16-02 — Leading Landscape Design Practices for Cost-Effective Roadside Water Management

Original Scope: Hotter, drier summers; warmer, wetter winters; and more frequent extreme weather events are confronting transportation agencies with increasingly frequent and intense floods, droughts, and temperature extremes that adversely affect transportation infrastructure. Transportation agencies, seeking ways to mitigate these adverse impacts, have been exploring principles and practices of “green infrastructure” for roadside water management, using such techniques as water harvesting, landform grading, rain gardens, micro-catchment basins, and large-watershed actions as components of transportation development projects and operations. The fundamental intent of these techniques is to work with natural processes, to “build with nature.” While the details of particular applications often are determined by geography, many of the techniques are transferable to other climatic and landscape settings; the principles and practices being developed for designing, developing, and managing green infrastructure are generally applicable.

This scan will review recent experience with green infrastructure practices for roadside water management to identify planning and design criteria, management practices, and exemplary applications that may be broadly useful in transportation agencies nationwide. Because much of the leading-edge experience is coming from local and regional (sub-state) agencies, an important feature of this scan will be consideration of how exemplary applications may be scaled up to inter-city corridor and statewide systems. The scan may contribute toward development of nationally useful guidelines and policies on effective green infrastructure practice.

Implementation and Impact

Following the scan workshop in November 2017, the scan team presented at the state, regional and national levels to advance scan findings. Highlights of these activities include:

• StormCon in Denver
• National Hydraulic Engineering Conference
• New England Transportation Consortium
• TRB Committee on Landscape and the Environment (AKD40) 

The scan team contributed to the development of NCHRP 14-41 Permanent Vegetation Control Treatments for Roadsides. Also currently in development is an NCHRP project to conduct a workshop to define Green Infrastructure. A panel is currently being assembled and an RFP will be posted to hire a consultant to lead the effort. 

An article entitled, 8 Steps to Green Infrastructure Success, which details best practices from Scan 16-02 — Leading Landscape Design Practices for Cost-Effective Roadside Water Management, was published in the February 2021 issue of Stormwater.

Scan team members (including Scan Member Garrett Jackson of Washington State DOT and Brian Smith of FHWA ) and scan participants, conducted two TRB hosted webinars which presented highlights, findings and insights on best practices for designing, developing, and managing green infrastructure for roadside water management.

TRB hosted a webinar based on the outcomes of this scan entitled, Designing Landscapes to Enhance Roadside Water Management. To view the slides or webinar recording, visit the webinar page on the National Academies website. 

Scan Members

• Jennifer Taira, Caltrans, AASHTO Chair
• Laura Riggs, Louisiana DOT
• Charles Hebson, Maine DOT
• Garrett Jackson, Washington State DOT
• Ken Graeve, Minnesota DOT
• Brian Smith, FHWA
• Lucy Joyce, Subject Matter Expert

Workshop Participants

This scan was held as a workshop in San Diego, CA from November 6-10, 2017. In addition to the scan team, workshop participants included:

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