* Historical Significance: Grandview is presented as an old town with a rich history. The tunnels could be remnants of a forgotten era, possibly built for transportation, mining, or even as an escape route during a conflict.
* Spiritual Significance: As a town known for its paranormal activity, the tunnels could be connected to the spirit world. They might act as a portal or conduit for spirits to move between the realms, or they might be a place where spirits gather or are trapped.
* Plot Device: The tunnels are primarily used as a plot device for the show. They provide a mysterious and eerie location for ghostly encounters and allow for the exploration of various storylines. The specific reason for their existence might not be essential to the overall narrative.
Ultimately, the exact reason for the tunnels' presence remains ambiguous. It's left open to the viewers to interpret based on the show's themes of the afterlife, history, and the supernatural.