Measuring Park Access in
Oregon
Author: Josh Roll
Unit: ODOT Research Unit
Email: josh.f.roll@odot.oregon.gov
Github Handle: JoshRoll
Unit: ODOT Research Unit
Email: josh.f.roll@odot.oregon.gov
Github Handle: JoshRoll
1 Introduction and Motivation
In 2022 the Oregon Legislature passed HB 4077 directed the Environmental Justice Council (EJC) to build a statewide EJ mapping tool and for agencies to consider its results when developing rules, policies, and programs. The tool’s core purpose is to pinpoint areas disproportionately affected by pollution, climate risks, health burdens, and socioeconomic barriers, so the state can prioritize outreach, services, and investments where need is highest.
Access to parks has been demonstrated to provide both physical and mental health benefits(Derose, Han, et al. 2021). However, access to parks is not uniform and past research has demonstrated that across the U.S. only 39% of people have access to parks with states like West Virginia only having access to parks for 9% of the population. Additionally, disadvantaged populations have been shown to have less access to parks than more affluent groups (Ussery et al. 2016).
The work documented in this report summarizes the technical process for developing a measure of access to parks for the EJC mapping tool. This measures will be combined with other measures suggested by the community through outreach as well as through the EJC to become a tool for helping agencies guide equitable government action. Agencies can use the tool to target community engagement, inform program design, and consider resource allocation to communities historically under-represented in public processes and harmed by environmental and health hazards.
The data and methods for the park measures are described below in three sections including Data, Methods, and Results. For questions about any of these technical processes feel free to email Josh Roll at Oregon Department of Transportation using the contact info above. All code is available at the repository here
2 Data and Methods
The goal of this analysis is to determine how access to parks by Oregon’s population varies across the state. To meet this objective an inventory of park locations is needed as well as routable street network. An up-to-date and constantly maintained database of park locations does not exists and given much of the uncertainty with federal government resources and technical assistance for data it was desirable to use data that does not require the federal government for maintenance and access. After reviewing data from USGS called Protected Area Dataset(PAD) and data from Open Streets Map (OSM) it was decided that OSM data best suited the needs for this project.
3 Park Location from OSM
Parks data from OSM was collected in September of 2025 using the osmdata (Mark Padgham et al. 2017) R package that harnesses an application programming interface(API) to streamline retrieving data. The API calls were made for each county and then combined with census block data retrieved using the tigris(Walker 2025) package using the R open source statistical computing language. Once the parks locations are retrieved that are spatially joined with Census blocks so that all blocks have a measure of the number of meters2 of park area.
4 Street Network Data from OSM
Measures of access to parks have mostly used Euclidean distance(Derose, Han, et al. 2021) but this approach can over estimate access since barriers to walking such as an interstate or rivers are not accounted for so a network-based approach was preferable. In order to use a network-based approach we need a network that is topologically accurate and able to be converted to a graph. Many applications and research efforts have shown that the OSM data, though not without its limitations, can work well for this kind of analysis (Graser, n.d.). Some of the limitations include the fact that these network data are mostly crowd sourced and transportation authorities do not officially endorse the use of the data. However, these data are the best available and also work well with an available routing algorithm described below. In the figure
5 Park Location from OSM
Figure 5.1: Process Work Flow