Schindler Lifts explains the inner workings and safety mechanisms that make taking the elevator the safest form of mass transport. The myth of free-falling elevators, doors closing on people and elevator cars rapidly ascending severing limbs or worse. Most of these are freak accidents, and the result of negligence, but misconceptions abound. Hollywood and theme parks don’t do elevators any favours either, with rides like the Tower of Terror and movies featuring elevators in free-fall. It is not surprising that more people have a phobia of taking the elevator, than crossing the road (which, statistically, puts people at greater risk of injury or fatality). Do you know that riding the elevator is a form of mass transport and, statistically, it is the safest form of getting people from one place to another?
With working 10, 20 and sometimes 30 floors above ground becoming more commonplace, we often step in and out of elevators without much thought, often occupied with our smartphones. How often do we think of the complex electro-mechanical systems that guide the elevator cars up and down without incident? A better understanding of what trips up a elevator system and the common causes of malfunction will help building managers and facilities professionals reduce elevator downtime and minimise callouts and costly repairs.
Why do elevators break down?
Elevators are controlled by a computer system – a sophisticated electro-mechanical system with an array of sensors, that constantly check on different aspects of the system to ensure everything is in correct working order. When one element trips in a fashion that may risk the safety or reliability of the unit, the safety circuit is triggered to bring the elevator to a stop.
The most common reasons for service callouts are related to door issues, either in the elevator car or on the elevator landing. They are the most active part of the system that interfaces with the outside, and there are a lot more doors in an elevator system compared to the other components. Because they are subjected to the more wear and tear, they accordingly require the most maintenance to reduce callouts due to system failure.
What about door safety?
Modern elevators have two sets of sensors – one is a light sensor that retracts the doors when it detects something within its beam. When that fails, there’s also a touch sensor, which physically senses an object and retracts. The elevator car is programmed not to move until the doors are completely closed and the locks are latched. The lock has two levels of checks, a mechanical one and an electro-magnetic one. Most of the cases of doors ‘bumping’ passengers are due to lack of maintenance.
Ropes snapping: how likely in the real world?
Most elevators feature between two and eight woven steel cables. Elevator engineers and technicians call them ropes. These ropes depend on ‘factor of safety’. The factor of safety in Australia is set at 12, which means that the combined strength of the ropes must be sufficient to hold 12 times the weight of a fully loaded elevator car, and each rope is more than adequate to hold the weight of an elevator car. If for some reason, the ropes do get severed, as happened in 1945 in the Empire State Building in New York when a B25 bomber crashed into it, there is also the elevator brake safety system. This kicks in when elevators travel at speeds faster than they are designed for, and brings the elevator to a stop.
The car safety brake was invented in the mid 1800s and has been one of the most fundamental safety features of modern elevators. In fact, it was the invention that made passenger elevators feasible. Prior to this, elevators were only used for freight, as hemp ropes would sometimes snap.
There is another safety feature – the counterweight. These weights weigh slightly more than an empty car and slightly less than a fully loaded car. If all other safety features fail, the counterweights make the elevator ascend rather than descend and when the counterweights reach the top or bottom of the shaft, they meet a cushion that would bring the elevator car to an abrupt, but hopefully survivable, stop. It wouldn’t be the most comfortable of stops, but it is an added layer of safety for elevators.
Realistically speaking, the issue passengers have with being stuck in a elevator isn’t the fear of injury or fatality, but the sense of helplessness when one is trapped in a elevator. Here, understanding the systems put in place to ensure their comfort until help arrives is important. Building owners and their facilitators should learn about the back-up systems their elevators offer. Contact your provider if you are not sure what measures are in place.
For high-end elevator systems, during a building-wide power failure, there is a two-hour battery back-up system for lighting and communication. Passengers shouldn’t be in an uncomfortable position with lighting and communication services available. The phone line to connect to monitoring services is usually powered by the line itself, and thus communications are always available even in a power outage. There will be changes with the new NBN (National Broadband Network) system as the industry works towards powering fibre optic lines. It will be a challenge for the industry, but this will only take place when the old phone lines are switched off which is still quite a while away.
While Australia does not keep accurate statistics on elevator fatalities and injuries like they do in the US, the key point to note is that elevators are the safest form of mass transport. According to The New Yorker, an average of 26 people die in elevators each year in the US. There are 26 car deaths every five hours. Also, most people who die in elevators are technicians and service staff, not passengers. And theses are usually due to falls within the shaft off the top of the elevator car.
And if you do get trapped in an elevator, note that you should never attempt to prise open the doors or hatches. In such situations, damage to the sensors built into the doors may lead to the elevator doing what it is programmed to do, which could put passengers at greater risk. The safest place to be in times of an elevator crisis is inside the elevator car. Keep calm and leave it to the professionals.
Steps to take to minimise incidences of elevator breakdowns:
- The simplest things any building manager or facilities manager can do is vacuum the elevator door tracks. While it seems like common sense, this is an oversight in many builds. During fitouts, increase checks on elevators, especially the door tracks, debris like Gyprock, electrical cables and nails can get stuck in the tracks. Increase the level of cleaning and visual checks of door seals and door operations during these times.
- Avoid wedging items in the elevator doors and always use the key switch to control doors during times of fitouts, when elevator doors need to be held open for transport of goods and workers. Breakdowns caused by misuse and abuse are chargeable callouts. If you’re not familiar with the key switch operation, call your service provider.
- Educate complementary service providers and residents on how to use elevators appropriately. Training for contractors may be useful in times of fitouts to prevent expensive damage to elevator systems and a comprehensive guide informing residents on the proper processes when moving in and out of a building will help reduce elevator malfunctions due to misuse. Highlight the cost borne by residents, if the elevator should require repairs due to their negligence.
- The Australian Elevator Association recommends regular inspection of floor levels, smoothness of operation, satisfactory operation of the emergency communication device, any unusual in-service conditions like stopping mid-flight and tendencies for doors to ‘bump’ passengers. These should be reported to the service provider.
- Finally, if you are concerned about the integrity of your elevator system, contact your service provider and request a copy of the last safety certificate. Safety certificates are issued annually and should list that the units have been maintained to relevant standards in compliance with the original manufacturer’s checklist.
Colin Carty, director of Technical and Field Support at Schindler Lifts Australia, has more than 12 years’ experience in the vertical transport industry. As a director on the national board, he is responsible for product quality and safety, quality assurance, employee technical training and technical support.