LED Lighting SSPs to Reduce Ecological Impacts on Terrestrial Wildlife

Project Description

The pervasive and extensive nature of road networks for vehicular transportation has led to concerted efforts to identify and reduce their adverse environmental impacts (Forman et al. 2003, van der Ree et al. 2015). Identified areas of harm, such as fragmentation and wildlife mortality, intersect substantially with the nighttime environment and the presence and design of roadway lighting (Beier 2006, Ditmer et al. 2021). As new roads are built, and lighting along existing roadways added or replaced, attention is being paid to minimizing the synergistic impacts of light at night on wildlife and ecosystems (Blackwell et al. 2015).

In a previous task, Caltrans supported research to investigate the effects of the transition to light emitting diode (LED) lighting types on terrestrial wildlife. As part of this study, the literature on LED effects on wildlife was compiled, showing that the only difference from other sources were in the characteristics of the light (intensity, spectrum) and not intrinsic to the technology (Longcore 2023b, 2024). The intersecting effects of light intensity and spectrum were investigated, showing their relative contribution to disrupting nocturnal animal behavior in a laboratory setting (Longcore et al. 2024). To understand spectral issues across wildlife groups, the visual sensitivity attributes of 170 different species were located, digitized, and analyzed (Longcore 2023a). Finally, a method was demonstrated to map the potential impacts of lighting from roadway projects in the environmental review process that considers relevant lighting levels and the variability in animal visual systems (Longcore 2023b).

Notwithstanding this progress, the incorporation of the knowledge of lighting impacts is not yet integrated into the day-to-day practices of Caltrans. Development of lighting assessment protocols is still at the proof-of-concept stage and needs to move into case studies and practice. The underlying processes and procedures of the agency, including standard and non-standard specifications and other systemwide guidance documents, could be updated to further integrate new knowledge about potential environmental impacts from artificial light at night. Some situations involving light at night, such as temporary construction lighting, have not yet been addressed, either in concept or through development of guidelines and specifications. In this project, the goal is to engage a team of experts to develop tools and guidelines that allow for the smooth integration of environmental analysis of artificial light at night into Caltrans’ practices and workflows. This effort will be focused in four areas. First, the project will bridge the gap between biologists and environmental review professionals and lighting engineers during the project design phase, by demonstrating and working through case studies where new lighting is being proposed. Second, it will make recommendations about the taxonomic resolution (should it be class? species?) at which spectral tuning should be considered as an environmental mitigation approach so that such recommendations can be incorporated effectively into standard plans and specifications. Third, it will consider and make specific recommendations for standard special provisions (SSPs) regarding lighting in Caltrans projects, which will focus on spectrum, lighting distributions, and shielding. Fourth, it will review the issues associated with temporary area lighting and make recommendations for standard provisions to reduce the impacts of lighting from nighttime construction.