Check Progressive Railroading, or Railway Age for Serious financing. Most large banks have a branch devoted to the Rail industry.

We've worked with what I'd call three kinds of banks:

1) Those that have a good business relationship with the client already (usually non-railroad) , but are scared to death of railroads and need help to understand regulatory issues, scrap values etc...and with a little handholding can understand the business and risks and do a deal. Our favorites..often works.
2) Those big guys that do this already...but may resist because 'your deal is too small' - but essentially understand how to collateralize railroad track and assets similar to the FRA RIF-loan model. You may get stuck on points and price....or not. Attend any ASLRRA meeting and they are all there!
3) Those banks that just laugh at you and walk away....