Destination Dispatch doesn’t solve the elevator bottleneck. Here’s why.
The leading elevator manufacturers are touting their destination dispatch systems as the premier solution to the elevator bottleneck problem that has arisen during the COVID-19 pandemic. But does destination dispatch really solve the bottleneck problem? We think it doesn’t for two reasons: tailgating, and lines to ride the elevator. When considering these common behaviors, the claims by elevator manufacturers that destination dispatch somehow remedies the problems that follow when limiting elevator occupancy become dubious at best.
What is this elevator bottleneck problem?
With the recent surge in COVID-19 cases, people are increasingly worried about being in small enclosed spaces with others. The elevator is perhaps the quintessential example of such a small, enclosed space. To limit the spread of COVID-19, most buildings are limiting elevator occupancy to 4 or fewer passengers at a time.
While limiting elevator occupancy prioritizes the health safety of your tenants, it has an unfortunate side effect: elevator efficiency is significantly reduced. To be sure, an elevator with a maximum capacity of 16 people has a greater throughput compared to an elevator that limits capacity to 4 people at a time—that’s common sense. The net effect of this reduced throughput has prompted many property managers to hire consultants to determine how much of their total building population can return to the building before the elevator system reaches saturation—or the point at which the elevators become overloaded and lines start to form.
With elevator capacity at a fraction of what it used to be, this saturation point occurs when only a small percentage of a building’s population uses the elevator system over a short period of time (in a commercial building we’ve analyzed, around 4% of the building population over a 5-minute period). Once this saturation point is reached, lines start to form, and wait times to use the elevator can rise anywhere from 10 minutes to over an hour! In other words, there is a disastrous bottleneck that can (and will) arise at the elevators. BISNOW, NPR, and Wired have published great articles describing the bottleneck problem in detail.
The bottleneck problem is amplified because elevators that have already reached their occupancy limit will still stop to pick up new passengers. In other words, an elevator carrying 4 people to the lobby will still respond to hall calls on the way down—even though no new passengers can enter the elevator.
These unnecessary stops are not only frustrating, but also time-consuming—worsening an already challenging bottleneck.
What is destination dispatch?
Destination dispatch refers to a system in which traditional two-button (up/down) hall call stations are replaced with a panel into which passengers enter their desired destination. Rather than picking up a passenger and then finding out where they’re going when they enter their desired floor inside the elevator, destination dispatch has the advantage of knowing where that passenger is going before any elevator stops to pick them up. In theory, this means that elevators can be allocated more efficiently by grouping passengers going to the same or nearby destinations to the same elevator.
Destination dispatch systems offer the greatest benefit to passengers arriving at the lobby during a morning rush hour—or “up peak” period. However, these systems have the same performance (or even worse) during the mid-day “lunch peak” and evening “down peak” periods as their simpler two-button counterpart.
During the COVID-19 pandemic, elevator manufacturers are reorienting the advertising for destination dispatch by claiming that it solves the elevator bottleneck problem. Specifically, they claim that the system can limit elevator occupancy by allocating only 4 passengers to an elevator at a time. At first, this makes sense, as destination dispatch is designed to allocate passengers to specific elevators. But in practice, these systems will not work as advertised because every passenger does not register their own hall call. The following section explains why this is the case.
Why doesn’t destination dispatch solve the bottleneck problem?
Destination Dispatch systems are designed to work optimally when every individual passenger registers his or her own own hall call — even if multiple passengers are going to the same destination.
But people do not act optimally in real life, which directly undermines the performance improvements offered by destination dispatch.
Tailgating
People typically go to lunch and leave work in groups. Often, these groups are all headed to the same destination: the lobby. Imagine a group of 4 people are leaving their office to head to lunch—do all 4 of them individually enter in the lobby as their destination? Of course not! Only one person in the group calls the elevator, while the rest wait and tailgate onto the elevator when it arrives.
Why do people tailgate onto elevators? Out of convenience, probably. People leaving their offices from the same floor typically are going to the same destination (the ground floor). If one person from the group calls the elevator, there is no need for the others to also call the same elevator. Think about it: how many times has someone already called then elevator, and then you went and called it again? Once someone has input the same destination you would have, it instantly feels weird to also input that destination.
Inputting the same destination twice (or more) is redundant, of course. But for destination dispatch to know how many people enter the elevator, each passenger is required to input their destination into a kiosk outside of the elevator. And since this behavior is unnatural, it would involve retraining people on how to properly use the elevator.
So, when people tailgate onto an elevator behind one hall call, the destination dispatch system incorrectly assumes that the car has only one passenger enter and will assign additional stops to it even if it’s actually filled with four or more passengers. Thus, even modern destination dispatch systems are unprepared to efficiently and safely allocate elevators in the post-pandemic world.
Lines
Destination dispatch fails to deliver on its promise of limiting elevator occupancy for another significant reason: lines. As previously discussed, for the system to allocate only 4 passengers to a specific elevator, each person waiting for the elevator must separately input their destination (even if it’s the same as others who have already called the elevator). So how does this work when there’s a socially-distanced line for the elevator?
As expected, only the person at the front of the line calls the elevator. In other words, the very prerequisite to destination dispatch’s claimed efficiency gain is compromised. If this were a line on an office floor and everyone in line is headed to the ground floor lobby, this means that only 1 call corresponds to an entire line of people waiting for the elevator. For the system to know exactly how many people are waiting, each person would have to violate social distancing, walk past the line, enter their destination, and then return to the line. However ridiculous this may sound, that procedure would be necessary for destination dispatch to “solve” the elevator bottleneck problem.
If destination dispatch doesn’t solve the problem, what are my options?
Rather than launching a massive modernization project, there are better and cheaper solutions available—which don’t require you to train your passengers on how to “properly” use the elevators. Abacus Sensor automatically determines how many passengers are inside of the elevator and directs the elevator to skip all unnecessary stops when it is full.
There is no need for adjusted user behavior, time-consuming installation, or to spend millions of dollars. Abacus installs in hours, is low-cost, and just works.
Best of all, Abacus Sensor gives property managers key insights into their elevator usage, and unlike destination dispatch, provides meaningful data to the building over time. A solution to the elevator bottleneck problem has finally arrived.
