Green streets use green infrastructure practices within the public right-of-way to manage stormwater while preserving the primary function of a street as a conduit for vehicles, pedestrians, bicyclists, and transit riders. In a densely populated state like New Jersey, the management of stormwater runoff is an important consideration for developed areas as impervious surfaces like roofs, roads and parking lots prevent water from seeping into the ground. As of 2012, the state had the highest percent of impervious cover in the country at 12.1 percent of its total area, and of course that percentage is far higher in cities and towns. A substantial portion of the impervious cover is in the form of streets, which also collect stormwater from nearby impervious surfaces. The expansion of impervious cover through development, coupled with the recent increase in the frequency and intensity of storm events due to climate change, contributes to a rise in the volume of stormwater generated. The result is increased localized and severe flooding, polluted downstream waters, and increased combined sewer overflows, which discharge untreated stormwater and wastewater directly to nearby streams and rivers..
In addition to managing stormwater, green streets deliver multiple environmental, social and economic benefits. Green streets can improve mental and physical health through beautification, improved air quality and contact with nature, especially in places where there is an absence of parks and/or open space. They also can increase pedestrian safety by aiding in traffic calming, and can become a cost-effective strategy by extending the lifespan of pavements and infrastructure. Realizing all these benefits, state agencies like the Pennsylvania Department of Transportation and a handful of municipalities across New Jersey are embracing green infrastructure as a primary approach to stormwater management.
In 2017, expert members of the Jersey Water Works Collaborative Green Infrastructure Committee, whose members reflect cross-sector perspectives and expertise (municipal, academic, professional, environmental, private sector and non-profit) conducted research and produced a white paper that includes green street policy recommendations for state government. This research project will evaluate three of the paper's recommendations: reviewing current funding processes for street improvements across the state, conducting a green street demonstration project on state roads, and developing guidelines that include design, maintenance, and monitoring.
In addition, a cost-benefit analysis of the initial costs and life cycle costs of designing, installing, and maintaining an NJDOT green street pilot project will be conducted as compared to the traditional, gray infrastructure approach.