Research Project Information

Research Project Summary Information

Guide for Optimizing the Effectiveness and Efficiency of Roadway Lighting(21151)

Rensselaer Polytechnic Institute


Lighting is an important element of roadway safety. Evidence suggests that roadway lighting is usually associated with reductions in nighttime crashes. After several decades of relatively slow and gradual change, light source technologies for roadway lighting are now evolving rapidly. Many new options for roadway lighting are available, and there is more information about how light interacts with the human visual system. The informational Guide developed under this project provides some information about these developments, and how they might be incorporated into lighting practices for several types of roadways and locations in New York State. The focus is on replacement of older roadway lighting systems near the end of their useful lives, and on maintaining or improving visibility and safety while minimizing energy use and associated costs.

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Project Description

In this project, the Lighting Research Center (LRC) at Rensselaer Polytechnic Institute synthesized the work it has done in developing recommendations for roadway lighting using the unified system of photometry for mesopic (nighttime) vision. The LRC has also produced a simple Guide that can be used by traffic and roadway lighting engineers in New York State to develop replacement recommendations for existing high pressure sodium (HPS) lighting systems with light sources better attuned to drivers’ and pedestrians nighttime visual requirements.


Lighting along roadways and highways serves a primary purpose of safety by supporting visibility of pedestrians, vehicles and other potential hazards for drivers. In New York State, an estimated 1.1 billion kilowatt hours (kWh) of electricity per year are currently used for roadway lighting: the equivalent to burning approximately 320,000 tons of coal, and corresponding to the production of about 740,000 tons of CO2, 6200 tons of SO2, and 2700 tons of NOX compounds. While precise quantification of the potential safety benefits of roadway lighting is difficult, lighting does appear to provide tangible reductions in nighttime crashes, particularly at intersections and in locations where pedestrians are commonly found. The New York State Department of Transportation (NYSDOT) Highway Lighting Policy includes criteria for lighting such locations with non-continuous lighting systems located only at intersections and crossings, as opposed to continuous lighting systems that delineate the entire length of roadways.

Project Results

A review of published literature and a survey of engineers from New York State and local transportation agencies were conducted. Based on this information, as well as data on new light source technologies, a series of roadway types for inclusion in the guide were selected, and recommendations for roadway lighting system replacement were developed. A number of new light sources producing “whiter” light than the incumbent HPS technology used on most roadways has been developed and significantly improved in the past decade. Using these technologies, in combination with recent information about driver and pedestrian vision under nighttime conditions, could result in energy savings for different roadway types. The Guide contains pointers to information about lighting policies, practices, technologies, and visual efficacy that could assist lighting decision-makers with other, potential scenarios, not specifically covered in the guide.


Rensselaer Polytechnic Institute
Research Adm & Finance, 4th Fl West Hall 110 8th Street
Troy, NY 12180

Principle Investigator

John Bullough

Universities Involved

Rensselaer Polytechnic Institute


Project Type:

Information Dissemination

Technologies Types:


NYSERDA Contact Information

Joseph Tario


R&D -Transport & Power Systems

Contract Details

Start Date: 4/27/2011
Project Status: Active
Contract Number: 21151

Last Updated: 8/20/2012