Green Credits versus Environmentally Sustainable Traffic Operations: Comparison of Contributions to Energy and Emissions Reductions

Although society is facing a variety of environmental issues, including the depletion of energy resources, and has a much greater awareness of climate change and its serious related social impacts, transportation systems have been pushed to increasingly greater limits because of the dramatic growth in traffic demand. A case study was performed to compare the contributions of green construction credits and those of environmentally sustainable traffic operations to reducing energy use and emissions. The study measured the impacts of green credits by using the Carnegie Mellon University economic input–output life-cycle assessment model. These impacts were compared with those achieved through sustainable traffic operation strategies, consisting of a high-occupancy vehicle lane and access to public transit. The study shows that the energy and emissions reductions obtained by use of the traffic operation strategies eclipsed those obtained by use of the green credit measures in just 1 month of traffic operations. The carbon dioxide emissions created and the total energy consumed by only 1 month of traffic were three times greater and 30% more, respectively, than those obtained by repaving the same roadway. In addition to reducing emissions, environmentally sustainable traffic operations offer social sustainability benefits, such as reducing traffic delays and improving flow, which reduce the demand for transportation infrastructure and which can ultimately reduce the need for new roadway construction. Although both green credit measures and environmentally sustainable traffic operations are essential to true sustainability, the relative impacts of both traffic operations and construction credits should be considered when research and infrastructure investments are prioritized.