Chemical shipments on U.S. railroads rose 5.4% last week, the Association of American Railroads said on Thursday. Chemicals shipments on trains, called rail car loadings, are a measure of demand for products ranging from plastics to fertilizers.

For the week ending February 13, chemical rail car loadings rose to 27,544 from 26,135 in the year-ago 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 11.9% compared with the same period in 2009.

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