Equipment problems that sidelined Amtrak's high-speed Acela Express trains cost about $9 million in ticket revenue and an estimated 76,000 passengers last month, reported the Associated Press. "As you could bet, having a lot of these trains out of service in August hurt our revenue," said Amtrak President David Gunn in a message to employees. A month after inspectors first discovered cracks underneath Acela Express locomotives, the service is still running only 12 trains compared to 15 normally, said the news service. Temporary repairs continue on the remainder of the fleet, while the cause of the cracking is discussed by Amtrak, federal railroad officials, and the train manufacturers, Bombardier Transportation of North America and Alstom Ltd, according to the AP.