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CHAPTER 6 Analyze and Document Data After the project team collects existing and new HMCFS data, it analyzes the data and docu- ments the commodity flows. A flow chart of the HMCFS process focusing on data analysis and documentation is shown in Figure 6-1. Analyses of HMCFS commodity flow data can be straight- forward or complex, depending on the existing or new data sources used and the amount of manipulation or cross-referencing required. 1. The simplest analyses will involve reviewing existing local, state, or national estimates for commodity flows (assuming those apply to the location of interest) and developing a listing of hazardous materials expected in a community by class, division, UN/NA placard ID num- ber, or specific commodity. 2. Analysis complexity increases as more locally relevant data are used (e.g., vehicle and/or plac- ard counts). 3. For most local entities, the most complex HMCFS data analyses will identify differences in commodity flows spatially (e.g., different network segments, intersections, etc.), temporally (time of day, day of week, season of year, etc.), or some type of spatialtemporal combina- tion (e.g., "hotspots"). 4. For most LEPCs, shipping manifest data would be used on a limited basis to provide an indi- cation of where hazardous material is going on major roadway networks, as well as amounts and types of non-placarded hazardous material being transported. Modeling of network flows using shipment origindestination (O/D) data from shipping manifests is typically performed by transportation specialists in large metropolitan planning offices, state agencies, universities, or consulting firms. This type of analysis is much more specialized than most local entities are equipped to handle. Although analyses of some existing data might not require any data manipulation, a more complex analysis involving other existing or new data sources will require computing resources and personnel that are skilled in data management and validation, spreadsheet creation and charting, mapping, and even statistical analysis. 6.1 Railway, Pipeline, Waterway, and Airway Data Analysis Generally, analyzing HMCFS information for railways, pipelines, and waterways is straight- forward. · Most data come from existing, previously compiled data sources. · The existing flow information is based on a census of all hazmat traffic in the case of railways and waterways, and assumed to be continuous in the case of pipelines. 57
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58 Guidebook for Conducting Local Hazardous Materials Commodity Flow Studies Figure 6-1. The HMCFS analysis and documentation process. · Typically, there is no need to deal with sampling limitations, except, for example, if the STB Railway Sample Data are used, existing information is provided by shippers, receivers, and carriers, or new data are collected using some type of sampling to identify daily, weekly, or seasonal patterns in rail traffic. It is likely that locally relevant existing flow information for airways will be unavailable if it is not provided by air carriers serving the jurisdiction, and the BTS Commodity Flow Survey rep- resents the only other major source of publicly available data on hazmat transport by air. Table 6-1 lists hazmat flow data characteristics for railway, pipeline, waterway, and airway modes. Table 6-2 lists hazmat flow data analysis output characteristics by data source for these modes, the maximum level of HMCFS objective for which they are typically applicable, their gen- eral relevance to a local HMCFS, and a rating indicating the expected effort required for analysis.