1. Roadway Modeling using CAL3QHCR (A Line Source Model)
Originally developed for CO hotspots
We work directly in the model; no interface
Today I will show you how to model PM from roadway, and how to calculate potential cancer risk.
Inhalation pathway only.

2. Line source model Input data
CAL3QHCR Model
Line source model
Input data
Sequential meteorological data (ISCST3 meteorological input files)
Emission factors
Roadway link information
Traffic data
Receptor locations

3. Methodology for Preparing Traffic Data Inputs
Procedure described in detail in the Guidelines
Data sources
Peak vehicles/hour for road segment from CALTRANS (
BURDEN run with hourly output from EMFAC
Key assumptions
Gasoline PM is as toxic as diesel PM
Ratio of cars to trucks is the same on all roadways throughout the county

4. Standard Inputs

5. Example Project Location
We’ll be using the peak hourly traffic volume from this stretch of business 80
Note the rail line to the south. We will not be modeling emission from that rail line, although in real life we’d ask for those emissions to be considered in the risk assessment

6. Cancer Risk Results

7. Graph Cancer Risks with Distance
Risk drops with distance

8. Other CAL3QHCR Features
Used for modeling only roadway sources
Add results from modeling other source types with ISCST3 or AERMOD
Can be used to model:
Traffic intersections
Traffic signaling
Queuing

9. Questions