If you want an actual railroad brush, I have one or I could tell you how to make one. Make a rectangle, about 3 or 4 times high as it is wide. This is the slat or crosspiece...the wooden thing. Then make the iron rail stick out a little bit from each side, top and bottom...enough so that there is enough space before the next slat comes into play. Save this as a brush then choose this brush as the active brush. In the brush editing menu, set the angle jitter to direction and save this as a new brush and delete the previous one. Now, using the pen tool, draw a path and then stroke the path with this brush. If you were doing a full realism thing you might want separate brushes for slats and for rails so that you could get wood textures onto the slats and iron gray color for the rails.