The F-40's were really old, with a whole lot of miles, with rebuilding and modernization costs that were becoming prohibitive. The P's and the "new" F59PHI fleet is now how many years old....? Choo-choo's wear out, and get old, and become costly and obsolete to operate and maintain.

The State corridors, in the short term, simply needed more engines and cars, both for corridor growth, and the Siemens engines are capable of higher speeds (125 mph.), better acceleration (so I am told?), and are a whole lot cleaner (just to help save short loads life...?). Locomotives, after an expected operating life of 20-30 years, and thousands of hours/miles of usage, do tend to wear out and need to be replaced.