About one quarter of 350 to 400 shippers, freight brokers, and motor carriers surveyed by investment firm Morgan Stanley and Co. LLC reported an abundance of truckload capacity, the survey's highest percentage reporting such conditions since January 2013, the firm said today.

The survey, which is regularly conducted, included carrier respondents that are mainly small to mid-sized fleets. Many of those fleets draw on the spot, or noncontract, market for their loads, and the spot market has been fairly stagnant for most of 2015, with few users reporting tightness in capacity. However, a source close to Schneider National Inc., one of the largest truckload carriers, said the Green Bay, Wis.-based trucker is having no problem covering its loads with company drivers, an indication that there is currently ample capacity on the road. Schneider was unavailable to comment at press time.

Alexander Vecchio, transportation analyst for Morgan Stanley, said in a research note accompanying the data that truckload pricing will begin to moderate in 2016 unless capacity tightens or demand accelerates, both in material ways, by the end of the year. Avondale Partners LLC, another investment firm, has pegged truckload rates to increase by between 4 and 9 percent by the time 2015 is in the books.

In an e-mail, Vecchio said the easing of capacity is likely due to an equal combination of existing oversupply and relatively tepid demand. But in a reflection of the data cross-currents swirling around the trucking industry, the American Trucking Associations (ATA) reported on Tuesday that its July for-hire truck tonnage index jumped 2.8 percent over June's totals, on a seasonally adjusted basis, to the best monthly gain since November 2013 and to the second-highest level on record. The strength in July followed a string of weak months that even had Bob Costello, the group's normally upbeat chief economist, concerned about the U.S. economy's near-term outlook.

In Tuesday's announcement, Costello said he remained concerned about high levels of inventory that "could have a negative impact on truck freight volumes over the next few months."

One big carrier, Omaha-based Werner Enterprises Inc., has added to its fleet over the past six months. As of June 30, Werner had 7,275 trucks in its fleet, compared to 7,050 at the end of 2014. While the proportional increase may be small given Werner's size, it does represent a reversal of a multiyear strategy of acquiring trucks just to replace existing equipment, and not for growth.

A Werner spokesman said improved driver recruitment and retention programs enabled the carrier to increase its fleet size on a net basis.