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Trees in the Curb Zone Pilot Project

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The Bureau of Environmental Services (BES) recently awarded the Portland Bureau of Transportation (PBOT) $500,000 from its "Percent for Green" program. The program collects a percent of development charges and uses that money to fund large-scale green infrastructure projects.
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Project Goals

The Bureau of Environmental Services (BES) "Percent for Green" grant award will be used to pilot a tree planting in the curb zone project. The goal of this project is to develop a framework for tree planting in the curb zone, in collaboration with Portland Parks & Recreation’s Urban Forestry team, BES, and others, with the end goal of constructing tree space in the curb/parking zone. In transportation planning projects, there often isn’t sufficient right-of-way behind the curb, so expanding the furnishing zone into the parking zone may be the only option to get space for street trees.  

This graphic shows how a tree bump out might be configured. This graphic is for illustrative purposes and final design may be different.
The Pedestrian Design Guide provides information on innovative tree planting treatments, such as Trees in the Curb Zone. This diagram is conceptual and not an engineering drawing.

Site Analysis and Implementation

The project is an early implementation project of the recently adopted Pedestrian Design Guide (PDG). One of the biggest things the project team heard from the public during the PDG process was the desire for innovative tree planting treatments. In preparation for the grant application, PBOT and Portland Parks & Recreation’s Urban Forestry staff conducted a citywide site analysis of potential corridors and are focusing the pilot on a cluster of streets in the Brentwood Darlington neighborhood. The site analysis looked at existing conditions of the corridors (such as the presence of on-street parking, lack of space for street trees, and location of underground and overhead utilities), as well as the urban heat index. Through this project, the project team will further analyze the potential sites for implementation, select the final sites, conduct neighborhood outreach to engage communities in the project areas, and construct the tree plantings in the curb zone.  

The project aims to plant a few street trees per block along a corridor (exact location to be determined) by repurposing on-street parking along corridors that currently do not have street trees or any space for street trees. Additionally, because trees can typically only be planted on one side of the street due to underground utility conflicts, the project will fund yard trees for the opposite side of the street, where street trees are not feasible. Project staff will work closely with adjacent property owners, residents, and businesses throughout the life of the project. Planning and engagement for this pilot project will take place over 2022-23 and construction will begin in 2024.   

This photo shows an example of a bump out constructed into the parking area, so that trees can be planted in the parking zone.
This example, from Directors Park in downtown Portland, shows how trees can be incorporated into the parking zone of a street.

While the exact corridor is still being determined, there is an opportunity to tie into a current planning effort already underway in the Brentwood-Darlington neighborhood.  The Lower SE Rising Area Plan, a project jointly led by PBOT and the Bureau of Planning and Sustainability (BPS), is already underway in Brentwood Darlington and has an existing community engagement process. This pilot project can utilize existing community engagement opportunities and work with the Lower SE Rising advisory committee to coordinate on these joint planning processes.

Policy Direction for this Project

The city’s Pedestrian Master Plan (PedPDX) (2019) and the Pedestrian Design Guide set the policy direction for PBOT and bureau partners to explore more innovative tree treatments. PedPDX includes Action 8.6, which calls for PBOT to update right-of-way design standards to provide sufficient room for trees and recommends “providing trees within the curb zone intermittent with on-street parking” as a potential strategy.  

This pilot project will allow staff to work through the design and technical implications of this treatment. Once there is a proof of concept, it will be easier to implement in other parts of the city, by allowing PBOT to go after additional funding, as well as have clear design standards from city engineers for capital and development projects.  

Project Updates

November 2022- Pedestrian Advisory Committee Presentation: PowerPoint Presentation (portland.gov)