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Elevator and Escalator Consulting Engineers

Destination Oriented (DO) dispatching

Below you will find relevant information briefly describing both the technology and installation of Corridor Control, known under the CSA/B44 Elevator Safety Code as Destination-Oriented (DO) dispatching systems.


Executive Summary

It is our view that Destination Oriented technology should be considered for any elevator group modernization or installation.

Each new construction project and each existing site that is being considered for elevator control replacement be subjected to a review to determine the cost/benefit factor for the use of DO. A DO system can improve passenger handling efficiency to a greater or lesser extent depending on the building parameters. More importantly, the appearance of a DO system creates a visible difference that impacts positively the public perception of the building. The DO system will be regarded over the coming years, as “state-of-the-art” and touch screen technology will become the standard interface for elevators. This review of each site will allow an owner or manager  to assess the key considerations and benefits of the DO technology as they relate to the realities of operation at their site.
 

What is Destination-Oriented Dispatching?

Elevator systems respond to input from the users. This input has traditionally been in the form of a push button actuation. The user presses an up or down button at the landing and when an elevator arrives in response to this call the user then presses a button in the elevator car to select the desired destination floor.


Destination Oriented (DO) systems are different in that the user, instead of pressing an up
or down button at the landing, selects – typically from a key pad or a touch screen – the
desired destination floor. The systems receive and act upon input from the hall buttons
(corridor screens or keypads) with this input consisting not only of the trip origin but also of
the trip destination.
 

The key advantage of the Destination Oriented system is that it gives the elevator control
computer more information. The computer not only knows that a call has been registered
at a particular floor in the up or down direction but it also knows how many calls have been
registered and to which floors the waiting passengers wish to go. This means that the
computer can assign the elevators to respond to the calls with more precision.


One result of this increased precision is that the computer will assign "duplicate" calls to one
elevator. For example, if an elevator is already designated to travel to floor X, then it may
be given a preference to answer any other floor X calls in its line of travel. Where there are
multiple calls and multiple elevator choices the computer will decide to which elevator calls
should be assigned for optimal efficiency.
 

Although some manufacturers are presently marketing DO systems in which the trip
destination is registered at the ground floor only, with car call buttons in the elevator and with
traditional up and down buttons at the typical floors (sometimes referred to as an “Up Peak
Boost System”) we recommend that the full DO system be provided in order to achieve the
full benefits of the DO system. This is particularly desirable when there is inter-floor and
cross-over floor traffic.
 

Technical Characteristics


The major elevator manufacturers' DO systems are marketed under different names such
as Schindler ID or Port (Schindler), Compass (Otis), Destination Dispatching (Thyssen Krupp) and
Polaris (KONE).


Each of the major manufacturers advertises various benefits such as “increase handling
capacity by 15% to 30%”, “reduce travel time by 50%” et cetera, although none provides
detailed information about the building type, total population, population distribution, number
of floors, number of elevators and the other input parameters upon which these numbers are
based. It is probably fair to assign these remarks to “promotional material” and not ascribe
to them a high degree of reliability.


The DO system is of special interest for situations where there is a pronounced morning up
peak. The improved traffic handling ability of DO is less apparent with balanced traffic - such
as might be experienced at lunch time.
 

It is obvious that for an elevator to collect passengers travelling to the same floor it will be
necessary to have a “pool” of waiting passengers from which to choose. This will inevitably
extend the average waiting time. The “duplicate call” passengers would have to wait until an
elevator arrives to serve them – as opposed to taking the first available elevator.
On the other hand, although the waiting time may increase, the actual total system trap time
(the waiting time plus the time to travel to the destination) may decrease; the elevator will
tend to make fewer stops on its way to the desired floors. Waiting time is generally
considered to be the key factor determining user satisfaction but the system trap time is
certainly not a negligible factor. A further consideration is the fact that the user suffers less
annoyance from the additional stops. This may be a particular consideration for buildings
where a single tenant occupies several floors. The calls can then be assigned so as to
minimize cross-annoyance between tenants. On balance, however, the waiting time is still
key and any extension of the waiting time is a negative; a well designed DO system must,
therefore, take this into account.
 

The key principles of the system (generalized but having validity in almost any DO
application) include: (a) handling capacity is increased (number of people moved per given
unit of time); (b) total system trap time is decreased (time from call registration to destination
arrival); (c) waiting time may be marginally increased.


DO systems work well with heavy traffic and large floor plates. On the other hand, with light
traffic and smaller floor plates there is less advantage to the DO system. From a purely
technical point of view the DO system has no disadvantage since it can always default to
operate in the same way as other systems if the traffic conditions so dictate.
 

Passenger and Tenant Perspectives
 

Destination-Oriented dispatching technology currently has a limited installed base in North
America although this is changing day by day. The comments below are based upon
observation of the operation of a number of these installations and discussions with building
managers.


 

A building with DO technology is noticeably different and gives the impression of cutting
edge technology. A DO system installed today can be regarded by a building manager as
a selling feature since it marks the building as “modern” and thus it may distinguish the
building from other competitive buildings. We anticipate these systems will become
sufficiently commonplace that 10 to 15 years from now any elevator without DO may be
regarded as dated.
 

The average person is often not familiar with the idea of selecting the destination floor from
the key pad or touch screen and then being directed to a specific elevator. This is not much
of a problem for the regular users but for visitors it can be disconcerting; we have heard of
strong negative reactions to the technology but cannot quantify this reaction and we believe
it will be short lived.


One of the advantages of DO is the improved organization of the lobby during peak hours.
A tenant may be more accepting of a slightly increased wait time if they are standing in front
of Elevator 6 in an orderly line-up with the other tenants also selected for Elevator 6. This is
an improvement on the situation in crowded lobbies where a tenant is in a general scrum and
wondering whether they will be close enough to whichever elevator happens to arrive next.
The touch screens commonly employed have a great deal of flexibility (logos can be
incorporated, messages can be displayed et cetera) which can assist the building in both
form and function. The DO systems can be integrated with modern security systems.
The integration of security systems and the presentation and the positioning of the touch
screens can alter the impact and impression of the building from a tenant and visitor
perspective. As an example, a DO system that reads a security card from a turnstile
checkpoint a fair distance from the elevator bank has more information by the time the
passenger reaches the elevator, which aids in efficient dispatching.
 

Financial Considerations

In the short term the cost of the DO systems will be higher than older systems. As the DO
technology becomes more commonplace we expect that the cost premium will drop.
The maintenance for the elevators for any controller upgrade, including a DO system, needs
to be considered and managed in advance. The specifications for an upgrade should
require the supplier to make diagnosis and maintenance tools available for their equipment.
There is always a practical consideration with controller upgrades as the willingness of a
“foreign supplier” to gear up and maintain competitor equipment will depend on the install
base of that equipment.
 

Summary

In our opinion the DO systems will benefit almost all buildings in terms of traffic handling but
in an office building with light traffic and small floor plates this benefit will be slight. From a
technical perspective, the DO system will be particularly effective in buildings with the
following characteristics:
• Low-rise
• Single-tenant
• High up peak traffic
• Group of eight or more elevators
• Large floor plates
Apart from these considerations, it is our view that the DO systems will mark a building as
being up-to-date.
 

There are many business reasons to consider a DO system. At a minimum, we certainly
recommend giving serious consideration to, and obtaining alternative pricing for, a DO
system whenever a controller upgrade is being tendered or a new construction project is
launched.