Chapter 5: Local Action Plan
Best Bets (Infrastructure)

This section describes Infrastructure as a best bet for developing a local action plan.  See the menu on the left for other sections within Chapter 5.
The below table of contents is “click-able” if you wish to jump to different sub-sections on this page.
Light-Emitting Diode (LED) Traffic Signals
+ CASE STUDY:  Sacramento, CA
+ CASE STUDY: Chicago, IL
+ CASE STUDY: Berkeley, CA
Traffic Flow Management Systems
+ CASE STUDY: Colorado Springs, CO
High Efficiency Street Lighting
  – High Pressure Sodium Lamps
  – Low Pressure Sodium Lamps
  – Metal Halide Lamps
  – Induction Lighting
Lamp and Light Fixtures
Remote Streetlight Control
+ CASE STUDY: Medford, MA
+ CASE STUDY: Flagstaff, AZ
+ CASE STUDY: San Diego, CA
Increase Efficiency of Municipal Water and Wastewater Utilities
+ CASE STUDY: Columbus, GA
+ CASE STUDY: Fairfield, OH
+ CASE STUDY: Austin, TX
+ CASE STUDY: San Diego, CA
Landfill Gas-to-Energy Projects
+ CASE STUDY: Los Angeles, CA
+ CASE STUDY: Riverview, MI
+ CASE STUDY: Orange County, FL
Additional Resources
[DOWNLOAD] the “Infrastructure” section of Chapter 5 (556 KB .pdf)

 

Infrastructure

Light-Emitting Diode (LED) Traffic Signals and Traffic Flow Management Systems

Many cities have begun replacing their old incandescent halogen bulb traffic lights with much more energy efficient and durable light-emitting diode (LED) traffic lights.  LED arrays in the new traffic lights include hundreds of individual LEDs each the size of a pencil eraser.  There are three principle advantages to upgrading municipal traffic lights to LEDs:

  1. LEDs are brighter.  LED traffic lights emit light more evenly, making them brighter overall and more visible in foggy conditions.

  2. LED traffic lights last for 100,000 hours, compared to incandescent bulbs, which have filaments that burn out and may last only 8,000 hours before needing to be replaced. Replacing bulbs costs money for materials and labor and the replacement inhibits traffic flow.  Fewer burned-out lights increases safety of intersections.

  3. LEDs consume less energy, about 85% less than incandescent bulbs.

Typical incandescent traffic lights use 100-watt or 150-watt bulbs that are operating 24 hours a day, utilizing more than 2.4 kilowatt-hours per day.  At 8 cents per kilowatt-hour, one intersection can cost almost $600 per year in electricity.  Large cities with thousands of intersections spend millions of dollars on electricity just for traffic lights.  LED arrays consume 12-20 watts instead of 100, reducing overall energy consumption considerably.  Portland spent $2.1 million to change out red and green traffic lights to LEDs and received a 4-year payback on the project.[1]  Solar panels can power LED traffic lights in remote areas, reducing the costs of installing power lines.

Another benefit of LED traffic signals is the fact that they do not burn out all at once.  When an incandescent filament burns out, the entire light ceases to function.  In an LED, a single diode or a cluster of diodes can stop working or burn out, but the other diodes operating independently will continue to function normally.  This feature eliminates the safety risks and traffic congestion problems of burnt-out traffic signals.

 

LED Traffic Signals

CASE STUDY:  Sacramento, CA

Sacramento upgraded the traffic lights in more than 1,000 of its 1,300 intersections.  The decade-long conversion from incandescent lamps to LEDs has reduced the energy consumption by the Sacramento Municipal Utility District (SMUD) by a total of 1.4 megawatts.  When all the intersections are completed, the estimated energy savings will be an estimated 2 megawatts.

Despite initial skepticism concerning the value of upgrading to LEDs given the higher upfront costs, the SMUD invested in the conversion of its first major intersection in April of 1995.  The city’s 30-day electric bill for that intersection dropped from $148 to $21.40.[2]  Current overall savings of the traffic light upgrades across Sacramento County are an estimated $557,000 a year.

Additional financial incentives provided by the SMUD include rebates of about $225 for each on-peak kilowatt that the city and county reduce.

A policy encouraging the upgrade of traffic lights to LEDs by the California Energy Commission (CEC) has resulted in the conversion of over 13,000 intersections throughout the state.  The stated goals of the policy are to assist local government agencies in saving money, conserving energy to avoid crises like the blackouts of 2001 and increasing the overall safety of intersections.  The CEC offers loans and grants to local agencies for the implementation of LED upgrades.

Results of the CEC incentive program include the replacement of nearly 250,000 old incandescent red, green and amber traffic signals, along with pedestrian walk and do not walk signals, with new LED lamps.  The new LED lights reduce the State’s need for electricity by nearly 10 megawatts, enough electricity to power nearly 10,000 homes.

The reduced electricity demand should save the state an estimated $7.9 million every year on electricity costs.

CONTACT

Interim Director

Fran Halbakken

Department of Transportation, city of Sacramento

mhanneman@gw.cityofsacramento.org

LED Traffic Signals

CASE STUDY:  Chicago, IL

The city of Chicago has an estimated 2,800 intersections.  Through a joint venture between the Chicago Department of Transportation (CDOT) and the City’s Bureau of Electricity, old traffic lights at 350 intersections have been replaced with LED traffic signals.  According to Matt Smith, Director of Communications at CDOT, the new LED traffic signals have demonstrated their efficiency through significantly reduced energy costs.[3]  The city estimates that it will save $2.5 million annually by retrofitting all of its intersections.  The program has already reduced the city’s annual CO2 emissions by 7,250 tons.

An added benefit of switching to LEDs is the ability to use backup power supply for traffic signals during power outages.  In conjunction with the LED retrofit program, the city of Chicago has installed PowerBack ITS Systems at approximately 800 new and existing traffic intersections.  The PowerBack ITS System is a complete battery backup system for traffic signal intersections that keeps traffic signals on when the power goes out.  The PowerBack ITS Series will operate traffic signals after a power outage in either normal or “flash” mode for up to 24 hours.  Although such backup power supplies can be used in traditional incandescent traffic signal systems, they provide a much longer range of emergency coverage with more energy efficient LEDs.

CDOT has also begun implementing the use of activated or actuated traffic signals that can detect when a vehicle is in the intersection.  This network of vehicle detectors automatically detects traffic movement and patterns and allows automated adjustments of the traffic signal operation to streamline the flow of traffic.  Stop-and-go traffic wastes energy since gasoline-powered cars use almost as much energy idling as driving.  Timing traffic lights, particularly during commuting hours in the commuting direction, will alleviate congestion and excessive stop-and-go traffic.  The results of CDOT’s integrated traffic management program are a better understanding of traffic patterns, better coordinated traffic signals at any particular intersection, increased efficiency of traffic flow, and fewer accidents.

Mayor Daley’s Traffic Management Task Force meets regularly to review major construction projects and special events that are likely to have significant impact on the city’s traffic.  Members of CDOT, the Mayor’s Office, and other key city departments and agencies work with media outlets to design solutions and inform the public on road closures, alternate routes and traffic advisories.

CONTACT

Director of Communications

Matt Smith

Chicago Department of Transportation

312-744-7261

LED Traffic Signals

CASE STUDY:  Berkeley, CA

The city of Berkeley received more than $225,000 in rebates from the utility, Pacific Gas & Electric (PG&E), for replacing nearly 3,000 traffic signal bulbs with energy-efficient LED fixtures.[4]  The city replaced old red and green traffic incandescent bulbs over several years as part of an energy conservation program sponsored by PG&E.  Amber bulbs, since they are used so infrequently, are seldom replaced and are usually the last priority for replacement in municipal retrofit projects.

According to the city of Berkeley’s Climate Action Plan[5], the retrofit costs for LED traffic signals are as follows:

  • 8” diameter red lights: $170 each

  • 12” diameter red lights: $240 each

  • Pedestrian control lights<: $160 each

LED technology has experienced significant growth in recent years and these prices will likely continue to decrease with time.

The city of Berkeley estimated that it will reduce its energy use for traffic signals by more than 563,000 kWh, which is roughly equivalent to $56,000 per year of reduced energy costs.[6]  According to Neal DeSnoo, energy officer for the Office of Energy and Sustainable Developed for the city of Berkeley, actual energy savings from 1998 to 2005 were 890,000 kWh for all the signals and exceeds the original estimate of 563,000 kWh.  Meter measured energy savings has been reduced from 1,341 kWh in 1998 to 451 kWh in 2005—approximately 66% in savings.  Additional savings in reduced maintenance costs increase the payback rate of the upgrade investment.  The amount of electricity saved also equates to the reduction of 323 metric tons of CO2.

Following The California Energy Commission’s (CEC) recommendation that cities optimize their traffic signals every three to five years, the city of Berkeley integrates signal coordination and traffic flow management into its transportation plan.  According to the CEC, cities participating in CalTran’s Fuel Efficient Traffic Signal Management (FETSIM) program reduced gasoline use by 19%.  As an added benefit, travel time was also reduced by an average of 7.5%.

CONTACT

City of Berkeley Energy Officer

Neal DeSnoo

Office of Energy and Sustainable Development

(510) 981-5434

Traffic Flow Management Systems

Traffic flow management consists of set light timing, activated traffic signals, signal synchronization and more techniques that work to improve traffic flow.  With these programs commuters should experience a reduction in travel time, less gas consumption and cost savings due to the coordination of signals.  These  strategies reduce air pollution and GHG emissions caused by idling.

Traffic Flow Management

CASE STUDY: Colorado Springs, CO

The city of Colorado Springs, Colorado traffic signal timing team studies 30-40 arterial streets each year to determine optimal traffic flow coordination.[7]  In 2005, the city released the Traffic Signal Coordination Planning Effort Report that describes the potential upgrades and new technologies the city could adapt to minimize traffic.[8]

In the report the city recognizes the potential time and cost saving benefits traffic flow management can have.  “Each dollar spent optimizing signal timing and implementing system improvements can yield up to $40 in fuel savings.”  “As national studies indicate, coordinating previously uncoordinated signals can result in a reduction in travel time ranging from 10% to 20%.  According to our own recent studies conducted along Academy in February, there is a 10% to 30% improvement in travel times resulting from coordinated signals.”

The key systems Colorado Springs uses to coordinate their traffic flow include:

  • Communications Links to Signals

  • Traffic Signal Controller Equipment

  • Advanced Traffic Detection System

CONTACT

Traffic Signal Timing Team

(719) 385-5966

Trafficeng@springsgov.com

High Efficiency Street Lighting

According to a review conducted by the California Energy Commission, street lighting accounts for as much as a quarter of a municipality’s electric bill.[9]  The choice of what kind of street lighting to use affects the city budget as much as it influences the city’s ambience.  New technologies in lighting provide more efficient ways to effectively illuminate neighborhoods and public spaces.  The quality and brightness of street lighting does not need to be compromised in order to significantly reduce the amount of electricity consumed.

High Pressure Sodium Lamps

High pressure sodium lamps (HPS) are a very popular option for municipal street light systems across the country. HPS lighting is 57% more efficient than incandescent street lamps and 32% more efficient than mercury vapor lamps.  HPS lamps produce 90-150 lumens per watt[10](compared to 30-48 lumens per watt in mercury vapor lamps).[11]  HPS street lighting systems have a payback period of about six years compared to mercury vapor lamps.[12]  However, the orange-yellow light produced by HPS lamps does not contain light in the blue spectrum, diminishing people’s ability to use peripheral vision at night.  It also does not render colors as well as other lamp types.

Low Pressure Sodium Lamps

Low pressure sodium lamps (LPS) are even more energy efficient than HPS lamps.  They were designed to operate at low temperatures and maintain luminance throughout the lamps’ lifetime.  The light produced by LPS lamps is a dull yellow color, does not allow for effective peripheral vision, and does not render colors well.  It is the lighting of choice around observatories since the monochromatic light can be filtered by telescopes.  LPS color limitations make it difficult to use.  Therefore, the intensity of sodium lamp lighting levels may need to be adjusted to perform as well as lower wattage, wider spectrum white lighting.

Metal Halide Lamps

Metal halide lamps use an electric current that passes through a gas to create light.  The bright white light is very effective for rendering colors at night and does not adversely affect peripheral vision.  Metal halide lamps produce large amounts of heat and can burn out quickly.  The brightness of the lamps also creates a high potential for glare.  Metal halide lamps are twice as energy efficient as the mercury vapor lamps they replace.  Metal halides require 60-100 lumens per watt and last on average 10,000-15,000 hours.[13]

Induction Lighting[14]

Induction lighting uses the energy from a magnetic field combined with a gas discharge to create light.  It is very energy efficient, has a long life, and produces a high-quality white light.  While the other lamp types last on average between 10,000-30,000 hours, the induction lamp has a100,000-hour life span.  Because it is a relatively new technology, induction lighting still has a high upfront cost.  The greater efficiency and lower maintenance costs can help to offset the additional cost of the system over the life of the bulbs.

 

Pros

Cons

MERCURY VAPOR

Inexpensive to install and purchase

Medium life

Dimmable

Good color rendering due to white light

Expensive to operate due to inefficiency

Tend to be glary due to intense light

Dramatic lumen depreciation over time

Use hazardous material (mercury)

HIGH PRESSURE SODIUM

Energy efficient

Widely used, reliable

Medium life

Orangish-yellow light

Safety concerns due to color rendition

Cannot restrike immediately

LOW PRESSURE SODIUM

Very energy efficient, medium life

Minimum glare

Able to restrike immediately

Do not attract most insects

Orangish-yellow color

Safety concerns due to color rendition

Expensive fixtures

METAL HALIDE

Good color rendering

More efficient than mercury vapor

Widely used

Short life, high maintenance

Less efficient than HPS, LPS and Induction

High temperatures burn out ballasts

INDUCTION LIGHTING

Energy efficient

Low maintenance costs due to long life

Good color rendering due to white light

Immediate ignition & re-ignition

No flickering

High initial cost

Difficult to retrofit existing fixtures

Use small amounts of mercury

Not dimmable

Need a high-frequency generator

Table: The Pros and Cons of Lamp Options [15]

 

Lamp and Light Fixtures

A significant factor in the efficiency of a street lighting system is the orientation and design of the lamp and light fixtures.  By focusing light in the direction it is most needed, a light fixture can decrease the total amount of light needed.  Additional factors affecting a light fixture’s overall efficiency include the lamp’s height, the distance between poles, and the fixture’s cutoff angle.  The most efficient streetlight design is the full cutoff fixture since it does not waste light into the night sky.