers 

set to retire in the coming years, 

transportation officials needed a safer 

and faster way to train new electrical 

workers to assess, repair, and maintain 

the nearly 18,000 light fixtures along 

the 294-mile (473-kilometer) Tollway 

system. Traditionally, the biggest 

challenge was performing the training 

alongside high-speed traffic and in vari

able weather conditions while working 

with high-voltage equipment.

-

Roadway lighting technician Ben 

Pierce, who has been with the Tollway for more than 20 years, 

teamed up with two of his peers and gathered input from others 

in the agency to develop a portable training device that models 

the tollway’s actual electrical equipment. With the device, electric 

workers can be trained in a safe environment more quickly and 

with less downtime for inoperable equipment.

Celebrating Innovative Solutions

“As always, we are excited about this year’s honorees and how they 

are helping to transform transportation,” says Joe Conway, director 

of FHWA’s Local Aid Support team. “Recognizing innovative 

agencies not only shines a spotlight on the public service they 

provide to residents, but it also encourages other agencies to move 

away from the standard ways of conducting business.”

For more information, visit www.fhwa.dot.gov/clas/babm.

TRINETTE BALLARD is an FHWA Local Aid Support Program manager in 

the Office of Transportation Workforce Development and Technology 

Deployment.
4 | PUBLIC ROADS | AUTUMN 2021

CARMASM: Boosting Safety, 

Efficiency, and Reliability on 

the Nation’s Highways

The CARMASM Program navigates advancements in transportation 

systems management and operations through emerging 

cooperative vehicle and infrastructure technology.

by TAYLOR LOCHRANE, GOVIND VADAKPAT, and NICOLE PALADEAU

As an integral piece in future safety, traffic flow, and energy improvements for the 

Nation’s transportation system, cooperative 

driving automation (CDA) technology 

facilitates the sharing of electronic messages 

between vehicles and equipped roadway 

infrastructure. Through its CARMASM

Program, the Federal Highway Adminis

tration advances emerging capabilities in 

automation and cooperation by conducting 

research, testing, and deployment of 

CDA features.

-

Partnerships between the Intelligent 

Transportation Systems Joint Program 

Office, Federal Transit Administration, and 

Federal Motor Carrier Safety Administra

tion support the development of cooperative 

driving systems aimed at improving basic 

traffic flow to reduce recurring congestion 

at traffic signals, intersections, and bottle

neck areas. Further details on the CARMA 

Program can be found in the article 

“CARMASM: Driving Innovation” in the 

Winter 2020 issue of Public Roads.

-

-

The CARMA Program includes three 

research tracks to facilitate targeted stake

holder participation in the goals of devel

oping, testing, simulating, and deploying 

CDA solutions in order to prepare for 

these impacts:

-

-

• Research Track 1—Traffic: Focuses 

on normal travel and recurring traffic 

conditions that result in congestion on 

freeways and arterials.

• Research Track 2—Reliability:

Focuses on nonrecurring congestion 

on freeways and arterials that is 

caused by work zones, inclement 

weather, traffic incidents, and other 

irregular instances.

• Research Track 3—Freight: Focuses 

on commercial motor vehicles 

operating in and around port facilities.

As defined by FHWA, transportation 

systems management and operations 

(TSMO) is a set of strategies that focus on 

operational improvements that can main

tain and even restore the performance of 

an existing transportation system before 

extra capacity is needed. CDA provides 

an opportunity to coordinate with TSMO 

operational strategies and the surface 

transportation system as a whole. Under 

the CARMA Program, several use cases 

-
accounting for CDA-equipped vehicles, 

human-driven vehicles, equipped infrastruc

ture, and the interactions between each are 

being researched.

-

“With innovations in CDA technology 

taking place every day, we are seeing that 

TSMO principles allow us to explore the 

future of our connected transportation 

system through the context of existing capa

bilities and solutions,” says Faisal Saleem, 

manager of the Intelligent Transportation 

Systems Branch at the Maricopa County 

Department of Transportation.

Advancements in cooperative driving automation are happening 

every day through FHWA’s CARMA Program.

Source: FHWA.

Ongoing research and development for cooperation 

between vehicles and infrastructure will enhance 

efficiency and safety for road users.

Source: FHWA.

WWW.FHWA.DOT.GOV | 5

-

Understanding the Background

All road users understand the complications 

posed by busy intersections, merging, and 

stop-and-go traffic. On the surface, these 

are seemingly unavoidable symptoms of 

a modern transportation system. But on 

a deeper level, these issues can increase 

traffic delays, escalate energy consumption 

and emissions, and interfere with safety. 

The good news is that developing tech

nology can help address these issues. As 

part of an interconnected system rooted in 

vehicle-to-vehicle, vehicle-to-infrastructure, 

and infrastructure-to-vehicle communica

tions, vehicles equipped with connected 

and automated driving systems have 

the potential to coordinate with one 

another and surrounding infrastructure 

to enhance safety, efficiency, and environ

mental benefits.

-

-

-

 “In order to prepare for a more 

connected, safe, and efficient path forward, 

we must first understand how all of the 

pieces fit together,” says Jennifer Toth, 

director and county engineer at the 

Maricopa County Department of Trans

portation. “Surrounding infrastructure is 

as important as the vehicles themselves 

because we only see success when both 

work together.”

-

FHWA has developed several use cases 

to study the impact of CDA on TSMO 

strategies for basic travel.

Basic Travel Use Case: Merging

Basic travel refers to recurring activities that 

transportation management services and 

traffic management centers will typically 

perform during normal operations when 

there are no incidents, special events, or 

other anomalies. A “notify and advise” 

operational action provides situational 

awareness to vehicles regardless of their 

automation level. The “merging” use case 

explores an automated vehicle merging 

onto a roadway and into the normal flow of 

traffic with other vehicles. Using cooperative 

lane change and unobstructed lane merge 

features on CDA-equipped vehicles, the 

CARMA Platform plans a smooth sideways 

motion from one lane into an adjacent 

lane, accounting for other automated and 

nonautomated vehicles through sensors on 

the vehicle.

Once the merge is complete, CARMA 

CloudSM (the cloud-based, open-source 

software systems enabling communication 

and cooperation between cloud services, 

vehicles, infrastructure, and road users) 

transmits geofence messages and speed 

commands to the first vehicle in line, which 

it then shares with the rest of the vehicles to 
6 | PUBLIC ROADS | AUTUMN 2021

ensure a successful transition to the desti

nation and the eventual termination of the 

line of vehicles. Through using this frame

work and reducing the influence of human 

behavior, solutions for increased highway 

throughput and traffic shockwave mitiga

tion become more attainable.

-

-

-

CDA solutions for road weather 

management, traffic incident management, 

and work zone use cases examining several 

operational actions are also in development 

in conjunction with the basic travel use case. 

All of these frameworks explore distinct 

actions that the entity determining TSMO 

activities must complete in order to execute 

TSMO strategies.

1. The vehicle begins its attempt to merge into a highway lane with another vehicle. 2. Using cooperative lane change and obstructed lane merge, the vehicle plans its 

entrance into the line of traffic, which uses route following to remain intact.

3. The vehicle has successfully merged onto the 

highway and flows with the other vehicle.

4. The first vehicle in the line (the platoon) transmits a speed 

advisory, which is received by rest of the vehicles. Source: FHWA.

Proof-of-Concept Testing 

for TSMO Use Cases

The CARMA proof-of-concept testing 

for TSMO use cases builds on previous 

research and leverages the CARMA Program 

ecosystem to enhance capabilities for CDA 

participants through four distinct arterial 

use cases. The aim is to reduce energy 

consumption and increase safety at multi

lane intersections. All vehicles in each use 

case were equipped with CDA technologies, 

and intersection infrastructure contained 

the necessary software and hardware to 

enable the two-way exchange, collection, 

and processing of electronic messages with 

all vehicles. CDA aims to improve the 

safety and flow of traffic by supporting 

the movement of multiple vehicles sharing 

the roadway in an increasingly auto

mated future.

-

-

Simulations

Researchers conducted a series of simula

tions for each use case including a humandriven vehicle as the baseline and four 

vehicles equipped with connected and auto

mated driving systems, representing Society 

of Automotive Engineers (SAE) operational 

classes C and D. The results showed that 

CDA technology reduced average fuel 

consumption, wait and stopping times, 

and delays. Additionally, the results showed 

that the proposed roadside components 

working together can accurately and effi

ciently control vehicle operations, coupled 

with the vehicle intent information. The 

results demonstrated that, generally, these 

outcomes improve as the operational class of 

a vehicle increases.

-

-

-

-

Society of Automotive Engineers 

(SAE) Operational Classes

Class Description

No cooperative 

automation No cooperation

Class A Status sharing (“Here I am and what I see.”)

Class B Intent sharing (“This is what I plan to do.”)

Class C Agreement seeking (“Let’s do this together.”)

Class D Prescriptive (“I will do as directed.”)

SAE Standard J3216 explains these operational classes as they relate 

to SAE Standard J3016, which defines six levels of driving automation 

ranging from no driving automation through full driving automation.

Types of Vehicle Status in the 

Communication Area

1. Entering Vehicles: Vehicles approaching the intersection that 

cannot enter the intersection box in the next time step.

2. Ready-to-Depart Vehicles: Vehicles stopped at the stop bars or 

moving within the intersection box. Each is associated with a fixed 

order index in the ready-to-depart vehicle sequence.

If there is more than one vehicle from an entry lane stopped at the 

intersection, only the leading vehicle will be considered as ready 

to depart and the rest will still be considered as entering vehicles.

3. Discharging Vehicles: Vehicles that have already departed the 

intersection box.

TSMO Use Case 1

The first TSMO use case is basic arterial 

travel—stop-controlled intersections. This use 

case has two main components, with the 

first, critical time step estimation (CTSE), 

designed to run on roadside equipment 

and the second, trajectory smoothing, on 

CARMA-equipped vehicles.

CTSE aims to estimate crucial points in 

a vehicle’s journey in an intersection, such 

as stopping at a stop sign and accelerating 

through an intersection. The CTSE is deter

mined either by the roadside equipment or 

by the vehicle itself, depending on its SAE 

operational class. Trajectory smoothing, 
WWW.FHWA.DOT.GOV | 7

which aims to streamline vehicle paths, is 

determined by the vehicle itself. 

In this use case, a vehicle enters the 

communication area, or intersection, joins 

the entering vehicle set, and begins trans

mitting information to roadside equipment 

and other vehicles. When the vehicle reaches 

the stop sign, it transitions to the ready-todepart vehicle set. This transition is referred 

to as the stopping time, and the vehicle 

stores this information internally. Next, 

the vehicle proceeds to enter and navigate 

through the intersection, then exits and 

transitions to the discharging vehicle set, 

and eventually leaves the communication 

area entirely.

-

With CTSE and trajectory smoothing 

working together, the roadway infrastructure 

provides critical high-level input regarding 

when vehicles will perform specific actions, 

and enables vehicle control over trajectories 

and collision avoidance. The research team 

determined that the communication area 

could be expanded by adding more roadside 

equipment if needed to share real-time oper

ational status (such as location and speed) 

and intents (such as movement group, 

stopping time, and entering time) among 

the intersection components.

-

With more testing planned for the future, the CARMA Program looks 

forward to sharing solutions for a better road ahead.

Source: FHWA.

The TSMO use case testing project defines and explores four 

basic travel scenarios surrounding intersections. 

Use Case 1 is a simple stop-controlled, four-way intersection.

TSMO Use Case 2

The second TSMO use case is CDA opti

mization at fixed-time and actuated traffic 

signals. Like the first use case, this use case 

contains CTSE for roadside equipment 

and trajectory smoothing for vehicles as its 

main components. In this scenario, CTSE 

aims to estimate when a vehicle will enter 

an intersection, and trajectory smoothing 

seeks to streamline the vehicle’s trajectory 

by estimating the time of its entrance. 

When a vehicle enters the communication 

area, it will start to transmit information 

to roadside equipment and other vehicles, 

including its desired entry time. Then, the 

vehicle will plan its trajectory for passing 

through the intersection, either at the speed 

limit or the highest speed safely allowed. 

As it travels through the intersection, it will 

transition from the entering vehicle group 

to the discharging vehicle set, and eventually 

leave the communication area.

-

-

-

Use Case 2 is a four-way intersection controlled by 

fixed-time and actuated traffic signals. Source: FHWA.

TSMO Use Case 3

The third TSMO use case is traffic signal 

optimization with CDA at signalized 

intersections, which deals with vehicles at 

intersections with traffic signals. To address 

this, the use case added a signal optimiza

tion component that runs on a centralized 

roadside server to support real-time vehicle 

information. Upon joining the entering 

vehicle set and gathering information from 

roadside equipment and other vehicles, the 

vehicle will estimate its entry time to the 

intersection to smooth its trajectory through 

the intersection. This use case explores 

solutions such as trajectory planning and 

smoothing for each stage of the vehicle’s 

journey through an intersection, including 

approaching an intersection with other vehi

cles, entering the intersection, and exiting 

the communication area.
8 | PUBLIC ROADS | AUTUMN 2021

Use Case 3 involves traffic signal optimization at a signalized intersection 

using a cooperative control framework that runs on a centralized 

roadside server to support real-time vehicle information.

Source: FHWA.

TSMO Use Case 4

The fourth TSMO use case is dynamic 

lane assignment along roadways with traffic 

signals. Along with CTSE and trajectory 

smoothing, this use case incorporates a 

signal- and lane-optimization component 

that employs a centralized roadside server 

and real-time vehicle information to assist 

with assigning vehicles to specific lanes. This 

use case primarily works to optimize traffic 

flow at signalized intersections and generate 

the best signal timing plans and lane control 

to increase traffic efficiency.

The four proof-of-concept TSMO use 

case frameworks explore how CDA can be 

used to reduce operational complexity and 

associated risks and liabilities for traffic 

operators. They also distribute the compu

tational burden among several entities, 

which makes the system more suitable to 

support real-time information. Additionally, 

the combination of cooperation between 

vehicles and between vehicles and roadside 

equipment can enhance the performance 

of the traffic system and improve the 

travel experiences of individual vehicles. 

The frameworks have the potential to 

reduce stop-and-go traffic and backward 

shockwave, increase throughput, and 

maintain safety for individual vehicles at 

stop-controlled intersections in a driver

less future.

-

-

Use Case 4 incorporates a signal- and lane-optimization component that employs a 

centralized roadside server (the DLA, or dynamic lane assignment, control point) and 

real-time vehicle information to assist with assigning vehicles to specific lanes. This use 

case primarily works to optimize the flow of each vehicle through and out of signalized 

intersections and generate the best signal and lane settings to increase efficiency.

Down the Road

CDA technologies offer a wider range of 

possibilities for the connected transportation 

system than vehicles without CDA capabil

ities. The benefits of the ability to exchange 

messages with CDA-equipped vehicles offer 

the opportunity to enhance and improve 

upon current traffic control strategies. 

The four CDA TSMO use cases could 

significantly improve the traffic system and 

individual travel experiences, reduce stopand-go traffic patterns, and maintain safety 

at conflict areas such as intersections and 

merge lanes. 

-

“The world is already headed in a 

more connected, automated direction,” 

says Cynthia Jones, a project manager at 

DriveOhio. “Now is the time to figure 

out how to bring all the benefits of this 

technology to the public in the safest 

possible way.”

Looking ahead, the CARMA Program 

continues to research, test, and optimize 

basic travel use cases and TSMO strate

gies in addition to exploring use cases for 

cooperative perception, traffic incident 

management, road work management, and 

work zones.

-

“Today’s research will set the foundation 

for a more sustainable, automated, and 

enjoyable transportation experience for 

everyone,” says Raj Ponnaluri, a manage

ment engineer for the Florida Department 

of Transportation.

-

Higher levels of safety, efficiency, and 

reliability are on the horizon because of 

FHWA’s research and testing for real

istic scenarios.

-

TAYLOR LOCHRANE is the CARMA program 

manager in FHWA’s Office of Operations Research 

and Development, leading the open source 

development and collaboration efforts of CARMA 

with partners and stakeholders. He earned 

B.S., M.S., and Ph.D. degrees in civil engineering 

focused on transportation from the University of 

Central Florida.

GOVIND VADAKPAT is the CARMA technical program 

manager in FHWA’s Office of Operations Research 

and Development, currently managing several 

CARMA projects focused in the area of cooperative 

driving automation. He holds a doctorate in civil 

engineering from Pennsylvania State University 

and a master’s degree in civil engineering from the 

University of Wisconsin–Madison.

NICOLE PALADEAU is a communications specialist 

contractor at the Saxton Transportation 

Operations Laboratory, contributing to marketing 

and engagement projects. She earned a B.A. 

degree from the University of Mary Washington.

For more information, contact Taylor 

Lochrane at taylor.lochrane@dot.gov or visit 

https://highways.dot.gov/research/operations

/CARMA.
WWW.FHWA.DOT.GOV | 9

Nature-based solutions can offer coastal roads protection from the 

effects of rising sea levels and extreme weather events. 

© Wangkun JIA / 123RF.com.

Nature-Based Solutions

for Coastal Highway Resilience

Natural strategies for efficient, cost-effective, and ecologically 

friendly protection for coastal roads can help transportation 

agencies address the effects of extreme weather events. 

by KATHERINE BUCKINGHAM and JESSICA TOROSSIAN

As the climate continues to change, extreme weather events—such 

as damaging coastal storms, drought, 

and extreme heat and precipitation—

are expected to increase in frequency. 

According to the U.S. Global Change 

Research Program’s Fourth National Climate 

Assessment report, in the United States, 

there are more than 60,000 miles (97,000 

kilometers) of roads and bridges in coastal 

floodplains and more than $1 trillion in 

coastal property that may be at risk from 

these effects of climate change.

Developing a network of resilient coastal 

roads is a priority for the Federal Highway 

Administration in order to ensure the safe 

passage of the American public on coastal 

roads and to maximize coastal investments. 

While several nature-based solutions have 

the ability to innately adapt to rising sea 

levels, traditional strategies to protect coastal 

infrastructure that rely on hardening shore

lines and other “gray” solutions may not be 

adaptable or must be specifically designed to 

do so, which can be costly. These solutions 

can also have unintended consequences, 

such as increased erosion or deposition, 

along other parts of the coastline.

-

Nature-based solutions that rely on 

existing or enhanced landscapes help 

improve roadway resiliency by reducing 

impacts to coastal roads from hazards 

such as rising sea level, storm surge, and 

“nuisance” flooding (such as high tide or 

windblown flooding). Often these “green” 

strategies are both more effective and less 

costly than traditional engineering or gray 

solutions on their own.

“More States and municipalities are 

turning to nature-based solutions to 

protect coastal highways and improve the 

environment while providing a natural 

aesthetic and other benefits to coastal 

communities,” says Elizabeth Habic, an 

environmental protection specialist with the 

FHWA Office of Natural Environment.

Considerations for Deploying 

Nature-Based Solutions

The term “nature-based solutions” refers to 

the use of natural materials and processes 

to reduce erosion, wave damage, and 

flood risks to coastal infrastructure. These 

solutions can be used instead of, or in 

conjunction with, traditional gray methods 

of shoreline stabilization and protection 

techniques. Nature-based solutions include 

the use of naturally occurring features, as 
10 | PUBLIC ROADS | AUTUMN 2021

well as nature-based features that are created 

or enhanced by human design, engineering, 

and construction.

In many coastal areas, naturally occur

ring habitats and geographic features 

can provide protection from the coastal 

processes and storm events that threaten 

coastal roads. The main habitats involved in 

nature-based solutions are tidal salt marshes, 

mangroves, maritime forests, coral and shell

fish reefs, beaches, and dunes. In addition 

to buffering storm effects, these habitats also 

provide other community benefits (called 

ecosystem services) related to recreation, 

water quality, local fisheries, and climate 

change mitigation.

-

-

State and local transportation agencies 

can capitalize on these ecosystem services—

and even enhance them—by deploying 

nature-based solutions in strategic ways 

that can use one particular intervention or 

layer multiple solutions to be as simple or 

complex as needed. The type of solution 

that a transportation or planning agency 

chooses to deploy will be location specific 

and highly dependent on local geography 

and ecology as well as the type, frequency, 

and severity of coastal impacts to road 

infrastructure. Additionally, each solution 

may have unique permitting and rightof-way requirements. Successful design and 

implementation of nature-based solutions 

often require input from a cross section of 

expertise, including transportation profes

sionals, coastal engineers, and environ

mental scientists.

-

-

Salt Marshes

There are three common solutions that can 

be deployed in regions where salt marshes 

are common: marsh vegetation, marsh sill, 

and marsh breakwater. Solutions that use 

salt marshes generally provide a medium 

level of protection against both increased 

wave energy (because of the structure of 

marsh vegetation) and erosion (because root 

systems hold soil in place). They also deliver 

some protection against coastal flooding and 

are more natural and aesthetically attractive 

for the community. Marsh-based solutions 

offer strong environmental benefits because 

salt marshes provide a variety of ecosystem 

services, including improving water quality 

and providing habitat and nurseries for a 

variety of species. Salt marshes also play an 

important role in denitrification and help 

trap atmospheric carbon.

Despite these benefits, there are several 

challenges associated with deploying 

marsh-based solutions. Marsh plants can 

require maintenance, especially during the 

early stages of life. Project funding should 

include costs for the removal of dead plants 

and debris from the marsh and the planting 

of new vegetation as needed. While the 

success of these projects is well documented, 

service life can be hard to predict because a 

marsh-based solution can be highly depen

dent on elevation and marsh slope. Tidal 

elevation may change as sea levels rise and 

marsh slope and local water conditions can 

heavily influence shoreline changes. While 

salt marshes can naturally adapt to many of 

these changing conditions, in some loca

tions, additional efforts to mitigate for sea 

level rise and high levels of runoff can help 

ensure an effective design.

-

-

This marsh in Mobile Bay, AL, has a segmented breakwater to help further 

attenuate wave energy beyond the marsh’s natural capacity. 

Source: 2017 NOAA Fisheries.

Types of Nature-Based Solutions

• Marsh Vegetation: The construction of a marsh, 

including fill and plantings but without structural 

elements, in the intertidal zone of a shoreline.

• Marsh Breakwater: The construction of a marsh, 

including fill and plantings, in the intertidal 

zone of a shoreline, including segmented 

breakwaters to reduce incident wave energy.

• Marsh Sill: The construction of a marsh, 

including fill and plantings, fronted by toe 

protection in the intertidal zone of a shoreline.

• Beach Nourishment: The placement of large 

quantities of good-quality and suitable sand 

directly on the beach to restore the beach.

• Pocket Beach: Beach nourishment 

coupled with the installation of headland 

breakwater structures to slow the movement 

of sand out of the project area.

• Dune Restoration: The placement of goodquality sand to either rebuild existing dunes 

or create an artificial dune by building up a 

mound of sand at the back of the beach.
WWW.FHWA.DOT.GOV | 11

An example of a pocket beach in 

Perdido Bay, AL, which uses beach 

nourishment coupled with the 

installation of headland breakwater 

structures to slow sand movement. 

© South Coast Engineers.

Beaches and Dunes

In areas where beaches or dunes are preva

lent, agencies can deploy solutions such as 

pocket beach creation, beach nourishment, 

and dune restoration. All three solutions 

are highly effective at protecting upland 

resources during storms, while pocket beach 

and beach nourishment solutions are also 

beneficial for reducing erosion. Beachbased solutions offer additional habitat for 

seabirds and other beach-going animals like 

sea turtles, and deliver added community 

benefits for local property owners, tourists, 

and recreational users.

-

For all three strategies, sand is sourced 

from a borrow-area located either offshore 

or from a coastal dredging project or upland 

sandpit. Sand should have an appropriate 

grain size that matches the native beach 

sand. Sourcing high-quality sand can create 

a challenge as source sand may impact 

historic and cultural resources or artifacts 

that should be avoided. Imported sand 

should be cleared of nonnative species 

that could potentially be introduced to a 

new area.

Dune restoration is often coupled with 

the planting of native vegetation, which 

may need to be maintained. Design life 

can be dependent on local conditions and 

renourishment may be required to maintain 

the beach or dune. Pocket beaches face the 

additional challenge of sizing and siting the 

headland structures, but the addition of 

these structures can increase the design life 

almost indefinitely.

Hybrid Solutions

In certain areas where wave energy may 

be particularly challenging to dissipate or 

local conditions lead to more flooding, it 

may be best to employ a hybrid approach 

that combines a nature-based strategy with 

gray infrastructure solutions to provide 

more robust protection. Hybrid solutions 

may also be best for other habitats such as 

mangroves, maritime forests, and intertidal 

and subtidal reefs.

Mangroves can act in a similar way to 

marshes by attenuating wave energy and 

preventing erosion from complex root 

structures. Upland forests can also be useful 

in protecting coastal infrastructure, but 

they can take quite some time to grow into 

a protective barrier. For this reason, efforts 

to conserve maritime forests are often more 

successful than re-planting or encouraging 

new growth. Nearshore shellfish reefs and 

coral reefs can help attenuate wave energy 

but do not provide much protection 

against any coastal flooding that is not 

wave induced.

Hybrid solutions can include:

• Constructed marshes with 

stone or timber sills

• Marsh/mangroves with breakwaters, 

reefs, or habitat devices

• Beach nourishment with 

breakwaters and/or groins

• Constructed dunes with 

reinforced cores

Corpus Christi’s Resilience 

Pilot Program

Laguna Shores Road is a major thoroughfare 

in the Flour Bluff neighborhood of Corpus 

Christi, TX. Currently, several locations 

along Laguna Shores Road are subject 

to periodic flooding under spring tide 

and other typical (nonstorm) conditions. 

Shoreline erosion has also undermined the 

roadway in multiple locations. The southern 

end of the project is particularly vulnerable 

to extreme weather because there is no 

habitat buffer between the roadway and the 

open water of the Laguna Madre. These 

sites are especially susceptible to the impacts 

of storm surge and extreme weather events, 

and this vulnerability will increase in the 

face of sea level rise.

As part of an applied research deploy

ment, the Corpus Christi Metropolitan 

Planning Organization (Corpus Christi 

MPO) received $110,770 from FHWA 

to support the design of an innovative, 

nature-based shoreline protection feature to 

enhance resilience to extreme weather. The 

city of Corpus Christi is currently initiating 

the design phase of a project to rebuild three 

separate portions of Laguna Shores Road to 

improve level of service and reduce suscepti

bility to inundation.

-

-

This hybrid solution involves a living shoreline paired with a pocket beach at the Virginia 

Institute of Marine Science’s Carl Hershner Teaching Marsh in Gloucester Point, VA. 

© Steve Droter, Chesapeake Bay Program.
12 | PUBLIC ROADS | AUTUMN 2021

A pilot project in Corpus Christi, TX, aims to improve the resilience of Laguna Shores 

Road, shown here under typical (nonstorm) conditions, to extreme weather events. 

© Corpus Christi MPO.

The Corpus Christi MPO conducted 

an alternatives analysis to assess the living 

shoreline. A multidisciplinary consul

tant team gathered data and conducted a 

metocean analysis. Metocean conditions 

refer to the combined wind, wave, and 

climate conditions found at a certain loca

tion, and may include measurements and 

statistics such as air temperature, humidity, 

wind speeds, water level fluctuations, 

bathymetry, salinity, and stratification. The 

team also conducted a site visit and habitat 

assessment, hydrographic surveying, and 

preliminary geotechnical testing.

-

-

The team developed two breakwater 

concepts, a riprap breakwater and a reef ball 

breakwater, to provide wave protection to 

Laguna Shores Road and to support hard 

substrate habitat. The crew also developed 

a marsh fill concept to provide additional 

habitat and living shoreline benefits. They 

designed both the breakwater concepts and 

the marsh fill concepts to be constructed 

with equipment typical for roadway 

construction and without additional special

ized equipment.

-

The next step was constructing the 

pilot shoreline protection project as part 

of the roadway reconstruction project and 

monitoring effectiveness in terms of habitat 

development and shoreline condition. The 

monitoring will help the agency to evaluate 

the utility of the pilot techniques to enhance 

the durability of other segments of Laguna 

Shores Road and other similarly vulnerable 

transportation infrastructure.

“This pilot project has been and will 

continue to be a collaborative effort of all 

the partners,” says Robert MacDonald, 

PE, MPA, the transportation planning 

director for the Corpus Christi MPO. “The 

MPO managed an interdisciplinary team 

of specialized experts from the academic, 

environmental nonprofit, municipal, and 

private sectors. This effort provides a realworld example of combining the elements 

of resiliency with a planned roadway recon

struction project.”

-

A Pocket Beach in Perdido Bay, AL

In Perdido Bay, AL, a single homeowner 

created a pocket beach in 2018 between two 

timber and sheet-pile bulkheads to restore a 

beach on a stretch of shoreline that is heavily 

armored by individual bulkheads. The two 

bulkheads act as headland structures, sepa

rating the beach from the adjacent coastline 

and creating the pocket beach—a type of 

isolated littoral cell. Neighboring bulkheads 

were used as the landward anchor points for 

the headland structures.

-

At a final cost of $40,000, the project 

generated multiple benefits. One is that the 

beach fill provides additional habitat for 

shorebirds and sea turtles. The structural 

elements attenuate waves and improve 

the stability of the beach, which can also 

decrease waves during storm events for 

upland resources. As a small, homeownerlevel project on private land, the responsi

bility falls on the homeowner to maintain 

the beach going forward, and the largest 

challenge will be ensuring that the beach 

will be monitored in the future.

-

Beach Nourishment in 

Dauphin Island, AL

In 2016, the town of Dauphin Island, 

AL, completed the Dauphin Island East 

End Beach and Barrier Island Restoration 

Project to prevent erosion and protect 

upland ecosystems and infrastructure in 

coastal Alabama. The project involved the 

placement of 320,000 cubic yards (240,000 

cubic meters) of sand on an eroding beach 

that protects a maritime forest, freshwater 

lake, and substantial upland infrastruc

ture. The $6.7 million project required 

an extensive, detailed survey of cultural 

resources in an offshore borrow area. The 

project also involved the interaction of State 

law and Federal policy because of a U.S. 

Coast Guard facility within the project 

limits. The beach nourishment included 

rehabilitating existing, detached rock groins 

perpendicular to the shore and converting 

them into breakwater headlands, which 

mitigates ongoing erosion. The project has 

successfully endured several tropical storms 

and hurricanes.

-

A major challenge was that the initial 

project grant funding was inadequate to 

cover all project costs. Fortunately, the 

town of Dauphin Island secured additional 

grant funding to cover the shortfall without 

compromising project design. The benefits 

of this project include increased property 

value, recreation, tourism, and habitat. The 

restored beach provides habitat to a variety 

of species, such as nesting habitats for shore

birds and sea turtles.

-

Creative Dune Solutions for 

Maximum Protection in Saco, ME

Relatively high beach and dune erosion—

approximately 3 feet (1 meter) per year—

prompted the Ferry Beach Park Association 

in Saco, ME, to undertake a dune resto

ration project to protect roads and homes 

from flooding and erosion. Given the high 

erosion rate, the organization constructed an 

800-foot-long (240-meter-long) secondary 

dune ridge landward of the existing dune 

crest and 1 foot (0.3 meter) above the 

effective 100-year base flood elevation 

determined by the Federal Emergency 

Management Agency. This approach helps 

protect upland resources from floods 

and waves during storms, enables native 

vegetation to grow, and provides additional 

dry sand habitat. Volunteers also planted 

native American beachgrass (Ammophila 

breviligulata) and installed fencing to help 

trap sand in the constructed dune.

-

The agency completed the project by the 

spring of 2009 at a final cost of $29,000. 

The benefit of this project is that the added 

sediment from dune restoration supports 

the protective capacity of the entire beach 

system (dune, beach, and nearshore area). 

Any sand eroded from the dune during a 

storm supplies a reservoir of sand to the 

fronting beach and nearshore area. Sand 
WWW.FHWA.DOT.GOV | 13

dunes provide a unique wildlife habitat, and 

dunes also act as a barrier to storm surges 

and flooding, protecting landward coastal 

resources and reducing overwash events.

FHWA’s Implementation Guide

Implementing projects like these examples 

can help individuals and organizations 

address and mitigate the effects of climate 

change. To help, FHWA is producing 

research and offering technical assistance to 

enable transportation agencies to use natural 

and nature-based features to improve the 

resilience of transportation systems.

In addition to sponsoring pilot projects 

to assess the potential for nature-based 

techniques to protect specific locations 

along coastal roads and bridges, FHWA 

developed Nature-Based Solutions for Coastal 

Highway Resilience: An Implementation 

Guide (FHWA-HEP-19-042) to help 

transportation professionals understand 

when, where, and which nature-based 

solutions may work for them. The guide is 

available at www.fhwa.dot.gov/environment

/sustainability/resilience/ongoing_and

_current_research/green_infrastructure

/implementation_guide.

The majority of the guide is organized 

around how nature-based solutions can 

be developed through the transportation 

project delivery process. The document 

provides guidance on how to consider 

nature-based solutions in the planning 

process and how to conduct a site assess

ment to determine whether nature-based 

solutions are appropriate. It also describes 

key engineering and ecological design 

considerations, permitting approaches, 

construction considerations, and moni

toring and maintenance strategies.

-

-

FHWA’s Hydraulic Engineering Circular 

No. 25: Highways in the Coastal Environ

ment, 3rd Edition (FHWA-HIF-19-059) 

also provides information on the planning 

and design of nature-based solutions for 

use on highways and bridges in coastal 

environments. HEC-25 is available at 

-

www.fhwa.dot.gov/engineering/hydraulics/pubs

/hif19059.pdf.

FHWA’s Elizabeth Habic says, “Working 

with nature and incorporating naturebased solutions into transportation projects 

is a proven and effective way to develop 

resilient infrastructure while simultaneously 

enhancing the surrounding environment 

with benefits to local ecosystems, residents, 

tourism, and recreation.”

KATHERINE BUCKINGHAM is an environmental 

protection specialist at the Volpe Center National 

Transportation Systems Center. She holds a 

master of city planning from Massachusetts 

Institute of Technology and a B.A. in politics from 

Oberlin College.

JESSICA TOROSSIAN is an operations research 

analyst at the Volpe Center National Transporta

tion Systems Center. She holds a Ph.D. in ecology, 

evolution, and marine biology from Northeast

ern University.

-

-

For more information, see www.fhwa.dot

.gov/environment/sustainability/resilience

/ongoing_and_current_research/green

_infrastructure/index.cfm or contact Elizabeth 

Habic, an environmental protection 

specialist in FHWA’s Office of Natural 

Environment, at elizabeth.habic@dot.gov.

The town of Dauphin Island, AL, undertook a beach nourishment project in 2016 to prevent 

erosion and protect upland ecosystems and infrastructure in coastal Alabama through the 

placement of 320,000 cubic yards (240,000 cubic meters) of sand on an eroding beach. 

© Sam St John, FlyTheCoast.com.

FHWA’s implementation guide provides transportation 

practitioners with step-by-step recommendations for 

integrating green infrastructure for coastal resilience. 

Source: FHWA.
CONFRONTING THE STORM: 

ARIZONA’S INNOVATIVE DUST 

DETECTION AND WARNING SYSTEM

14 | PUBLIC ROADS | AUTUMN 2021

The 

ADOT 

Dust Storm 

Warning System 

offers the promise of 

intelligent transportation 

solutions to decrease the impact of 

hazardous weather occurrences.

by TONY COVENTRY and KEVIN DUBY

I

nnovations to boost safety on U.S. roadways may look different 

depending on the region. In some parts of the southwest United 

States, factors like climate change, land use, farming practices, and 

desert environments have combined to create a serious problem—

major dust storms that can block visibility for miles and make 

driving unsafe.

In the desert regions of Arizona, factors like these have increased 

the severity and number of dust storms, which can emerge as a side 

effect of thunderstorms. Thunderstorms frequently produce down

bursts and straight line winds, which can blow loose sand and dirt 

from the ground, causing a large wall of dust and debris, or a dust 

storm, to form. These dust storms, sometimes called “haboobs,” are 

unpredictable and unexpected and can reduce visibility to near zero 

in seconds, resulting in deadly multivehicle crashes on roadways. 

The National Weather Service’s research finds that dust storms are 

the third deadliest weather event in Arizona. According to its report, 

157 people died and 1,324 were injured in 1,521 “dust incidents” 

on Arizona highways between 1955 and 2011. Since 2000, dust 

has contributed to 1,207 collisions resulting in 40 fatalities and 

1,136 injuries.

-

In order to address this issue and mitigate the impact of dust 

storms, the Arizona Department of Transportation (ADOT) 

developed a state-of-the-art, fully automated dust storm detection 

and warning system along a critical 10-mile (16-kilometer) segment 

of I–10 between Tucson and Phoenix—an area prone to sudden 

blowing dust events. The system uses multiple intelligent trans

portation system technologies to detect events, warn drivers, and 

modify driver behavior using a dynamic variable speed limit system 

and dynamic message signs. The primary objective is to enhance 

safety and driver awareness during blowing dust events.

-

This solution is an excellent example of a weather-responsive 

management strategy (WRMS). WRMS is a Federal Highway 

Administration initiative focused on deploying methods to mitigate 

the impact of weather on the transportation system.

“One of the primary benefits of developing WRMS is that those 

strategies can be used for a myriad of weather events, including 

dust storms and low-visibility issues, that impact our roadways and 

public safety,” says David Johnson, the team leader for the FHWA 

Road Weather Management Program. “ADOT’s dust detection 

system offers a perfect example of a regional approach to mitigate 

weather impacts through WRMS.”

The ADOT Dust Warning System

ADOT installed 13 sensors—12 that measure visibility and 1 that 

measures both visibility and precipitation—in strategic locations on 

I–10 from milepost 209 to 219. The instruments are installed 8 feet 

(2.4 meters) off the ground to record the quality of visibility that 
WWW.FHWA.DOT.GOV | 15

drivers are experiencing. Placed about a mile (1.5 kilometers) apart, 

the spacing gets tighter closer to milepost 214, which is used as the 

center, or ground zero, for the system. The instruments measure the 

number of particles in the air and then calculate the visibility in feet.

“We chose these sensors because we have used them in the past; 

they are reliable and easy to maintain and calibrate,” says David 

Locher, P.E., ADOT’s manager for Transportation Systems Manage

ment and Operations (TSMO) Systems Maintenance.

-

In addition to the ground sensors, the system also uses an 

X-band (between 8.0 and 12.0 gigahertz) radar with a 60-mile 

(97-kilometer) radius. During the project design phase, ADOT 

discovered that the two major weather radars nearby, one in Phoenix 

and one in Tucson, did not sufficiently detect the area of concern. 

The two existing radars could determine high-rising thunderstorms 

but could not spot dust events closer to the ground. To complement 

the real-time ground observations the visibility sensors provide 

during an event, ADOT installed X-band radar near the new inter

section of SR–87 and I–10. This system provides advance notice 

and warning of approaching storms.

-

The radar, the first and only to be owned by a State DOT, 

has the capability to rotate 360 degrees, and the current scanning 

pattern is designed to see both rain and dust. With each rotation, 

the radar increases one degree in elevation, starting at 0.5 degrees 

and going up to 5.5 degrees. The change in elevation enables 

ADOT to create 3-D images of a storm within a 60-mile radius. 

Leveraging the FHWA Road Weather Management Pathfinder 

program, ADOT can also send the radar imagery directly to the 

National Weather Service, where this data could be used in research 

and development to potentially better forecast sandstorms in 

the future.

Dust storms can rapidly drop driver visibility to almost nothing. 

The Arizona Department of Transportation (ADOT) is piloting 

a system to detect dust events and warn motorists.

© KevinRimcoski, Shutterstock.com.

ADOT installed radar on light 

poles along a section of I–10 

to help spot dust events.

© ADOT.
16 | PUBLIC ROADS | AUTUMN 2021

A roadside sign alerts motorists to the variable speed limit corridor that is part of the dust detection system on I–10 between Phoenix and Tucson.

© ADOT.

ADOT’s Traffic Operations Center can receive CCTV 

images, like this one of dust storms along I–10.

© ADOT.

Adjusting Speed Limits for Safety

The system also contains a variable speed 

limit component, which includes a series 

of programmable speed limit signs that 

can display changes to the legal speed 

limit from a maximum of 75 miles (120 

kilometers) per hour to as low as 35 miles 

(56 kilometers) per hour. Eight of these 

units are tightly spaced, around 1,000 feet 

(300 meters) apart, on the I–10 corridor, 

four on the eastbound side at milepost 209 

and four on the westbound side at mile

post 219. Additional variable speed limit 

signs lie at 2-mile (3-kilometer) intervals 

approaching the corridor. As the sensors 

begin to measure a reduction in visibility, 

the data (visibility measured in feet) are 

analyzed and, when appropriate, messages 

are sent to the system to reduce the speed 

limit in increments.

-

Locher explains further: “For example, 

if the visibility sensors record a visibility 

between 900 and 1,200 feet [270 and 

370 meters], we have designed the system 

to automatically lower the speed limit 

to 45 miles [72 kilometers] per hour for 

that degree of visibility. We did not want 

drivers to see a speed limit sign go from 

75 to 45 miles [120 to 72 kilometers] 

instantly, so we designed the series of four 

close-spaced signs. The four consecutive 

signs may [indicate] 65, 65, 65, 65; then 30 

seconds later, 65, 55, 55, 55; then another 

30 seconds, 65, 55, 45, 45. If we need to 

reduce to 35, it takes a total of 2 minutes to 

do the steps.” 

The system goes back to its normal status 

of 75 miles (120 kilometers) per hour in 

a 5-minute interval. The slower return is 

intended to make sure the dust event is over.

In addition to warning motorists of 

conditions using variable speed limit 

messaging, ADOT installed four new 

dynamic message signs within the corridor 

and uses existing ones outside the corridor. 

The signs, or “boards,” are preprogrammed 

with messages that automatically change, 

depending on the sensed conditions, to 

prepare motorists for the expected condi

tions they will experience.

-

ADOT’s Traffic Operations Center 

can monitor the health of the system and 

measure the impact it has on driver behavior 

through additional system components. 

Embedded loop sensors in the pavement 

measure and report traffic speed and 

volume. The data can be used to measure 

the change in driver behavior and response 

to the changing speed limit. Six CCTV 
WWW.FHWA.DOT.GOV | 17

cameras can be accessed by the center to 

monitor both the health of the system and 

dust events.

 The radar provides advance warnings 

while sensors measure visibility. When the 

visibility goes down, the system reduces the 

speed limit and populates the dynamic signs 

with messages indicating the severity of the 

dust event.

“All of it can be monitored and managed 

by the Traffic Operations Center, but almost 

everything is fully automated, hands free,” 

says Locher.

Overcoming Design Challenges

ADOT hired a firm to design the system 

in 2016 and added it to a widening project 

that broke ground in December 2017. The 

system used crash data from 2010 to 2015 

to identify the most effective location for 

deployment. While building the system, 

ADOT ran into several challenges. Any 

system like this requires solid communi

cations, and the quality of the available 

communications at the device locations 

often wasn’t optimal. Integrating multiple 

devices from multiple vendors also proved 

to be demanding, but the project overcame 

this obstacle with consistent communi

cation and a collaborative approach with 

the contributors. Finally, designing and 

implementing the algorithms that deter

mined what speeds the variable signs should 

be changed to relative to what observa

tion analytics were available was difficult. 

However, the system design includes 

flexibility and scalability so that as it grows 

and evolves, these algorithms and analytics 

can be modified and become even more 

effective. The system, including the X-band 

radar, cost $6 million; it was completed and 

operational in the summer of 2020.

-

-

-

-

The Dust Warning System is still 

operationally new, and the monsoon season 

following its debut produced fewer than 

average events, making initial evaluation 

of its functionality difficult to determine. 

Even so, the system has garnered attention 

and accolades, including a nomination for 

an American Association of State Highway 

and Transportation Officials Operational 

Excellence award. In addition, the National 

Weather Service has named ADOT a 2020 

Weather Ready Nation Ambassador of 

Excellence for the agency’s work on this 

project and others.

Looking to the Future

As transportation-related technologies 

continue to advance, new challenges 

related to the effects of climate change and 

other related issues will arise and need to 

be addressed. For example, the increased 

deployment of connected and autonomous 

vehicle technology will require intelligent 

transportation system solutions to provide 

real-time, relevant information to equip 

vehicles to lessen the impact from weather 

events. Weather-responsive management 

solutions will continue to be a corner

stone to meeting those challenges. The 

ADOT Dust Warning System is the perfect 

combination of proactive, collaborative, 

and forward-thinking development and 

deployment of new sustainable technol

ogies, solutions, and strategies that create 

systemic resiliency.

-

-

TONY COVENTRY is a transportation specialist with 

FHWA’s Road Weather Management Program. His 

current focus area is developing climate change 

impact mitigation and resiliency strategies for the 

Nation’s surface transportation system.

KEVIN DUBY is the statewide road weather 

manager for ADOT, coordinating the road weather 

information system networks and supporting 

winter operations. He has been with ADOT since 

2002. He holds a master’s degree in emergency 

management from Arizona State University.

For more information, contact Kevin Duby 

at kduby@azdot.gov.

New technologies, like Arizona’s Dust Warning System, 

can help address weather-related challenges from 

the effects of climate change and other issues.

© ADOT.
18 | PUBLIC ROADS | AUTUMN 2021

SAFETY

Ice roads are critical to seasonal transportation in the North. FHWA and its partners are working to 

 on ICE

improve safety and establish uniform standards for their design, construction, operation, and use.

by ADAM LARSEN and BILLY CONNOR

Frozen rivers and lakes provide natural, relatively smooth trails for walking and 

pulling sledges. As a result, they have served 

as important transportation corridors for 

thousands of years in the circumpolar north. 

The sled dog originated in Russia several 

thousand years ago and eventually came 

into use in North America. Because dogs 

pulling sleds move much more quickly than 

a person on foot, the dogs and their owners 

could fall through thin ice before they 

have time to see it. Luckily, stories abound 

concerning the innate ability of dogs to 

sense and avoid thin ice, thus cementing 

a strong bond between the handler and 

the dogs.

While the modern snowmobile was 

patented in 1916, it did not become popular 

until the 1960s with the introduction of 

lightweight frames. These speedy, highly 

maneuverable machines rapidly replaced 

the sled dog. Traveling at speeds that exceed 

100 miles (160 kilometers) per hour, riders 

could find themselves on thin ice before 

they could take evasive action. Riders rely 

on word of mouth and an intimate knowl

edge of local rivers to avoid danger, because 

few of the rivers offer markings that identify 

safe routes. Consequently, fatalities occur 

every winter as unwary travelers fall through 

the ice.

-

More recently, ice roads have carried 

passenger vehicles as well as heavy freight 

vehicles. As the weight of the vehicles 

increases, the danger of falling through 

the ice also increases. Vehicle recovery also 

becomes increasingly difficult.

The effects of climate change and shifts 

in weather patterns have also impacted ice 

roads. Shorter ice road “seasons” and warm 

mid-winter storms can make ice roads 

even more hazardous. These challenges will 

require more frequent inspections of ice 

thickness during and after winter storms, 

and may limit the length of the ice roads 

that can be built and maintained.

Despite these dangers, ice roads continue 

to be a common transportation corridor in 

the north. They provide an efficient means 

of moving supplies, equipment, people, and 

resources such as gravel between commu

nities and commercial operations that are 

inaccessible by roads. For example, the 

ice road on the Kuskokwim River enables 

freight to be distributed from Bethel, AK, 

to surrounding villages at a cost significantly 

lower than that of moving freight solely 

by air.

-

Ice roads are essential to local accessibility in Alaska and other northern regions, but 

present challenges in establishing and maintaining them safely and efficiently. Here, 

the ice road created on the frozen Kuskokwim River in Alaska is seen from the air.

Source: FHWA.

To maintain ice roads, like this one near 

Bethel, AK, crews must clear snow and check 

for hazards like cracks and thin ice.

© 2021 Nathan Belz, University of Alaska Fairbanks.
WWW.FHWA.DOT.GOV | 19

An example of the increased use of ice 

roads is the river crossing at Tanana, AK, 

which connects a newly constructed road 

on the south side of the Yukon River to the 

village of Tanana on the north side. The 

ice road connects Tanana to the rest of the 

Alaskan highway network, reducing the cost 

of freight coming into the community.

To address the challenges of safely using 

and maintaining ice roads, the Federal 

Highway Administration’s Office of Tribal 

Transportation hosted a peer exchange 

and initiated an ice road research project 

with the University of Alaska Fairbanks to 

develop a guide for establishing and main

taining ice roads.

-

Representatives from FHWA, villages served by the 

Kuskokwim Ice Road, the Bureau of Indian Affairs, 

and the University of Alaska Fairbanks met in 

Bethel, AK, for a peer exchange in March 2020.

Source: FHWA.

Ice Road Peer Exchange

In March 2020, FHWA’s Office of Tribal 

Transportation, the Bureau of Indian 

Affairs, and the Center for Safety Equity in 

Transportation at the University of Alaska 

Fairbanks facilitated a peer exchange on 

ice roads. The discussion brought together 

representatives from 17 Tribes from 

southwest Alaska and centered around the 

construction, operation, and benefits of 

ice roads.

One speaker at the meeting was Mark 

Leary, the director of development and 

operations for the Native Village of 

Napaimute in Alaska, who leads the annual 

effort to clear the frozen Kuskokwim River 

and create the ice road. In most years, 

Leary and his crew can establish an average 

of 200 miles (320 kilometers) of ice road. 

In 2020, they set a record by clearing and 

maintaining the river from Tuntutuliak to 

Sleetmute, a distance of about 355 miles 

(571 kilometers). Communities along 

the ice road provide what assistance they 

can, including fuel, equipment, lodging, 

and manpower.

Attendees of the peer review listened 

raptly as Mr. Leary described his experiences 

in the construction of the ice road. “With 

few resources and little time, he and his 

team accomplished a near miracle,” says 

FHWA’s Todd Brockmann. “Even more 

impressive, Mr. Leary drew on his knowl

edge of the river and what he learned from 

the literature published by the Canadian ice 

road operators and talking to others.”

-

The longer ice road caused an immediate 

impact on the villages it served. Air freight 

flown into the main airport at the hub city 

of Bethel on large aircraft could be ferried 

from Bethel to communities along the ice 

road in all but the most extreme weather—

instead of being flown in on light aircraft 

when that method was not made impos

sible by the fickle weather of the Lower 

Kuskokwim. This resulted in a significant 

cost savings for freight between Bethel and 

the villages.

-

The ice road also enables other critical 

services such as mail delivery, access by the 

State troopers, and medical services. In 

addition, village residents can access the 

hospital and other government services in 

Bethel even when air taxis are grounded. 

The Alaska Department of Transportation 

and Public Facilities acknowledged the 

public transportation benefit of ice roads 

in 2020 by contributing both State and 

Federal funding toward the construction, 
20 | PUBLIC ROADS | AUTUMN 2021

maintenance, and operation of the 

Kuskokwim Ice Road.

At the peer exchange, as representatives 

from several of the communities affected 

by the ice road told their stories, it became 

clear that the ice road meant more than the 

lower cost of freight. Community members 

commented that the ice road is a source of 

pride for the communities along the route, 

creating a bond that few other projects 

could ever produce.

The ice road also freed communities 

from the unpredictable weather that makes 

air traffic unreliable. Ice roads offer not only 

the prospect of dependable freight move

ment, but also an alternative to air medivac 

for the sick or injured when the weather 

does not allow flights. Other community 

members discussed the ability to visit friends 

and relatives and attend regional events, 

such as watching their children play basket

ball in the next village.

-

-

In short, the ice road means freedom to 

safely travel along the river in winter as well 

as in summer, when the river enables travel 

by boat or barge and all-terrain vehicles 

provide overland travel on trails that are 

impassable in winter.

The thickness of the ice can be measured using an auger, as shown 

here, but this method enables monitoring only at individual locations.

© 2021 Nathan Belz, University of Alaska Fairbanks.

Taking a core sample of ice, like this one from the Tanana 

Ice Bridge, provides information about the quality and 

type of ice in addition to measuring the thickness. 

© 2020 Svetlana Stuefer, University of Alaska Fairbanks.

Addressing Challenges 

in Ice Road Design

The FHWA Office of Tribal Transportation 

understands the importance of ice roads to 

communities along Alaskan rivers. While 

the work of people like Mark Leary and 

his crew is impressive, the lack of standards 

poses a potential public safety concern. 

Standards include the determination of ice 

thickness required to carry the expected 

traffic and the selection of routes, mainte

nance standards, speed limits, and traffic 

control devices.

-

To address this gap, the Office of Tribal 

Transportation has published information 

on how to establish and maintain ice roads 

in the Tribal Transportation Program Delivery 

Guide, available at https://highways.dot.gov

/federal-lands/programs-tribal/guide/tribal

-transportation-program-delivery-guide. In addi

tion, the FHWA Office of Federal Lands 

Highway is funding research to establish 

these standards, and has selected the Univer

sity of Alaska to lead the effort.

-

-

The variability in the ice and river char

acteristics throughout the winter months 

creates one of the most challenging envi

ronments in which to design, construct, 

and maintain a transportation corridor. 

The safety of an ice road requires an under

standing of the properties of ice, which vary 

with how it was formed, its temperature, 

and the rate at which it is loaded (vehicle 

speed). How to design, construct, and main

tain ice roads can vary from a highly math

ematical approach based on ice mechanics 

and structural analysis of plates to a fully 

-

-

-

-

-
WWW.FHWA.DOT.GOV | 21

empirical approach based on the experience 

of those involved. In practice, the process 

blends these two approaches because of the 

variability of ice type and thickness along 

the routes and because of the changing 

characteristics of the rivers.

As part of the research effort, the team 

conducted a literature review of existing 

guidelines such as those developed in 

Canada for Alberta, the Northwest Terri

tories, and Nunavut. The literature shows 

that the most common design for ice 

roads derives from mathematical equations 

tempered with empirical coefficients based 

on acceptable risk levels. The use of a risk 

management framework provides a means 

of balancing user needs and requirements 

with the resources available to the ice road 

operators. The final design depends on the 

type of ice, ice thickness, anticipated ice 

temperatures, vehicle weights, and traffic 

speeds. Ice road operators can manage all 

of these factors except the type of ice and 

its temperature.

-

Ice thickness must be continuously 

monitored during road construction and 

throughout the winter. One of the most 

common methods of monitoring the ice 

thickness is simply to drill a small hole in 

the ice using small hand or powered augers. 

A thickness gauge with a hook attached 

to the bottom is then fed through the 

ice and pulled up against the bottom of 

the ice. While this method is accurate, it 

only allows for the measurement of ice at 

discrete points.

Ground-penetrating radar (GPR), 

commonly used to obtained continuous ice 

thickness, proves to be a helpful tool but 

has limitations. While GPR can identify 

individual layers, it cannot distinguish one 

type of ice from another. Nor is it useful 

when water flows over the surface of the ice 

or between ice layers. Consequently, GPR is 

best used in conjunction with conventional 

ice assessments and thickness 

measurements.

Generally, the thickness of the ice as the 

river or lake freezes and human experience 

dictates the routing of ice roads. Alaska’s 

rivers are geologically young. As a result, 

their channels change frequently, which 

alters the optimal routing each year. Further, 

the routing may vary through the winter if 

the thickness of the ice falls below minimal 

thickness because of water conditions, or if 

cracking occurs as the result of loading.

Cracking from vehicle loading consti

tutes a major safety hazard to travelers 

because of the danger of falling through the 

ice. While ice thickness, vehicle weight, and 

vehicle speed help manage this risk, cracking 

can and does occur. In these cases, agencies 

can apply remediation and repair techniques 

such as surface flooding to increase the 

thickness of the ice and in effect glue the 

cracks together. If cracking is severe enough, 

the location of the ice road may change.

-

Unmanned aerial vehicles (UAVs)—or 

drones—fitted with the appropriate sensors 

can scout appropriate routes and detect thin 

ice and cracks in the ice without putting 

workers in harm’s way. The use of UAVs 

for this purpose is fairly new. As part of the 

research project, the University of Alaska 

Fairbanks will investigate which sensors may 

be required and which aircraft are appro

priate for the task. UAV data will likely be 

used in concert with GPR and ice thickness 

measurements to assess the health of the 

ice sheet.

-

Ground-penetrating radar (GPR) can quickly map ice depth, but does not distinguish one type 

of ice from another and cannot work if water flows over the ice or between the layers.

Source: FHWA.

Signage for Ice Road Safety

Keeping the public safe on the ice continues 

to be the greatest challenge of creating and 

maintaining ice roads. Ice conditions, speed 

limits, weight restrictions, and delineation 

all require constant communication with the 

public. Signage offers a critical tool in that 

communication. Signs at entry points can 

show the level of risk and remind travelers 

to check public information sources and any 

other necessary warnings. While there are a 

few existing destination signs and warning 

signs in use, these signs do not meet current 

signage standards. Improved signs meeting 

the requirements in the Manual on Uniform 

Traffic Control Devices, including the sign 

size, color, and placement, are expected to 

be installed during the winter of 2022.

Founding these devices on the ice 

presents unique challenges. While signposts 
22 | PUBLIC ROADS | AUTUMN 2021

can be embedded in the ice, they must be 

removed before spring thaw. The timing is 

critical because the signs need to remain in 

place as long as safely possible. If the opera

tors wait too long, the signs cannot be safely 

removed and will be lost. While general 

guidance can be given, the timing will vary 

each year based on conditions and must rely 

on the judgment of the operator.

-

Signage for speed limits is critical. 

Speed limits on ice roads not only ensure 

that the vehicle can traverse the route, but 

also serve to protect travelers and the road 

itself. Following maximum speed postings 

guarantees that the ice does not break 

because of the wave that is generated in the 

water ahead of the loading. If the speed is 

too great, the wave becomes large enough 

to generate tension in the surface of the 

ice, which results in radial cracking. Radial 

cracking provides the last warning before 

the vehicle falls through the ice.

Public Information

Hazardous conditions, like open holes 

and thin ice, can develop throughout the 

winter. Travelers on the ice roads need to be 

aware of these conditions. Local crews or 

operators will commonly mark hazardous 

areas using willows around the perimeter 

of the hazard. In some cases, these willows 

are wrapped with reflective tape to improve 

visibility during the long hours of winter 

darkness. Social media is also used to spread 

the word about incidents and hazards. 

However, no formal system currently exists 

for distributing public 

information about ice 

road conditions.

FHWA’s Tribal 

Transportation Program 

Safety Fund awarded 

a grant to the Native 

Village of Napaimute to 

develop a public infor

mation app or website. 

In partnership with 

other entities involved 

in the management of 

the ice roads, the village 

hopes to deploy a pilot 

of the system by the end of 2021.

-

Temporary signs, like this one, warn drivers about hazards on the ice roads.

© Mark Leary, Native Village of Napaimute.

Warning signs remind travelers that road conditions may change. 

The arrow marked KLG indicates the direction of Kalskag, AK.

© Mark Leary, Native Village of Napaimute.

The Future of Ice Roads

Construction and operation of ice roads 

present numerous challenges. After listening 

to the users of the Kuskokwim River Ice 

Road, it is clear that the value of ice roads to 

village residents far exceeds the costs associ

ated with the road. While some costs, such 

as freight expenses can be quantified, the 

benefits of watching a child play basketball 

or visiting friends and family in adjacent 

villages cannot be calculated.

-

The cost of conventional roads makes 

their construction in the region unlikely. 

Consequently, river, trail, and air travel offer 

the only viable options.

The FHWA Office of Tribal Transpor

tation and the University of Alaska’s Arctic 

Infrastructure Development Center recog

nize the need for uniform practices related 

to the design, construction, and operation 

of ice roads. The manual being developed 

under FHWA funding will help ensure 

the safety of those who are increasingly 

dependent on ice roads.

-

-

ADAM LARSEN is the safety program manager 

with the FHWA Office of Tribal Transportation. 

He holds a B.S. in civil engineering from Portland 

State University.

BILLY CONNOR is a professional engineer at the 

Arctic Infrastructure Development Center at the 

University of Alaska Fairbanks. He holds a B.S. 

in civil engineering and an M.S. in engineering 

science management from the University of 

Alaska Fairbanks.

For more information, see https://cset.uaf.edu

or contact Adam Larsen at 306-619-2601 

or adam.larsen@dot.gov or Billy Connor at 

907-474-5550 or bgconnor@alaska.edu.
WWW.FHWA.DOT.GOV | 23

BOLSTERING THE SAFETY

OF AMERICA’S BRIDGES

FOR HALF A 

CENTURY

FHWA’s national bridge 

inspection program 

marks 50 years of 

improving safety.

The Federal Highway Administration adopted the National Bridge Inspection 

Standards (NBIS) in 1971. Bridges, like this one on Foothills Parkway 

in Tennessee, are inspected following the program’s standards.

 Source: FHWA.

by JOEY HARTMANN

I

t is in the vital interest of the United States to have a strong 

national bridge inspection program and maintain an inventory of 

the Nation’s bridges. Regular and thorough bridge inspections are 

necessary to maintain safe operations and prevent structural and 

functional failures. In addition, data on the condition and perfor

mance of bridges are necessary for bridge owners to make informed 

investment decisions as part of an asset management program.

-

Safety—including bridge safety—is the Federal Highway 

Administration’s top priority. The agency’s longstanding and 

successful national bridge inspection program has been at the core 

of highway bridge safety, and 2021 commemorates its 50th anni

versary. The program requires regular bridge inspections and data 

collection by trained professionals.

-

FHWA adopted the National Bridge Inspection Standards 

(NBIS) regulations in 1971, prompted by the U.S. Congress 

enacting the Federal-Aid Highway Act of 1968. The NBIS were the 

direct result of the Silver Bridge collapse in Point Pleasant, WV, on 

December 15, 1967. The tragic event brought nationwide atten

tion to the issue of bridge safety and led to a systematic effort to 

ensure bridge safety at the national level—and the birth of FHWA’s 

Federal program. It was an event of historical significance and one 

-
24 | PUBLIC ROADS | AUTUMN 2021

that many would agree was a wake-up call 

that propelled the Nation into a new era of 

bridge safety.

By 1971, when the NBIS were estab

lished, the new standards required that 

bridges, and their various component 

parts—ranging from pilings to deck slab—

be inspected at least once every 2 years, 

with special emphasis on identifying and 

assessing fractures, corrosion, and fatigue. 

In addition, FHWA was ultimately charged 

with using the data from bridge inspections 

nationwide to create the National Bridge 

Inventory (NBI) and to standardize bridge 

inspector qualifications.

-

“The Silver Bridge tragedy and the 

resulting legislation drastically changed 

the way we approached bridge safety and 

made sure that the hundreds of millions of 

Americans who have driven over a bridge 

any time in the last 50 years were safer in 

doing so,” says Thomas D. Everett, FHWA’s 

Executive Director.

In addition, the tragedy raised many 

questions about the state of bridges nation

ally. For starters—How many bridges were 

there in the United States? How were they 

designed, what were they made of, and how 

old were they? How much traffic did they 

carry? There were no answers to basic ques

tions like these, because there was not yet a 

nationwide collection of bridge information. 

The establishment of the NBIS aimed to 

answer these questions.

-

-

A half century later, FHWA’s bridge 

inspection standards continue to ensure 

that only bridges safe for travel are open 

to traffic.

An inspection of the John Coffee Memorial Bridge, part of the Natchez Trace Parkway over the Tennessee River.

 Source: FHWA.

Timeline of Bridge 

Program Evolution

Over the last decade, FHWA has implemented 

new measures to boost its oversight role and 

to target the inspection of areas critical to 

bridge safety. For example:

• In 2011, FHWA instituted a risk-based, 

data-driven approach to more clearly and 

easily identify bridge inspection issues 

in each State. FHWA replaced written 

general assessments of State bridge 

inspection programs with measurements 

of 23 key metrics to more easily identify 

potential safety issues. The newer process 

provides for more bridge inspection 

consistency and simplifies efforts to 

identify challenges State by State.

• In 2015, FHWA began collecting new 

data for bridges on the National Highway 

System to more closely monitor bridge 

conditions nationwide. Previously, bridge 

inspectors assigned one summary 

rating for the condition of a bridge’s 

major components to reflect both the 

severity of a problem and whether it was 

widespread or confined to a small area. 

The new format calls for each square 

foot of the bridge deck to be assigned 

a rating, and its other elements—such 

as the joint seals—receive separate 

ratings. Dividing bridge components 

into smaller, more manageable elements 

helps engineers more easily assess the 

extent of bridge deterioration, which 

leads to more informed decisions about 

preservation, repair, and replacement.

• FHWA is in the process of updating the 

NBIS. A Notice of Proposed Rulemaking 

was published on November 12, 2019, 

and the comment period was open 

until March 13, 2020. FHWA has been 

reviewing the comments received 

and is preparing a Final Rule.

A Robust Program

FHWA provides oversight of State bridge 

inspection programs. While States, local 

agencies, Federal agencies such as the 

National Park Service, and Tribal govern

ments own most highway bridges, FHWA 

maintains the NBIS—the Federal bridge 

inspection regulations that States, Federal 

agencies, and Tribal governments are 

required to follow. The NBIS apply to all 

highway bridges on all public roads. FHWA 

assesses compliance with the regulations 

through a detailed annual review process.

-

Working with FHWA division offices, 

State transportation departments, and 

Federal agencies, hundreds of qualified 

inspectors from the NBIS program evaluate 

the condition and safety of the Nation’s 

highway bridges every day. These bridges are 

inspected on a routine basis, typically every 

24 months, and the results are reported 

to FHWA. If inspectors deem a bridge 

unsafe, immediate action is taken, which 

may include closure, prompt repair, or load 

posting (weight limit) that does not allow 

heavy vehicles to use the bridge.

FHWA continues to maintain the 

comprehensive NBI, a compilation of 

bridge data that States and Federal agen

cies provide to FHWA on an annual basis. 

-
WWW.FHWA.DOT.GOV | 25

It contains more than 100 data items for 

each of the Nation’s approximately 618,000 

highway bridges, representing a database of 

more than 60 million pieces of information.

“FHWA’s NBI has gotten more robust 

over the years. Just looking at the data 

amassed in the 21st century, the number of 

highway bridges has grown from 587,735 

in 2000 to 618,456 today,” says Hari Kalla, 

the Associate Administrator for the FHWA 

Office of Infrastructure. “Bridge owners 

continue to build new bridges and replace 

or rehabilitate others that have deteriorated. 

Today, the average age of the 618,000 

highway bridges in the NBI is 45 years old. 

The oldest bridge in the NBI is in Pennsyl

vania and was built in 1697. In fact, there 

are more than 1,700 bridges built before 

1900 that are still being used today.”

-

The program has been successful in 

identifying bridge deficiencies, while Federal 

and other funding programs have supported 

efforts to address these deficiencies. As 

owners have repaired bridges, the percentage 

of bridges in poor condition has dropped 

from 11.9 percent in 2000 to 7.3 percent 

in 2020. Bridge conditions have steadily 

improved over the years due to the commit

ment to bridge safety by FHWA and State 

departments of transportation.

-

While State departments of transporta

tion are on the front lines conducting the 

inspections, FHWA provides the standards 

and oversees State programs to ensure safety 

and track bridge conditions nationwide. 

FHWA has worked constantly over the 

years to improve the national program and 

ensure that bridge inspections continue to 

be robust.

-

The agency is continually committed to 

finding new and better ways of making sure 

bridges are safe.

Flexible Response to Bridge 

Safety Challenges

Since FHWA established NBIS regulations 

in 1971, the agency has worked to evolve, 

improve, and refine the program on an 

ongoing basis. Some improvements have 

included requiring more rigorous inspec

tions for certain steel bridges with less 

redundancy, requiring underwater inspec

tions for bridges over water, and taking 

appropriate and timely followup actions 

when inspections identify critical safety 

issues. FHWA has also updated training 

requirements for bridge inspectors.

-

-

Another bridge tragedy occurred on 

August 1, 2007, when the Minneapolis 

I–35W Bridge collapsed during evening 

rush hour. Although the collapse was not 

a result of a failed inspection, it brought 

renewed interest in the bridge inspec

tion program.

-

In response, FHWA moved from 

a qualitative process to a risk-based, 

data-driven process in 2011 to assess 

compliance with the NBIS. FHWA now 

requires annual assessments using a grid 

of 23 specific inspection program areas 

to determine how well State transporta

tion departments and Federal agencies 

are meeting the regulations. In addition, 

FHWA dedicated more staff to support 

bridge inspection efforts. The aim was to 

improve consistency in bridge inspections 

and simplify efforts to identify challenges 

State by State. FHWA also expanded 

the amount of data collected on bridges 

to more closely monitor bridge condi

tions nationwide.

-

-

The Minneapolis I–35W Bridge collapse 

in August 2007, while not a result of 

failed bridge inspections, sparked 

renewed interest in the NBIS program.

 Source: FHWA.

-

Key Bridge Rating Definitions

• Good – A bridge classified in good 

condition has all primary bridge 

components rated in good condition 

or better. Good condition would 

indicate the structural elements of 

the bridge have no deterioration or 

some minor deterioration. A bridge in 

good condition may need preservation 

or cyclic maintenance activities.

• Fair – A bridge classified in fair condition 

has one or more primary bridge 

components rated in satisfactory or fair 

condition, and none of these components 

rated worse than fair condition. Fair 

condition would indicate that some 

structural elements of the bridge have 

minor deterioration that could include 

section loss, cracking, spalling, scour, 

or other defects of similar significance. 

Typical needs of a bridge in fair condition 

would include preservation, cyclic 

maintenance activities, or conditionbased maintenance activities.

• Poor – A bridge classified in poor 

condition has one or more primary bridge 

components rated in poor or worse 

condition. Poor condition would indicate 

that some structural elements of the bridge 

have advanced deterioration. Typical 

needs of a bridge in poor condition would 

include condition-based maintenance 

activities, rehabilitation, or replacement. A 

bridge in poor condition may require more 

frequent inspections, closer monitoring, or 

weight restrictions to ensure it remains safe 

for public travel. Unsafe bridges are closed.

Tradition Alongside 

Technology

FHWA continues to explore new ways 

of keeping bridges safe, including using 

unmanned aerial vehicles, also known as 

drones, and various other cutting-edge 

tools to support or assist bridge inspec

tions. Applying science and technology 

to such matters helps inspect bridges 

more quickly, and more thoroughly, 

than ever before. On any given day, 

hundreds of bridges are being inspected 

across the country and evaluated by 

qualified inspectors.
26 | PUBLIC ROADS | AUTUMN 2021

Despite certain advances in technology, however, physical and 

visual inspection methods continue to be valuable in the inspec

tion world. These remain the primary tools in the toolbox that 

bridge inspectors use in assessing the condition of a bridge. Other 

technology-based tools used by bridge inspectors are sometimes 

referred to as advanced inspection methods, or nondestructive 

evaluation (NDE) techniques. These include methods such as 

ultrasonic testing, which uses sound much like a sonogram to 

detect subsurface characteristics, and infrared thermography, which 

uses the heat radiating from bridge components as an indicator of 

their condition.

-

“In addition to traditional, manual methods, the bridge inspec

tion industry has embraced technological advances when they can 

add value to the inspection results,” says Cheryl Richter, Director of 

the FHWA Office of Infrastructure Research 

and Development.

-

FHWA supports the use of advanced 

technology, including the use of drones, to 

supplement bridge inspections. Technologies 

may not replace the human inspector at this 

time, but they can accelerate inspections and 

improve inspector safety. NDE technologies 

can be used to improve the accuracy of some 

inspections and the proper identification of 

certain issues. Bridge inspectors are trained to 

identify when those technologies are needed.

Looking Toward the Future

FHWA is in the process of updating the NBIS 

to address statutory requirements, provide 

flexibility, and address ambiguities identified 

since the last update to the regulation in 2009. 

The improvements will include expanding 

the requirements to Tribally owned highway bridges, updating the 

training and qualifications for bridge inspectors, and establishing 

a national certification for inspectors. In addition, requirements 

for the intervals between inspections will be updated using a riskbased approach, and procedures for the reporting and monitoring 

of critical findings will be established. The changes are primarily 

aimed at ensuring the uniformity of inspections and evaluations and 

clarifying responsibilities.

JOSEPH (JOEY) HARTMANN, Ph.D., P.E., is the director of FHWA’s Office of 

Bridges and Structures.

For more information, contact Joey Hartmann at 

joey.hartmann@dot.gov or visit www.fhwa.dot.gov/bridge.

Inspectors perform ultrasonic testing, a nondestructive evaluation technique, on two bridges.

 Source: FHWA.

Inspectors use a bucket truck on the Snake 

River Bridge in Grand Teton National Park.

 Source: FHWA.

Bridge Inspection 

Technologies

• Acoustic emissions testing

• Acoustic wave sonic/ultrasonic testing

• Dye penetrant testing

• Magnetic particle testing

• Magnetic flux leakage testing

• Eddy current testing

• Ground-penetrating radar

• Stress wave/pulse velocity testing

• Impact echo testing

• Infrared thermography

• Magnetic field disturbance testing

• Radiographic and other 

nuclear methods

• Vibration testing
Source: FHWA.

Source: FHWA.

Zero traffic deaths or serious injuries is our goal, and the Winter 2022 issue 

of Public Roads will highlight the revolutionary Safe System Approach that 

transportation leaders are advancing to help us get there.

• Discover how a growing number of cities, States, and 

countries are successfully applying the Safe System 

Approach to reach zero traffic deaths and 

serious injuries

• Learn about how FHWA is making strides to 

advance the Safe System Approach in safety 

funding, planning, and programs, including 

strategic highway safety plans, intersections, 

and speed management

• Learn about how NHTSA is integrating the 

Safe System Approach to protect all road users, 

support safe vehicle technology, and emphasize 

post-crash care 

• Be inspired to advance the Safe System Approach in your 

community to reach zero deaths and serious injuries

Source: FHWA.

Be sure to check out the next issue of Public Roads!
28 | PUBLIC ROADS | AUTUMN 2021

REHABILITATING the 

Historic ARLINGTON 

MEMORIAL BRIDGE

The National Park Service and the Federal Highway Administration 

partnered successfully to restore the iconic bridge. 

The Arlington Memorial Bridge underwent a huge 

rehabilitation project, completed in December 2020.

Source: FHWA.

Line drawing courtesy of Historic American 

Engineering Record, National Park Service, delineated 

by Brianna Kraft and Ashley T. Walker, 2013-2014.

by SANDY SINCLAIR

Since 1932, the Arlington Memorial Bridge has been a lasting symbol of 

national unity after the Civil War. Spanning 

the Potomac River, the neoclassical bridge 

links the Lincoln Memorial in Washington, 

DC; Arlington House (also known as the 

Robert E. Lee Memorial) in Arlington, VA; 

and Arlington National Cemetery—the 

final resting place for more than 400,000 

service members who died on active duty, 

veterans, and their family members.

“Arches of Ever-Enduring Granite”

The Arlington Memorial Bridge is the 

realization of nearly a century of imagina

tion, speculation, and planning. President 

Andrew Jackson envisioned a bridge over 

the Potomac River during his term in office 

from 1829 to 1837, and in 1851, Secretary 

of State Daniel Webster credited the former 

president for championing a bridge “with 

arches of ever-enduring granite, symbolical 

of the firmly established union of the North 

and South.”

-

Decades of periodic studies into the 

feasibility of a bridge, and even a design 

competition in 1899, generated little more 

than paperwork. On his final day in office 

in 1913, President William Howard Taft 

authorized $25,000 for a commission to 

investigate how to link Arlington National 

Cemetery to the District of Columbia across 

the Potomac River. Funding shortfalls and 

other delays prevented the bridge from 

becoming a reality until President Calvin 

Coolidge approved construction. The bridge 

cost about $7 million and was dedicated on 

January 16, 1932.

Today, Arlington Memorial Bridge is 

one of the five vehicular bridges connecting 

the District of Columbia and Virginia and 

serves as an iconic element of the entrance 

to the Nation’s Capital. Decades of gradually 

increasing vehicle traffic, vehicle tonnage, 

weather, and the natural freeze-thaw cycle 

aged the bridge severely. By the early 21st 

century, it was in serious need of repair.

The bridge is a key component of the 

greater Washington, DC, area transporta

tion network, with an estimated 68,000 

vehicles crossing the bridge daily. The bridge 

is also designated as an emergency evacua

tion route for the Nation’s Capital.

-

-

Since it first opened to traffic, the bridge 

structure had never been rehabilitated at this 

magnitude. Following guidelines from the 

Federal Highway Administration’s National 

Bridge Inspection program, bridge inspectors 

noted that components of the bridge had 

deteriorated to a critical level. The National 

Park Service (NPS), which has jurisdiction 

over the bridge because of its status as a 

national monument, conducted a series of 

temporary emergency repair projects on the 

bridge between 2010 and 2017. Despite 

these efforts, Federal officials determined 

that—without substantial renovation—the 

bridge would be forced to close by 2021.

NPS and FHWA Partnership With the Arlington Memorial Bridge 

serving as both a monument and a 

connector, NPS and FHWA shared a 

mutual interest in preserving the bridge and 

keeping the public safe. The two agencies 

worked together to restore the historic 

bridge to its original grandeur and in 2018 

began a 3-year, $227 million program to 

make the most comprehensive set of repairs 

to the bridge since its original construction.

The design-build project repaired or 

replaced the bridge deck, sidewalk, and 

bascule (drawbridge) span, and restored 

the remainder of the structure. The work 

extended the bridge’s useful life for 75 

years. In December 2020, NPS completely 

reopened the rehabilitated bridge.
WWW.FHWA.DOT.GOV | 29

The construction crew works on the wall 

of a replacement bridge span. 

Source: FHWA.

“I am very honored to have been part 

of this large historic rehabilitation project,” 

says FHWA construction engineer Joe Fabis. 

“The coordination with Federal agencies, 

local agencies, contractors, subcontractors, 

and suppliers that led this project to be 

completed on time kept this bridge in 

service for the local community and for 

visitors from all over the world.”

Replacing the Historic Bascule Span By many accounts, at 94 feet (29 meters) 

wide and 2,162 feet (659 meters) long, the 

Arlington Memorial Bridge is a structural 

masterpiece. The bridge consists of 10 

reinforced concrete arch approach spans 

and features a 216-foot (66-meter) doubleleaf bascule span at its center. The bascule 

span was the longest, heaviest, and fastest 

opening in the world when it was built, but 

it has not functioned since 1961 because the 

closed position provided sufficient clearance 

for the navigational traffic below after that 

time. The steel experienced significant rust 

and section loss during this time of disuse.

Between the bridge’s completed construc

tion in 1932 and the drawbridge closure in 

1961, the bascule span would periodically 

open and close to provide access for large 

ships to the Georgetown waterfront. Over 

time, as shipping traffic on the Potomac 

River decreased and the construction of a 

fixed, low-clearance bridge nearby ended 

access for large ships, the bascule span was 

permanently closed in 1965. With no ship 

traffic, there was no expectation it would 

ever need to open again.

-

The rehabilitation of the Arlington 

Memorial Bridge was one of the largest 

and most important infrastructure projects 

in NPS history. In 2016, the project team 

completed the required environmental 

assessment under the National Environ

mental Policy Act (NEPA). The assessment’s 

preferred alternative for the project priori

tized historic preservation by combining a 

mixture of replacement and rehabilitation 

practices to preserve the structure’s original 

character. During the NEPA review process, 

the project team considered multiple 

proposals for the bascule span replacement 

in coordination with the historic preserva

tion offices of Virginia and the District of 

-

-

-
30 | PUBLIC ROADS | AUTUMN 2021

Columbia, the U.S. Commission of Fine 

Arts, and the National Capital Planning 

Commission. The final plan called for the 

bridge’s bascule span to be replaced with a 

new fixed span comprised of variable-depth 

steel girders.

Designing to Reduce 

Future Maintenance

The deterioration of the bridge prior to 

construction occurred in part because of 

the intrusion of water and winter salting 

for snow. The design of the new structure 

prevents water and chlorides from entering 

the bridge. The new center span design also 

supports the roadway above using multiple 

simple plate girders, adding redundancy 

compared to the original complex two 

truss-floor beam system with lattice steel 

members. The new design reduces the 

amount of future maintenance needed 

compared to the original. The renova

tion integrated several FHWA initiatives 

to preserve the bridge and minimize 

construction time, including accelerated 

bridge construction techniques, prefabri

cated bridge element systems, and the use 

of ultra-high performance concrete, which 

will also help future maintenance. In addi

tion, passive corrosion anodes help reduce 

chloride corrosion. These initiatives, along 

with a concrete overlay, delivered a final 

watertight bridge and reduced construction 

duration and long-term maintenance.

-

-

-

“The FHWA initiatives we used 

promoted durability and minimized impact 

to the public,” says FHWA structural 

engineer Hratch (Rich) Pakhchanian, who 

helped lead the restoration project. “These 

methods, with cutting-edge construction 

and materials technology, accelerated our 

construction schedule.”

The design team also faced challenges 

related to the bridge’s sidewalks, which 

enabled water to enter the bridge at the 

interface between the deck and the sidewalk. 

Though mainly at the center span, water 

and road salts could reach the steel members 

and turned out to be one of the primary 

contributing factors to the steel’s corrosion 

issues. The new deck extends below the 

sidewalk to prevent water from entering 

the bridge.

The existing bascule span had exterior 

fascia girders with floor beams holding up 

the structure. To replace it while minimizing 

impacts to bridge traffic, the project team 

created a working platform atop the water 

using a specially designed “jack-up barge” 

of 22 “flexi-floats” with shoring towers 

supported by pipe pile. The barge and 

shoring towers supported the floor beams 

on the bascule span, enabling workers to 

cut the bascule span in half while live traffic 

drove overhead.

The construction replaced the existing 

concrete deck using accelerated bridge 

construction techniques with more than 

450 full-depth precast concrete deck panels. 

The use of precast concrete enabled the deck 

to be assembled in a controlled environ

ment, rather than cast in place at the project 

site, where additional variables—from air 

temperature, humidity, precipitation, and 

evaporation to materials delayed by periodic 

traffic congestion—could have resulted in 

considerable delays and increased costs. The 

offsite production meant that the precast 

deck panels could be constructed and 

stored until needed onsite. This led to more 

control of the schedule, reducing weather 

and supplier impacts and unanticipated 

cold joints. The project used stainless steel 

reinforcing in the precast deck panels to 

further improve quality, which significantly 

reduced concerns of possible corrosion in 

steel reinforcements.

-

The rehabilitation project considered historic 

architectural details, like the decorative 

fascia shown being removed here, to be 

important features to preserve and restore. 

Source: FHWA.

The project team used floating barges to help with the rehabilitation. 

Here, the underside of the replaced bascule span is visible. 

Source: FHWA.
Preserving Historic Elements

NPS and FHWA committed to preserving 

as much of the structure’s unique design 

elements as possible while incorporating 

engineering and construction materials and 

methods that would extend the life of the 

bridge. To maintain the original look of 

the bascule span/drawbridge, the project 

used a fixed span bridge with 216-footlong (65.8-meter-long), 170,000-pound 

(77,000-kilogram) high-performance steel 

plate girders, along with 70 kilopound 

per square inch (ksi) (480 megapascal) 

bottom flanges and 50 ksi (340 megapascal) 

top flanges.

“The Arlington Memorial Bridge project 

highlights the exceptional work National 

Park Service and Federal Highway Admin

istration staff accomplished together,” says 

Charles Cuvelier, superintendent of the 

George Washington Memorial Parkway, 

which connects to the bridge. “Our collab

oration helped protect this iconic memorial 

and ensure it will continue to serve as a 

reminder of the sacrifices of our Nation’s 

veterans and as a symbolic link between the 

north and the south for decades to come.”

-

-

Once installed, the fitted trusses under

neath the girders recreated the original shape 

of the historic bascule span/drawbridge. 

Additionally, NPS considered the original 

pop-up protective bollards on the bascule 

span/drawbridge to be a historic element 

of the bridge and developed a design to 

preserve the posts in place.

-

Throughout construction, NPS and 

FHWA took special care to protect the 

bridge’s historic architecture and enhance 

its iconic appearance. Since work began 

in 2018, workers methodically removed, 

cleaned, repaired, and reinstalled more than 

4,500 pieces of granite and rehabilitated the 

bridge’s historic structure.

“The partnership between FHWA and 

NPS was key to the success of this project,” 

says FHWA’s lead structural engineer 

George Choubah. “Everyone on the team 

worked very hard to make sure that the fastpaced design and construction schedules 

were met without jeopardizing the quality 

of the final product.”

In addition to upgrading this historic 

bridge to contemporary standards, and 

restoring its role as an integral part of the 

efficient flow of traffic in the Nation’s 

Capital for decades to come, the rehabil

itation of the Arlington Memorial Bridge 

has given new life to the most prominent of 

entrances to the District of Columbia.

-

Working with NPS, FHWA tackled 

an urgent and complicated infrastructure 

challenge head-on. The project succeeded 

in rehabilitating the national Capital's 

ceremonial entrance and preserving its 

historic character for future generations.

ALEXANDER (SANDY) SINCLAIR is a public affairs 

specialist in FHWA’s Office of Public Affairs, 

where he helps promote the agency’s multifac

eted agenda to the media, stakeholders, and 

FHWA employees. With the Department since 

1999, Sinclair graduated from the University of 

California-Los Angeles with a bachelor’s degree in 

political science.

-

For more information, see www.nps.gov

/gwmp/learn/management/amb

-rehabilitation.htm.

The project used precast concrete 

bridge deck panels to shorten 

construction time and minimize 

future maintenance needs. 

Source: FHWA.

The rehabilitation project replaced the bascule span, which had not been 

used since 1961, while maintaining the bridge’s historic look. 

Source: FHWA.

WWW.FHWA.DOT.GOV | 31
32 | PUBLIC ROADS | AUTUMN 2021

ALONG THE ROAD

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.

Public Information and Information Exchange

FHWA’s MATCH program offers mentoring to local and 

Tribal agencies to improve roadway safety.

Source: FHWA.

FHWA Launches MATCH for Local and Tribal Agencies

The Federal Highway Administration recently launched the Mentoring, Assistance, Training, and Communication Help 

(MATCH) program to provide broad-based technical assistance 

to local and Tribal agencies facing roadway safety challenges. The 

program connects agencies requesting assistance (mentees) with 

peer mentors who have specific expertise to help successfully 

address the identified challenges. The technical assistance is free for 

mentees, and mentors volunteer their time to help peers.

Local and Tribal agencies own and operate approximately 75 

percent of the Nation’s roadway network, much of which is in 

rural areas. These agencies often face unique safety challenges on 

their roads involving roadway departures, intersection safety, speed 

management, and pedestrian and bicyclist safety. The MATCH 

program will augment FHWA efforts and support local and Tribal 

road practitioners with integrating safety into their roadway 

programs. The program leverages the mentor’s knowledge and 

experience to provide short-term technical assistance to local and 

Tribal agencies wanting to resolve safety or safety-related concerns 

or issues. Mentors will assist in identifying the problem and 

recommend appropriate implementation strategies when paired 

with mentees. This enables mentee agencies to benefit from this 

knowledge to potentially save lives and reduce serious injuries 

on roadways.

All local and Tribal agencies are eligible to apply for tech

nical assistance from a mentor through the MATCH program. 

Public agency transportation safety professionals and those from 

centers of learning who have specific expertise related to local or 

Tribal road safety can serve as mentors. Mentors must be actively 

employed by or retired from a public transportation agency and 

have a minimum of 5 years of continuous transportation safety 

experience. Both mentors and mentees will be required to produce 

a short report once the activity is completed to document and 

share noteworthy practices.

-

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

/local_rural/MATCH or contact Rosemarie Anderson at 

rosemarie.anderson@dot.gov.

USDOT Announces Expanded Workforce Pilot Programs

I

n May, U.S. Transportation Secretary Pete Buttigieg announced 

expanded construction hiring and workforce development 

pilot programs to be managed by FHWA and the Federal Transit 

Administration. Buttigieg made the announcement at an event 

at the construction site of the new Frederick Douglass Memorial 
WWW.FHWA.DOT.GOV | 33

Bridge, where he joined Wash

ington, DC, Mayor Muriel Bowser; 

the director of the District Depart

ment of Transportation; and other 

Federal and local leaders. The bridge 

replacement project is the largest 

public works project in DC history 

and is tentatively scheduled to open 

in fall 2021.

-

-

Both FHWA’s and FTA’s 

programs will give contracting agen

cies expanded flexibility to use hiring 

preferences to enhance workforce 

development opportunities for those 

in economically or socially disad

vantaged communities. A similar 

USDOT pilot program was in effect 

from 2015 to 2017. The local hire 

initiatives will improve participation 

in existing training and appren

ticeship programs, such as FHWA’s 

on-the-job training programs.

-

-

-

FHWA’s Enhancing Work

force Development Opportunities 

Contracting Initiative will help to 

rebuild the skilled workforce needed 

to improve the Nation’s transpor

tation infrastructure. The 4-year 

pilot program will enable State 

transportation agencies and contractors to better recruit qualified 

construction workers, which can be challenging in many parts of 

the country.

-

-

For more information on FHWA’s pilot program, visit www.fhwa

.dot.gov/construction/workforcedevelopment. For more information on 

the bridge project, visit www.newfrederickdouglassbridge.com.

The new Frederick Douglass 

Memorial Bridge in Washington, 

DC, is the city’s largest ever 

public works project.

© Tony Quinn / Shutterstock.com.

NHTSA Launches Recall Dashboard

I

n July, the National Highway Traffic Safety Administration 

unveiled a new cloud-based recall dashboard to make searching 

for auto safety recall data easy and efficient. The dashboard offers 

user-friendly and transparent ways to sort, filter, visualize, and 

export recall data.

NHTSA’s interactive dashboard provides improved access to vehicle recall information.

Source: NHTSA.

The dashboard, available at https://datahub.transportation.gov 

/dataset/NHTSA-Recalls-by-Manufacturer/mu99-t4jn, will be updated 

daily. It enables users to sort and filter data; search by keyword; 

and export data in CSV, TSV for Excel, XML, and other formats. 

It also presents data in easy-to-read charts and graphs.

Previously, NHTSA made its recall data available through a 

bulk download, requiring users to download large data files and 

import them into a database like Microsoft Access. The new dash

board makes this information easier to access and analyze.

-

NHTSA encourages everyone to search for open recalls by 

using NHTSA’s VIN Look-Up Tool (www.nhtsa.gov/recalls) and to 

download the SaferCar app (www.nhtsa.gov/campaign/safercar-app) 

to stay informed on current recalls. Make sure to promptly address 

any open recalls.

Arizona DOT Works to Preserve Rare Cactus

The Arizona Department of Transportation (ADOT) is helping to relocate a rare and endangered species of cactus growing near 

the Pinto Creek bridge replacement project along U.S. 60 near 

Globe-Miami. The project is expected to wrap up in 2022.

Initiated in 2018, this relocation effort is the latest step in a 

long-term partnership between ADOT and the Desert Botanical 

Garden in Phoenix, AZ, to protect the hedgehog cactuses that only 

grow in one tiny area of the State.

ADOT is helping to preserve the endangered hedgehog cactus.

© Arizona DOT.

The rescue effort required botanists to rappel into the canyon 

and carefully dig up, cover, and transport the plants to the botan

ical garden’s complex in Phoenix. There, the botanists will care 

for the cactuses and breed them so there are more of them when 

returned to the Pinto Creek Bridge site in a few years.

-

In June, a wildfire burned the area near the Pinto Creek bridge 

project. The project itself was undamaged, but many cacti were 

burned in the fire. ADOT’s partnership with the Desert Botanical 

Garden to rescue, preserve, and propagate more of the cacti at 

the garden in Phoenix will help ensure the continued survival of 

the species.

Visit https://azdot.gov/adot-blog/redoing-bridge-saving-endangered 

-cactus-pinto-creek for more information.

ADOT
34 | PUBLIC ROADS | AUTUMN 2021

Technical News

INDOT Partners with Purdue to Develop 

Innovative Highway Infrastructure

The Indiana Department of Transportation (INDOT) and Purdue University recently announced plans to develop the 

world’s first highway segment paved with contactless wirelesscharging concrete. The project will use innovative magnetizable 

concrete, developed by a German startup, that enables wireless 

charging of electric vehicles as they drive.

Indiana is working to develop an innovative highway that can 

wirelessly charge electric vehicles that drive on it.

© Isamare / Shutterstock.com.

The project is part of the Advancing Sustainability through 

Power Infrastructure for Road Electrification (ASPIRE) initiative, 

an Engineering Research Center funded by the National Science 

Foundation, and involves the collaboration of universities, govern

ment laboratories, businesses, and other stakeholders developing 

next-generation charging technologies for the electrification of 

transportation vehicles of all classes.

-

The project will include three phases. Phases 1 and 2 will 

feature pavement testing, analysis, and optimization research 

conducted by the Joint Transportation Research Program at 

Purdue’s West Lafayette campus. In phase 3, INDOT will 

construct a quarter-mile-long testbed at a location yet to be 

determined, where engineers will test the innovative concrete’s 

capacity to charge heavy trucks operating at high power (200 

kilowatts and above). Upon the successful completion of testing 

of all three phases, INDOT will use the new technology to 

electrify a yet-to-be-determined segment of interstate highway 

within Indiana.

INDOT

NCDOT Pilots New Commercial Trucking Alert System

The North Carolina Department of Transportation (NCDOT) is taking a novel approach to reducing the risk of commer

cial truck crashes to help keep work zones and highways flowing 

smoothly. The department is partnering with a Canada-based 

company that provides innovative connected-truck technology, 

including in-cab communications. The in-truck messaging 

provides real-time alerts of urgent road conditions. The alerts will 

help commercial drivers react more quickly before encountering 

stopped traffic or major slowdowns.

-

“We want drivers to have every tool and technological 

advancement necessary to reach their destination safely and 

efficiently,” says Beau Memory, NCDOT’s chief operating officer. 

“This collaboration demonstrates our commitment to driver 

safety with technology that could become an invaluable tool 

for transportation.”

The first-in-the-Nation pilot covers all 182 miles (293 kilo

meters) of I–95 and the rural portions of I–40. The safety alerts 

under the pilot can reach commercial drivers even where there are 

no digital signs to provide traffic updates. The alerts have messages 

such as “Sudden Slowdown Ahead” and “Congestion Ahead” 

about 2 or 3 miles (3 to 5 kilometers) before commercial truck 

drivers encounter the slowed traffic or incident.

-

Big rigs need more time to slow down, and crashes involving 

tractor-trailers can close highways for extended periods and 

contribute to secondary crashes, such as rear-end collisions. A 

fully loaded tractor-trailer traveling at 65 miles (105 kilometers) 

per hour takes 66 percent longer to stop than a passenger car, 

according to the trucking industry.

The 1-year contract to employ the alerts began on May 17, 

2021. After the pilot period, NCDOT will evaluate the safety 

benefits of the pilot.

NCDOT

A pilot program in North Carolina is exploring in-cab alert messaging 

to provide traffic updates to commercial truck drivers.

© Vitpho / Shutterstock.com.

ALONG THE ROAD
WWW.FHWA.DOT.GOV | 35

TRAINING UPDATE

Source: FHWA.

Scaling Probabilistic Risk-Based 

Estimating to Project Size

by GAY DUGAN and CHRISTINE KEMKER

How much is an accurate cost and schedule estimate worth? Accurately estimating project cost has been a challenge for 

decades. The National Highway Institute’s new eBook training, 

Probabilistic Risk-Based Estimating (PRBE) for Highway Project Cost 

and Schedule (FHWA-NHI-134205), aims to provide participants 

with the knowledge and tools needed address this challenge. This 

self-paced training introduces fundamental concepts and recom

mended processes to successfully implement PRBE procedures 

within any organization.

-

The PRBE process, which can help reduce cost overruns, is an 

evolution from traditional project estimates that rely on historical 

data from similar projects. Instead, PRBE provides a framework to 

assess project risks to cost and schedule objectives. This provides 

agencies more certainty in funding projects and setting completion 

dates. Although FHWA and several States are successfully imple

menting PRBE, this course is the first time the PRBE concepts and 

process have been put into a training format.

-

“Project estimates often have a lot of uncertainty, especially in 

the early stages of project development,” says Michael Smith, a 

project management engineer in FHWA’s Resource Center in the 

Office of Innovation Implementation. “PRBE is a process that 

exposes areas of uncertainty and provides the project manager a 

reliability-based estimate of cost and schedule completion while 

identifying significant project risks.”

For States that use an enterprise risk management framework, 

PRBE can be another tool for implementing risk management. It 

applies the risk framework at the project level to cost estimates. 

With an appropriate level of effort, scaled to the size and 

complexity of the project, State and local agencies can benefit from 

the application of the PRBE process.

In addition to achieving improved reliability, users will benefit 

from earlier understanding of the project and its associated risks; 

enhanced ability to set achievable budgets and schedules; better 

control of costs to optimize budgets; more useful, credible ways to 

manage budgets and communicate risks to the public and stake

holders; and enhanced collaboration to achieve project objectives.

-

“The objective of this eBook course is to provide awareness 

of PRBE,” says Smith. “Our goal is to give State departments of 

transportation the knowledge and tools they need to implement 

the PRBE process, to be able to deliver more projects within 

budget and on time.”

NHI’s new eBook training course is a self-paced, interactive 

PDF that learners can download on any device to study.

Source: FHWA.

What is an eBook training?

An NHI first, this eBook training is designed to be both inter

active and independent. The course is built as an interactive 

PDF, with expandable graphics, check-in questions that provide 

feedback, job-related questions, terminology popups, and a case 

study embedded throughout. Learners can take notes and answer 

questions directly in the PDF. It also remains a resource reference 

after the training is complete.

-

As an eBook, this training can be downloaded and taken at the 

learner’s leisure, minimizing disruption to regular work schedules. 

Once downloaded, it can be accessed from any device, and all the 

interactive features are present even if the device is not connected 

to the internet. Learners only need to log back into NHI’s My 

Training site to take the exam after reading the eBook.

Taking the Course

The course can be found at https://bit.ly/NHI_134205 and it costs 

$50 to register and download the eBook. This eBook is an 

intermediate-level course. Transportation professionals inter

ested in this PRBE training should have some familiarity with 

the American Association of State Highway and Transportation 

Officials’ Practical Guide for Cost Estimation or experience with cost 

estimation, project management, and/or risk management. NHI 

estimates that reading the eBook will take 10 hours of active study 

time. Participants who successfully complete the course will earn 

one continuing education credit.

-

What’s next?

Starting next year, FHWA will offer free onsite PRBE training that 

includes an application tool to implement the process. Interested 

participants should reach out to their local FHWA division office 

for more information after passing this eBook training.

GAY DUGAN is the training program manager for this course with the FHWA 

Office of Innovation Management, Education, and Partnership - NHI.

CHRISTINE KEMKER is a contracted marketing analyst for FHWA NHI.
36 | PUBLIC ROADS | AUTUMN 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/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).

Developing Crash Modification Factors for Adaptive 

Signal Control Technologies 

Publication Number: FHWA-HRT-20-072 (Report) and 

FHWA-HRT-20-073 (TechBrief)

Adaptive signal control technologies (ASCTs)—using traffic sensor 

systems to measure traffic conditions in a corridor—can alter 

traffic signal timing in real time. They enable a better distribution 

of signal green time that reduces delay and traffic congestion. 

Research has found that ASCTs reduce fuel consumption, emis

sions, and air pollution; prioritize public transport and emergency 

vehicles; and improve accommodation of roadwork and special 

events traffic.

-

As part of FHWA’s Development of Crash Modification Factors 

Program, members of the technical advisory committee for the 

Evaluations of Low-Cost Safety Improvements Pooled Fund Study 

conducted a project evaluating the safety effectiveness of ASCTs 

at urban intersections. This 

study looked at how the 

implementation of ASCTs 

impacted safety improve

ments through a crash-based 

evaluation. For this study, 

the researchers collected and 

analyzed crash data for traffic 

intersections with ASCT 

installations from three 

States: Florida, Texas, and 

Virginia. The project team 

also conducted an economic 

cost/benefit analysis of 

installing ASCTs at traffic 

intersections in those 

three States.

-

The report is available at 

www.fhwa.dot.gov/publications/research/safety/20072/20072.pdf. 

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

/safety/20073/index.cfm. 

Effective Indicators of Partially Automated Truck Platooning 

Publication Number: FHWA-HRT-21-016

 As automated trucking tec

nology continues to develop 

rapidly, full-scale commercial 

deployment of partially auto

mated truck platoons (two 

to four cooperative adaptive 

cruise control-equipped 

trucks that follow each 

other closely over long trips) 

on public roads is on the 

horizon. Establishing positive 

interactions between these 

truck platoons and other 

vehicles is crucial to the 

continuing implementation 

of automated driving tech

nologies. To help facilitate 

these safe interactions and 

increase road user understanding of truck platooning operations, a 

team of researchers conducted experiments for developing effective 

novel signage on roadways.

-

-

-

The project team conducted two experiments. The first exper

iment surveyed a group of drivers’ feelings toward, and behavior 

around, trucks (conventionally driven and partially automated) 

on the road. They also surveyed how certain novel signs might 

-
WWW.FHWA.DOT.GOV | 37

influence these drivers’ feelings and behavior. The second exper

iment had a different group of participants examine and answer 

questions related to scenarios with two truck platoons, evaluating 

how novel signs could impact these participants’ judgment around 

platoons on roadways.

-

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

/research/safety/21016/index.cfm.

Statistical Analysis of Pavement Profiler Data to 

Evaluate the Bump at the End of the Bridge 

Publication Number: FHWA-HRT-21-037

The bump at the end of 

the bridge (BEB) remains 

a chronic problem for the 

Nation’s roadway bridges. 

Occurring at the point of 

transition onto and off 

the bridge deck, the BEB 

can cause many problems, 

including user discomfort 

and safety concerns, vehicle 

damage, and increased 

maintenance. The occur

rence of the BEB is often 

related to bridge and 

approach roadway design 

and construction processes, 

but factors like pavement 

or deck roughness at bridge 

approaches are often not quantified.

-

This study aimed to quantify the magnitude and roughness 

of the BEB on various bridges throughout the United States by 

evaluating results collected from high-speed inertial profilers. The 

researchers also employed statistical analysis of these BEB data to 

analyze the effects of different site and bridge characteristics on the 

magnitude and roughness of the BEB.

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

/infrastructure/structures/bridge/21037/index.cfm.

Long-Term Pavement Performance Information 

Management System User Guide 

Publication Number: FHWA-HRT-21-038

Existing for more than three decades, FHWA’s Long Term Pave

ment Performance (LTPP) program has become an important 

database for pavement performance research.

-

This document provides an overview of the LTPP’s Information 

Management System (IMS). It gives an overview of the three main 

parts of the IMS: products 

(for example, research find

ings and new software tools), 

the Pavement Performance 

Database, and the Ancillary 

Information Management 

System. The various database 

modules for specific types of 

data tables are also outlined, 

including administration, 

automated weather station, 

climate, and Modern-Era 

Retrospective Analysis for 

Research and Applications 

(MERRA) modules.

-

The report is available at 

www.fhwa.dot.gov/publications

/research/infrastructure/pavements/21038/index.cfm.

Developing Analysis, Modeling, and Simulation Tools for 

Connected and Automated Vehicle Applications: A Case Study 

for I–66 in Virginia 

Publication Number: FHWA-HRT-21-050

FHWA continues to support 

research related to connected 

and automated vehicles 

(CAVs), sponsoring three 

case studies examining the 

impact of CAVs on traffic 

and energy, and the appli

cations of CAV and traffic 

management strategies on 

various freeway and arterial 

corridors. In this case study, 

the researchers investi

gated the effectiveness of 

certain CAV applications 

(platooning, speed harmo

nization, and cooperative 

merge) in mitigating traffic 

congestion. The research 

team used roadway simulations on a 13-mile (21-kilometer) strip 

of I–66 in northern Virginia. The project team also looked at the 

potential benefits of dedicated ramps and a realistic managedlane concept.

-

-

-

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

/operations/21050/21050.pdf.
FHWA’s TRANSPORTATION 

POOLED FUND PROGRAM

Leveraging resources to achieve common research goals

The Transportation Pooled Fund (TPF) Program 

enables public and private entities to combine 

resources to conduct high priority research 

on a wide variety of shared, highway related 

problems. Over more than 20 years, the 

TPF Program has supported more than 750 

successful multi-State projects.

Leverage Expertise 

Across the Country

By participating on the technical advisory 

committees of TPF studies, partners are able 

to form connections with peers in other States 

to share subject matter expertise across 

the country.

© Colorado Department of Transportation.

Participate in Diverse 

Research and Topic Areas

Investing in TPF studies helps partners stretch 

their research dollars to support a diverse array 

of topic areas.

Make an Impact Through 

a TPF Study!

The TPF Program is a great resource to 

leverage limited funds to address important 

transportation issues. Learn more about 

initiating a pooled fund study and browse 

the list of open solicitations on the TPF 

website at www.pooledfund.org.

For more information, contact Tricia 

Sergeson, TPF Program Manager, at 

Patricia.Sergeson@dot.gov.

Source: FHWA.

© 2011-2021 National Cooperative Highway Research Program.
Introducing the 

Building Information Modeling 

(BIM) for Infrastructure 

© Stockr / Shutterstock.com

National Strategic Roadmap

The BIM for Infrastructure National Strategic Roadmap is a 

framework and path to help highway agencies strategically develop:

• A uniform, nationwide policy related to BIM for Infrastructure

• Open data exchange standards and methods for adopting those standards

• A robust personnel training program

Using the roadmap, FHWA proposes to collaborate on 

a shared vision, goal, and objective for BIM:

• The vision is to digitalize project delivery, operations, and maintenance 

for the Nation’s highway infrastructure and make information 

available to anyone who needs it, when they need it.

• The goal is for State departments of transportation 

to adopt BIM for Infrastructure practices.

• The objective is for FHWA and State DOTs to develop 

and implement a set of activities to incentivize achieving 

progressively higher degrees of BIM maturity over time.

Pooled fund TPF-5(480) provides an opportunity 

for collaboration on BIM Roadmap activities 

and is still open for additional participants.

For more information, visit www.fhwa.dot.gov/publications

/research/infrastructure/pavements/21064/index.cfm.

Source: FHWA.
40 | PUBLIC ROADS | AUTUMN 2021

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