Escalators have come a long way since inventor Jesse W Reno created the world’s first as a temporary amusement ride in 1895. They are now able to move people more efficiently, faster, further and more sustainably than ever before, and the technology used in their construction continues to evolve.
Reno’s original ‘inclined elevator’ rose seven feet at an angle of 25 degrees and at a speed of 75 feet per minute. Some 75,000 visitors took a ride during its fortnight-long installation.
The latest innovation for horizontal passenger movement is ACCEL, an accelerated continuous transportation system capable of covering distances between 10 and 1,500 metres.
Created by ThyssenKrupp, ACCEL is ideal for urban mobility projects like airport terminals and Metros.
ACCEL can move up to 7,300 passengers per hour per direction. Using a band of overlapping pallets that expand to three times the original size of each pallet, ACCEL’s revolutionary technology, applying the linear motor technology of the magnetic train Transrapid, ensures that passengers step onto the belt at normal walking speeds of 0.65 metres per second (2.35 kilometres per hour), accelerate smoothly up to two metres per second (7.2 kilometres per hour), and then decelerate back to normal walking speeds before leaving the system. For passengers who continue walking while on the belt, speeds of up to 3.3 metres per second (12 kilometres per hour) can also be achieved.
As congestion in urban transport networks rises in tandem with the population increase in cities, city governments are under continual pressure to reduce road traffic congestion and combat the costs it imposes in terms of immense wastage of time, energy, and environmental resources.
Indeed, modern escalators and moving walkways have been designed to consider people moving far beyond the confines of buildings.
In Hong Kong’s Mid-Levels residential district, one can find the world’s longest, outdoor covered escalator carrying users over 800 metres in distance and 135 metres in elevation. Now a tourist attraction in itself, the escalator remains a well-traversed commuter corridor, carrying nearly 43,000 people per day.
With the seeming success of this central escalator project, several more similar projects are at various stages designed to improve accessibility for aging residents and to reduce traffic congestion.
When considering horizontal transportation within buildings, space-saving solutions are of paramount importance to engineers looking to generate value for their clients.
For a space-saving option that also has an aesthetic wow factor, one need look no further than Mitsubishi Electric’s spiral escalator. The application of a pioneering technology enables the escalators to follow smooth curving paths to their destinations.
Spiral escalators in the entrance lobby leave the ground floor with a wealth of space and create a breathtaking first impression. They can also easily be installed in the corners or at the sides of a large room, greatly increasing the amount of usable floor space.
Another space-saving innovation is iwalk by ThyssenKrupp. Its slim dimensions require very little construction work and its technical features ensure low energy consumption.
The system only needs a shallow pit - just over 14 inches - or it can even be installed on top of the existing floor. All that is then needed are two ramps, one at each end. This makes it possible for it to be installed and removed quickly to deal with temporary traffic needs or moved from one side of a building to another for renovation work.
As well as being significantly more compact and flexible than conventional systems, iwalk features technology that can monitor how many people it is carrying and adjust power usage accordingly.
Of course, sustainability credentials are an important consideration given the potential energy usage of escalator and moving walkway systems.
Variable Voltage Variable Frequency (VVVF) controllers are now being incorporated into escalator applications incorporated with automatic start/stop control or automatic two-speed control to vary the escalator speed according to the passenger flow. The operation of these kinds of escalator is determined by the presence or absence of passengers, hence energy can be saved when the escalator is idle.
Various kinds of detection methodologies can be employed for sensing the presence of passenger, such as optical detectors, step sensors, light barriers etc. The detectors for monitoring the approaching passengers can be integrated into a pair of sensing post installed at the entry of the escalator, or they can be incorporated into the handrail entry of the escalator.
There has been some conjecture as to how energy efficient escalators/moving walkways that don't start until you get on them actually are. It has been argued that power surge needed to get them started almost negates the benefits.
“Basically it depends on the number of start/stop intervals and the length of the escalator,” said Michael Ridder, head of communications at ThyssenKrupp. “For example, an escalator with a rise of 4.5 metres and 7.5 kW engine is saving energy when the intervals last longer than 20 seconds. The longer the escalator, the longer the intervals get.”
The amount of savings depends on the type of buildings and passenger flow pattern. Based on a measurement carried out by the Electrical and Mechanical Services Department of Hong Kong, the energy saving of service-on-demand escalators can be up to 52 per cent for automatic start/stop escalators and 14 per cent for two-speed escalators in an office building.
Other energy saving measures and technologies include:
This is a solid-state controller that reduces losses in AC induction motors in the form of energy efficiency and soft starting capability, which reduces motor starting current and excessive wear of mechanical gears, chains, belts etc.
The energy saving potential is again dependent on the actual load of the escalator. The Electrical and Mechanical Services Department of Hong Kong conducted a study of a retrofit project in a government office building which showed that the average energy savings can be up to 10 per cent.
Reducing escalator step load
Replacing traditional heavy escalator steps with a glass fibre material can reduce their weight by up to 30 per cent. Initial material expense can be clawed back as this reduced step motor loading results in lower energy consumption.
Reducing escalator load
Similarly, by replacing power transmission chains with non-metallic materials or plastic-based materials (e.g. fibre glass reinforced plastic) can reduce the motor loading and result in lower energy consumption.
In the 100-plus years since their invention escalators and moving walkways have become far more than a funfair sideshow. They are an integral part of our daily lives and new ideas and technologies are transforming how we move not only around buildings but through our cities.