All aboard!

We are all familiar with the old adage of 'you wait ages, then three turn up at once!' , but how often do we consider this in relation to other modes of transport which have a tangible effect on most of our daily lives?This article takes a brief behind-the-scenes look at how advances in technology bring efficiency to transport within today's buildings.

Traffic Patterns

It is generally accepted (and the subject of various studies and published guides and accepted standards) that traffic within typical buildings (generally medium to high rise 'office' applications but can equally apply to other formats) presents itself in a fairly uniform format as follows:

Morning or Up-Peak traffic : Mostly in an up direction and typically occurring between the hours of 8 am to 10 am (although this may obviously be affected by flexible hours working etc.)

Lunch or Midday peak traffic: Bi-directional traffic which occurs as the occupants of the building go to and return from lunch. The busiest peak of the day, involving the movement of a sizeable number of occupants within the building not once, but twice within a relatively short period of time.

Evening Peak traffic: Mostly in down direction as occupants of the building begin their journey home. (Again this will be affected by flexible working hours etc.)

Evolution

At its most basic inception, an electrical lift control system consisted of a series of mechanical switches, buttons and electro-mechanical relays which sensed an input from the user in the form of a call button and completed a circuit despatching the lift to the floor where the button was pressed. Early lift systems would answer one call at a time on a 'first come first served' (often referred to as 'APB' - Automatic Push Button) basis ignoring other calls until it had completed its first journey - a very analogue and sequential method of operation.Gradually, as technology advanced and the use of electro-mechanical selectors and switches were introduced, lift control systems improved and evolved to become more efficient and 'intelligent', including the ability to sense multiple calls from different floors and stop along the way to pick up more passengers on the way to their ultimate destinations.

The introduction of 'collective' control provided a leap forward in efficiency, but was still limited due to it's reliance largely on mechanical switch-gear and hard-wired format which required a number of lift controllers in a group to be wired into a central 'despatcher' unit and a complex number of physical wired interconnections, cabinets and relays. During the 1970's a motor room controlling a group of let's say 6 lifts was more alike a telephone exchange than a plant room!

With advancements in solid-state technology in the 1970's and thereafter the introduction and continued evolution of microprocessor technology during the 1980's and 1990's, it has been possible to continually improve the efficiency of lifts and the way in which they interact to better serve the traffic patterns and requirements within a building.

It was possible to introduce facilities such as 'zoning' where lifts within a group would park at different floors when at rest which effectively reduces the overall time taken to destination by one (or more) lifts being closer to any given floor than if they all parked at let's say the main floor. Additionally it was possible to alter via means of timed switches the sequence and location of the parking zones and the number of lifts parked at any given location , etc.etc. by the time of day to further enhance response and tailor it to the changing, but repetitive patterns of traffic within a typical building. ('Morning-peak', 'lunchtime-peak' and evening-peak' traffic).

During this period, the introduction of load-weighing switches within lift cars which also enable today's control system to calculate whether the lift is approaching full capacity and therefore whether to stop en-route or to bypass floors on its way to its terminal destination proved another beneficial addition in our never-ending race to achieve maximum efficiency and reduce travel-time. However, given all the advancements we were still fast approaching 'peak performance limits' with regard to what could be done without taking a fresh approach from a different angle......

The next seminal moment came when the industry took a closer look at the more 'human' aspect of the vertical travel experience and assessed behavioural and traffic patterns of passengers more closely:

During the 1980's, 1990's and beyond we are doubtlessly all aware of the increasing reliance on the gathering and interpretation of data and the use of same to interpret patterns and format algorithms which affect the performance of all manner of things around us from the delivery of our groceries to our supermarkets to space travel and everything in between.

Up until then, lifts generally got to a floor having answered a call from that floor and passengers got in and pressed the buttons within the lift to select which floor they wanted to travel to. Fine, but consider that not everyone wanting to go to a particular floor was in the same lift as people don't generally group themselves together in orderly ranks and you can begin to see how you could have a number of partially loaded lifts within the building answering calls to all the same floors and in particular meaning that individual lifts made a higher number of stops en-route to their terminal destination.

It was time to 'coerce' lift passengers into behaving as an orderly mass rather than an dis-organised one!

Hence was born the next leap forward in lift control technology, for which today there are many names but is generally known as 'Destination Control'.

The system works under the premise of removing push-buttons from the interior of the lift cars and installing 'Destination control floor selection stations or 'terminals' ' at each floor - the passengers then select the floor to which they want to travel from one of the screens ('terminals') in the lobby, and the group control system will then indicate to the passenger which lift to go to. (During this time, the algorithm within the control system is working furiously at calculating how many passengers at that floor wish to go to the same destination, whether the number of passengers wishing to go to the destination means the lift is at full capacity and therefore allocating one lift to go to that floor only, or if its not at full capacity allocating that lift to go to several (but intelligently grouped) floors until the full capacity of that lift is reached etc.etc.etc)

Where before you could have had, for example, a 12 person capacity lift in a 12 floor building stopping at every floor en route to the 12th floor if all passengers wanted to go to different floors, now you are more likely to have 12 persons wanting to go to one floor in the same lift, or smaller groups of people wanting to go to a couple of different floors within the same lift - reducing greatly the number of stops any particular lift makes and therefore reducing inefficiency both in terms of time taken to destination and energy usage.

A typical (many formats/designs/sizes are available) Destination control system terminal incorporating a touch-screen for floor selection.

A typical in-car indicator for destination control - in this instance showing the lift travelling in the up-direction in transit, at the eighth floor with the scheduled next stop (highlighted) at the tenth floor.

Considerations

While it is undoubtedly the most efficient method available to date of moving occupants within a building, destination control does have it's plus and minus points and therefore will be suitable for certain locations and provide little benefit in others when viewed in terms of benefit against installation cost.

Some points to consider are:

• Population and height of the building - As both factors increase so does the benefit of installing a destination control system.

• Number of lifts within the building and floors served.

• Usage of the lifts (i.e. actual traffic throughput) - This is affected by many different variables including the work habits of the occupants, whether they travel between floors during the day in the pursuit of their duties, whether there is a facility such as a restaurant or gym within the building and where the facility is located, whether the building is single or multi-tenancy occupation etc.etc.

• The population itself - Destination control requires a brief period of 'mind-set alteration' and getting used to, mainly due to the lack of buttons within the lift cars (although some hybrid systems exist with buttons within the lift) and operation from floor terminals instead. 

  This is generally a brief period where the building population re-orientates itself to the new conditions and hardly, if ever, presents a stumbling block.

Therefore, a building where the majority of the population is usually resident, for example a high rise office block would benefit more than a building where the population isn't, for example a Hotel,.......and many other factors in between.

It is not a 'one size fits all' solution.It is therefore essential to look at the solution 'in the round' as part of an overall look at the requirements of the business in the context of the overall traffic strategy of the building, and this is where a reputable Lift Consultant will be able to assist by carrying out various calculations and surveys such as:

• Data logging survey

• Feasibilty study

• Traffic analysis

And then correlate the data gathered and assist you with coordinating this into the overall strategy for the building.

All of which can save a considerable amount of time and expenditure which may result if the wrong solution is chosen at the outset.

We trust that this article proved useful and informative - Please do not hesitate to contact us via the details below for further advice or assistance.

To find out how we can assist you with inspection, condition surveys, design, maintenance management and all other aspects of lift and Escalator consultancy services please contact us via our office or website at www.consultalift.co.uk