content_image/552663.jpg content_image/552661.jpg
<img src='content_image/552663.jpg'>

Source: Highway Capacity Manual (Transportation Research Board, Special Report 209, 2000). 

<img src='content_image/552661.jpg'>

Source: Highway Capacity Manual (Transportation Research Board, Special Report 209, 2000). 

Based on EPA guidance (i.e., 40 CFR 93.123) intersections that are at a LOS of D, E, or F or that will deteriorate to LOS D, E, or F with the proposed action, should be modeled for CO concentrations. Intersections that are at LOS D, E, or F with a significant number of diesel vehicles or that will change to LOS D, E, or F with the proposed action, should be modeled for PM$_{10 }$and/or PM$_{2.5 }$concentrations. 

Typically the top three critical intersections are selected based on the abovementioned criteria (i.e., significant number of diesel vehicles and worst LOS) and highest traffic volumes. 

## E.2.3 Obtain Project Data 

It is recommended to obtain project-specific data when co mputing a hot-spot analysis. These data include peak traffic data (i.e., traffic volumes, traffic speeds, signal timing and type intersection control), and roadway configurations and geometry (i.e., layout of intersections delineating approaches and departures, number of lanes, roadway width, and number of turning movements). For PM$_{10 }$ and PM$_{2.5 }$more detailed data (i.e., hourly traffic data) is necessary. This 

