Freight and four other measures of the trucking industry’s economic health showed a slight improvement in August, but the numbers still remain well below normal, according to FTR Associates, a transportation forecasting organization.

The FTR Trucking Conditions Index (TCI) was calculated at -20.18 for the month, a “modest improvement” from a low reading of -28.80 in March, the company reported. An index of 0 is considered neutral.

Despite the better numbers, FTR expects its index will “remain well below normal levels until freight growth takes off in the second half of 2010.” In addition to freight volume, the index tracks capacity, costs, driver supply and other operational factors.

“Even though the TCI is trending upward, real acceleration of the index must await a substantial recovery in capacity utilization that we don’t expect until 2011,” said Eric Starks, FTR president.