Trees in the Curb Zone Pilot Project

Light green banner with dark green words that says Expanding Portland's tree canopy with innovative planting. Icon illustration of tree with people sitting underneath it.
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 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 Lents 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.  

A photo of 2 trees planted into the street on SE Hawthorne Boulevard. The trees have concrete curb surrounding them.
This example on Hawthorne Boulevard shows how trees can be planted between the vehicle travel lane and the sidewalk.

The project aims to plant a few street trees per block along a corridor 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 2023-24.   

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.

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 Lents & 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.  

There are many benefits of trees, which are illustrated in this graphic:

Project Updates

November 2022- Pedestrian Advisory Committee Presentation: PowerPoint Presentation (

Project Corridor 

PHASE 1: After careful analysis, the project team has selected SE Duke Street from 82nd to 94th Avenues and 89th and 90th Avenues. There will be approximately 13 trees planted as part of this phase.  Households along the corridor will also have the opportunity to receive free yard trees. Construction will begin in early 2024.

PHASE 2: Site analysis is currently underway to plant another 15-20 trees in late 2024.

Trees in the Curb Zone concept map (phase 1)


Ownership & Maintenance of Pilot Project Trees

The trees planted as part of this pilot project with be owned and maintained by Portland Parks & Recreation Urban Forestry team. Typically, street trees are the maintenance responsibility of the adjacent property owner. However, as this is a pilot project, the project team worked together to figure out the best strategy for the ownership and maintenance of these trees. Properties along the project corridors will be given information on how to report any issues with these street trees.