roadway intersections. $_{40}$,$_{41 }$ CAL3QHC combines the CALINE model with a traffic algorithm to estimate delays and queues that occur at signalized intersections. This model is used as a screening model and is the EPA-recommended model for this application. 

EPA also developed the CAL3QHCR model, which is a more refined version of CAL3QHC that requires local hourly meteorological data. 42 CAL3QHCR incorporates enhancements to process up to a year of meteorological data and emissions data that vary by day of the week and hour of day. The model has the capability, with the use of various concentration-averaging algorithms, to predict 1-hour, 8-hour, 24-hour, and annual concentrations, compared with only the maximum hourly average computed by CAL3QHC. CAL3QHCR is the EPA-recommended model for PM (i.e., PM$_{10 }$ and PM$_{2.5}$) hot-spot modeling for highway and roadway intersection projects/action and also EPA-recommended for CO when a CAL3QHC analysis with conservative assumptions indicates a potential to exceed the NAAQS. 

For further information on CAL3QHC/CAL3QHCR model inputs and guidance on how to conduct a CO and PM hot -spot analysis see Section 7.2 ( Roadway Dispersion Modeling ) and Appendix E ( Roadway Dispersion Modeling [Hot-Spot Analysis] ). 

