Modeling Traffic Noise and Light on Natural Landscapes at the State Scale

Anthropogenic noise and light have been shown to impact wildlife behavior, distribution, movement, and population fitness and survival. Traffic noise and light can inhibit wildlife use of areas adjacent to roads, impair wildlife perception of traffic risks, and cause a barrier effect to wildlife occurrence and movement well beyond road edges. A critical action being taken by states to repair wildlife movement across roadways is construction of wildlife crossings, theoretically providing a safe passage across roads. Planning the location of theses crossings and to some degree their design currently does not take into account traffic noise and light impacts on wildlife approaching the structures. The authors developed statewide models of traffic noise and light intrusion into areas adjacent to state highways to aid understanding of wildlife responses to noise and light and to aid locating and designing crossings to maximize wildlife approach and use. These models have the added benefit of estimating traffic impacts as part of environmental analysis associated with delivering transportation projects. The authors used the NoiseModeling software in QGIS and novel light-modeling tools developed in ArcGIS to model the “noise-scape” and “light-scape” at high-resolution around California state highways. They used different putative sources of traffic noise and light and model propagation (depending on traffic volumes) of both across adjacent landscapes out to at least 1 kilometer. The authors tested the models in the field using transects of noise and light measurements. The outputs were digital (raster) maps that showed the high and low impact areas. View the NCST Project Webpage