What are the specific requirements for emergency stop buttons on escalators, including their placement and functionality?

Emergency stop buttons on escalators are crucial safety devices designed to immediately halt the escalator's operation in the event of an emergency. There are specific requirements governing their placement, design, and functionality to ensure they are readily accessible and effective. Regarding placement, emergency stop buttons must be located at both the top and bottom landings of the escalator. This ensures that passengers at either end of the escalator can quickly stop it in case of an accident or hazard. The buttons must be easily accessible and visible to passengers. They are typically mounted on or near the escalator's handrail support or on a nearby wall. Clear signage must be provided to indicate the location of the emergency stop buttons. The buttons must be labeled with the words "Emergency Stop" or a similar clear and unambiguous message. Regarding design, the emergency stop buttons must be of a distinctive color, typically red, to make them easily identifiable in an emergency. The buttons must be of a size and shape that allows them to be easily activated by passengers of all ages and abilities. They must also be designed to prevent accidental activation. This is often achieved by recessing the button slightly or by requiring a deliberate push to activate it. Regarding functionality, when an emergency stop button is pressed, the escalator must immediately stop. The braking system must be engaged to bring the escalator to a halt as quickly and smoothly as possible. The emergency stop button must latch in the activated position, preventing the escalator from restarting until the button is manually reset. This ensures that the escalator remains stopped until the cause of the emergency has been addressed. The emergency stop button must be connected to a safety circuit that directly interrupts power to the escalator's drive motor and activates the braking system. The safety circuit must be designed to be fail-safe, meaning that it will automatically stop the escalator if any component of the circuit fails. After the emergency stop button has been activated and the escalator has been stopped, it must not be possible to restart the escalator from the normal operating controls. The escalator can only be restarted by a qualified technician after the emergency stop button has been manually reset and the cause of the emergency has been investigated and resolved.