Railroad Spikes are typically used in hoodoo practice to honour Ogun, The Orisha of Metalwork. Place 3 inside an iron cauldron and place it on your altar to dedicate to Ogun... However, whether it is hoodoo or witchcraft, they are typically used to protect the home or business!
Railroad spikes are a powerful tool for home protection. Their properties come from the purpose they serve on railroads, keeping the tracks secured to protect trains and their passengers. It's also believed that iron can help keep spirits away, like the wrought iron fences found around cemeteries and mausoleums to keep all spirits from following people home (think of the fences that point towards the cemetery). You can use these to create a protection grid around your home by placing them in the four corners of your apartment or house. If you've got a larger space with a yard you can insert a spike into the ground in every corner to create a larger energetic boundary.