Chemical shipments on U.S. railroads rose 11.5 percen, the Association of American Railroads said.

Chemicals shipments on trains, called rail car loadings, are a measure of demand for products ranging from plastics to fertilizers.

For the week that ended April 3, chemical rail car loadings rose to 28,776 from 25,808 in the year-earlier period, the AAR said.

The figures often provide an early glimpse of broader trends for the chemical industry as well as manufacturing, according to analysts.

The weekly data indicated that year-to-date rail car chemical loadings have risen 13.5 percent compared with the same period in 2009.

Rail car loadings represent about 21 percent of chemical volumes by tonnage. Trucks, barges and pipelines carry the rest. (Reuters)