This is a really interesting question because I'm not sure how to answer it. Lichens aren't actually a single organism, they're actually a mixture of fungi and bacteria living off each other in what's called symbiosis.
Different types of lichen grow well in different environments. One particularly well known species of lichen (the technical name I can't remember) which is a sort of orangey colour tends to grow on the north side of trees in the northern hemisphere. The reason is because in the northern hemisphere the Sun doesn't rise and fall perfectly in the middle of the sky, it's actually tilted toward the South a little, meaning the south sides of trees get more sunlight. The opposite is true in the Southern hemisphere, the Northern sides of trees get extra sunlight.
The side which gets the most sunlight is usually not a good place for lichens to grow because they bake in the light and heat, so they tend to grow on the shaded side. So lichens can definitely be used to navigate.
Your question about the TV program and railways is more mysterious. I've never heard of lichens being used to map out railways, so here's a question posed to anyone reading: have you heard of this? Do you remember the same TV program Varena is talking about? I'd love to hear your responses in the comments!