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By James R. Helmer, P.E., T.E., PTOE, Gordon Meth, P.E., PTOE, PTP, and Seth D. Young, P.E., PTOE
ow can we make traffic signals “future-proof?” What can we do to minimize the
amount of the investment that has to be scrapped as components become obsolete;
and how can we build them so they are more easily modified to accommodate new
features for all road users?
As you plan, design, or construct a transportation project, do you ever ask yourself: Will
this project even exist in ten, twenty, or fifty years?
The response to that question is the key issue being explored by the ITE Sustainable
Traffic Signal Development (STSD) Committee. The purpose of this article is two-fold; first to
share the work of the committee and its presentation made at the 2014 ITE Annual Meeting
and Exhibit in Seattle, WA, USA, and second, to seek feedback on your agency’s or company’s use of sustainable principles, design, construction methods, materials, innovation, and
technology in stages of signal development.
Traffic signals have a long history dating
back to the 19th century. The reasons for
their installation and their designs have
gone through many changes. History
shows the first traffic signal using colored
lights was installed in London, England
at the intersection of Bridge and George
Streets.1 The pole was approximately 22
feet in height (7 meters), with mechanical
semaphore arms indicating “stop” when
extended horizontally or “caution” when
lowered to a 45-degree angle. The pole
contained a gas night light on top to help
identify it after darkness, and the semaphore arms were equipped with colored gas
lights—red for stop, and green for caution.
After testing, the installation was approved
by the English Parliament, because it
proved superior to the prior method of
police (cornermen) blowing whistles and
moving their arms and hands to control
horse traffic and people crossing on foot.
Early efforts of manually and mechanically controlling traffic in the United
States also proved unsustainable, as police
officers fought the weather elements and
risked injury. Figures 1 and 2 show early
attempts of U.S. police traffic control. The
installation of what is believed to be the first
electric traffic signal in the United States in
Cleveland, OH, just celebrated its 100-year
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birthday in 2014.2 However, this signal and
other early 20th century installations did
not last but a few years in most cases.
Even traffic signals built just 50 years
ago, if they still exist, likely contain few of
their original parts. For example, pedestrian
head indications have gone from green and
red neon walk-wait messages, to incandescent bulbs utilizing white and orange
messages, and now to light-emitting diode
(LED) panels with numeric countdowns.
Traffic Signals—A Look Forward
Installing traffic signals today involves
a very complex, time-consuming, and
expensive process. Signals have always
had the primary purpose of getting people
safely through an intersection, whether on
horse or foot, riding a bicycle, or driving a
vehicle. Often though, signal installations
are accompanied by public controversy
Institute of Transportation Engineers
Traffic Signals—A Look Back
The only remaining original part might be
the housing. While the purpose for installing the pedestrian signal has not changed,
technology advancements, human factors
testing, and energy efficiency continue to
improve, and thus upgrades are regularly
performed and old parts discarded.
Today, the traffic signal still performs the
same basic function of allocating right of way
and providing safety for all users at intersections, but engineers and maintenance teams
are constantly retrofitting and upgrading the
original components. Because traffic signals
are expensive to design, install, and operate,
we should make every reasonable effort to
ensure each has a long service life.
Figure 1. Woman police officer in Washington,
DC, USA directing traffic under a hand-rotated
umbrella with stop-go signs on top, circa 1918.
Figure 2. Detroit, Michigan traffic towers or
“crows nests.” The “stop” and “go” instructions
were supplemented by red and green
illuminations, circa World War I.
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and high emotions if their installation was
due to a history of tragic incidents. Every
intersection is unique as is the make-up
of the users. This is why detailed attention
must be given to the traffic mix, prevailing
speeds, geography, building setbacks, street
and sidewalk widths, visibility obstructions,
transit stops, and more.
Besides the more common parameters that influence a signal design, there
are many new considerations that need
due diligence that were not a factor a few
decades ago. These issues include, but
are not limited to, municipal policies on
sustainable procurement, changes in energy
supply from alternating current to direct
current, vehicle-to-vehicle communications,
and self-driving cars. In looking at some
examples of sustainable signal development
currently being applied, the committee
hopes to raise interest and questions about
how our profession of signal planners,
designers, builders, and operators will
respond to a rapidly changing transportation system and smart car development.
The committee divided its research of
the traffic signal development process into
the key focal areas that have a direct effect
on the ultimate installation and operation of
a traffic signal: Policies, Planning, Design,
and Construction. Within each of these
areas, examples of sustainable practices and
innovation were explored.
Policies and Planning
Traffic signals are generally the responsibility of public agencies, and before one is
considered for installation, it must meet
the policy requirements and follow the
necessary planning procedures established
by that agency. The policy and planning
requirements are the initial steps to the
development of a traffic signal, yet the establishment of these requirements is often the
result of issues encountered in the design,
construction, operation, or maintenance of
past signal installations. The proliferation
of innovation and technology also leads to
the adoption of new policies and planning
processes. The committee seeks to include
several examples of sustainable policies and
planning procedures in the information
report in order to inform and inspire agencies to adopt similar practices.
Sustainable traffic signal policies and
directives are requirements an agency may
have in place to ensure all traffic signals
installed are safe, energy efficient, and accessible to all potential users. These documents
can take the form of general plans, master
transportation plans, bicycle and pedestrian
plans, accessibility guidelines, directives,
and signal timing and phasing policies.
Looking back, in the September 1927
Annals of the American Academy of Political
and Social Science, Burton Marsh noted the
following observation: “In brief, an officer
while working at his best can use brain
power for the handling of traffic at that
corner, and brain power efficiently used, is
of course, usually better than mechanical
control for a single corner.”1 However, with
the rapid growth of vehicle ownership in
the USA, 8,000 in 1900 to about 8 million
in 1920, cities were being challenged to
provide police staffing at a fast growing
number of intersections requiring control.1
The police commissioner of New York City
realized that police traffic control would not
be a sustainable practice with such growth,
and thus enacted a policy to transition to
mechanically controlled signals for intersections. By the late 1920s, New York City had
grown to approximately 3,000 mechanically
controlled intersections at an annual cost of
$1,000,000 USD. The same number of intersections would have required 6,000 police
officers at an annual cost of $15,000,000.1,3
Through research and with the help of
ITE members and affiliates, the committee
has discovered several current, forward
thinking examples of sustainable traffic
signal policies. An example of a general plan
containing sustainable traffic signal recom-
About the
Formed in early 2013, the
ITE Sustainable Traffic Signal
Development (STSD) Committee
represents a wide range of experts,
comprised of engineers, planners,
controller and equipment suppliers,
lighting experts, accessibility
advocates, and other disciplines.
The committee first established its
Mission Statement:
To create and produce an information
report for the Institute of Transportation
Engineers that explores the most
common practices and activities that led
up to the operation of traffic signals, and
to identify ways to plan, design, and build
them in a more sustainable manner.
Initially, because there were
widespread views on what an STSD
was, the committee next established
the following definition:
A sustainable traffic signal development
is one that is planned for, designed,
and constructed in such ways that
when operational it serves all users,
operators, and other stakeholders in a
safe, efficient, accessible, equitable, and
informative way, without compromising
the needs of future generations
With its mission and STSD definition
in place, the committee began the
work of researching, surveying, and
interviewing those involved in four
developmental stages of traffic signal
installations: policies, planning, design,
and construction. In each of these
stages the committee’s objective was
to identify sustainable and innovative
practices resulting in longer lasting and
less impacting signals that better met
the needs of all users. The committee
appreciates receiving information
about STSD from ITE members and
affiliates to help it achieve its mission.
We also invite you to contact any of
the authors if you have an interest in
joining the committee.
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mendations can be found from San Jose,
CA, USA—Envision San Jose, 2040.4 This
general plan includes recommendations for
the installation of smart street lights, transit
signal priority, and adaptive signal controls.
The Baltimore, MD, USA Sustainability Plan
and Report contains recommendations and
goals for all aspects of the community such
as education, the economy, and transportation. Adopted in 2009, the plan includes
strategies to implement software upgrades
for transit signal priority and install countdown pedestrian signals citywide. The plan
is supported by an annual report which
tracks the progress of the goals and recommendations. The 2013 edition of the report
recorded the completion of 751 countdown
pedestrian signals.5
Many agencies across North America
are mandating designs that improve access
and mobility for all users. The California
Department of Transportation’s (Caltrans)
Traffic Operations Policy Directive No.
09-06 is an example. It requires bicycle and
motorcycle detection be provided on all
new and modified approaches to traffic-actuated signals in the state.6 This policy
reflects sustainability by accommodating
the accessibility of all modes of travel. The
Maryland State Highway Administration
(SHA) has committed to install accessible
pedestrian signals (APS) at all pedestrian
activated locations by 2016.7 In order to
support this commitment the SHA has
developed a policy for the installation of
APS, which includes prioritization criteria
and a systematic installation approach.
Policies requiring the replacement of all
incandescent traffic signals with LEDs
have become commonplace for most North
American public agencies, with many using
innovative financing programs with loans
being paid back through energy savings.
The STSD Committee is seeking innovative
funding strategies for sustainable traffic
signal improvements.
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In order to investigate the planning
stage of the development of traffic signals
for sustainable practices, we must take
a step back and ask the question, “why
are traffic signals installed?” This question can be answered by looking at who
requests the traffic signals and for what
purpose. The installation of a traffic signal
is generally initiated by concerned citizens
and local governments, or is the result of
crash history, new developments, or capital
improvement projects.
Most transportation professionals can
agree traffic signals are not the solution to
all traffic control problems. Alternatives to
signalized intersections include education,
the installation of roundabouts, and other
initiatives. Recurring feedback the STSD
Committee received from the ITE community was that the most sustainable practice
would be to not install the signal at all. This
emphasizes the importance of public education of the advantages and disadvantages
of traffic signals in the planning process. A
good example of this is the Georgia Department of Transportation’s Traffic Signals
Public Information Document.8 Prepared by
the ITE Georgia Section Technical Committee Group in 2011, it walks through the
installation process and answers frequently
asked questions concerning the installation
of traffic signals.
After a traffic signal has been requested,
the next step is the review and approval
process. In order for a traffic signal to be
approved for installation, it must meet
federal, state/provincial, and local requirements. The STSD Committee has begun
investigating these processes for more
sustainable outcomes. A common initial
requirement in the approval process is
a traffic engineering study. Traffic engineering studies for intersections with the
potential for signalization will include a
warrant analysis. Several of the Manual on
Uniform Traffic Control Devices (MUTCD)
warrants have remained unchanged for
decades. Revisions to these warrants, state
and province warrants, and international
requirements such as the Transportation
Association of Canada’s Traffic Signal
and Pedestrian Signal Head Warrant
Handbook will be considered for sustainable
practices. 9 Sustainable traffic engineering
studies may also include alternative traffic
control and intersection design analysis. An
example of this is the roundabout policy for
the City of Calgary, Alberta, Canada, which
calls for the consideration of roundabouts
as the preferred traffic control option where
a signal may be warranted.10 Caltrans Operations Traffic Operations Policy Directive
13-02, implemented in 2013, also requires
an evaluation of roundabouts on new interchange projects.11
Additional aspects of the traffic signal
planning process that are being considered
for improved sustainability are the development review process, requirements for
temporary and emergency signals, capital
improvement projects, and traffic signal
removals. The requirement to analyze an
existing traffic signal for warrants and
phasing when it is impacted by a capital
improvement project can be considered a
sustainable planning practice. The Alabama
Department of Transportation’s Traffic
Signal Design Guide and Timing Manual
states that a signal warrant analysis be
performed for any traffic signal impacted by
a federally funded project and if the signal is
not warranted, it be considered for removal.12
The STSD Committee believes it has only
scratched the surface of sustainable policies
and planning processes in place for traffic
signals and encourages fellow ITE members and affiliates to share examples from
their communities.
Design and Construction
There are a number of sustainability
considerations and issues that one needs
to consider when designing traffic signals.
Some relate to the impact of the signal as
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with pedestrian modifications.13 Crosswalk
lengths should be minimized and run
perpendicular to curb faces where possible to
minimize the time pedestrians are exposed
to moving traffic. Temporary pole placement
during roadway construction should also
follow ADA requirements.
Traffic signal design needs to consider
several factors for sustainability. It is recognized that agencies owning traffic signals
may assume significant liability when
signals fail to function properly. Signal
installations should be designed to reduce
the number of signal knock-downs by not
placing poles in locations that are part of
the likely vehicle turning paths of oversized
vehicles. Redundant signal heads can help
reduce the potential impacts of signal indications being burned out, snow covered,
or otherwise obstructed, in addition to
enhancing the visibility of signals during
normal operation. A maintenance and
operations plan should be developed for
each new traffic signal. Asset management
systems should be employed for major components of traffic signal installation, so that
replacements can be programmed, funded,
and performed in a preventive manner.
One area of criticism with respect to
traffic signals has been the fact that traffic
signal cabinets have grown larger instead
of smaller over time, constraining the space
available for pedestrians on the sidewalk as
shown in Figure 3. In many respects, this is
the impact of legacy analog design of traffic
signals. Low power smaller cabinets and
components are currently under development and may be widely available in the next
few years. The cabinets under development
will include the ability to self-diagnose problems with intersections, and send alarms to
maintenance personnel. Further reductions
in power consumption of signals may allow
the use of solar power in the future, allowing
signals to operate without needing to be connected to the power grid. Including battery
backups, fuel cell, and generator hookups in
new signal installations can help prevent the
negative consequences of power outages, and
free up police from having to direct traffic in
these situations.
In addition to the basic needs to convey
maintenance alarms and operate in a
flexible or adaptive traffic signal timing
environment, the traffic signal will be a hub
of information collection and disbursement
Gordon Meth
part of the entire transportation system,
and some relate to the installation itself.
A traffic signal can be a significant
source of vehicle delay and vehicle emissions. When designing signal phasing and
operations, it is important to remember
that the traffic signal will be used 24 hours
a day, 7 days a week. Often, we make decisions about operations for the sake of peak
period operation instead of the entire week
(i.e., 5–20 hours of the 168 hours per week).
Further, pedestrians are often delayed at
intersections with complicated phasing or
long cycle lengths, and this is often overlooked as a potential issue during design.
Short cycle lengths and free-float operation
in off-peak times can help these issues.
In all but the most urban of settings,
vehicle detection is commonplace. Vehicle
detection helps eliminate unnecessary
delay and reduce the delay and emissions
impact of a traffic signal. Several alternative technologies for detection exist, and
some are better for certain climates. The
important factor is, if detection is utilized,
a plan must be put into place to maintain
and replace the detection devices over time,
as the useful lives of alternative detection
technologies vary substantially. Whatever
technology is used needs to be able to detect
bicycles, and preferably distinguish bicycles
from other traffic, so that minimum green
times can be adjusted when necessary.
Historically, push buttons have been used
to detect pedestrians. If traffic signal coordination or complicated phases are used, it is
helpful to add an LED indicator to the push
button, so the pedestrian knows a call has
been registered (i.e., similar to an elevator
button). When push-buttons are utilized,
consideration should be given to utilizing
APS and compliance with the Americans
with Disabilities Act (ADA) requirements.
It is noted at the time of writing, the draft
Public Rights of Way Accessibility Guidelines
(PROWAG) mandated the use of APS on
all new traffic signal installations, and any
Figure 3. Type “P” traffic signal cabinet and service cabinet in less than desirable location for
pedestrians, Millburn, New Jersey, 2015.
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in the future. For this reason, traffic signals
in the future should be equipped with communications ability, even if the backbone
network is not presently available. Modems
connected via cell phone, DSL line, copper
wire, fiber optic cable, or wireless mesh
should be added to all new traffic signal
installations, or any modified installations.
Specifying readily available traffic signal
equipment, such as poles and arms, can
help reduce costs and downtime in the
event of knock-downs. Using standard
signal specifications and pre-approved lists
for components can reduce design risks and
costs. Specifying life expectancy of materials and using recycled or reusable materials
helps minimize waste reduction and often
reduces transport costs.
Using 3D modelling in the design of
traffic signals may enhance and improve
designs by better identifying and resolving
conflicts, particularly with overhead utilities.
3D models can also allow better analysis of
sight lines in areas of vertical or horizontal
roadway curvature, or with roadside and
overhead structures and vegetation.
During the construction of traffic
signals, it is important to provide appropriate protection of traffic and pedestrians
and provide continued accessibility for
all modes. Pedestrian routes need to be
accessible during construction. Circuitous
pedestrian detours should be avoided, even
if this results in having to stage sidewalk
and curb ramp construction.
The STSD Committee also seeks innovative
practices and solutions that may not be
commonly thought of as part of a traffic
signal installation. The committee believes
public agencies will seek more and more
opportunities to provide services not related
to traffic control, as part of the infrastructure at an intersection. Examples of these
opportunities would be providing extra
cables or conduit for cell phone wireless
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communications antennae, utilizing
electricity to heat the concrete under ADA
ramps where ice and snow are common,
installing air monitoring equipment, and
providing surveillance cameras or public
announcement systems for public safety.
Agencies should be seeking solutions
that benefit as many sectors of society as
possible, thus making the end solution
more sustainable. Using “Universal Design”
design principles, wheel chair ramps not
only benefit those in wheel chairs, but those
with minor disabilities, aging pedestrians
who have limited mobility, and parents
pushing strollers.14 Thus, applications like
heating ramps in areas that have freezing
temperatures can be thought of as a universal solution aiding as many users of the
signalized intersection as possible.
Utility companies often have restrictions
in their billing schedules that limit the
types of equipment that can be attached
to the service meter that feeds a traffic
signal. Some utilities limit increases in
electrical load to no more than 5 percent
over the total load of the traffic signal.15
However, when you consider most signals
have had their loads significantly reduced
(some by as much as 90 percent) due to the
conversion of incandescent lamps to LED
indications, there may be more available
power that could be used for other applications. Examples include: an ADA accessible
electric vehicle charging station installed
on-street in the first parking space near the
signal, providing lighting and advertising
power to an adjacent bus shelter, or allowing advertising kiosks for marketing special
events or nearby businesses.
Agencies may wish to work with their
local electric providers or their regulators
to see if traffic signal electrical meters could
be used for non-traffic signal equipment.
Third parties would likely have an interest to pay a government for the benefit
of convenient electrical power to provide
service to communications equipment,
promote large events, or operate security
systems. Since traffic signals are installed at
most of the busiest intersections in a city, it
is highly likely that private parties through
encroachment permits could benefit from
an agency that looked at the traffic signal as
an innovative opportunity to provide public
benefit other than traffic safety.
Cabinets will decrease in size, but
increase in density as batteries, solar
energy, and fuel cells begin to play a greater
role in supplying energy to operate the
signal. Easy maintenance plug-in modules
will reduce the amount of wasted space and
wiring connections.
Self-driving cars are no longer a dream.
States such as Michigan and California
have made them legal to operate under
special conditions on their highways.
Vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I) communications are
key to assuring the safety and reliability
of autonomous vehicles. Working with
auto-manufacturers, traffic signal controller
companies are now testing two-way communications between vehicles and signals.
As Doug Davenport, CEO of Prospect Silicon
Valley, the first nonprofit, Silicon Valley-based
technology commercialization catalyst for
smart cities says: “Traffic signals of the past
have merely been the voice of a traffic system,
telling drivers when to stop, start, turn safely...
tomorrow’s signals need eyes and ears as they
will also need to look and listen to a range
of mobile devices in vehicles or carried by
pedestrians.”16 He sees the traffic signal as a
“vast, untapped market” for municipalities to
provide services to its community.
In this time of increasing costs, rapidly
changing technology, and broadening needs
for accessibility, it is imperative we “future
proof ” new traffic signals as far as possible.
The STSD Committee is confident there are
more examples of innovation and sustainability currently being deployed in traffic
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signals. The committee welcomes your
participation as well as providing examples
and your ideas. The committee also seeks
examples of sustainable policies, planning
documents, design standards, and construction techniques and/or materials, to be
shared in its information report. Please help
us by taking a few minutes to forward them
to the authors of this article. The Committee’s PowerPoint presentation, presented at
the 2014 ITE Annual Meeting and Exhibit
in Seattle, WA, USA is also available in the
ITE Library at itej
1 Gordon M. Sessions (principal writer). Traffic
Devices: Historical Aspects Thereof. Institute of
Traffic Engineers, 1971.
2 “Happy 100th Birthday to the Electric Traffic
Light,” USA Today.
3 C.A.B. Halvorson. International Commission
on Illumination, Saranac Lake, New York,
4 Envision San Jose 2040 General Plan.
5 2013 Annual Sustainability Report.
Baltimore Office of Sustainability.
6 Traffic Operations Policy Directive No. 09-06.
California Department of Transportation
7 Maryland State Highway Administration.
8 Georgia Department of Transportation Traffic
Signals Public Information Document. http://
9 Transportation Association of Canada Traffic
Signals and Pedestrian Head Handbook.
Roundabout Guidelines-The City of Calgary,
2011, 2012, 2013.
Caltrans Operations Traffic Operations Policy
Directive 13-02.
Alabama Department of Transportation’s
Traffic Signal Design Guide and Timing Manual.
Public Rights of Way Accessibility Guidelines
Universal Design.
Electric Schedule TC-1, Traffic Control Service,
January 2015.
Prospect Silicon Valley.
James R. Helmer, P.E.,
T.E., PTOE worked 32 years
in local government, most
recently serving as director of
transportation for the city of
San Jose, CA, USA. He holds a
B.S. and M.S. in transportation from Cal Poly,
San Luis Obispo and Mineta Transportation
Institute. He currently is sole proprietor of LightMoves, a company focused on sustainable
transportation and adaptive lighting solutions.
Jim is an ITE Fellow. He can be reached at
[email protected]
Gordon Meth, P.E., PTOE,
PTP is a senior associate and
director of Traffic Engineering
for The RBA Group in Parsippany, NJ and Silver Spring, MD.
He has both a bachelor’s and
master’s degree in civil engineering from the Uni-
versity of Waterloo, and a master of business
administration from Montclair State University.
He has 25 years of experience in traffic engineering and has designed in excess of 200 traffic
signal installations. He is a licensed professional
engineer in NY, NJ, CT, MD, DE, DC, and Ontario,
Canada. He is presently Northeast District Chair
for ITE, as well as being part of the executive
committees for the Traffic Engineering Council,
the Complete Streets Council, and the Sustainability Task Force. Gordon is a Past President of
the ITE Metropolitan NY/NJ Section. He also has
served on the Transportation Professional Certification Board since 2012. He is an ITE Fellow. He
can be reached at [email protected]
Seth D. Young, P.E., PTOE
is an associate and senior
traffic engineer at STV Incorporated with more than 12
years of experience in transportation planning, analysis,
and design. He currently manages a team of
engineers specializing in traffic control device
design for various U.S. state and local agencies
in the Mid-Atlantic region as well as nationwide. Throughout his career, Seth has been
responsible for the planning and design of hundreds of traffic signals in Maryland, the District
of Columbia, Pennsylvania, New Jersey, Connecticut, and California. These traffic signal
designs include innovative techniques and
technologies and accommodations for all users
such as accessible pedestrian signals and bicycle signals and detection. Earlier in his career,
Seth served several years as an on-site project
manager at the Maryland State Highway
Office of Traffic and Safety, Traffic Engineering
Design Division. Seth has a bachelor’s degree in
civil engineering from The Pennsylvania State
University and is a licensed Professional Engineer in Maryland, Pennsylvania, Virginia, North
Carolina, South Carolina, the District of Columbia, Georgia, and Florida. He is also a certified
Professional Traffic Operations Engineer. He is a
member of ITE. He can be reached at seth.
[email protected]
May 2015