Institute of Planning

Data Sources & Methodology

Transparency in municipal math is the only way to combat aesthetic-only planning. Below are the assumptions used in our tools and analyses.

Infrastructure Replacement Costs

In the Density Breakeven Calculator and our Liability essays, we use standard civil engineering estimates for 2023:

  • Asphalt Paving: $1.2M - $2.5M per lane mile, based on FHWA (Federal Highway Administration) baseline cost models.
  • Water/Sewer: $150 - $300 per linear foot, varying wildly by soil conditions.
  • Lifespan: 30 years for asphalt surface courses; 50-75 years for deep utilities.

Parking Construction Costs

The Parking Minimums Cost Burden Calculator relies on data sourced from WGI's annual Parking Structure Cost Outlook:

  • Surface Lot: ~$5,000 per space (includes land prep, asphalt, striping).
  • Above-Ground Structure: ~$25,000 - $35,000 per space.
  • Underground/Podium: ~$50,000+ per space.

Value Per Acre

Our comparisons of tax yield (e.g., comparing Walmart to a downtown Main Street) are inspired by the data methodology pioneered by Urban3 and Strong Towns. To verify this locally, pull public assessor data for a big box store, divide the total property taxes paid by the total acreage of the parcel, and compare that figure to a downtown mixed-use building.

See the Municipal Finance page for more context.