Elevator Door Strikes Expert Article

Door strikes are one of the most common elevator injuries. A door strike can cause passenger injuries due to being knocked over, into other passengers/objects, or being caught in the elevator doors. In these cases, the elevator door reopening device, door speed, and door pressure are all factors to be assessed. This article focuses predominantly on elevator door reopening devices.

Elevator Door Strike Injury Investigations

The forensic investigation of an elevator door strike will often include an examination of the equipment used to:

1. Control the door
2. Detect obstructions
3. Reopen the door in the event that obstructions are detected

Within the elevator industry there are generally two types of door reopening device technologies in use: mechanical and infrared. 

Mechanical Door Reopening Devices

A mechanical door reopening device or safety edge relies on physical contact with a passenger (or other obstruction) to recognize the need to stop closing and reopen the elevator doors. A mechanical reopening device works by:

• A plastic device on the leading edge of the elevator doors that gets pushed and then slides away as the door contacts an obstruction
• The act of sliding actuates a mechanical switch, triggering the doors to reopen

While these safety edges still exist, they are considered obsolete and dangerous within the elevator industry because they require the doors to contact the passenger.

There is nothing in the ASME A17.1 Safety Code for Elevators and Escalators that prevents this contact, but the elevator industry recognizes the increased potential for injuries to the riding public. As technology improved, many elevator companies incorporated a photoelectric sensor in addition to the safety edge. This allows the door to reopen without striking the passengers, but with limitations.

Generally, these photoelectric sensors were in a single or double beam configuration, meaning that the photoelectric sensor could detect obstructions only along one or two specific horizontal planes. Having only one or two points of detection leaves blind spots in the system’s ability to detect obstructions, allowing passengers to still be struck by the doors under certain foreseeable conditions. These devices have largely been replaced by the infrared style of door reopening device.

Infrared Door Reopening Devices

An infrared door reopening device is an electrical device as opposed to the mechanical design of the safety edge. The infrared device works as follows:

• An emitter sends infrared beams to a detector.
• The detector senses whether the beams have been broken. (Broken beams signal that there is an obstruction.)
• If the infrared beam is broken, the elevator will signal to reopen the doors. 

This type of reopening device does not require the doors to physically contact the passenger, making it the safer option for the riding public. This type also monitors almost the entire doorway, preventing the dead spots typical of photoelectric systems.

Modern Standards for Elevator Door Passenger Detection

The 2019 version of the A17.1 Code has increased the requirements for a door reopening device for all elevators that are installed to this standard. The door reopening device is now required to sense objects that are between the doors, approaching the doors, and in front of the doors, and to generate an audible signal. The sensing of objects between the doors is what a door reopening device has always been required to do. These changes come in response to the prevalence of door strike incidents.

Which Elevator Standards are Relevant in Your Case?

It is possible that the information presented on the elevator nameplate is not reflective of the actual components driving the system. Within the elevator industry, modernization is more common than complete replacement. It may be necessary to review the system history to determine exactly which standards are relevant in your case.

Elevator Door Strike Expert Witness Investigations

While there are other factors that can increase the severity of a door strike, including the door speed and door force, any contact between the elevator doors and a passenger can cause injury to the riding public. Door strikes remain one of the leading causes of injury in the elevator industry and one of the most frequent types of elevator cases we review at Robson Forensic.

To connect with an elevator expert about your case, submit an inquiry or call us at 800.813.6736.

Featured Expert

Michael Vallone, C.E.I.

Elevator & Escalator Expert

Michael Vallone is an elevator and escalator expert with over 20 years of industry experience as a field mechanic, maintenance supervisor, and operations manager. His expertise extends to all aspects… read more.