What feature allows roller coasters to operate safely over water?

The feature that allows roller coasters to operate safely over water is the use of special water-resistant materials. This is essential because roller coasters that are positioned over or near water are exposed to moisture, which can lead to corrosion or damage if standard materials are used. By incorporating materials that can withstand exposure to water and resist degradation, manufacturers ensure the longevity and safety of the ride.

Using water-resistant materials also enhances the ride's structural integrity, allowing it to handle the additional challenges that come from being in a humid or wet environment. This consideration is critical both for the safety of the riders and the maintenance requirements of the ride over time.