Canada’s two biggest freight railroads reported mixed earnings this week.

Kansas City Southern reported its third-quarter earnings rose to $100 million, or 91 cents a share, from $50 million, or 48 cents, the previous year.

Frozen Food Express Industries said it will sell more than 400 dry vans and almost 300 tractors to truckload carrier Celadon Trucking Services.

Union Pacific Corp.’s third-quarter profit increased 16% from a year ago as higher prices offset slower growth in shipments and fuel costs.

CSX Corp. said its third-quarter net income rose to $464 million, or 43 cents per share, from $414 million, or 36 cents, a year ago.

A surge in tank truck business, spurred by oil and shale gas drilling, is fueling an “incredibly hot” market for tank trailers to haul crude oil, sand and related products, industry officials said.

Trailer manufacturers said they received 12,524 net orders in August, a 10% increase from a year ago, but below July’s level, ACT Research Co. reported last week.

Truck fleets ordered 13,200 new commercial trailers during July, a 20% increase over July 2010, but the fourth straight month of declining figures, ACT Research Co. reported.

Trailer Bridge Inc. reported a second-quarter loss of $3.6 million, or 30 cents a share, compared with net income of $900,000, or 7 cents, a year ago.

The more than year-long surge in orders for new trailers showed signs of leveling off in June, increasing just 6% from 2010 levels, compared with an overall 65% gain over the first half of 2011, ACT Research Co. said.