Destination control (ACA)

Destination Control or Adaptive Hall Call Allocation (ACA) requires every passenger to enter their destination on the landing. When a call is entered, the system makes an allocation and immediately displays the selected elevator to the passenger.

When a new call is introduced, the system calculates every passenger’s remaining waiting and transit times for each possible allocation. The allocation is made according to the selected Cost Function, which is either Minimum Waiting Time or Minimum Journey Time.

Minimum Journey Time is generally applied during the morning uppeak. Either function may be applied at other times of the day.

Minimum journey time with waiting time constraint is a Minimum Journey Time function. However, a penalty is applied if the dispatcher anticipates the waiting time will exceed the specified threshold level.

Reduction in number of stops can be applied to increase the chance of people travelling to/from the same floors being allocated to the same elevator.

For a detailed discussion of this algorithm, please refer to the Elevator Traffic Handbook by Dr Gina Barney.

Allow allocations requiring doors to re-open is an option which determines whether or not the dispatcher is allowed to allocate a new destination call at the elevator’s current floor. Re-opening the doors delays the passengers already in the car, but may reduce the new passenger’s waiting time significantly.

Destination Control can dramatically improve performance during uppeak traffic.

Caution! This improvement is not consistent across all traffic conditions. If you select fewer, slower, or smaller elevators because of the performance improvements realised by destination control, it is very important to analyse other peak traffic conditions (e.g. down peak and lunchtime traffic).

Please also see Mixed Control (Enhanced ACA) which is based on ACA but includes enhancements reflecting the ongoing improvements in this technology achieved by developers in recent years.