Trade and shipments between countries, regions and cities have been expanding dramatically in recent years. Yet, transportation planners and social scientists studying these phenomena have mostly relied on rules-of-thumb or infrequent and expensive shipper surveys to estimate freight flows. These two approaches are no longer adequate. We suggest that it is possible to estimate most of a metropolitan area's (MA) highway network truck shipments from secondary data sources, using these sources to generate relatively inexpensive and updateable link-specific estimates. The major research steps involved are the following. 1. Utilize a regional input-output transactions table to estimate intraregional commodity-specific trip attractions and trip productions, and allocate these to small-area units. 2. Estimate commodity-specific interregional and international trip attractions and trip productions for those locations where airports, seaports, rail yards, or regional highway entry-exit points are located. 3. Create a regional commodity origin-destination (O-D) matrix using estimates from steps i and 2. 4. Load the O-D matrix onto a regional highway network with known passenger flows.
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