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Major Activity Centers

Criteria for Major Activity Centers


This project was initiated as a result of Communities in Motion (CIM) Task #1.1.2. with the intent being to define, identify, and map those areas considered major activity centers and determine how they relate to the roadway functional classification system. The end product is to be a database of these attraction/generation locations in Ada County and Canyon County that can then be mapped as part of other studies.

Initial Findings

In searching other local jurisdictions, there appears to be no single definition of a major activity center (MAC). Even the title itself comes in many flavors sometimes referred to as; regional, economic, employment, or destination centers.

The Capital District Transportation Committee in Albany, New York defines an MAC as “a geographical area characterized by a large transient population and heavy traffic volumes and densities; for example, central business district, major air terminal, large university, and large shopping center, industrial park, or sports arena.”

The Chattanooga-Hamilton County Regional Planning Agency identified six classifications of major activity centers:

  1. Employment centers
  2. Shopping areas
  3. Educational institutions
  4. Tourist destinations
  5. Medical services
  6. Major regional transportation facilities.

However, these classifications are a function of scale and relative to a local area. For example, a major activity shopping center in Boise may only be a neighborhood shopping center in Los Angeles.

There are also a number of ways to evaluate an MAC:

  1. Geographic area (i.e. central business district)
  2. Population (raw number of employees, consumers, students, etc)
  3. Density (population/geographic area)
  4. Commercial building square footage
  5. Traffic volume


For purpose of this analysis, regional MACs in this area will focus on three categories and are defined as follows:

1) Main Activity Centers (Figure 1):

•  Central business districts linked to the interstate
•  Boise State University
•  Boise Airport
•  Regional Medical Centers

These areas seemed to be most common among other locations and arguably the most obvious in this area. A polygon shape file was created that outlined these respective locations.

2) Employment Activity Centers (Figure 2)

•  Employment areas with a density of 5 employees per acre

Using Spatial Analyst, a raster was created from a geo-coded Department of Labor (DOL) points file using kernel density. Kernel density calculates a magnitude per unit area of the point features. By adjusting the criteria we could evaluate any number of employees/acre. From this analysis, we determined that 5 employees per acre was a good balance across the region. The resulting map was shaded according to this interpretation and the areas that had an employment density higher than 5 employees per acre were highlighted. A polygon shape file was then created from the raster which reflected that criteria.

3) Commercial Activity Centers (Figure 3)

•  500,000 commercial square footage within a ¼ mile radius

Using Spatial Analyst, a raster was created from a parcel based shape file of commercial property. Using the square footage field a neighborhood analysis was run which summed all the square footage within a quarter mile radius. By adjusting the criteria we could evaluate any number of square foot values. From this analysis we determined that 500,000 square feet within a ¼ mile radius was a good balance. The resulting map was shaded according to that interpretation. A polygon shape file was created from the raster which reflected that criteria.


The composite map below shows the results of this analysis. The temporal nature of this information should be realized, as MACs are a dynamic element in transportation planning. New businesses open, old businesses move or close, and changing employment status will affect transportation travel patterns. MACs are an element that will have to be reviewed with each long-range transportation plan update.

Click here for the pdf document of this map.

Click here to download Major Activity Centers pdf document