Many urban regions outside of booming metros experience “sprawl without growth” — where the urban core loses population and new sprawl development is added at the fringe even as the overall regional population remains stable (or even declines). Thus far the planning field didn’t have a great way to model scenarios for this situation. Together together with collaborators Ian Varley from City Explained, Inc. and John Egelhaaf, executive director of the Southwest Michigan Planning Commission, I was involved in a project to tackle this issue, which resulted in a working paper with the Lincoln Institute of Land Policy titled, “Scenario Planning for Slow-Growing Regions.” I explained the project through this recent Tweet thread, and the full abstract is below.
Legacy cities and regions often have low overall growth rates, making traditional scenario approaches, such as sketching possible future land uses, less relevant. However, they are often undergoing important changes, such as center city decline accompanied by new development at the urban fringe.
In this study we built on a scenario analysis framework developed by urban planners for a large legacy region in Northeast Ohio (Vibrant NEO). Vibrant NEO used an exploratory scenario approach, examining different amounts future growth using different growth patterns. For our project, we modified the Vibrant NEO framework by adding scenarios that specifically consider regional decline. The result is a six-scenario framework that describes growing, flat, and declining populations, each modeled either assuming development patterns stay the same or shift to a â€œdifferentâ€ pattern. We then implemented this framework using the CommunityViz software program.
In order to demonstrate the method, we developed a case study by partnering with the Southwest Michigan Planning Commission and using a region comprised of two counties in Southwest Michigan. This project area represented an opportunity to explore the granularity of potential land use change within a slow or no-growth environment. We developed multiple estimates of population change and used CommunityViz to step through a relatively conventional â€œrulesbasedâ€ process of estimating build-out potential, developing land suitability analyses and running population allocations. In addition to modeling growth, elements of the traditional modeling process were reversed in CommunityViz to model population decline. Unlike other modeling software, no modifications are needed for CommunityViz; modeling decline or low-growth were accomplished simply by changing the types of inputs and adapting the process to fit new concepts. For the case study, this process was adapted to remove existing residents as well as add as add them via the traditional allocation process. Metrics and maps were developed to measure impacts to different jurisdictions, school districts, impacts to agricultural and conservation areas.
The primary strength of this methodology is to be able to illustrate what may happen if policy and population trends donâ€™t change their current trajectory. However, assuming practitioners find ways to define plausible trend and alternative development patterns, we think a major strength of this methodology is the ability to conduct impact analysis. Our method allows decision-makers to understand better the path the region is on, helping them to anticipate possible problems in the future.
Read our full paper: “Scenario Planning for Slow-Growing Regions: A Guidebook and Case Study“