Tunnel lighting has long been accomplished using incandescent, fluorescent and High Pressure Sodium lighting technologies. Each of these types of lights have their own advantages and disadvantages. In the last decade, Light Emitting Diode (LED) systems have advanced to a level that economically allows their widespread use in tunnel facilities. While their use has become more widespread in roadway lighting, challenging conditions within tunnels have tempered their acceptance for underground application. Brightness, color, and dispersion of light from LEDs each affect the utility of the lamps. While Roadway and Tunnel Lighting share similar needs, they also each have their own challenges. The enclosed space of a roadway tunnel can accentuate both the positive and negative qualities of a particular light type. This study focuses on tunnel lighting, which differs significantly from roadway lighting. Tunnel lighting was specifically excluded from the ongoing NCHRP Project 05-22: Guidelines for Solid-State Roadway Lighting
The capital cost of LED lighting initially made its use prohibitive when compared to other more energy and maintenance intensive lighting. However, LED costs have dropped very rapidly in recent years, and generally, it is economically competitive with other technologies especially when maintenance frequency and life cycle costs are included. With the rapid advancement and changes in LED technology, it is necessary to study how this new technology of lighting can best be used to meet existing lighting standards and requirements. The rapid advancement of technology has also resulted in obsolescence of early installations of LED systems-forcing owners to retrofit systems well before the end of their expected life because of lack of available replacement parts. The tunnel environment presents unique challenges, both in lighting performance and in reliability. Road salt, constant moisture, and the proximity of the equipment especially when maintenance frequency and life cycle costs are included.
The objective of this project is to develop a guidelines with on the applicability of LED lighting for tunnel use. The guidelines shall include a catalog the various types of LED lighting techniques commonly available and identify benefits and challenges with each when used to light tunnels including associated cost and maintenance. The guidelines shall also include a set of recommendations on what will be needed for LED tunnel Lighting for future adoption into the AASHTO Lighting Design Guide 2018.
Task 1. Conduct a literature review of relevant domestic and international research, guidelines, and current practices to determine the current state of knowledge on (1) the performance of actual LED lighting installations and (2) cost and maintenance of LED tunnel lighting.
Task 2. Conduct a survey of tunnel owners and other stakeholders to collect data related to the research objective. Follow-up with participants as needed. The survey plan, including questions and participants, shall be submitted to the NCHRP for review and approval prior to distribution.
Task 3. Synthesize existing practice and issues. Prepare an outline of the proposed guidelines, including discussion of the contents and intent.
Note: Submit a draft of the synthesis and detailed outline no later than 4 months after contract award. NCHRP approval will be required before proceeding with the remaining tasks.
Task 4. Analyze the energy and maintenance costs of a sampling of various legacy lighting technologies, and compare them to the life cycle costs of installing, operating and maintaining a replacement LED system. This life cycle analysis should include electrical supply, driver circuits, and the LED itself.
Task 5. Identify existing LED systems that are generally used on roadways and tunnels, and evaluate their effectiveness on roadway-regardless, as to whether they are feasible in tunnels. From the list of effective systems, identify those that could be used in tunnels, and develop a list of best practices for their use in tunnels. Identify any shortcomings that exist in available LED systems, and provide recommendations to improve these shortcomings.
Task 6. Develop the draft guidelines according to the approved outline. Submit the draft of the proposed guidelines no later than 4 months after the Task 3 approval.
Task 7. Review and proposeed revisions to the AASHTO Lighting Design Guide with respect to tunnel lighting.
Task 8. Revise the draft guidelines and proposed revisions to the AASHTO submitted in Tasks 6 and 7 according to the NCHRP comments.
Task 9. Present the recommended guidelines to the AASHTO Committee on Bridges and Structures, Technical Committees: T-20 Tunnel and the AASHTO subcommittee on Roadway Lighting.
Task 10. Submit a final report describing the entire research effort including the guiltiness and the proposed revisions to the AASHTO Lighting Design Guide. Following receipt of the draft final report, the remaining 2 months shall be for NCHRP review and comment and for research agency preparation of the revised final report.
STATUS: Research in progress