Life-Cycle Cost Analysis: Step 5 - Select Analysis Period and Service Life

Historic and HEC-17 Approach

To ensure that the economic analysis is clearly economically-justified as required by 23 CFR 668.109, select an analysis period based on the chart below.

Functional Classification Analysis Period
Local (most Tribal and Federally Owned Roads) 30-years
Collectors 40-years
Arterials 50-years

The analysis period is limited to account for uncertainty in:

  • Discount Rates
  • Road use (traffic type and volume)
  • Future maintenance and asset deterioration
  • General obsolescence
  • Natural processes and climate
  • Land management priorities

The service life of the primary feature of the alternative will be used in the economic analysis. The following is a guide in determining the service life to use.

Primary Feature Service Life
Roadways and associated materials (e.g., pavement and riprap) 35-years
Metal culverts 30-50 years
Concrete culverts 50-years
Concrete bridges 50-100 years

Metal culverts and bridges at the longer service lives require design measures to protect against corrosion.

While the service life of some elements of a facility may extend past the end of the analysis period, this does NOT change the analysis period. In the life-cycle cost analysis, the service life remaining at the end of the analysis period will be credited back to the initial cost of the alternative. The remaining service life may have two components:

  • Remaining Service Life of the key element or structure (bridge or culvert)
  • Remaining Service Life of the previous repair

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