1. Roadway Lighting Database
Multi-State In-Situ Roadway Lighting Measurement Data
Virginia Tech Transportation Institute (VTTI)
Federal Highway Administration (FHWA)
Highway Safety Information System (HSIS)

2. On One Hand… Nighttime safety needs improvement
About 25% of vehicle miles traveled (VMT) but 50% of traffic fatalities at night
About 36,000 traffic fatalities in 2014 during nighttime, dawn, and dusk
Roadway lighting is commonly considered an effective safety measure
Many previous studies pointed to a positive safety impact with the presence of lighting.
Other considerations
Driver comfort, security, roadway aesthetics…
Light or not light a roadway is a dilemma policy makers frequently face. On one hand, a number of factors suggest that it is imperative to have sufficient lighting on roadways.
More than half of the traffic fatalities occur during night even though nighttime traffic represents only 25 percent of the total travel on the nation’s roadway system.
References:
Traffic Safety Facts 2012 – A Compilation of Motor Vehicle Crash Data from the Fatality Analysis Reporting System and the General Estimates System. National Highway Traffic Safety Administration, U.S. Department of Transportation. Accessed 02/01/2014.
Highlights of the 2001 National Household Travel Survey 2001, BTS03-05, Bureau of Transportation Statistics, U.S. Department of Transportation, 2003.
Fatality Analysis Reporting System (FARS).

3. On the Other Hand… Funding shortages at state transportation agencies
Many states currently face budget deficits
The nationwide transportation funding shortage is estimated at $94 billion per year
More areas (e.g., maintenance, operations, new facilities) competing for state resources
Energy conservation and carbon reduction
Roadway/street lighting electricity = 1.9 million households
Roadway/street lighting greenhouse gas emissions = 2.6 million cars
On the other hand, transportation agencies frequently feel the pressure to minimize roadway lighting to conserve energy and costs, and to meet EPA carbon emission reduction goals.
In its 2013 study, “Report Card for America’s Infrastructure,” the American Society of Civil Engineers (ASCE) estimated that roughly $3.6 trillion in total investment is needed by 2020 to return the nation’s facilities to good repair, which ASCE defines as safe and reliable with minimal capacity issues and minimal risk. Based on this study, the nation’s surface transportation systems are facing a funding gap of about $94 billion per year under current projected spending levels.
The DOE has also estimated that 26.5 million streetlights in the US consume as much electricity each year as 1.9 million households, and generate greenhouse gas emissions equivalent to that produced by 2.6 million cars.
References:
Solid State Lighting: LEDs for Street Lighting – Here Today. Document DOT/EE-1059, Building Technologies Office, U.S. Department of Energy, November 2013.

4. The Lighting Dilemma To light, to not light, and those in-between
Continuous lighting on urban freeways
Minimal lighting at complex roadway locations
Do not own, maintain, or operate any lighting
Guidelines
National: AASHTO, IES, and FHWA
State lighting design manuals and guidelines
Analysis and decision making tools???
Currently, states vary significantly in lighting practices across the country. Many states recognize the importance of roadway lighting and add continuous lighting on many urban freeways. Some others only light critical locations of freeways (e.g., interchanges) believing that continuously lighting does not provide significant safety benefits. The remaining states, however, do not own, maintain, or operate any roadway lighting.
There is a variety of lighting design guidelines used nationally. Many states have entirely or partially adopted the Roadway Lighting Design Guide developed by American Association of State Highway and Transportation Officials (AASHTO) in The guide book includes detailed warrants for the use of lighting, among which are those for continuous lighting of freeways in urban areas. The latest national roadway lighting guide is the Roadway Lighting published by the Illuminating Engineering Society (IES) in 2014 that provides updates to its earlier version of Roadway Lighting and the AASHTO lighting design guide. In addition, the FHWA also published the FHWA Lighting Handbook in 2012 to assist states roadway lighting design and application. Many states have also developed their own design policies in roadway lighting.
References:
AASHTO Roadway Lighting Design Guide. American Association of State Highway and Transportation Officials, 2005.
FHWA Lighting Handbook. Publication FHWA-SA-11-22, Federal Highway Administration, Accessed 01/23/2016.
Roadway Lighting. ANSI/IES RP-8-114, Illuminating Engineering Society of North America, 2014.

5. Roadway Lighting Database
FHWA project Strategic Initiative for Evaluation of Reduced Lighting on Roadways
Optimal times and conditions for reduced lighting
Appropriate lighting levels for various roads and road features
Approaches for reducing lighting
Energy savings and reduction in greenhouse gases
Potential legal implications
VTTI collected in-situ lighting measurements and imagery data for 2,000+ miles of roadways
Roadway lighting database is now part of HSIS
The Federal Highway Administration (FHWA) funded the project “Strategic Initiative for Evaluation of Reduced Lighting on Roadways” (FHWA Project DTFH61-13-D-00018), to update Reduced Lighting on Freeways during Periods of Low Traffic Density (Publication No. FHWA-RD ), and to develop application guidelines that address the following issues:
Optimal times and conditions for reducing lighting.
Appropriate lighting levels for various roads and road features.
Appropriate approaches for reducing lighting.
Energy savings and reduction in greenhouse gases that may result from reducing lighting.
Potential legal issues related to reducing lighting, including the development of such issues since the release of the original report.
As part of the FHWA project, the Virginia Tech Transportation Institute (VTTI) collected in-situ lighting performance data on sample roadways in seven states including California, Delaware, Minnesota, North Carolina, Vermont, Virginia, and Washington. The lighting performance data were collected as part of the FHWA project to enable detailed lighting-related analyses in support of the aforementioned project objectives.
FHWA is making this lighting performance data available through the Highway Safety Information System (HSIS). This document provides detailed metadata information about the lighting performance data files. Note: most safety studies involving lighting data require other types of data as well, such as roadway data, traffic data, crash data, and/or weather data. Users should contact state and/or federal transportation agencies to request the latest versions of these datasets.

6. Other Freeways and Expressways Other Principal Arterial
Data Coverage
Roadway Type CA DE MN NC VA VT WA
Total
Interstate
160 41 68
167
372 22
151
981
Other Freeways and Expressways 77 27 59 61 7
101
359
Other Principal Arterial 31
155 51
102 47 98
490
Minor Arterial -- 30 52 25 28
232
Major Collector 9 26 16
269
153
317
613
100
394
2,114
Note: Freeway miles measured by direction
This table shows the roadbed miles where data was collected by state and by roadway type. Divided freeways are measured for separate roadbeds (i.e., by direction).

7. Lighting Data Collection
Lighting measurements collected for 7 states between late 2011 and early 2013
Each data collection conducted between 10:30PM – 3:30AM
lighting measurements collected at a frequency of 20 Hertz (Hz) (= 4.4-ft spatial resolution at 60mph)
Imagery files collected at a rate of 3.75 frames per second (fps)
Measurements collected for both the right-most and left-most lanes

8. Why Important
Multi-state scale in-situ, high-resolution lighting measurements made available first time
Enable a wide range of nighttime safety and roadway design related analyses
Potential in optimization of lighting design guidelines with actual field data
Provide a powerful tool for lighting-related decision and policy making
The roadway lighting database contains in-situ roadway lighting measurements on major roadways in seven states across the nation. This is first time such a massive roadway lighting measurement database becomes available to the public.
With the actual lighting measurement data available, transportation agencies and researchers can now conduct a wide range of nighttime safety analyses. Previously, researchers commonly use lighting as a binary variable (i.e., with versus without) in most safety analyses due to limited data availability. With the roadway lighting database, researchers can now analyze the relationship between safety and detailed lighting characteristics. In addition, lighting-related analyses that previously relying on simulated lighting data now can be improved with actual field lighting data.
The availability of the roadway lighting database enables further improvement of the current roadway lighting design guidelines, which are mostly developed based on limited lighting data. Particularly, the roadway lighting database makes it possible to understand exactly where lighting is needed and how much lighting is needed to ensure safety. This knowledge is critical to decision makers at transportation agencies to, improve nighttime safety, optimize agency resources, and meet energy and environment related goals.

9. Why Important Lighted Without Roadway Lighting Database
Light poles?
Lighted
With Roadway Lighting Database
Measured lighting level
Previously, analysts consider a roadway segment lighted when they know there is light presence. Now, people can actually know exactly how much light a spot on the roadway segment has. This figure is an example of the measured lighting levels on a freeway corridor. The yellow dots are where the measurements were taken and the size of the dots represents the relative lighting levels.

10. Set Priorities RLD in state safety planning
More accurate Crash Modification Factors (CMFs) in the Highway Safety Manual process
RLD in individual safety improvement project decisions
Better understanding how lighting improve safety with specific roadway/traffic configurations
Better understanding of lighting impacts leads to better informed investment priorities
Roadway lighting database can help the state safety planning process. For example, using roadway lighting database, states may develop more realistic and state specific crash modification factors (CMFs) to use during the highway safety manual (HSM) based safety planning process. CMFs are indicators of crash rate reductions due to the implementation of a traffic control measure or a combination of traffic control measures (in this case, the use of roadway lighting).
Roadway lighting database can also be an effective tool for project-specific decision making relevant to lighting improvements. When used in conjunction with specific roadway and traffic data, decision makers can better evaluate if lighting is an effective safety treatment for the specific roadway and traffic settings in question.
With more accurate understanding of the safety impacts of roadway lighting, agencies can now more better informed decisions relevant to the priority of a lighting related investment comparing to other investments.

11. Improve Current Lighting Design
Studies using RLD may provide insights for:
Where lighting should be used (e.g., lighting warrants for roadway and traffic conditions)
How much lighting is needed (illuminance/ luminance design criteria to ensure safety)
How lighting should be used with other traffic control measures (e.g., combining signs, markings, and lighting)
Provide basis for adaptive lighting
Making lighting decisions on a real-time basis based on traffic conditions
The roadway lighting database enables studies with outcomes potentially result in more realistic lighting design guidelines such as:
Lighting warrants: where and when lighting should be used. For example, should all traffic lanes be lighted? Is continuously lighting necessary? Which areas at a given roadway location needs to be lighted?
Improvements to existing lighting design criteria: minimal lighting levels and lighting uniformity required for specific roadway and traffic conditions.
Knowledge from studies using the roadway lighting database (or other similar data) can also result in guidelines for adaptive lighting, enabling agencies to develop lighting systems that change lighting characteristics on a real-time basis based on traffic conditions.

12. Target Audiences and Users
Federal transportation agencies
FHWA, NHTSA, etc.
State and municipal transportation agencies
Transportation-related researchers and consultants
Other potential audience
Institute of Transportation Engineers
Illuminating Engineering Society of North America
International users

13. Data Submission Users are encouraged to contribute to RLD
Field lighting measurement data
Lighting design and/or infrastructure data
General considerations when contributing data
If the data can be integrated into the roadway lighting database
Is the data valuable to other transportation agencies and researchers
FHWA encourages the submission of additional roadway lighting data by other stakeholders including particularly state/local agencies and individuals conducting work for such agencies to further improve the database. Users may submit similar field lighting measurement data, lighting infrastructure data, and/or lighting design data. A data submittal should include detailed and accurate metadata.

14. For More Information Ron Gibbons (VTTI, RGibbons@vtti.vt.edu)
Craig Thor (FHWA,
Joe Cheung (FHWA,
Forrest Council (HSIS,