For me the same problem. But here I get the error that it uses too much RAM after the DLC. After checking multiple times the amount rises in 15 minutes to about 4GB for TF alone before it shuts down without warning beforehand. This is with 10 lines with about 20 vehicles each (of which 7 lines are busses).
Specs: Core i7 930, 6GB DDR3 RAM, 128GB SSD, Windows 8.1, AMD 7850 2GB.