Low-Sulfur diesel

Now that low-sulfur diesel fuel is being produced for ON-ROAD vehicles such as trucks and transit buses, and is required to be in all U.S. gas stations by October 1, 2006, are any commuter railroads planning on using low-sulfur diesel? Low-sulfur diesel is not required to be used in locomotives, but I'm wondering if any commuter railroads will be making the switch?

Most railroads do not use Diesel as in trucks but use Home heating oil and it still has Sulfur in it.

MBTA I believe converted to either low or ultra low sulfur diesel recently as part of an agrement over overall vehicle emissions.

They supposedly have been using ULSD in buses for a while too despite it not being required at the time.

Just to clarify, it is Ultra Low Sulfur Diesel that is the new standard. We already had Low Sulfur Diesel for years.