Old Dominion Freight Line expects Q2 earnings in the range of $0.62 to $0.64 per share, above $0.51 per share estimated by analysts.The company cited a 10.2% rise in tonnage year-over-year, more stable prices, and improved productivity for the earnings growth in Q2.The company also boosted its fiscal 2008 earnings forecast, projecting earnings between $1.90 and $1.95 per share, up from the earlier estimate of $1.85 to $1.90 per share. Analysts forecasted earnings of $1.83 per share.