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2011

TRAFFIC SIGNAL LED CONVERSION STUDY

Almin Ramic, EIT ALMIN RAMIC, EIT 5/3/2011


In 2003, the City of Minnetonka replaced 75% of its red and about 50% of its green incandescent traffic signal lights with new signal lights featuring highly efficient light-emitting diodes (LEDs). The right timing and carefully arranged financing resulted in a successful energyefficiency project, with energy and maintenance savings and fast net payback for the project. At the time, yellow and green LEDs were less efficient and much more expensive then red, so the city opted for replacing mostly red and pedestrian lights. Traffic signals that use LEDs consume up to 90 percent less energy and generally last 7-10 years, compared to just a year for a incandescent light signal. In the signal survey which was completed in the April of 2011 in the City of Minnetonka it was determined that most of the LED traffic signals that were installed in 2003 are still fully operational. Only 10% of all LED green traffic lights, and 1% of red, pedestrian and arrow signals are in condition for replacement. Most of these are still operational, but have a number of diodes burned out. Moving away from incandescent to LED traffic lights will not only save energy, but will allow moving from reactive, emergency maintenance and developing a plan for preventative maintenance.

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Table of Contents Introduction ................................................................................................................................. 4 Typical Power Ratings ................................................................................................................ 5 Survey Results ............................................................................................................................. 6 Energy and Cost Savings ............................................................................................................. 7 Improved Safety .......................................................................................................................... 9 Preventative Maintenance vs. Reactive Maintenance Plan ...................................................... 10 Material and Installation Costs Estimate:.................................................................................. 11 Recommendations ..................................................................................................................... 12 Appendix 1: Xcel Energy Lighting Efficiency-Led traffic signal retrofit rebate Form (4) ....... 13 Bibliography .............................................................................................................................. 15

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Introduction Light Emitting Diode (LED) lights are more efficient option for traffic signal lights than traditional incandescent bulbs (STD). The key advantages of having LED signals are Low power consumption 4 W to 12.5W, Life span of approximately 7 to 10 years, The elimination of catastrophic failures, and The elimination of phantom illumination. A typical incandescent bulb that is used for traffic signals is between 135 and 150 Watts. In the current economy, where prices of gas and coal are rising, the cost of electricity is going up. Energy savings resulting from the usage of LED signals can be as high as 90%. LED traffic signals also offer significant peak demand savings since they operate 24 hours a day. In addition to the low energy usage, the long life of LED signals means low maintenance costs, which makes LED signals a worthwhile investment while at the same time being environmentally friendly. Another very important benefit of LED signals is the elimination of catastrophic failures. Unlike an incandescent bulb which has only one filament, an LED signal is made out of a matrix of several dozen LEDs. The signal continues to function even if several of these miniature diodes stop working. Catastrophic failures in LED’s are very rare, and mostly caused by abrupt surge of power. On the other hand, when the filament of an incandescent bulb fails, the display goes dark requiring immediate replacement. This characteristic of LED lights will allow for the move from reactive maintenance to plan driven preventative maintenance. Preventive maintenance plan is a schedule of maintenance actions aimed at the prevention of breakdowns and failures. The primary goal of preventive maintenance is to prevent the failure of equipment before it actually occurs. LED signal lights are brighter than an incandescent traffic signal. This characteristic improves intersection safety because is eliminates phantom illumination. During morning and evening hours on signals east-west approaches, all colors seem to light up when the sunrays fall directly on these signals. This problem is eliminated when LED signals are used because in they do not use reflectors like in Incandescent traffic signal bulbs to increase the lights brightness. There is only one downside to the LED lights and that is their initial cost. It can range from $100.00 for a 12�red light, $127.00 for a pedestrian display, to $170 for 12� green light depending on the type, quality and the manufacturer. Some lower quality LEDs can be purchased cheaper than shown in this study. Compare this to typical incandescent traffic signal bulb costs of about $2.75 per bulb. Still, in most of the cases this initial cost is made up by the savings in energy cost in less than 5 years.

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Typical Power Ratings LED signals require very low power to operate. The typical power consumption ranges anywhere from 4 to 22 watts, depending on type of LED light, number and color of diodes. The Table1 and Chart 1 illustrate the power usages for incandescent bulbs and LED signals obtained from Act One Communications Inc. Display Type Incandescent Bulb (Standard-STD) Pedestrian Incandescent 12" Red LED 8" Red LED 12" Red Arrow LED 12 " Yellow LED 8 " Yellow LED 12 " Yellow Arrow LED 12 " Green LED 8" Green LED 12" Green Arrow LED Pedestrian LED

Typical Power (Watts) 135 60 7.5 4 7 10 8 8 12.5 5 9 6

Table 1: Typical Power Usage of LED and Incandescent Bulbs in Traffic Signals

Chart1: Typical Power Usage of LED and Incandescent Bulbs in Traffic Signals

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Survey Results The survey of traffic signals done in April of 2011 in the City of Minnetonka produced these findings. In Table 2 are presented surveyed totals of the types of the light bulbs used for specific type and size of traffic lights. 12" SOLID RED LED

STD

8" SOLID YELLOW

GREEN

RED

LED

STD

LED

513 169 129

504

311 313 5

9" WALK

STD

LED

9" DON'T WALK

12" ARROW YELLOW

GREEN

RED

YELLOW

STD

LED

STD

LED

STD

LED

0

0

22

0

22

124 25

12" WALK

STD

GREEN

LED

STD

LED

STD

45

214

58

237

12" DON'T WALK

12" WALK/DON'T COMBINED

LED

STD

LED

STD

LED

STD

LED

STD

LED

STD

48

24

48

24

103

49

101

51

123

18

Table 2: Current number and types of traffic lights in the City of Minnetonka The current situation in the City of Minnetonka traffic signals is shown in Table 3, where at the signalized intersections 44% of signals for vehicular traffic, and 72% for pedestrian traffic was replaced to LED lights. Number of Lights 1185 1506 423 166

TOTAL LED SIGNAL LIGHTS TOTAL STD SIGNAL LIGHTS TOTAL LED PED SIGNAL LIGHTS TOTAL STD PED SIGNAL LIGHTS

Percentages 44% 56% 72% 28%

Table 3: Current totals of LED and STD lights in the City of Minnetonka Type Of Signal Light

LED R,Y,G and Arrow

Signal Lights City is responsible for re-lamping % of Total % By Type 761 40.31% 48%

Signal Lights City is responsible for energy cost % of % By Total Type 1185 36.13% 44%

LED PED Walk/DW

253

13.40%

84%

423

12.90%

72%

INCONDESCENT R,Y,G and Arrow

826

43.75%

52%

1506

45.91%

56%

INCONDESCENT PED Walk/DW

48

2.54%

16%

166

5.06%

28%

TOTAL R,Y,G and Arrow

1587

2691

TOTAL PED Walk/DW

301

589

Table 3a: Current totals of LED and STD lights in the City of Minnetonka by city duty

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Energy and Cost Savings As a part of the study, two intersections were looked at. One mostly retrofitted with LED signals and other with all of the lights incandescent. The intersections studied were Co Rd No. 101 and Co Rd No. 5 and Co Rd No. 62 and Woodland Road. The types of light bulbs that each intersection has are show in the Tables 4 and 5. Their energy usage was monitored and compared. INTERSECTION 1

12" SOLID

Signal LOCATION Co Rd No. 101 and Co Rd No. 5 (Minnetonka Boulevard) Co Rd No. 101 and Co Rd No. 5 (Minnetonka Boulevard) Co Rd No. 101 and Co Rd No. 5 (Minnetonka Boulevard) Co Rd No. 101 and Co Rd No. 5 (Minnetonka Boulevard)

RED LED 4

12" ARROW

12" WALK/DON'T COMBINED

YELLOW GREEN YELLOW GREEN LED LED INC INC 4 4 2 2

LED 2

4

4

4

2

2

2

4

4

4

2

2

2

4

4

4

2

2

2

Table 4: Number and Types of lights at Intersection of Co Rd No. 101 and Co Rd No. 5 INTERSECTION 2 Signal LOCATION Co Rd No. 62 and Woodland Road Co Rd No. 62 and Woodland Road Co Rd No. 62 and Woodland Road Co Rd No. 62 and Woodland Road

12" SOLID

RED

12" ARROW

YELLOW GREEN

RED

12" 12" WALK DON'T WALK

YELLOW GREEN

INC 2

INC 2

INC 2

INC 1

INC 1

INC 1

INC 2

INC 2

2

2

2

1

1

1

2

2

4

4

4

1

1

1

2

2

4

4

4

1

1

1

2

2

Table 5: Number and Types of lights at Intersection Co Rd No. 62 and Woodland Road Based on actual meter readings over a period of one month, the power consumption of the two intersections was compared. Intersection 1 retrofitted with LEDs and Intersection 2 with standard incandescent lights. The total power consumption was 252 kWh for CR-101 and CR-5, and 1790kWh for CR-62 and Woodland Rd. As can be seen in the Table 4 at Intersection 1, there are 16 incandescent bulbs used for yellow and green arrows, the total number of 12” solid lights is larger by 16, and the number of 12” arrow lights is greater by 4 than at Intersection 2. 7|Page


Based on the gathered data, number and types of lights, Table 6 shows the estimates for current and predicted hourly power consumption for all of the signalized intersections in the City. Display Type Incandescent Bulb Pedestrian Incandescent 12" Red LED 8" Red LED 12" Red Arrow LED 12 " Yellow LED 8 " Yellow LED 12 " Yellow Arrow LED 12 " Green LED 8" Green LED 12" Green Arrow LED Pedestrian LED TOTAL

Minnetonka Power Usage (kWh) 203.31 9.96 3.85 0.02 0.87 1.29 0.00 0.36 3.89 0.00 0.52 2.54 226.60 kWh

Predicted Power Usage If Switched to LED (kWh) 0.00 0.00 5.12 0.02 1.04 6.33 0.18 2.07 7.80 0.11 2.66 3.53 28.86 kWh

Table 6: Estimate for current and predicted power consumption in the City of Minnetonka Based on the above estimate for hourly consumption, the LED signals consume about 90% less energy than conventional signals with incandescent bulbs. For the 64 intersections that the city is paying for power consumption we can calculate current annual power consumption for the two different types of signal lights and predicted consumption after all of the signals were retrofitted to LED lights.

Incandescent Power Consumption LED Power Consumption TOTALS

Current Annual Consumption kWh 921,326

Current Energy Costs

Predicted Energy Cost

$73,838

Predicted Annual Consumption kWh 0

57,599 978,925

$4,616 $78,454

124,654 124,654

$9,990 $9,990

0

Table 7: Estimate for Annual Energy Consumption and Energy Cost Based on the above averages, the LED signals consume about 90% less energy than conventional signals with incandescent bulbs (1). For the 64 intersections in the city, the annual power consumption for the two different types of signals is shown in the Table7. If all of the 64 intersections in the city were fully converted to have LED signal lights, the average energy savings would be about 855,000 kWh per year, or almost $70,000 with current price of electricity.

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Improved Safety LED signals eliminate catastrophic failures of signals. LED signal is a matrix of large number of individual diodes and a chance of all of them failing at exactly the same point in time is very rare. The signal continues to function even if multiple miniature diodes have stopped working (see Pictures 1,2,3). This is not a case with incandescent bulbs. When incandescent Bulb filament fails, it requires immediate replacement.

Picture 1: Failing LED Signals at Ridgedale Drive and Hwy394 west bound ramp, Minnetonka,MN LED signals are brighter when compared to incandescent traffic signals. Brightness of the light enhances intersections safety especially for signals on east‐west approaches during morning and evening hours. If the sunrays falls directly on the non LED signal all colors seem to light up. This event is known as the phantom illumination. The sun’s light then reflects off the surface of the lamps, possibly giving the false impression that the lamp is on. Example of this is obvious in the sunny morning hours going west of Minnetonka Ave, at the intersection with McGinty Rd. The task of the driver is then to determine which of the three color lamps is actually illuminated. The LED signals have a great advantage because its lens reflects much less of the sun’s light back at the observer then the Incandescent traffic signals.

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Preventative Maintenance vs. Reactive Maintenance Plan Preventative and Reactive maintenance efforts and costs can be related to the quality of design practices, construction methods, and the use of quality parts. Effective preventative maintenance practices can decrease the cost of operating and maintaining a traffic signal infrastructure (3) - resulting in safe and reliable intersections. Preventive maintenance (PM) considers a schedule of maintenance actions aimed at the prevention of breakdowns and failures by replacement of equipment before it actually occurs. Preventive maintenance activities include inspections of equipment, keeping condition of equipment data, and partial or complete overhauls at specified periods. In addition during inspections, maintenance workers can record equipment deterioration in order to replace or repair worn parts before they cause system failure. Gather data will also help continuous development of PM plan. The ideal PM program would prevent all equipment failures before they occur with reactive maintenance only performed on a hierarchical priority basis considering the seriousness of reported problems. In the City of Minnetonka traffic signal maintenance plan, a large part of the maintenance work would be inspecting traffic control equipment, but the main element is replacing parts before they fail. This replacement program would be scheduled with consultation of LED lights manufacturers’ specification about the lights life expectance. The reactive maintenance would be only performed on an on call/as needed basis. As the replacement program moves forward, the number of hours spent in a reactive maintenance should considerably decrease. The PM includes: Semi-annual inspections and testing of control equipment, intersection hardware, vehicle detector loops, pedestrian pushbuttons, poles, signs, signal heads, and mounting hardware(3); Annual cleaning of all signal lenses; Planned re-lamping cycle of 8-10 years of all LED Red, Yellow, Green, Don’t Walk, RGY arrows, and countdown timers; and Reactive re-lamping of failed LED and non/LED light bulbs Long-term benefits of preventive maintenance include: Improved system reliability; Decreased cost of replacement; Decreased system downtime; and Better spare parts inventory management. Implementation may start with initial reliability training in PM and inspection monitoring. The goal of inspections is to achieve a condition monitoring and preventive maintenance program that is Documented Executed Tracked

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Material and Installation Costs Estimate: Material 12"(Red) 12"(Red Arrow) 8"(Red) 12"(Yellow) 12"(Yellow Arrow) 8"(Yellow) 12"(Green) 12"(Green Arrow) 8"(Green) Pedestrian Separated Pedestrian Joined Labor (per retrofit installation)

LED $100.00 $114.00 $114.00 $110.00 $114.00 $115.00 $170.00 $157.00 $130.00 $127.00 $127.00 $55.00

Incandescent Bulb $2.75 /bulb

$55.00

Table 8: Estimate for Material and Labor cost per light (Prices were obtained from Act One Communications Inc.)(2)

Cost to replace ALL to LED Cost to retrofit all non-LED to LED

COST MATERIAL $400,000

LABOR

TOTAL COST

$180,000

$580,000

$210,000

$90,000

$300,000

Table 9: Total Estimate for Retrofitting

Above numbers only take into consideration savings in energy cost. The savings in change of maintenance approach and safety improvement should also be considered. Another thing that has to be considered is that the cities energy company Xcel energy has the Lighting Efficiency-Led traffic signal retrofit rebate program (see Appendix 1). This rebate program could cover up to between $10,000 and $25,000 of project cost, depending on the number of lights retrofitted. This is something that could play a very important role with the retrofit planning schedule.

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Recommendations LED traffic lights are steadily replacing the original traffic lights because they are more efficient than the incandescent bulbs. When traffic signal lights fail, it causes lots of confusion among drivers, accidents occur and lives are endangered. Due to the many operational advantages, lower energy consumption, and safety, the benefits of LED signals outweigh the initial investment. The City of Minnetonka should retrofit all the traffic signals to LED signals and require all new traffic signal installations to be LED. The net payback should be very fast. Based on the performance of LED signals that have been installed in 2003 the life of the LED lights in these types if conditions is more than 8 years. The benefits in energy savings, maintenance and safety largely outweigh the initial investment. The City should develop the plan to replace all of the traffic signal lights, including the ones installed in 2003 over the next 5 years. This would mean retrofitting about 13 intersections per year. This approach would allow for easier transition from emergency to preventative maintenance. The best cost/benefit ratio is received by first replacing all of the non-LED lights that the City is paying the electricity for. By doing this, the City could seek a partnership from the Hennepin County, because they are responsible for re-lamping 30 out of 64 intersections. This approach would need less funding, had faster implementation (1-2 years), but the transition from emergency to preventative maintenance would be longer. This option would require more frequent inspection to prevent outages of the older previously installed LEDs. Keeping the good records on replaced traffic signals is detrimental to development of extended preventative maintenance plan. Another benefit that could play an important role in deciding to invest in the retrofits is the Xcel energy rebate program (see Appendix1). This program is currently available, and could allow for up to $25,000 rebate after retrofits are implemented. If there is a chance to retrieve some of the total project cost for replacing non-LED to LED, the City may consider additional retrofits of traffic lights each year. Replace & Retrofit to LED All the lights the City is paying electricity for Only non-LED lights the City is paying electricity for All the lights the City is responsible to re-lamp Only non-LED lights the City is responsible to relamp

COST OF COST MATERIAL OF LABOR

TOTAL COST

Cost/ year based on 5year plan

SAVINGS Total in XCEL Energy/year REBATE

$ 290,000

$ 180,000

$ 470,00

$ 94,000

$ 70,000

$ 25,000

$ 210,000

$ 90,000

$ 300,000

$ 60,000

$ 70,000

$ 25,000

$175,000

$105,000 $280,000

$55,000

$37,000

$10,000

$107,000

$48,000

$31,000

$37,000

$10,000

$155,000

Table 10: Summary of Cost and Savings for Retrofitting 12 | P a g e


Appendix 1: Xcel Energy Lighting Efficiency-Led traffic signal retrofit rebate Form (4)

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Bibliography

(1) United States. TED, Department of Public Works, City of Little Rock “Conventional Vs LED Traffic Signals” http://www.cee1.org/gov/led/little_rock.pdf , July 1, 2003. April 2011. (2) Act One Communications Inc. http://www.actone1.com/Traffic/signals.htm May 1st, 2002. April 2011 (3) United States. City of Richmond, CA “Traffic Signal Maintenance” http://www.richmond.ca/services/ttp/signals/maintain.htm 2011.April2011. (4) Xcel Energy, Minnesota. “Lighting Efficiency- Led traffic signal retrofit rebate” http://www.xcelenergy.com/staticfiles/xe/Marketing/MN-Bus-Lighting-LED-TrafficSignal-Retrofit-Rebate-2010.pdf 2010. April 2011.

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