What device is used for customer safety to prevent boarding between R44 and R46 cars?

The device used for customer safety that prevents boarding between R44 and R46 cars is referred to as barrier springs. These springs are designed to keep the doors securely closed and inhibit access to the area between the train cars, thereby preventing accidents that could occur if a passenger were to try to board or exit between moving cars. This safety feature is essential in promoting passenger safety in transit systems, as it reduces the risk of falls or injuries that might happen if someone were to attempt to cross the gap between the cars while the train is in motion.

In contrast, while safety barriers are important, they may refer to a different kind of protective structure not specifically designed for the gap between these types of cars. Preventive locks might also play a role in securing doors but are not specifically associated with the mechanism that prevents boarding in this context. An emergency stop is crucial for stopping the train in case of emergencies but does not specifically address the boarding issue between the cars. Thus, the focus on barrier springs is the most accurate answer for this specific safety scenario.