Van Buskirk, Ryffel & Associates, Inc.
About Us Interactive Growth Model
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We deal almost exclusively with rapidly growing cities, counties and wider regions. It is our business practice to work in places where a staff team can be assembled and participate, thereby saving the community on consulting fees, time, and providing staff with an important educational opportunity. We utilize the population forecast to build-out methodology, our Interactive Growth Model™ a variety of sub-models selected by the client based on their needs and priorities. Some of these sub-models include: commercial land use allocation, timing and location model, parks and recreation, industrial land use, schools, fire stations and TAZ (Traffic Analysis Zones) updates. The output of these and other sub-models is geared to keep pace with population growth at a specific point in time.      

Dr. Van Buskirk and city staff team members reviewing basic input maps used to create their growth model.

An accurate population forecast to build-out is a key factor to any study area’s long range planning effort. Our population forecasts, unlike many others, forecasts population by 5-year increments to build-out, not just a short-term forecast of say, 10 years. Both principals have a well-documented track record for forecasting population, over long periods of time, with an accuracy level of between 95-99.9%.

Historically, and unfortunately, population forecasts have underestimated growth for fast growing areas. Accurate population forecasting is necessary to optimize the return on both public and private investment. For example, underestimating growth results in infrastructure that becomes obsolete before it reaches its useful life.  Overestimating growth can result in premature financial investment and under-utilization of capital improvements. Also, other negative impacts can result such as low economic activity, lower property values, and poor quality of life from inappropriate apportionment of land uses to meet the needs of its future residents.

This graphic shows a typical sigmoid growth curve of a fast growing community and the
effects of using a linear projection, i.e., over or under-estimating growth.

The total population forecast to build-out in five-year increments is an essential part of developing an interactive growth model for a community. Our Interactive Growth Model™ is not a mandatory part of our scope of services. In other words, a community could choose to stop there, with an aggregate population forecast and prepare their own version of a growth model if they had the time and felt capable of doing so. However, ours is trademarked and copyrighted and is state of the art as evidenced by our several publications in Planning magazine and its presentation at the National APA conference in Washington DC, the International ESRI Users Conference in San Diego and the Florida APA meeting in St. Petersburg in 2005.

This graphic shows the historical growth curves of 3 built-out communities that had
distinct similarities with the community under study. Note that they are all sigmoid
curves. The various similarities and the individual growth curves are used to validate
the population forecast for the client community.

The Interactive Growth Model™ uses the population forecast as a key input element and distributes the population, in five-year increments, over time to build-out. It can also be applied to commercial corridor allocation models, comprehensive plan updates, economic development, and TAZ updates. The Interactive Growth Model™ can be used to determine the timing of  utilities, school facilities’ timing and location, recreation, fire stations and the data for a community’s budget allocations to mention just a few. It can also be used to demonstrate “What If?” scenarios of alternative growth management policies and decisions of the community, allowing the results of different planning decisions to be studied.


Copyright 2011 by Van Buskirk, Ryffel and Associates, Inc.