The Institute for Transportation Research and Education at North Carolina State University conducted a follow-up study to a previous North Carolina Department of Transportation (NCDOT) project, comparing mobile inventory data collection vehicles to manually-collected data techniques. The follow-up study included two additional aspects: 1) a visual component to the comparison analysis using GIS software ArcMap 10, and 2) a two-way communications loop with a thorough submission of a sample data set to be analyzed prior to the submission of a full data set. The results show that vendors can accurately locate the vast majority of assets, the primary exception being those that are occluded by vehicles or surrounding landscaping, such as those assets in the median. Following location of the asset, vendors showed promise collecting many of the feature descriptions such as asset type and condition. Many of the elements that vendors struggled with were only problematic for one of the vendors, showing room for further improvement through additional communication and updates to the catalog definitions and examples. Using measurement tolerances, the research team determined that measurements of height, grade, and azimuth were generally accurately obtained; however, measurements parallel to the direction of travel such as offset and width posed problems with accuracy. Last, accuracy of data elements was acceptable for finding the elements in the field; however, many specific point features such as drop inlets or attenuators were not geo-located, but instead measured from the van's location in the lane. Although mobile data collection is sufficient for most efforts, there is still room for improvement if more detailed location is necessary.
