A measure of base linehaul truckload rates show increases last month while intermodal rates fell for the sixth straight month, according to reports released Wednesday.

The Cass Truckload Linehaul Index rose to a reading of 123.4, a 3.6% improvement from the same time a year ago and 0.5% better than the month before, but still the second lowest reading so far this year.

This marks only the second time this year that it has improved both year-over-year and month-over-month,

With demand improving and capacity remaining extraordinarily tight, the investment firm Avondale Partners said it expects contract rate increases will continue to filter into the index at higher levels.

“We would point out that contract pricing, which applies to more than 95% of the public carriers' freight, has been accelerating after a drawn-out bid season last year. As a result, although spot market pricing has decelerated, we are not surprised to see our index continue to post mid-to-high single digit gains and we expect this to continue,” said Avondale. “We see truckload pricing increasing between 4% and 9% in 2015, depending on how much rate increases each carrier was successful in obtaining in 2014 and when those rate increases were achieved.”

The Cass Truckload Linehaul Index is an indicator of market fluctuations in per-mile truckload pricing. that isolates the linehaul component of full truckload costs from other components, such as fuel and accessorials, providing a reflection of trends in baseline truckload prices.

Meantime, a separate report on intermodal freight rates showed a 2.8% drop in June from the same time in 2014 and 4.7% lower than in May.

The Cass Intermodal Price Index registered 123 for June, its lowest level since June 2013.

As lower fuel surcharges continue to affect the cost of truckload shipping (the truckload index does not take fuel into account), many loads are shifting from intermodal to truckload, according to Avondale. However, it pointed out that intermodal rates typically mirror changes in fuel and remain competitive while efforts to shift freight transportation modes continue to be challenged by limited capacity.

“We expect intermodal rates will continue to decline in 2015 as the dramatic drop in diesel prices and even more dramatic drop in oil takes its toll on US domestic demand,” said Avondale “We concede that the extent to which loads can be shifted from domestic intermodal back to over-the-road truck is dependent on trucking capacity, but the around 20 cents per mile decline in fuel surcharges collected by truckers in the last year has to challenge demand and pricing power for domestic intermodal, especially in shorter lengths of haul.”

The Cass Intermodal Price Index is an indicator of market fluctuations in per-mile U.S. domestic intermodal costs that includes all charges associated with the move, such as linehaul, fuel and accessorials.

Data within both measures is based on actual freight invoices paid on behalf of Cass Information Systems clients, totaling over $23 billion in 2013.