Hello:
Here's the web site of ALL North American's Railroad frequencies. There is a total of 100 standard frequencies! There are a few odd ball's in the list.
http://zippy.ci.uiuc.edu/~roma/rr-freqs/index-old.html#byfreq
I am a Ham radio Operator. So I use my VHF/UHF radios and antennas. The most important part of radio is the antenna! I can't stress this enough! A good ground if you use a base antenna. You can use Radio Shack's scanner antennas. They have a discone for base. A couple of mag-mounts and glass mounts for your car. I would reconmend the Radio Shack 2 Meter (Ham) antenna for your car. It has a 5/8 wave at 3db gain over a quater wave. In other words. It can hear alot more! Oh yes, you will probbly need a SO239 to a BNC adapter.
Hope this helps,
Andy KF4JQD