eBook High-Low Method for a Service Company Boston Railroad decided to use the high-low method and operating data from the past six months to estimate the fixed and variable components of transportation costs. The activity base used by Boston Railroad is a measure of railroad operating activity, termed "gross-ton miles," which is the total number of tons multiplied by the miles moved. Transportation Costs Gross-Ton Miles January February $1,055,700 351,000 1,177,100 392,000 March 831,900 254,000 April 1,128,600 380,000 May 946,500 306,000 June 1,213,500 413,000