Employee headcount levels for the U.S. rail operations of Class I railroads hit a new low in October amid a slump in U.S. rail traffic and the transition to precision scheduled railroading (PSR).

The total number of employees working for Class I railroads in the U.S. was 134,582 last month, which is the fewest for 2019, according to data collected by the U.S. Surface Transportation Board. That is 9.5% lower than October 2018 and nearly 1.7% down from September of this year.

Of that total, October staffing levels for train and engine crews fell to 55,361, an 11.8% drop from October 2018 and a nearly 3.1% decline from September 2019. Train and engine crew headcount levels can be an indicator of rail demand, with levels rising and falling depending on network capacity needs.

October’s decline in overall U.S. Class I rail employment levels was the largest year-over-year decline in over three years, according to transportation analyst Bascome Majors of investment firm Susquehanna Financial Group. Train and engine crew totals also saw their biggest year-over-year decline in over three years, Majors said in a Nov. 20 research note.

October’s totals come as the railroads have furloughed workers amid declining rail volumes and the transition to PSR, an operating model that seeks to streamline rail operations and cut costs. Canadian National (NYSE: CNI) announced earlier this month that it was trimming staff amid lower rail volumes, while Norfolk Southern (NYSE: NSC) and Union Pacific (NYSE: UNP) have made similar moves in recent weeks as they transition to PSR.Year-to-date rail volumes, meanwhile, were down 4.5% in the U.S. to 23.8 million carloads and intermodal units for the week ending Nov. 16, the Association of American Railroads reported last week.