by emfinite
It was said that when the GP38s and MP15s were to be retired, the Railroad wanted to order the next generation hood unit (which would be the current day GP60). It could be easily modified with a HEP sled and would eliminate the need for a bulky powerpack or P-engine. You could run it either direction without a problem, you could switch with it, but you couldn't slow down fast enough with it.
One reason that stands out as to why the LIRR special ordered the DE/DM30ACs from EMD is the braking rate. The LIRR needed a locomotive that could travel at 80MPH when needed, but also slow itself fast enough to stop within the LIRR's closely positioned blocks. A locomotive manufacturer could get any engine to travel at 80MPH, that's the easy part, but for the braking rate to be as rapid as the LIRR wanted was a different story. It was realized that every locomotive that GE and GM had on their shelves at the time did not have the braking rate that the LIRR needed, so they had no choice but to custom build their own locomotive. This is why the LIRR doesn't have a P32 on the head end of every train.
Joe
One reason that stands out as to why the LIRR special ordered the DE/DM30ACs from EMD is the braking rate. The LIRR needed a locomotive that could travel at 80MPH when needed, but also slow itself fast enough to stop within the LIRR's closely positioned blocks. A locomotive manufacturer could get any engine to travel at 80MPH, that's the easy part, but for the braking rate to be as rapid as the LIRR wanted was a different story. It was realized that every locomotive that GE and GM had on their shelves at the time did not have the braking rate that the LIRR needed, so they had no choice but to custom build their own locomotive. This is why the LIRR doesn't have a P32 on the head end of every train.
Joe