Whether it’s; drains, rooftops, abandoned buildings, tunnels, or covert infiltrations of live sites, it’s all different aspects of Urban Exploration in general. Risks involved can range from being no more dangerous than crossing the street, to seriously life threatening. Besides the physical danger, there are the legal risks inherent from being where you aren’t allowed to be. With such a great diversity in locations and risks, we felt it easiest to separate the explorations by general difficulty/danger. Not foolproof by any means, but for the most part it works. Green is the simplest, Yellow intermediate, and Red the toughest (whether because of physical dangers or security “issues”).
Sites often change over time though. A perfect example would be Woodlands Hospital (now demolished). When we began exploring there years ago, there were police K-9 units on the grounds (and I am aware of at least one fellow explorer that was caught there by the K-9 unit way back then, a huge difference in comparison to the potential hazard of a security guard dozing off on a folding chair) but towards the end of the site’s “life”, security was virtually non-existant. The moral is, sites change, and what once was easy can become secure and vice versa. Our categories separate sites based on how they were when we explored them, not current situations.