Vertical traffic flow in buildings

Where do people go when they enter a building? How do they move between floors and when do they use lifts the most? This is what the subject “Traffic flows in buildings” is concerned with.

Something that also plays a central role in lift planning and the development of lift controllers.

BY DR STEFAN GERSTENMEYER

If people have to wait for lifts for a long time, simple measures, such as mirrors in front of the lifts, can reduce the number of complaints. Passengers are distracted and occupy themselves with their appearance [1], which reduces the perceived waiting time.

However, as the building height and number of passengers increase, efficient lift groups become essential. Optimal occupancy and operation ensure adequate conveyance capacity and avoid long waiting times at peak hours.

Photo: Grafik: © Peters Research

Traffic flows are above all determined by the number of passengers and their destinations. A common description is the “traffic mix”, which distinguishes between the share of incoming, outgoing and interfloor traffic (see Figure 1).

The frequency with which trips to upper floors occur depends on their use and occupancy. The precise arrival times of the passenger in particular are subject to statistical fluctuations.

TRAFFIC PROFILES

The lift traffic during the day or a week is usually considered in five-minute intervals. The traffic mix and total passenger activity are stated for each interval, the latter usually in relation to the building occupancy and absolute passenger numbers.

Profiles for office buildings are for example available for 2007-2009 from Dr Richard Peters (Peters Research) [2] or from Dr Marja-Liisa Siikonen (at the time Kone) from 2000 (see Figure 2) [3].

BUILDING TYPES/USE

Apart from the number of people in the building, traffic flows also are also heavily dependent on the use of the floors served by a lift group. A particular distinction is drawn here between the office, residential, hotel and hospital use types [2].

For example, in the mornings incoming traffic flows dominate in offices and outgoing in residential buildings. The traffic also varies within office areas: several floors occupied by one company increase the interfloor traffic. In addition, the location and use of the company restaurant also influence passenger traffic.

ABBILDUNG 3 / FIGURE 3: TOTAL PASSENGER ACTIVITY

DIFFERENCES AND DEVELOPMENT/ CHANGE

The traffic profiles of buildings have greatly changed over the course of time, especially in office buildings. Flexible working hours and home office have a major influence on daily and weekly profiles [4].

Whereas earlier traffic profiles for the most part used to show just the up- and downward traffic, traffic mixes are usually presented in current profiles. The traffic profile of an office building by Dr Gina Barney from the 1970s demonstrated still very pronounced downward traffic (Figure 3 on page 36), while in the case of Siikonen the morning and midday traffic dominate (Figure 2).

TRAFFIC PROFILE RECORDING

Detailed passenger surveys [6], [7], [8] [9] are making the database for traffic flows increasingly precise. Thanks to increasingly intelligent sensors integrated in the lift and improved data recording and evaluation, identification of traffic flows can be integrated into normal lift operation.

RELEVANCE OF TRAFFIC PATTERNS

Precise understanding of traffic flows is essential when it comes to the planning and design of lifts. These are preconfigured in traffic simulations and can be adjusted. [10]. The focus is on peak traffic times, as described in planning guidelines (e.g. Cibse Guide D [2], ISO 8100‑32 [11]). This also applies to the optimal operation of lift groups using control algorithms [12].

Traffic patterns and capacity utilisation are already taken into account during the development of the algorithms and also adjust themselves during operation to individual traffic situations.

ABBILDUNG 2/FIGURE 2: TOTAL PASSENGER ACTIVITY

Consequently, continuous recording, evaluation and updating of traffic profiles is indispensable. They should be regularly integrated into planning guidelines. Consideration of regional differences is also becoming increasingly relevant in this regard.

The author is CTO at Peters Research.

Typical traffic at peak traffic hours

BÜRO/OFFICE:
Morgens/Mornings:
Auslastung 12 Prozent der Gebäudebelegung in 5 Minuten
Capacity utilisation 12 percent of the building occupancy in 5 minutes

Incoming: 85 Prozent/percent
Outgoing: 10 Prozent/percent
Interfloor: 5 Prozent/percent

Mittags/Midday:
Auslastung 13 Prozent der Gebäudebelegung in 5 Minuten/
Capacity utilisation 13 percent of the building occupancy
in 5 minutes
Incoming: 45 Prozent/percent
Outgoing: 45 Prozent/percent
Interfloor: 10 Prozent/percent

WOHNGEBÄUDE/RESIDENTIAL BUILDING
Morgens/Mornings:
Auslastung 6 Prozent der Gebäudebelegung in 5 Minuten/
Capacity utilisation 6 percent of the building occupancy in
5 minutes

Incoming: 15 Prozent/percent
Outgoing: 85 Prozent/percent
Interfloor: 0 Prozent/percent

Abends/Evenings:
Auslastung 6 Prozent der Gebäudebelegung in 5 Minuten/
Capacity utilisation 6 percent of the building occupancy in 5 minutes

Incoming: 50 Prozent/percent
Outgoing: 50 Prozent/percent
Interfloor: 0 Prozent/percent

Quelle/Source: © CIBSE Guide D [2]

START-/DESTINATION MATRIX

Traffic flows that require more precise description and cannot simply be represented by the traffic mix can be described using a detailed start-destination matrix.

The latter states the percentage share of each start-destination combination of the total traffic for a particular period [13]. This includes passenger arrival rates and probabilities for passenger destinations per floor [2].

SOURCES:
[1] D. Maister, ‘The Psychology of Waiting Lines’. [Online]. Available: http://davidmaister.com/articles/the-psychology-of-waiting-lines

[2] CIBSE, CIBSE Guide D: 2025 Transportation systems in buildings. London: The Chartered Institution of Building Services Engineers, 2025.

[3] M.-L. Siikonen, ‘On Traffic Planning Methodology’, in Elevator Technology 10, Proceedings of Elevcon 2000, The International Association of Elevator Engineers, 2000.

[4] R. Smith, ‘Determination of Lift Traffic Design Requirements based on New Technologies and Modern Traffic Patterns’, The University of Northampton, 2011. 

[5] G. Barney, Elevator Traffic Handbook. London: Spoon Press, 2003.

[6] M.-L. Siikonen and N.-R. Roschier, ‘Determination of the number of persons entering and leaving and elevator car’, 1995

[7] R. Peters and E. Evans, ‘Measuring and Simulating Elevator Passengers in Existing Buildings’, presented at the Elevator Technology 17, Proceedings of Elevcon 2008, The International Association of Elevator Engineers, 2008.

[8] R. Peters, R. Smith, and E. Evans, ‘The appraisal of lift passenger demand in modern office buildings’, Build.Serv.Eng.Res. Technol., vol. 32, no. 2, pp. 159–170, 2011, doi: 10.1177/0143624410385378.

[9] D. Batey and M. Kontturi, ‘Traffic Analysis for High Rise Buildings to be Modernized’, presented at the Elevator Technology 21, Proceedings of Elevcon 2016, Madrid (Spain): The International Association of Elevator Engineers, 2016.

[10] ElevateTM. (1998 to present). Peters Research Ltd. [Elevator Traffic Analysis & Simulation Software]. Available: www.petersresearch.com

[11] ISO 8100-32:2020, Jun. 2020. [Online]. Available: https://www.iso.org/standard/73084.html

[12] Elevate Dispatch. Peters Research Ltd. [Elevate Dispatch Controller]. Available: https://www.peters-research.com/elevate-disptach

[13] L. Al-Sharif and A. M. Abu Alqumsan, ‘An integrated framework for elevator traffic design under general traffic conditions using origin destination matrices, virtual interval, and the Monte Carlo simulation method’, Building Services Engineering Research and Technology, vol. 36, no. 6, pp. 728–750, 2015