Northwestern Indiana Regional Planning Commission (NIRPC) developed green infrastructure (GI) guidelines to complement NIRPC's Living Streets Policy within roadway public rights-of-way for Lake County, Porter County, and LaPorte County. NIRPC adopted the Living Streets Policy for local transportation project sponsors to follow when seeking federal highway funds. This policy requires sponsors of local projects selected for funding to scope the feasibility of including functional green infrastructure and complete streets features up to 15% of the project costs. The developed GI guidelines are to be used by applicants to select and plan for appropriately functional GI elements for proposed transportation projects. NIRPC envisions incorporating demonstration of appropriately planned GI technologies into the evaluation criteria for project selection. The goal of the policy is that while Northwest Indiana's highway funds improve the transportation infrastructure, they can also improve the natural and built environment using more ecologically-friendly and sustainable management practices.   Integrating GI into projects will provide more resilient stormwater runoff management and additional benefits that improve community quality of life.

The guidelines identify critical design parameters for GI facilities within transportation settings that focus on reducing stormwater quantity and improving water quality for the Northwest Indiana counties. These guidelines focus on strategies to achieve maximum function based on common site constraints and requirements.

Roadway classification is a primary consideration in determining eligibility for the federal highway dollars that NIRPC allocates to local road projects. Because it is also useful when initially evaluating and selecting GI practices, these guidelines are organized by roadway classification. Other considerations for GI selection include location, site constraints, and performance objectives. These guidelines do not address all potential GI available but highlight the most common GI and provide a basic overview of benefits and ecological functions, applications, typical design considerations, and maintenance associated with the GI practice. These guidelines are intended to provide early planning guidance and a tool for planners and designers when considering the inclusion of GI into right-of-way development and retrofit projects. They are not a substitute for appropriate project engineering and design. These guidelines do not supersede regulatory requirements and should always be considered in conjunction with authorities having jurisdiction code requirements.

Green infrastructure utilizes vegetation, soil, and engineered systems to mimic natural processes of slowing or storing stormwater. These practices can improve water quality and reduce flooding by intercepting, infiltrating, filtering, and evapotranspiring stormwater. Green infrastructure can provide additional ecological services that traditional gray infrastructure does not, such as improving air quality, reducing the urban heat island effect, providing pollinator habitat, and beautifying communities. Although there are many green infrastructure practices to consider, this guide will focus on some of the best practices to apply in transportation settings including:

• Bioinfiltration
• Flow-Through Planters
• Vegetated Swales
• Urban Street Trees
• Pervious Pavements
• Hydrodynamic Separators