Rates for spot market freight moved significantly higher over the past week following big gains over the past month, according to the freight matching service provider DAT.

Van reported the largest gain, 3.5%, for the first week in June compared to the final week in May, hitting an average of $2.05 per mile. Flatbeds increased nearly as much, 3.4% for an average of $2.44 per mile, while reefers added 2.6% for an average of $2.38 per mile. All are four-week highs or better.

This happened as the number of spot market loads jumped 35% while available truck capacity fell by 8.8% and load-to-truck ratios in all three categories posted impressive double-digit increases.

Spot market freight availability as measured by the DAT North American Freight Index has run high since July 2013 due to various factors including extraordinary weather events, regulatory changes and driver shortages, according to the company.

May 2014 numbers extend the trend, becoming the eleventh consecutive month to post a year-over-year record high with a 40% increase over last May. Month over month, however, May freight volumes declined 2.1% compared to April's.

Freight for vans, the predominant equipment category, was up 25%, refrigerated freight increased 18% and flatbed freight volume rose 85% compared to May 2013.  Month-over-month van freight availability was fairly stable with a 1% decline, while reefer freight dropped 4.8% and flatbed volume lost 1.6%.

The increase in freight, together with capacity constraints, added pressure to rates. Compared with May 2013, van rates last month rose 18%, reefers added 20%, and flatbeds commanded a 12% increase. Month over month, rates declined 2% for vans while reefers got a 3.4% rate increase and flatbed rates rose 1.1%