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Traffic Signal Light Emitting Diode (LED) Implementation Process
Click on any of these links to find out more about the City's LED
Whether you are a visitor to Midland or a resident, you may
have noticed some differences in the cityís traffic signal operations.
Most traffic lights are brighter and easier to view than before, even
when the sun is shining on them. That's because the City of Midland has
installed Light Emitting Diode (LED) traffic lights in place of pre-existing
Compared to incandescent traffic lights, LEDs have greater light intensity
and are designed to absorb, not reflect, most sunlight that enters the
lenses. Also, LED lights are more visible, last much longer, and use much
Various forms of LEDs have been in use in the U.S. for many years.
Most of the tiny red and green indicator lights you notice on your
appliances, radios, and other digital visual effects are LEDs. However,
in the last decade, their use has expanded to many other areas,
including use in automotive tail lights and turns signals, as
well as traffic signals.
Research: Timing is Everything
For several years, the City of Midland monitored the development of LEDs as an alternative means for street signal operation. Since LEDs
require much less energy to operate, they cost less to operate.
Until recently, LED traffic light implementation was not an economically
sound investment due to operations and reliability concerns as well
as high costs for materials. However, technology has changed significantly in
recent years, making LED light implementation an economical
possibility for the City.
The City reviews signal operations
annually and determines necessary upgrades to Midland's signal
system. During one of these reviews, it was determined that many of the City traffic
signal components (see photos at right) were scheduled for upgrade
or replacement. To save on installation costs, LED traffic light
implementation was considered as part of the traffic signal
upgrade or replacement program.
The City of Midland
also consulted with several Michigan municipalities that use LED traffic lights and determined that
these lights have become
very reliable considering the various climate changes in the state.
Efficiency of LED vs. Incandescent Lights
The basic mechanics of how LEDs create light are very different than
that of incandescent lights used in traditional traffic signal
operations. As described below, efficiency can be measured by the amount
of useable energy.
Efficiency of Incandescent Lights
A standard light bulb relies upon electrically heating an element to
emit visible light. Light emission requires a significant amount of
power to occur. This process is called incandescence. Approximately 2%
of the emitted energy from an incandescent source is useable visible
light with the remaining 98% being wasted heat. Incandescent bulbs are
likely to burn out frequently and require replacement each year.
Efficiency of LED Lights
In contrast, LEDs are much more efficient and last longer. Thatís because LEDs emit light by using an electrical current
to create a bond between positive and negative charges. This process is
called electroluminescence. This is much more efficient, as nearly 100%
of the emitted energy from an LED source is useable visible light. Due
to varying energy use, LED traffic lights are known to last approximately 10 times longer
than incandescent traffic lights. LED traffic lights usually have a
replacement warranty of five years, but are expected to last longer.
Standard incandescent light is diffused light, which basically means
the light spreads out when in operation. Standard LEDs produce direct light but can
be manipulated to diffuse, or spread out, so the light is visible at
different angles. This can be controlled by altering the size, shape and
location of some of the LED components that make up an LED traffic light.
Researching LED Costs
When determining costs of LED implementation, the City of Midland utilized
Michigan Department of Transportation (MDOT) research regarding
acceptable LED traffic light products in Michigan. Acceptable products
must meet State standards regarding light intensity and reliability,
among other things.
Cost of LED vs. Incandescent Lights
When looking at cost comparisons between incandescent and LED lights,
the City considered three main
factors: costs for materials, energy use, and labor.
Material Costs: This includes all signal
components required for LED or incandescent traffic light installation.
Up front costs for LED traffic light materials are substantially higher
than incandescent traffic light materials.
Energy Costs: Energy costs for LED traffic
lights are considerably less than costs for incandescent traffic light
Labor Costs: Labor and equipment to material
assembly and installation are necessary costs. When comparing labor
costs between qualified City of Midland staff and private contractors,
it was found that installation by City staff in a five-year period would
cost less than contracting out the work.
Considering the LED/incandescent comparison of materials, energy
and labor costs, it was determined that the new LED system will pay for itself in approximately
four years. As indicated in the table below, it will cost the City
less to replace lights with LED materials than it would to replace
traffic lights made with incandescent materials.
Total Installation and Operating Costs - LED vs. Incandescent Lights
After 1st Year
After 5th Year
After 10th Year
Replacement with Incandescent
Replacement with LED
The table below shows the estimated total savings for using LED
lights when comparing the installation and operations costs between LED
and incandescent lights.
Comparison of Installation and Operating Savings Using LEDs vs.
After 1st Year
After 5th Year
After 10th Year
Installation of the new LED lights took about five years. By spreading the implementation over
that time span, City staff has been able to balance LED light maintenance and replacement with their regular
After five years, the LED warranty expires; therefore LED
replacements will occur in five-year increments.
In order to develop and balance the work necessary for a five-year
LED installation plan, City staff considered:
signalized intersection locations,
type of LED traffic light installation needed,
the amount of time required for each signalized intersection
time of day, month and year for performing the work
In Midland, there are various types of LED traffic light
installations to consider when scheduling the work:
1. Type I, LED Inserts
LED inserts, or fixtures, can be placed in newer existing
incandescent signal heads at the intersection location. However, only
newer signal heads that can convert from incandescent to LED lights
will be changed. Completing the work on site saves time by avoiding
assembly in the shop using new signal head components.
2. Type II, Shop Assembly for Mast Arm
Work involves building and installing new signal heads with LED inserts and mast
arm components. Mast arms are rigid horizontal posts to which signal
heads are attached. This type of work requires assembly in the City's
3. Type III, Shop Assembly for Span Wire
Related work involves building and installing two-way, three-way or four-way
signal heads with wiring for span wire connections. This type of work
requires assembly in the City's Signal Shop.
4. Type IV, Pedestrian LED Install
Pedestrian LEDs are assembled
at the Signal Shop. Installation is time-consuming since LED
pedestrian signals are unlike pre-existing incandescent lights.
Field modification of the bracket assembly is required.
Reduction in Energy Costs
Through a coordinated effort with Consumers Energy, a system has
been developed to make sure that once the LED work at each signalized
intersection is completed, Consumers Energy will be immediately
notified. Once notified, Consumers Energy will place the information in
their system and reflect the changes on their next billing cycle to the
City of Midland.
To Find Out More...
For more information regarding LED lights,
contact the City of Midland Engineering Department at 989-837-3348, or
send an e-mail to