Case Study:

Waterloo, Iowa

Conclusions

Extension to Regional Analysis

While the Waterloo case study focuses on the area surrounding a major highway intersection, this methodology could be extended to analyze the regional impacts of transportation projects and policies, as well as land use policies. Some of the policies that might be tested include:

• Regional highway construction or expansion programs;

• Pricing, land use, or other strategies that significantly affect regional VMT;

• Truck traffic policies, such as exclusive truck lanes or routing restrictions, that change the composition of traffic on various roadways; and

• Land use policies that affect the siting of residences in relation to transportation facilities.

Since the noise and air quality analyses must be carried out on a facility-level basis, doing this for every major facility in the region is not practical. An alternative approach would be to identify areas of potential greatest impact for more detailed analysis. Such an approach might be done as follows:

1. Traffic volume data for both future baseline and proposed conditions (e.g., a "no-build alternative" and a "build alternative 1") would be used to identify links of greatest potential impact as well as greatest changes in impacts. These data could be obtained from regional travel demand model output for each future transportation and/or land use scenario.

2. Maps of population data illustrating expected population density (for total, low-income, and/or minority population) at the census tract or TAZ level would be developed.

3. These data would be overlaid to identify areas of greatest potential population exposure to noise and emissions (baseline as well as increases). A few "high-impact" areas would be selected for more detailed analysis.

4. Exposure of total, low-income, and minority populations to unacceptable levels of emissions and noise would be estimated under the "baseline" and "alternatives" conditions, using the methodology described previously.

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