Freight volume followed a common seasonal pattern of declining in August on the spot freight market as linehaul rates also moved lower, pushing the latest DAT North American Freight Index down for the second straight month.

Overall volume fell 8.8%, the fourth July-to-August drop in the past 10 years, as this year's fall freight season, which sometimes begins in mid-August, appears to be starting a few weeks later, the company reported.

By equipment type, van freight levels dropped 3.7% month over month, refrigerated freight edged down 0.4%, and flatbeds were off 18%.

The company added that early indications suggest improving van and reefer freight availability in September, with van-load posts up 6% and reefers 4% higher Aug. 30-Sept. 5 compared to the previous week.

Compared to the extraordinary high volume of 2014, August freight availability was down 44% overall, as vans declined 35%, reefers fell 29% and flatbeds dropped 57%.

Volume for August also fell below same-month totals for the past four years, but freight availability remained strong compared to the previous five-year period, from 2005 through 2010, which included an economic recession, according to DAT.

Line haul rates on the spot market followed the month-over-month volume trends by equipment type, declining 1.3% for vans, 2.7% for reefers and 2.2% for flatbeds. However, the average total rate paid to carriers declined more steeply, due to lower diesel prices that yielded a 14%reduction in the fuel surcharge compared to July. Carriers are typically paid a sum of the line haul rate and the fuel surcharge, on a per-mile basis. With fuel included, the total rate declined 3.3% for both vans and flatbeds, and fell 4.2% for reefers.

Compared to August 2014, line haul rates declined only 1.3% for vans, while reefer rates dipped 1.1% and flatbeds lost 5.8%, but total rates declined by 11% to 15%, due to a 49% decline in the fuel surcharge over the year.

The DAT North American Freight Index reflects spot market freight availability on the DAT Solutions network of load boards in the U.S. and Canada.