After several years of false starts, it seems the trucking capacity crunch is finally arriving.

The latest evidence came today from consultancy FTR, whose monthly index of trucking conditions showed "unprecedented capacity constraints" in February, similar to the month before. Severe winter weather amplified an already-tight supply situation, and FTR expects a sellers' market for truckload services to persist for the rest of 2014.

When taking the bad February weather into account, the monthly reading represented the "tightest truck market on record," FTR said.

Jonathan Starks, FTR's director of transportation analysis, said the imbalance is driven largely by changes in the regulatory landscape that have compressed driver and rig supply. However, he added in an email that "demand has held up pretty well so far this year."

In a statement accompanying the results, Starks said shippers and carriers "have to be on the lookout for a potential tipping point when freight demand is able to keep [up] the current high level of truck use well into the summer months." If that scenario unfolds, shippers will be forced to bid up rates to ensure they have adequate capacity during the fall shipping season, Starks said.

The first two months of the year saw dramatic spikes in spot-market rates as shippers who were unable to get contracted capacity were forced into the premium-priced category to get their loads moved. The current combination of moderating demand and the spring thaw has eased fears of a full-blown capacity crisis, Starks said. But he warned that it would only take a relatively modest and short-lived uptick in industrial production to tighten up the market yet again.

The good news for carriers—and conversely a warning for shippers—was also found in a first-quarter survey of small and large carrier executives issued last week by the consulting company Transport Capital Partners (TCP). About 77 percent of respondents said they expect volume increases over the next 12 months, up 74 percent from the fourth quarter 2013 consensus, the group said. Four out of five carriers expect rates to increase over that period, a 62-percent jump from the prior quarter, TCP said.

Because of the powerful spikes over such a short time span, Richard Mikes, a TCP partner, leader of the survey and long-time industry veteran, said in a statement that the "literal mother of all rate increases may be here in 2014." Through the first half of the year, rates will rise at a mid single-digit pace rather than by a low single-digit amount as forecast earlier by carriers, Mikes projected.

About 60 percent of carriers reported that their days sales outstanding (DSO) had not increased, according to the survey. This trend indicates that shippers are paying with reasonable promptness so they don't fall out of favor with their carriers, TCP said. Mikes said he expects DSO to continue narrowing as capacity tightens further.

During the past several months, shippers and carriers alike have complained about a shortage of qualified drivers and available rigs. While the capacity problem was most acute in the winter months, the dilemma is starting to take on a secular feel. Howard Mingo, who runs transportation out of Wal-Mart Stores Inc.'s LaGrange, Ga., facility, about 60 miles south of Atlanta, told an industry conference last month that attracting drivers who fit the retail giant's specifications—Wal-Mart does not hire drivers without a certain amount of logged miles under their belt—is a growing problem.

"It's difficult to get drivers nowadays," said Mingo, who supervises 165 drivers that run, on average, about one million miles per month. Apparently, though, it's not for a lack of supply; Mingo said he has received as many as 753 applications for one driver opening.

Mingo said he tries to get his drivers home every week, and offers a 5-cents-per-mile bonus for drivers who work over a weekend.