The Bureau of Transportation Statistics in partnership with the U.S. Department of Transportation's Office of Intermodalism and the Federal Highway Administration sponsored the development of an Intermodal Bottleneck Evaluation Tool (IBET) to provide information and assist transportation planners and policymakers in identifying potential freight bottlenecks in the U.S. transportation system. IBET analyzes freight moved through three types of intermodal facilities: airports (truck-air transfers); seaports (truck-water, rail-water, inland water-deep sea transfers); and truck-rail interchange terminals. It calculates and measures the intensity of infrastructure use for each intermodal facility; estimates the relative significance of these facilities to national, regional, and international freight movement; and ranks facilities on the intensity of use.
IBET uses data from a variety of sources and distributes the freight flows over national transportation network models maintained at the U.S. Department of Energy's Oak Ridge National Laboratory. The freight flows are then assigned over the nation's highway, rail, maritime, and aviation networks using a geographic information system. Modal and intermodal networks, and origin-destination use patterns are displayed by IBET as well as rankings of highway and aviation delays, average annual daily traffic volumes, national freight volumes, and highway freight generated by the major ports.
Five categories of bottlenecks are addressed by IBET: highway-seaport access, seaport congestion, highway-airport access, airport congestion, and highway-rail terminal access. For each bottleneck, IBET can show domestic import and export flows, as well as through traffic by state of origin and destination. IBET, however, does not evaluate the intermodal operations of specific facilities or terminals, measure the impact of operational change on congestion, or incorporate time-of-day fluctuation in analyzing congestion. The evaluation of infrastructure improvements or the calculation of the monetary impact of congestion or mitigation projects is also not measured by IBET. A variety of measures used by IBET to assess intermodal freight bottlenecks are listed below.
|Intermodal facility||Bottleneck measure||Land-side access||Within terminal access||Port-side access|
|Airports||Intensity of use||AADT per lane-mile||Aircraft operations per runway|
|Airports||Intensity of use||Annual tons per lane-mile||Tons of throughput|
|Airports||Observed delay||Delay per 1,000 operations|
|Airports||Estimated delay||Delay per highway lane-mile|
|Seaports||Intensity of use||AADT per lane-mile||Throughput tons per terminal capacity|
|Seaports||Intensity of use||Annual tons per lane-mile|
|Seaports||Estimated delay||Delay per highway lane-mile|
|Truck-rail terminal access||Intensity of use||AADT per lane-mile||Throughput tons per terminal capacity||AADT per lane-mile|
|Truck-rail terminal access||Intensity of use||Annual tons per lane-mile||Annual tons per lane-mile|
|Truck-rail terminal access||Observed delay|
|Truck-rail terminal access||Estimated delay||Delay per highway lane-mile|
KEY: AADT = average annual daily traffic.
SOURCE: U.S. Department of Transportation, Bureau of Transportation Statistics, "Intermodal Bottleneck Evaluation Tool," prepared by Oak Ridge National Laboratory, September 2000.