Abstract
Streetlights have performed well for drivers and vehicle visibility, and LED streetlight luminaires, with their brighter illumination, have increased that visibility. Unfortunately, streetlighting for pedestrians has not been a high priority and LED streetlights exacerbate the problem with their directional light throw and higher contrast characteristics. It is possible to stand behind an LED streetlight pole, for example, and not be seen. LED streetlights’ directional lighting compromises a driver’s ability to detect vertical objects because the light is narrowly focused down with little horizontal light scattering often places pedestrians in silhouette. Increasing intersection illumination for greater driver visibility reduces pedestrian visibility.
This project is focused on creating---and ultimately automating---better pedestrian lighting at roadway intersections where pedestrian visibility is critical. Three items are proposed: (1) Control of LED luminaires’ individual array diodes to improve crosswalk visibility, (2) luminary positioning for optimal driver visibility of pedestrians in crosswalks and at intersection sidewalks, and (3) synchronization of the proposed PedX system with Safety21’s PedPal app at intersection streetlights. PedPal’s PI, Stephen Smith, will serve as an advisor to ensure proper system integration.
(1) Diode Control: LED streetlight arrays illuminate each diode equally when the luminaire is activated and perform equally when dimmed. The lumen intensity is equal at the light source and object illumination decreases depending on distance from the luminaire. Streetlights located at intersection corners are brighter across the intersection and fade outward toward oncoming drivers. Given diodes’ directional properties, pedestrians are either lit from top down or backlit the closer they are to the luminaire. By independently controlling the number of lumens produced by each diode, the source light can be selectively increased to highlight pedestrians in the crosswalks and automatically maintained year-round throughout the dusk-dawn cycle.
(2) Streetlight Positioning: Streetlights are often atop the same pole that holds the traffic signal(s) with the luminaire positioned on the intersection’s diagonal axis or orthogonally in line with the signal arm. Pedestrians are either lit from the center of the intersection or in line with the pedestrian’s front/backside, not from the side as viewed by drivers. While they provide high visibility for drivers making turns, they cast pedestrians in shadows or silhouettes to oncoming drivers. In combination with diode control, positioning the luminaire is critical to good pedestrian illumination.
(3) Smartphone Application: PedPal is an app for pedestrians requiring assistance crossing intersections. PedPal provides pedestrians with intersection information, including crossing options and signalization sequencing, notifies the signal controller of intent to cross and the person’s walking speed/traversal time, sets the signalization time for safe passage, and notifies the pedestrian when to cross. Working with the PedPal research team, the study will coordinate crosswalk lighting with the app and signalization.
We expect this work to span two years, with the initial year (this project) dedicated to establishing the feasibility of the three outlined objectives. The subsequent year will concentrate on the development of a prototype for deployment and extensive field testing.
Description
Timeline
Strategic Description / RD&T
The US DOT promotes transportation systems where serious injuries and fatalities are eliminated (p. 5). This project aligns closely with the US DOT strategic goals by leveraging new technology for safety, considering human factors, focusing on safe design, employing a data-driven approach, and adopting a multidisciplinary strategy (Table 1, p. 11). This project addresses these concerns by focusing on pedestrian safety at urban intersections, a critical area where transportation-related fatalities and injuries occur.
One US DOT priority is to leverage innovative technologies to monitor, predict, and plan ways to reduce injuries/fatalities among the traveling public (“Safe Technology,” p.19). The proposed project’s use of advanced control systems for LED streetlight luminaires and its integration with the PedPal app aligns with this goal. By controlling the lighting intensity and position, the project aims to enhance pedestrian visibility at intersections, directly contributing to reduced risks of accidents.
The US DOT emphasizes the importance of safe design and evaluation of infrastructure design to develop effective safety countermeasures (“Safe Design,” p.19). The proposed project’s focus on the optimal positioning of streetlights and the design of a responsive lighting environment using PedPal data fits into this category. It represents a practical application of safe design principles in urban infrastructure.
The US DOT prioritizes data-driven system safety, emphasizing the need for research and data to understand systemic causes of transportation safety challenges (Table 1, Table 3, p.18). This project will generate valuable data from field tests and simulations that can be used to further research in pedestrian safety and urban lighting.
Lastly, the US DOT’s plan highlights the necessity of multidisciplinary approaches to improve safety outcomes (p.14). This project, with its combination of technology, civil engineering, and collaboration with the PedPal team, exemplifies a multidisciplinary approach, aiming to design and build safer transportation infrastructure and systems.
Deployment Plan
First Year by Quarter:
Quarter 1: Literature and patent research, including overview of current LED streetlight luminaire products and analysis of diode and control management. Purchase and investigation of typical streetlight luminaire lighting mechanics, circuiting, and data communication. Take in-field lighting measurements of Pittsburgh intersections (typical and amplified intersections [4 luminaires] to confirm thesis assumptions). Confer with PedPal team on intentions and develop shared needs criteria and app compatibility. Update City of Pittsburgh DOMI personnel with progress and for feedback.
Quarter 2: Explore circuiting options for individual diode control and data communication protocol. Virtually investigate geometric models for streetlight in-situ positioning and related diode control to match crosswalk locations. Continue literature research as needed. Work with PedPal team to design communications protocol with luminaire control system. Update City of Pittsburgh DOMI personnel with progress, including geometric positioning findings.
Quarter 3: Refine equipment and circuiting feasibility leveraging PI Flanigan’s fully-equipped Advanced Infrastructure Systems Lab (all hardware and development equipment already exists), communications protocol, geometric models for virtual testing, and literature research as needed. Confer with PedPal team. Present findings with City of Pittsburgh DOMI for feedback.
Quarter 4: Prepare research report and present findings to City of Pittsburgh DOMI.
This four quarter progression is necessary to set the stage for full-scale deployment with the City of Pittsburgh during the second year of this project.
Expected Outcomes/Impacts
The City of Pittsburgh will be installing 50,000 new LED streetlights, some with controls, beginning in 2024 and through 2027. The timing of this project coordinates well with Pittsburgh’s streetlight conversion plan and has the potential for integrating its findings for intersection lighting management, particularly along the city’s major arterials and connectors and with PennDOT-designated highways throughout Pittsburgh.
Brighter intersection lighting is recognized by many cities by installing higher lumen and cooler-temperature luminaires with the idea that more/brighter lighting increases safety for all. However, most pedestrians do not dress for safety at night and many wear darker-colored clothes, which is mostly ineffective for seeing persons either standing or moving. This project recognizes that a better safety solution is to prioritize changing the lighting need. Proper pedestrian lighting at intersection crosswalks would provide oncoming drivers with greater visibility of people (and objects) than standard streetlighting and headlights combined.
At newly-signaled intersections Pittsburgh’s current practice is to light them from each corner, installing four LED luminaires atop the signal poles. This proposal assumes the luminaire count is maintained; however, their location may be different to achieve its objectives. We anticipate this work resulting in an additional patent to augment the research results.
Expected Outputs
The anticipated outputs of this research project encompass both technological advancements and practical applications in the field of urban infrastructure and pedestrian safety.
(1) New lighting control technology will be developed to enable individual diode control. This technology allows for a more nuanced and dynamic lighting environment at pedestrian crossings and intersections. (2) Paired with this technology, the project will produce geometric models for the optimal positioning of streetlights, which will serve as guidelines for future urban planning and streetlight installation. (3) The project will directly integrate with Safety21’s PedPal app, providing a responsive lighting environment that adapts in real-time to the presence and needs of pedestrians at intersections. (4) The project will produce an extensive data set from field and laboratory tests, simulations, and literature reviews. This data will be invaluable for further research in the field and contribute to the academic and practical understanding of urban lighting and pedestrian safety. (5) The findings/developments from this project will inform policy recommendations for city planners, including guidelines for deploying smart LED lighting systems in the upcoming streetlight replacement project. (6) It is anticipated the project will lead to one or more patent filings in the area of lighting control technology.
TRID
Two areas reinforce this work’s importance: Streetlighting’s impact of pedestrian safety and local infrastructure’s influence on streetlight illumination. Li (2023) points out that roadways and intersections vary significantly by design and vehicle speed allowances. Where pedestrians approach an intersection the lighting method influences the reaction time of motorists and collision accident risk. Ferenchak (2022) correlates injury severity by lighting conditions. Studies also find lighting safety standards commonly fall out of compliance without individual adjustments to pavement and weather conditions.
Work exploring the customizability in streetlight patterns is poorly studied. Just one article was found. Pan (2021) explores the optimal design of LED high-mast lamp based on TIR freeform lens for annular lighting.
Most streetlight research discusses the popularity of LED streetlight conversions and lessons learned. As more cities convert to LED, work is needed to maximize the safety and efficacy of streetlights with control systems and local customizability. Beckwith (2010) notes that LED luminaires with new light control systems provide for overall light control, with beneficial outcomes for maintenance, luminaire life, and reduced operating costs.
The TRID search reveals that while there is literature supporting the need for the proposed project, this work is substantially different from existing research efforts.
Individuals Involved
| Email |
Name |
Affiliation |
Role |
Position |
| hcain@andrew.cmu.edu |
Cain, Heather |
Carnegie Mellon University |
Other |
Staff - Business Manager |
| kaflanig@cmu.edu |
Flanigan, Katherine |
Carnegie Mellon University |
PI |
Faculty - Untenured, Tenure Track |
Budget
Amount of UTC Funds Awarded
$95000.00
Total Project Budget (from all funding sources)
$200000.00
Documents
Match Sources
No match sources!
Partners
| Name |
Type |
| City of Pittsburgh |
Deployment & Equity Partner Deployment & Equity Partner |
| Robotics Institute |
Deployment Partner Deployment Partner |
