Empirical investication on pedestrian crowd dynamics and grouping

Empirical Investigation on Pedestrian Crowd
Dynamics and Grouping
Andrea Gorrini1, Stefania Bandini2, Giuseppe Vizzari2

1 Information Society Ph.D. Program, Department of Sociology and Social Research

University of Milano-Bicocca, Italy

2 Complex Systems and Artiﬁcial Intelligence Research Center (CSAI)

University of Milano-Bicocca, Italy

TGF 2013 - Jülich Supercomputing Centre - Sept. 25-27, 2013
Outline
• Why observing groups? Motivations and fundamental
research question

• Available literature, data and observations on group
inﬂuence on pedestrian behaviour

• An observation and analysis of group inﬂuence in Vittorio
Emanuele II Gallery in Milano

• Towards an interdisciplinary research on pedestrian and
crowd analysis and synthesis

• Conclusions and discussion

Crowds of pedestrians as 
complex systems
• Overall system behaviour depends
on individuals’ decisions and
actions…

• … that are generally inﬂuenced
by a large number of factors

• … intertwined in an often
unpredictable way

• Mixed and conﬂicting mechanisms

• Competition for the shared
space…

• … but also cooperation (non
written social norms) to prevent
stall situations

• Imitation...

• ... but also natural tendency to
stay at a distance (proxemics)

• Emergent phenomena
• …

Impact of groups in pedestrian
and crowd dynamics
• Current approaches to modeling
and simulation generally consider
every pedestrian as a individual with
almost no relationships

• Considering only his/her own
goals

• Considering other pedestrians
as moving obstacles or
movement opportunities

• Nonetheless, in several situations
pedestrians are bound by
relationships inﬂuencing their
movement

• Generally speaking, a crowd is
made up of groups of
pedestrians...

• What do we miss by neglecting this
aspect of pedestrian behaviour?

Groups in the literature
- Observations
• At least two studies report observations
about groups

• Willis A, Gjersoe N, Havard C, Kerridge J,
Kukla R, 2004, "Human movement
behaviour in urban spaces: implications
for the design and modelling of eﬀective
pedestrian environments" Environment
and Planning B: Planning and Design
31(6) 805 – 828

• Michael Schultz, Christian Schulz, and
Hartmut Fricke. “Passenger Dynamics at
Airport Terminal Environment”,
Pedestrian and Evacuation Dynamics
2008, Springer-Verlag, 2010

• Observations carried out in low density
conditions

• Groups of small size were most frequently
observed

• Little data about dynamic group proxemic
behaviour

Admission test
University of Milano-Bicocca
• Admission test of the Faculty of
Psychology at the University of Milano-
Bicocca - September 1, 2011

• Counting activity supported by video
footages of the event

• About two thousand students attended
the test

• About 34% individuals, 50%
couples, 13% triples and 3%
groups of 4 members (!)

• Statistically validated relationship
between group size and velocity

• Additional quantitative analyses
about the arrival and entrance
process, LOS

• Qualitative analysis of group shapes
and related phenomena

• More details in PED and ACRI (C&CA)
2012 papers

Scenario Analysis
The Vittorio Emanuele II gallery is a popular commercial-touristic walkway
situated in the Milan city centre; it represents an optimal scenario
for video recording pedestrian ﬂows
 

Data Collection 
The survey was performed the 24th of November 2012 from 2:50 pm to 4:10 pm.
Thanks to the ofﬁcial authorization of the Municipality of Milan, the video footages
were performed from the balcony of the gallery; the staff was composed of four
observers; the equipment consisted of two video-camera with tripods

Data Analysis
The survey was aimed at collecting data about: level of density and walkway level of
service; presence of groups; group size and proxemics spatial patterns; trajectories;
walking speed; group proxemics dispersion
 

Data Reduction and Analysis 
A selected portion of the gallery was considered for the analyses (12.8m – 12.8m).
A grid of square cells (designed by using Adobe Photoshop CS5) was used in order
to discretize the environment in cells and to perform data analyses

1. Results – Fruin’s LOS 
The bidirectional pedestrian flows were measured every minute; the total flow
was composed of 7773 people; the level of density was low; the average walkway
level of service corresponded to the B level (7.78 ped/min/m) that correspond
to an irregular flow in low density situations

2. Results – Presence of Groups 
The video was sampled considering one minute every ﬁve: a subset of 15 minutes
was extracted (1645 people - 21.16% of the total); the presence of groups (84.19%),
their size and proxemics arrangements were detected
Patterns Couples Triples ≥ 4 Members
Lane 94.43% 31.91% 29.61%
River 5.57% 9.57% 3.12%
V-like - 58.51% 10.39%
Rhombus - - 7.79%
Two Dyads - - 32.47%
Triad + Single - - 10.39%
Single + Triad - - 6.23%

3. Results – Walking Path and Speed
A sample of 30 singles, 15 couples, 10 triples and 8 groups of four member was
considered related to the B level of service. Data analysis was aimed at checking
any differences in walking path and speed between singles and group members
Singles Couples Triples 4 Members
Walking Speed 1.22 m/sec (sd
0.16)
0.92 m/sec
(sd 0.18)
0.73 m/sec
(sd 0.10)
0.65 m/sec
(sd 0.04)
Path 13.96 m
(sd 1.11)
13.39 m
(sd 0.38)
13.45 m
(sd 0.27)
13.16 m
(sd 0.43)

Identiﬁcation of groups (and elderlies)

3.1 Results – Trajectories and Path
Within B level of service the differences in walking path between singles-couples and
singles-triples were signiﬁcant (t-test, p < 0.05); no signiﬁcant difference in path
between couple-triples (p > 0.05). The path of singles is 4.48% longer the the average
path of group members
Singles Couples Triples 4 Members

3.2 Results – Walking Speed
Within B level of service the differences in walking speed between singles-couples,
singles-triples, singles-4members, couples-triples and triples-4 members were
signiﬁcant (t-test, p < 0.01). The average walking speed of group members is 37.21%
lower than the one of singles

4.1 Results – Proxemics Dispersion
Within B level of service situations the differences in proxemics group dispersion
(distance from the centroid of the group) between couples-triples and couples-4
members was signiﬁcant (t-test, p < 0.01). The average spatial dispersion of triples and
groups of 4 members is 40.97% higher than the one of couples
Couples Triples 4 Members
Distance
Centroid
0.58 m
(sd 0,22)
0.76 m
(sd 0,11)
0.67
(sd 0.12)

4.2 Results – Proxemics Dispersion
The normalized position of each pedestrian with respect to the centroid and the
movement direction show that couples tend to walk with a line-abreast layout and a
distance of 0.4 m; triples tend to walk with a line-abreast pattern of 0.6 m (from left to
right members); no particular pattern regarding groups of 4 members can be detected
Couples Triples
Groups of 4

Towards integrated analysis and synthesis?
Model and
simulator
Target system
Simulation
results
Empirical data
Simulation campaign
execution
Modelling
and design of
a simulator
Analysis of
results and
interpretation
Analysis of the
dynamics of target
system
Synthesis
Analysis
(i) Formalisation of
phenomenologies
(ii) Metrics, indicators,
techniques
(i) Motivations and goals
for model innovation
(ii) Data for calibration
and validation

Towards integrated analysis and synthesis?

Conclusions and
discussion
• Groups are relevant and
signiﬁcant

• Models for the simulation of
crowds of pedestrians
focused on collective events
should consider them

• More observations,
experiments and
simulations are necessary
to improve our understanding
of the phenomenon

• More tight collaboration
between researchers working
on synthesis and analysis of
crowds is promising and
possibly beneﬁcial for both

Grazie dell’attenzione!
Thanks for your attention!
Giuseppe Vizzari

Empirical investication on pedestrian crowd dynamics and grouping

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