It is a familiar situation 

that likely all drivers have 

experienced. To the driver, 

it is that anxious feeling, a 

quick decision to make in 

higher speed traffic. 

To U.S. Department of 

Transportation (DOT) 

researchers and engineers, 

it has a technical term: 

the dilemma zone (DZ). 

Small Business Innovation Research

SBIR SuccessSTORY

The Dilemma Zone

June 2022

Source: FHWA

Figure 1. Photograph. Intelligent transportation system at intersecting roadways. 

Funding Research To Create 

New Opportunities

The DZ phenomenon is described 

as the moment when drivers 

face a predicament as a stoplight 

suddenly turns yellow, requiring 

either an abrupt stop or a rapid 

acceleration through the 

intersection. This situation is 

dangerous because a vehicle may 

have neither adequate braking 

distance to safely stop nor 

sufficient time to safely proceed 

through the intersection before 

the light turns red. As such, 

this aptly named scenario has 

caused high-speed rear-end and 

side-impact crashes at lighted 

intersections. However, in the last 

5 yr, an SBIR-funded technology 

has helped make progress through 

a combination of technologies to 

alert drivers in advance of being 

caught in a DZ. 

Intelligent Automation, Inc. (IAI) 

won both phase I and II SBIR 

awards (2014–2017) to find 

solutions to the DZ problem. 

The project’s goal was to create, 

develop, and implement a 

multitechnological approach 

to warn drivers of the DZ, by 

integrating both infrastructure 

and onboard warning systems. 

A few important technologies used 

in these systems included artificial 

intelligence (AI); dedicated 

short-range communications 

(DSRC), which is a short-range 

wireless communications system 

specifically designed to connect 

vehicles to each other and to the 

infrastructure; and a detection, 

control, and warning system 

(DCWS) that uses collected data 

to determine travel time (versus 

more conventional methods that 

use fixed areas). Furthermore, 

IAI had an existing technology 

it developed that focused on 

increasing dilemma zone safety

using Intelligent Transportation 
SBIR SuccessSTORY June 2022

 2 

Systems (ITS). This system 

accurately identifies vehicles in 

the DZ based on the time it would 

take each vehicle to stop once a 

yellow light appears. Using 

sensors, the system identifies each 

vehicle’s size, speed, and location 

to estimate the time needed to 

reach the intersection. When the 

two-part system determines that a 

vehicle will be trapped in the DZ

at the onset of a yellow light, it 

uses advanced signal control 

protocols to adjust light phases 

and prevent DZ situations. 

Infusion To Bring New 

Intelligence Capabilities

Because of the integrated warning 

system, when drivers are 

approaching or encountering the 

DZ, roadside flashers are activated, 

alerting them to slow down and 

stop safely. Ultimately, when the 

AI detects a car or truck (which 

have different braking distances), 

the AI will check its database for

the vehicle type and its weight and

length. Then, the AI determines the 

braking distance of the vehicle. In 

addition, the AI will factor in what 

the weather conditions have been 

to help calculate braking distance. 

(For example, if it has recently 

rained, the wet pavement will 

affect braking distance times as

the moisture reduces the friction 

and traction. The tires will have 

less grip, which then requires a 

greater braking distance.) Based on 

all these collective data, the AI will 

then send a signal to the sensors at 

precisely the right time to activate 

the flashers at the signal light. 

Promising Results in Early 

Stages of Development

IAI worked with the Delaware 

Department of Transportation 

(DelDOT) to test this technology 

at two strategically selected 

intersections. Over 3 yr 

(2015–2018), the IAI team 

collected data and observed some 

informal patterns. Dr. Peter Huang, 

the contracting officer for this 

SBIR, said that the technology is 

showing promising results and 

likely improving safety at these 

intersections. However, he said 

that it is important to note that 

“there are not any real percentages 

to point to yet because it takes a 

few more years to gather and 

analyze data. It normally takes 

about 5 yr of data before and

after the technology has been 

implemented to determine any 

patterns or decreases in crashes.” 

At the completion of the SBIR 

phase II, IAI wanted to continue 

to work with Federal Highway 

Administration (FHWA) and 

DelDOT to implement this 

technology at 10 additional 

intersections. In addition, IAI 

planned to make improvements 

to its DCWS system to make it 

more advanced. By doing so, IAI 

Source: FHWA.

Figure 2. Photograph. Intersection of four two-lane roadways. 
SBIR SuccessSTORY June 2022

 3 

committed to integrating the 

DCWS technology with signal 

controllers already on the market 

to make DZ protection become a 

basic safety feature for traffic 

signal-controlled intersections. 

Another key success of this 

technology is that DelDOT 

decided to use State funds to 

continue improving the technology 

and to implement it in those 10 

intersections. The willingness of 

DelDOT to keep investing its

own funds, to continue the tests 

and research activities, and to 

upgrade the systems shows that 

there is real promise to this 

approach and that IAI’s 

innovations are opening new 

doors for intersection safety that 

will only grow as the adoption 

of its technology becomes more 

widespread. Since the significant 

findings of the improved AI 

technology, DelDOT is planning 

to continue to make improvements 

and to deploy the technology 

even further: In 2019 DelDOT 

received a $5 million grant through 

FHWA’s Advanced Transportation 

and Congestion Management 

Technologies Deployment 

Program, to which DelDOT is 

adding $5 million of its own 

funding, for a total investment 

of $10 million. 

Furthermore, this technology has 

significant value because it will 

support connected and automated 

vehicles (CAVs) in the future. 

Currently, CAVs do not have 

this technology and will need it 

to safely communicate to drivers 

in the vehicle. However, in the 

future, this technology can be 

easily integrated into automated 

cars with DSRC wireless 

communications. When asked 

how to make other State DOTs 

aware of this game-changing 

technology, Huang said that it can 

be a challenge but external reports, 

publications, and conferences are 

vital to ensuring State DOTs 

remain aware of these innovations. 

However, Dr. Huang continues 

to highlight the promise these 

innovations offer by presenting at 

the Transportation Research Board 

annual meeting in recent years 

and by authoring several articles 

about this technology that have 

been published online and in 

technical journals. 

State Funding Fosters 

Future Innovation

In the future, these systems 

can be integrated into the 

vehicle-to-infrastructure 

communication environment 

that the Federal Government is 

developing in coordination with 

State DOTs, private industry, 

and international partners. This 

DZ system should have significant 

advantage in making use of CAV

infrastructure and technology as 

the research and use of connected 

vehicles continues. In the 

meantime, “...DelDOT plans 

to deploy these AI technologies, 

as well as other promising 

solutions, across the State in an 

effort to create a truly innovative, 

next-generation approach to traffic 

management that uses smart 

sensors and AI to provide the 

most efficient and safe operations 

of our highway network,” said

Dr. Huang. 

Digital Object Identifier (DOI): 

https://doi.org/10.21949/1521913

HRTM-10/06-22(WEB)E 

FHWA-HRT-22-084

“It normally takes about 5 yr of data before and after 

the technology has been implemented to determine 

any patterns or decreases in crashes.”

—Dr. Peter Huang

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