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SPave is a lightweight version of the StreetPave design framework for jointed plain concrete roadway pavements.

To maintain simplicity, there are no help screens or built-in calculators for trucks per day or the composite k-value, and the only available traffic categories are from ACI PRC-330-21 or StreetPave12.

The residual strength for fibers also is not added as a feature, but the modulus of rupture input can be directly adjusted; see the Cracking section of the Equations page for guidance.

The LOG to LN Error

It was not a goal of this effort to find an error in StreetPave12 or pavementdesigner.org.

In 2019, Jorge Olavarría used the references detailed here to recreate the StreetPave design framework for a Spanish-language and metric-unit app for his website ingenieriaelemental.com. In doing so, he could not replicate the results of StreetPave12 without introducing an error in the concrete fatigue equation.

Independently, in 2025, Robert Rodden replicated the StreetPave equation framework in Excel only to confirm the issue — in the concrete fatigue equation developed by ERES (now ARA), a base 10 LOG operator had been replaced with base e, or natural log (LN).

References present the ERES (ARA)-developed fatigue equation differently, including:

These are mathematically identical.

Figure 7 from ERES 2004a can only be replicated if a base 10 log is used in the reliability part of the fatigue equation, as shown in the following plots; see the Excel section for more details.

ERES 2004a Fig. 7 — Plot of predicted log N versus SR for different levels of probability of survival.

Replication of the results from ERES 2004a, confirming log₁₀.

Further confirmation comes from Figure A.3 from ACI 330R-08, where again results can only be replicated with a base 10 log in the reliability part of the fatigue equation, as shown in the following plots; see the Excel section for more details.

ACI 330R-08 Fig. A.3 — Fatigue relationships for varying overall reliability.

This work validates that a base 10 log is correct; see the Excel section for the source of these plots and the Example section for illustration that StreetPave12 and pavementdesigner.org results can only be matched if base e is erroneously used in the concrete fatigue equation.