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Citation: Kaparias, I., Bell, M. G. H., Biagioli, T., Bellezza, L. and Mount, B. (2015).
Behavioural analysis of interactions between pedestrians and vehicles in street designs with
elements of shared space. Transportation Research Part F: Traffic Psychology and
Behaviour, 30, pp. 115-127. doi: 10.1016/j.trf.2015.02.009
This is the accepted version of the paper.
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version.
Permanent repository link: https://openaccess.city.ac.uk/id/eprint/6942/
Link to published version: http://dx.doi.org/10.1016/j.trf.2015.02.009
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1
BEHAVIOURAL ANALYSIS OF INTERACTIONS BETWEEN
PEDESTRIANS AND VEHICLES IN STREET DESIGNS
WITH ELEMENTS OF SHARED SPACE
I. Kaparias
1
, M.G.H. Bell
2
, T. Biagioli
3
, L. Bellezza
1
, B. Mount
3
1 Collaborative Transport Hub, City University London, UK
2 Institute of Transport and Logistics Studies, University of Sydney, Australia
3 Centre for Transport Studies, Imperial College London, UK
ABSTRACT
This paper describes the development and implementation of qualitative behavioural criteria in order
to analyse the conduct of pedestrians and vehicles when they are required to interact with each other,
with particular interest to street designs with elements of shared space. The new behavioural analysis
technique is developed by identifying the fundamental principles that underpin existing traffic anal-
yses, such as traffic conflicts techniques, and adapting those to a qualitative framework that describes
the mindset and rationale of road users. The technique is then applied to a case study in London, using
video data from periods before and after the redevelopment of the Exhibition Road site from a con-
ventional dual carriageway to a modern design with some elements of shared space. With the main
goals being to assess the pedestrians’ confidence and the vehicles’ tolerance/patience when forced to
interact with each other, behavioural trends are related to instantaneous characteristics of the vehicle
flow (vehicle approach speed and traffic density). The data produced are used to develop and validate
qualitative behavioural relationships for pedestrian-vehicle interactions, as well as location-specific
conclusions for the Exhibition Road site.
1 INTRODUCTION
Urban street design has traditionally been very closely tied with road safety. The latter has been a
concern since the introduction of motorised vehicles, and became paramount with mass motorisation
from the 1950s onwards. Of particular importance was the protection of pedestrians, who, being more
vulnerable, faced greater risk of suffering injury or death. This was pursued by means of their segre-
gation from vehicular traffic, which, dating back at least to the work of Le Corbusier in the 1930’s,
relied upon the design and implementation of structures including pedestrian subways and bridges, as
well as guardrails and walls separating pedestrian pathways from the road, which in turn was reserved
for vehicles. The concept is set out most lucidly in Buchanan’s ‘Traffic in Towns” report (1) of 1963,
2
which served as a street design manual in the UK for many decades.
In recent years, however, there has been a trend away from traffic segregation, driven by develop-
ments in architecture and urban planning. Instead, street design and traffic engineering have seen a
shift in focus from vehicles to pedestrians as a means of creating a better public realm, mainly by as-
serting the function of streets as places rather than arteries and designing more to a scale aimed at eas-
ier pedestrian movement and lower vehicle speeds. Examples of this approach include: the removal of
segregating features such as street furniture, signage and kerbs; the introduction of more “informal”
(uncontrolled) pedestrian crossing facilities; or the re-engineering of layouts with a single surface and
little or no delineation between pedestrian and vehicle areas (2-6).
As part of the trend away from traffic segregation, the concept of “shared space” has emerged in re-
cent years. Shared space is defined by the UK Department for Transport as “a street or place designed
to improve pedestrian movement and comfort by reducing the dominance of motor vehicles and ena-
bling all users to share the space rather than follow the clearly defined rules implied by more conven-
tional designs” (7). As such, and conversely to popular belief, the term “shared space” is not used to
characterise entire streets and places as “shared” or “not shared”, particularly given that streetscape
design cannot be standardised and needs to be context-sensitive. Instead, shared space is used as an
“umbrella” term to collectively refer to a range of streetscape treatments, aiming at creating a more
pedestrian-friendly environment. Examples of streets with varying extents of shared space elements
can be found around the world and include: the concept of “woonerf” and “home zone” in residential
areas in the Netherlands and UK respectively; the “Manual for Streets” approach in the UK (8-9); and
the “Complete Streets” initiative in the USA (10).
The shared space concept has been met with mixed reactions from different road user groups. Oppo-
nents of the concept (such as some elderly and disabled road users) have expressed their discomfort
towards the idea because they perceive it as less safe (6, 11). Proponents, on the other hand, have sug-
gested that shared space actually contributes to the improvement of road safety, mainly due to the in-
troduction of ambiguity, which makes both drivers and pedestrians more vigilant (3). From a traffic
engineering perspective, the latter view is a paradox, since shared space introduces a greater degree of
vehicle-pedestrian interaction. This highlights the need to analyse the interactions between vehicles
and pedestrians from a behavioural perspective. It should be clarified here, though, that this is differ-
ent from traffic conflicts analysis, a method of which has recently been developed and applied (12-13),
as it does not focus on the mechanics of the interaction (i.e. speed, direction etc.), but on the qualita-
tive behaviour of the road users which may or may not lead to a conflict (or accident) situation.
More specifically, the framework defined by Hydén (14) and conceptualised by Svensson and Hydén
3
(15) is followed here, according to which the range of interactions is represented by a pyramid, the
height and width of which denote the severity (from “undisturbed passages” to “fatal accidents”) and
occurrence frequency of interaction events respectively. In an extension of the framework (16), inter-
actions are further classified in a diamond, as it is argued that the occurrence of the least severe events
is rare when road users are undisturbed by other road users. The framework is illustrated in Figure 1,
as fully presented by Laureshyn et al. (17), and the present work focuses on what is defined as “en-
counters of medium severity”, which comprise the majority of road user interactions. In the graphical
representation, these cover roughly the “potential conflicts” and the top half part of the “undisturbed
passages” slices of the pyramid (Figure 1a), and the central portion of the diamond (Figure 1b).
[Figure 1 here]
The present paper has two key objectives. The first objective is to present a new qualitative behav-
ioural analysis technique for the vehicle-pedestrian interaction events defined, for use in both conven-
tional and shared space environments. This is expected to complement the work of Laureshyn et al.
(17) by providing a means of conducting behavioural observations in the public realm in a systematic
way. The second objective is then to apply the new method on a redeveloped street layout in a before-
and after-context and to draw conclusions as to changes in the behaviour of drivers and pedestrians
following the redevelopment. The work has been carried out as part of a traffic monitoring pro-
gramme of the Exhibition Road project, comprising the conversion of the layout of the Exhibition
Road site in London’s South Kensington area from a conventional dual carriageway to a single sur-
face, featuring a number of elements of shared space.
The paper is structured as follows: Section 2 presents the background of the study through a review of
traffic conflicts and behavioural analysis methods. Section 3 describes the new qualitative behavioural
analysis method developed for vehicle-pedestrian interactions, while Section 4 deals with its imple-
mentation, which includes the description of the test site and the data collection. Section 5 provides a
summary of the results obtained, and. Section 6, finally, concludes the paper and identifies areas of
future research.
2 BACKGROUND
Most of the research that has been carried out with the objective of monitoring vehicle-pedestrian in-
teractions so far has been concerned with traffic conflicts analysis. A wide range of traffic conflicts
techniques have been developed, many of which are based on well-established vehicle-vehicle meth-
ods and adapted so as to account for pedestrian movement. Notable examples include: the “Swedish
