Abstract Manager

Incorporating Low Impact Development (LID) measures in a stormwater management (SWM) strategy is particularly challenging for Complete Streets design, due to the competing priorities of active transportation facilities, streetscaping, congested utility corridors, road design profile limitations, and grading constraints. Historically, SWM planning for road expansions has emphasized siting end-of-pipe facilities within greenfield development areas, due to the limited opportunity for linearly-configured SWM infrastructure within a narrow public right-of-way. Accordingly, the implementation of LID measures for roadway projects has often been reduced to “best-efforts” during detailed design, while other elements within the right-of-way are prioritized.

However, the recent shift towards intensification has required the enhancement of existing urban roadways through currently developed areas, where greenfield areas for SWM facilities are not available. This shift in planning practice, combined with the growing emphasis on sustainability and resiliency in infrastructure design, has increased reliance on LID measures as part of roadway SWM strategies. To undertake a true “best-efforts” approach to implement LID measures in a Complete Streets project, feasibility assessments and interdisciplinary coordination can no longer be deferred to detailed design, and are needed during the functional planning process. Given the various elements competing for space within the boulevard, this approach necessitates information gathering and details of LID measures earlier in the overall design process to demonstrate their feasibility.  

This presentation presents several case studies where LID measures have been planned, selected, and integrated into the preliminary road design through functional planning processes in a Complete Streets context. The functional planning process provides opportunity for a comprehensive planning approach for public infrastructure, to develop an overall design considering transportation, environmental, social, and engineering elements.

These studies included a coordinated and integrated process between engineering and streetscaping design to incorporate linear bioretention facilities in the planter areas, as well as a review of the active transportation facilities for opportunities to incorporate exfiltration trenches. This integrated approach identified utility conflicts, relocation requirements, and engaged stakeholders and agencies proactively through the planning process, streamlining the project requirements at the detailed design stage. 

The forethought applied to LID planning through these processes established practical and implementable stormwater management strategies within Complete Streets designs in a limited right-of-way. Accordingly, for major transportation improvement projects within the public realm, integrating the planning and selection of LID measures into the planning phase can help to inform infrastructure decisions and integrate LID measures into Complete Streets designs more effectively.