It's probably a style/css issue.
Try setting the fill to none on the path..
path {
fill: none;
stroke: black;
stroke-linejoin: round;
stroke-width: 1.0;
}
or something like that. You prob also want to add a class to the path so your css selector can be specific to the railroad path (not sure if that's what the "rail-line" class is for).