Behavioural Model of the Pedestrian Interaction with Road Traffic
V Airault, INRETS and University of Paris V, FR; S Espié, INRETS, FR
Simulating pedestrians in an urban environment is still badly dealt with in simulation tools. In this paper, we present a model which manage realistically interaction between pedestrians and vehicules in the trafic simulation software: ARCHISIM.
Behavioural model of the pedestrian interaction with road traffic
1. Problematic and state of the art
In the field of the simulation of pedestrians, the majority of the
existing models concern pedestrians in homogeneous situations, i.e.
interacting with other pedestrians (situations of corridors, entries/left
part, crossings of flow, etc). There exists few programs simulating a
behavior of pedestrian in urban environment, and more particularly at the
time of road crossing. The majority of the studies within this
framework describe succinctly some normative behaviors of pedestrians, the
central point of the articles is often a different subject, such as 3D
modeling of the pedestrian, or the general facilities at a crossroad.
During his displacement, a pedestrian must first choose his itinerary
to reach his destination. Then this itinerary is divided into parts on
pavement, and crossings of streets. On the pavement, the main
obstacles are generally only other pedestrians, this is similar to a study of
situation of corridors. On the other hand, at the time of
road-crossing, the pedestrian enters in conflict with vehicles, which have
trajectories, speeds and reactions very different from those of the pedestrians.
This is why the pedestrian often has facilities to reduce the intensity
of the conflict with the vehicles.
The cross of the road is thus a complex task what makes difficult the
application of simple formulas between pedestrians and vehicles. We
need to understand how the pedestrian decides to cross.
Although there are many studies of psychologists that describe or
interpret the behavior of pedestrians at the time of road-crossing, the main
objectives are often differents (evaluation of safety or comfort,
children's education, etc). By the way, we will use a part of these datas
to allow us to implement and then to validate a model of pedestrian
whose behavior is in conformity with what is described by these studies.
2. Suggested model
The problem we treat in this article is thus synthesized; a pedestrian
must go on the other side of the roadway. For this, he has at his
disposal various facilities of the infrastructure (pedestrian road-marking
with or without traffic lights, raised passage, central midblock, etc),
and constraints (fixed obstacles, mobile vehicles).
Some articles give us a list of tasks that achieves the pedestrian. We
can resume it as follows: -1- appreciation of the level of safety of
the environment (density of the traffic, visibility, passages), -2-
decision to cross or to continue in the border of the road, -3- to cross
while avoiding the vehicles.
The level of safety perceived by the pedestrian results from studies
when questioning the pedestrians. Other studies are specified on the
influence of the traffic density. By taking again the results of these
studies, we can determine at which point the pedestrian can decide to
cross. For example he can decide to cross immediately, in diagonal or
straight line, or to reach a more distant pedestrian road-marking.
Then, about the vehicles avoidance, many studies determine the 'gap
timing' or the 'gap acceptance', i.e. the evaluation of the margin
available to the pedestrian to pass before a vehicle which moves towards him.
He can thus decide either to go before or behind a vehicle.
3. Experiments and results
We use the traffic simulation software ARCHISIM, whose driver model
results from studies of driving psychology, that have been implemented
following a multi-actor point of view.
We develop our model of pedestrian, integrated into ARCHISIM, using
both homogeneous algorithms of avoidance (between pedestrians), and a
model of crossing inspired of the studies in psychology quoted previously,
which we will detail more.
The validation of the model of crossing is very difficult; for the
moment we try to validate only in statistic level, using some other studies
of psychologists, for example one gives us percentages of choice of
crossing points along a long street. By reproducing this highway type, we
try to find the same distribution. As for the vehicles avoidance, it
is a question of simulate experiments and of find the results given by
the same already quoted articles.
Association for European Transport