It would be helpful to know what you have tried up to this point, if anything. You might do what I have done, which is to use a wall-mount platform, a Brightstar Audio BigRock under the table, and spring suspension under the Brightstar. Not too expensive, very effective. I don't live next to the Long Island Railroad, but it might, and should, help to some extent. Can be used under all your source components.
Try also Mapleshade Nanomounts, drains unwanted vibrations away from the cartridge into the headshell, through the arm, and into the plinth. The plinth has to be firmly engaged on the BigRock, via some kind of spikes or other, to make sure to complete the eliminatiion of vibration. Worth a try, what do you have to lose?
The springs can be had through McMaster-Carr. You can see how it's implemented by visiting my system.
Best of luck,
Dan