Using GIS to Develop a Sampling Program for Traffic Counts on Local Functional Systems in Small Urban and Rural Areas

Sampling roads in the local functional systems (i.e., local roads and minor collectors) for traffic counts is important for small urban and rural communities that need to perform air quality conformity analysis. Existing sampling methods based on traffic volume stratification were developed for roadways in the higher functional classes. These methods are not applicable for communities that do not have an adequate collection of existing traffic counts on the local functional systems. This paper describes an innovative sampling approach developed with a GIS for a small urban community (i.e., the Fairbanks North Star Borough in Alaska). Instead of sampling local roads based on traffic volumes, densities of built tax parcels surrounding the roads are used as the sampling stratum. The validity of the proposed approach is backed by a statistical analysis that shows a significant positive relationship between traffic volumes and parcel densities. Stratified sampling subgroups based on parcel density levels and the sample size for each density subgroup are then defined. Finally, sampling frames for all roads in the local functional classes are developed using the mid-points of all local road and minor collector GIS segments, where parcel density levels were calculated for stratified sampling.