MODAL BREAKDOWN OF HAZARDOUS MATERIALS INCIDENTS

Hazardous Materials Incidents by Mode (monthly data, not seasonally adjusted)

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All 2001 data are preliminary

Hazardous Materials Incidents by Mode (monthly data, not seasonally adjusted)

All 2002 data are preliminary

Most reported releases of hazardous materials occur on the highways.

* Preliminary estimates.

NOTE: The current value is compared to the value from the same period in the previous year to account for seasonality.

Incident reporting requirements were extended to intrastate motor carriers on October 1, 1998, which may partly explain the subsequent increased volume of reports. Beginning in April 1993, there was sharp improvement in reporting of incidents by small package carriers.

A reported incident is a report of any unintentional release of hazardous material while in transportation (including loading, unloading, and temporary storage). It excludes pipeline and bulk shipments by water, which are reported separately.

A trendline has been provided for highway incidents. The trend has been calculated through a statistical procedure called Structural Modeling, in which the time series under study is decomposed into seasonal, trend and irregular components. For further information on this statistical procedure, see: S.J. Koopman, et al., Structural Time Series Analyser, Modeller and Predictor (STAMP), London: Timberlake Consultants Ltd., 2000

SOURCE: U. S. Department of Transportation, Research and Special Program Administration, Office of Hazardous Materials, Planning and Analysis, Hazardous Materials Information System data obtained through personal communication.