Lighting Research Center Lighting Research Center

Traffic Signals Roundtable

John Bullough, Kun Michelle Huang and Kathryn Conway

Executive Summary and Afterthoughts: LED Research Issues and Options Roundtable

JUNE 5, 1998
Pacific Energy Center, San Francisco, CA

Sections 1-7 summaries, afterthoughts and suggested actions; list of attendees; new bibliography items.

1. Codes and Specifications

Participants acknowledged that codes and specifications should have a strong link to research on visibility and response time, and be written as performance specifications, not technology specifications-but some need to act now, and cannot always wait for a thorough investigation. Furthermore, nearly all the participants agreed that harmonization of codes is beneficial. Again, some cannot wait for the ANSI/ITE consensus process; they feel that it is far too slow for a rapidly evolving market.

Several participants pointed out that the proliferation of specifications could also lead to some good ideas, which then could be incorporated into other specifications. Many of the municipalities developing local specifications do contact other jurisdictions to find out what they have included in their specifications and testing methods. This networking does not always lead to harmonization, though. For example, a city might adopt a different specification than its surrounding county.

Suggested Actions

1.1. Follow up with most of the participants to find out more details about their projects and products. (LRC)

1.2. Gather more procurement notices, specifications, testing and qualification procedures. Compile a table to compare the criteria in the specifications, and the methods of testing. Separate technology criteria from performance criteria. Compare criteria to published research results, if any. (LRC)

1.3. Outline a timeline for various organizations' activities. Indicate ITE/ANSI comment and consensus milestones, deadlines for responses to procurements, and utility or other program deadlines. Post on LRC web site. (LRC)

2. Energy Efficiency

System efficacy seems to be of less interest to those participants who are actually purchasing and installing signals than it is to researchers, sponsors, manufacturers and energy conservation advocates. Evidently the relatively low input power of LEDS compared to the conventional incandescent lamps that they replace is compelling, given the other benefits of LEDs. Some participants expressed a concern about newer red LEDs that they believe "are too bright at night." A few participants are interested in off-grid PV applications, and also in battery-operated emergency operation modes, where low power demand is critical. Overall, though, cost is of far more importance to the participants than is energy efficiency.

Suggested Action

2.1 Address the development of the system efficacy definitions and lamp-to-lamp comparisons to a different audience, such as the Illuminating Engineering Society, or the CIE. (LRC and other researchers.)

3. Cost

This is obviously the greatest barrier to wider acceptance and installation of LED traffic signals, and to the development of new products. Concern about the first cost of green signals was greatest, followed by some concern about amber. Most seemed optimistic that the costs of red LEDs would continue to decrease, while performance would increase. Each organization seemed to have its own definition of "cost." Many were eager to coordinate their procurements, in order to aggregate the demand, and thus help lower the costs for all.

Traffic signal manufacturers challenged the LED manufacturers to lower costs, so they could offer better prices to their customers. As Gary Fernstrom notes, "Cost is high while the production volume is relatively low. Developing and providing information on visual acuity, if it results in lower luminosity (sic) requirements as we expect, clearly falls into the realm of public policy energy efficiency as it would lower the first cost barrier to greater adoption of red, but especially green and yellow LED lamp systems."

Lowering first cost is a difficult challenge involving the balance of supply and demand both of components and of finished products. Advocacy or buyers' groups may have the organizational means needed to work on this challenge. Large-scale procurements definitely have an impact on first cost, if they lead more buyers into the market. For example, after the roundtable, the LRC learned that the International Energy Agency is launching a new procurement project for LED traffic signals. The timeframe is twelve to eighteen months until the IEA announces the terms of the procurement.

Suggested Actions

3.1 Share available life cycle cost spreadsheets or calculators. If the developers are willing, they could post their spreadsheets on the web, or offer to send copies to interested parties. (Participants)

3.2. Look at life cycle costs more closely and consistently, possibly developing some projections for other benefits, such as the possibility of smart LED signals helping to decrease pollution from idling vehicles. (Participants, particularly ACEEE or CEE).

4. Visibility

This is the area that seems to call for the greatest research effort. Most participants are making decisions without adequate information about signal performance and human response. Many questions were raised, and a great deal of concern was expressed about liability and avoiding risk. Little was known about research efforts from other continents, but participants speculated that Europe and Japan might have relevant information used in those countries to justify lower intensity requirements. Some LRC research conducted in parallel to that being conducted by ITE (through NCHRP and Westat) was strongly encouraged by the participants, especially if results could be provided sooner than fall of 1999. Darcy Sullivan of ITE noted that complimentary findings could greatly strengthen and expedite the standards approval process. Interest was also expressed by participants for relating the results of visibility research to life safety and accident data, such as that collected by the Insurance Institute for Highway Safety.

Suggested Actions

The LRC will write two proposals, and seek additional funding for the projects described below. Organizations interested in providing ideas and funds to support this work should contact Kate Conway at the LRC.

4.1 The first proposal is for short-term work to establish human response to a range of luminous intensity values for red, yellow and green signals, first in a "best case" total darkness condition, and later in "worst case" conditions of glare, or competing background signals. These experiments will first be conducted with subjects with normal vision abilities, and later could be conducted with subjects with color vision deficiencies. This project will include a literature review and interviews conducted with U.S. and overseas researchers and standards organizations. PG&E and HP have provided funds for the first phase of this project to the LRC so that the experiments can be designed and initiated this summer. The LRC is seeking support for further experiments. (LRC)

4.2 The second proposal will be for longer-term research, to evaluate designs for radically new traffic and other signals or outdoor lighting applications that could optimize both visual and energy performance, and offer innovative control integration options for "smart" roadway systems. For example, the City of Philadelphia and several partners have initiated a project for PV-Powered LED Lighting. (LRC; any and other interested parties)

4.3 Some organization may want to pursue a means of collectively lowering, or underwriting, the risk of adopting the new LED signals. (Volunteers step forward!)

5. Operation: Power and Environment

Utilities had differing points of view on the importance of power factor in LED signals; the difference lies in their rate schedules for customers. For some, it is irrelevant because the devices draw less power than is measured by their meters. For others, it is important as a matter of principle, or because they have more sensitive metering devices.

Many participants pointed out the need for good power quality characteristics for any signal that interacts with sophisticated controls. Power factor also is a more critical issue for signals designed to be operated by batteries.

Evidently several participants have already conducted environmental operating tests of LED traffic signals, and have some "rules of thumb" that they use regarding performance at various temperatures; some even have devices that they developed to measure performance (luminous intensity) in field conditions.

Suggested Actions

5.1 Contact those participants who have conducted testing to see if they would share results and testing protocols with the LRC and the other participants. Pool the data in a common format, if possible. Encourage consensus on a common method of testing for each characteristic. (LRC and others)

5.2 As the market progresses, consider convening a more focused workshop just for technical staff from utilities, transportation agencies, and LED signal and controls manufacturers, to encourage coordinated development of new products. (LRC and others)

6. Other Applications

The LED market does seem to be developing very rapidly, more at the pace familiar to the semi-conductor industry, rather than the (slow) pace common in the lighting industry. With assurances from the LED manufacturers that product supply will keep up with demand, more products will be introduced with increased efficacy, and lower cost green, and blue and white packages will be available within several years, it appears that using objective information to draw attention to LEDs could help coordinate and spur innovation in the luminaire industry. However, the luminaire market players are far more disjunct than even the traffic/roadway market players are.

Suggested Action

6.1 The participants' organizations seem very open to cooperating, sharing information publicly, and not duplicating efforts. The LRC will continue to network, and work with its sponsors to identify the strategic activities best matched with the LRC's expertise and available resources. All participants are encouraged to stay in touch, bring other interested organizations into this discussion, and to coordinate efforts. A list of participants is included in this summary.

7. Market

The evolution of the red-replacement traffic signal market is rapid, but other replacement colors and development of innovative signals are being held back by cost and performance concerns. Supply and demand concerns soon could be adequately addressed, so long as open dialogue continues amongst the key players. Saturation of the traffic signal market clearly would be hastened by adoption of federal and international standards. This saturation point could coincide with the introduction of LEDs in other applications, if efforts by manufacturers and other innovators are coordinated. So far, enthusiasm and field experiences with LED signals has been shared freely amongst some of the participants; however, as the market opens up further, these early adopters may be less able and willing to share their time with more people. This opens opportunities for market transformation organizations to serve the public in an information delivery and coordination role.

Suggested Actions

7.1 With support from PG&E and HP, the LRC plans to expand its Lighting Transformations web pages ( to include several sections on LEDs, with links to the sponsors, to manufacturers, and to other organizations conducting LED programs. The pages will provide objective information and updates as a public service benefit. They will include an interactive area for comments from visitors, and if enough information is available, also include a matrix comparing the characteristics and requirements found in various organizations' specifications, and a timeline or calendar of LED traffic signal activities, programs, and procurement bid deadlines. (LRC; other organizations are encouraged to suggest relevant links and to provide specific information about their own programs.)

7.2 Encourage additional, but coordinated, market transformation activities through CEE, ACEEE, NEEA, US DOE, US EPA, NYSERDA, and any other market transformation. For example, Gary Fernstrom has suggested that it might be appropriate for PG&E to work with co-sponsors or contractors "to survey local traffic authorities to see what they need to move forward. The barriers might be cost/sources of capital, lack of standards, lack of information, etc. We then could develop a public policy program to work within the market to help eliminate those barriers. This tactic could be replicated through CEE by interested utilities around the country." (PG&E, CEE, ACEEE or others)



Executive summary/afterthoughts prepared by Kathryn M. Conway with contributions from Michelle Kun Huang, John Bullough, Gary Fernstrom and Jim Leising. The LRC wishes to express its appreciation to the participants for a very productive workshop, and to the sponsors for their leadership in this market transformation effort. --June 16, 1998.


  • Ray Deese - Electro-Techs, CA
  • Claude Demers - Ecolux, Inc., Quebec, Canada
  • Susan Draa - California Energy Commission, CA
  • John Dunlap - Washington Water Power, WA
  • Andy Eckman, Northwest Energy Efficiency Alliance, OR
  • Jan Lucas Hagreis - LumiLeds Lighting B.V., Netherlands
  • Marc Hoffman - Consortium for Energy Efficiency, MA
  • Sam Koch - El Dorado County Department of Transportation, CA
  • Lucy Labruzzo - New York Power Authority, NY
  • Marc LaFrance - US Department of Energy, DC
  • Virginia Lew - California Energy Commission, CA
  • David Liu - City of Roseville, CA
  • Jerry K. Lo - City of West Sacramento, CA
  • John Luoma - Illinova Energy Partners, NV
  • Stephen Prey - Caltrans, CA
  • Michael Schneider - Traffic Signal Field Supervisor, Las Vegas, NV
  • Michael Siminovitch, Lawrence Berkeley National Laboratory, CA
  • Michael Stewart - Nichia America Corporation, CA
  • Stephen Stinson - Sacramento Municipal Utility District, CA
  • Darcy Sullivan - Institute of Traffic Engineers, TN
  • Margaret Suozzo - (via phone) American Council for an Energy Efficient Economy, TX
  • Jennifer Thorne - American Council for an Energy Efficient Economy, DC
  • James E. Walker - Lighting Sciences, Inc., AZ
  • Don Winans - Boca Flasher, FL


  • David Evans - Hewlett Packard
  • James Leising - Hewlett Packard
  • Dave O'Brien - Hewlett Packard
  • Peter Turnbull - Pacific Gas and Electric
  • Gary Fernstrom - Pacific Gas and Electric
  • Marty Chetaitis - Pacific Gas and Electric

Lighting Research Center (LRC):

  • Kate Conway
  • John Bullough
  • Kun (Michelle) Huang

Additional Bibliography

Bullough, John, Michelle Huang and Kathryn Conway. 1998. Optimizing the Design and Use of Light Emitting Diodes for Visually Critical Applications in Transportation and Architecture: Research Issues and Options. Troy, NY: Lighting Research Center, Rensselaer Polytechnic Institute. May 22, 1998.

European Committee for Standardization, Central Secretariat. 1997. Traffic control equipment: signal heads and poles. (Draft) European Standard CEN/TC 226/WG 4 N 211 E. Brussels, Belgium.

Murray, I.J., S. Plainis, K. Chauhan and W.N. Charman. 1998. Road traffic accidents: The impact of lighting. The Lighting Journal. May/June 1998, 42-46.

Nakamura, Shuji. 1998. Blue lasers meet tough commercial requirements. Photonics Spectra. May 1998, p. 130-135.

Retting, Richard A., Robert G. Ulmer, and Allan F. Williams. 1998. Prevalence and characteristics of red light running crashes in the United States. Arlington, VA: Insurance Institute for Highway Safety. May 1998. (

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