=Paper=
{{Paper
|id=Vol-158/paper-3
|storemode=property
|title=Gaps between rules and uses of the road
|pdfUrl=https://ceur-ws.org/Vol-158/3.pdf
|volume=Vol-158
|dblpUrl=https://dblp.org/rec/conf/context/BazireBLT05
}}
==Gaps between rules and uses of the road==
https://ceur-ws.org/Vol-158/3.pdf
Gaps between rules and uses of the road
Mary Bazire1, Patrick Brézillon2, Brigitte Cambon de Lavalette3, Charles Tijus1
1
Laboratoire Cognition & Usages 2 rue de la Liberté 93523 Saint-Denis Cedex
mary.bazire@cognition-usages.org
tijus@univ-paris8.fr
2
LIP6, Case 169, Université Paris 6
8 rue du Capitaine Scott, 75015 Paris, France
Patrick.Brézillon@lip6.fr
3
INRETS-LPC
2, avenue du Général Malleret-Joinville 94 114 Arcueil cedex France
cambon@inrets.fr
Abstract. Regarding the high rate of transgressions of the Highway Code, the
paper is about how do road users agree to be exposed to such risks? We
consider that this issue must be addressed within an “ergonomic” point of view:
there is a gap between prescribed and effective task and the non-respect of the
road safety laws has to be analyzed in those terms. Data show for instance that
the more people drive, the less people are able to recall the meaning of road
signs. We hypothesize that acquiring expertise in driving means taking the
whole driving situation into account. As a consequence, the context of the task
at hand then becomes more important than the formal meaning of a road sign.
We propose the use of contextual graphs to represent the different possible
actions regarding the different contexts in which the driver is involved. It
appears then that the driving task can be assimilated to a contextualization of
the Highway Code prescribed procedures.
Introduction
Let’s recall first some statistics about road crashes in France: in the year 2003, 90
220 corporal accidents were recorded by the observatory of the road safety, including
5 731 persons killed. Infringements to the laws of road safety appear as a frequent
phenomenon and relationship between infringement and accident has often been
pointed out [1]. . With a so high rate of transgression in the driving activity and a so
high rate of road crashes, how can we explain the road users tolerance to the hazard
they are exposed to? Is it a problem of insubordination or an inadequacy of laws
prescribed to road users?
Our study tries to explain some of these transgressions as being involuntary
disrespects of laws. We postulate the existence of involuntary transgressions that are
caused by erroneous interpretations of road signs. Such erroneous interpretations
that cause highway code transgressions appear when the driving situation context
influence the driver decision making to an action that is not the one prescribed by the
Bazire, Brézillon, Cambon de Lavalette et Tijus
law. Our hypothesis is that road signs transgressions come under a problem of
discrepancy between laws and uses. More particularly, we consider that the observed
gap between the prescribed tasks and the practiced uses is analyzable in terms of
context. Context might be the key word to explain why there is no match between the
prescribed and the effective practices of system users in general.
Procedures versus practices
Road signs aims at ensuring safety measures and regulating road traffic [2].
However, road users have generally a different viewpoint. They often consider road
signs like constraints (speed limits, actions prescriptions, etc.) described by law
articles, and, in some cases, useless overloads.
The violation of these constraints leads to juridical sanctions with more or less
dramatic consequences, but it clearly appears that their transgression is very frequent.
How can we explain that phenomenon while lives are threatened? Classically, some
hypothesis are proposed: insufficiency of the juridical sanctions, lack of knowledge of
laws, bad appreciation of risk, impossibility to respect the law (when the
infrastructure is inadequate) or inadequacy of laws in some of the contexts in which
drivers are involved. For example, a given road sign may appear in different contexts
that imply different interpretations for the user that is obliged to grasp a number of
contextual elements for attempting a correct interpretation of the road sign. Several of
these hypotheses, maybe all of them, are useful to understand laws transgressions.
Nevertheless, we chose to turn our attention to the driver’s decision-making in
situation, notably because we think that it is an innovative point of view. Our
approach leads to an interesting practical range in the domain of road safety given that
it is easier to intervene on the device than on the user's behavior. Finally, we think
that driver’s decision-making in context intervenes upstream with regard to the other
accounts of Highway Code transgressions.
According to Allen, Lunenfeld & Alexander [3], the information retrieval made by
drivers depends on the activity at hand. The authors distinguish three levels of activity
in the driving task. First, at the lower level, the activity corresponds to tasks of control
and regulation of the speed or the trajectory. At the intermediate level above, one
finds the tasks of adaptation of the trajectory to specific states of the traffic. At the
upper level, the activity is oriented towards a global organization of planning and
spatial orientation of the trajectory. Thus, there is a relationship between the objective
corresponding to one of these sub-tasks and the information retrieval made by the
driver. Thus, the processing of information depends on the task at hand. An
information could be perceived but not taken into account by the driver because s/he
can not connect this information with the task at hand: the information is not related at
the level of the activity at hand. For instance, a “Do not pass” road sign would not be
taken into account by a driver that has not to the goal of passing cars. On the opposite,
it could be taken into account by a visitor of other country looking for their way, as
advertised: “The road sign Do Not Pass means No overtaking, or in other words Do
not pass other vehicles. It does not mean No entry, nor Do not proceed beyond this
Gaps between rules and uses of the road
point, as visitors from other countries might perhaps think”. Does this mean that
visitors from other countries that understand the “Do not pass” road sign as ‘”No
entry” will pass cars when forbidden by the road sign?
Our proposal is based on the distinction between on the one hand, the logic of
functioning (or the prescribed task, here the laws) and on the other hand, the logic of
use (or the effective task, the observed behavior). This is a useful distinction in the
different domains where a technical device is used [4, 5], that we use for
understanding drivers decision making in situation.
The resolution of incidents in the Parisian subway is a good example of this
discrepancy. The RATP (French company of urban public transportation) propose a
whole set of procedures (built on observed practices and decontextualized for
covering a large class of problem) to operators but we state that they tend to tailor
(and transform) official procedures according to the occurring context [6] and, finally,
there are as many practices as contexts and operators. Why do they choose to plan
their actions real time (which seems more expensive, in terms of cognitive
investment) whereas they dispose of many official procedures? Indeed, procedures are
not perfectly adapted to the concrete situations, because they are averaged, that
impose to operators to develop sub-optimal strategies of problem solving. Real time
planning allows an adaptation to the whole situation (which includes the action
context) and its potential evolution.
According to this example, the gap between prescribed and effective tasks is not
due to an imperfect knowledge of the laws or a will of transgression but because of a
certain expertise level which leads to a better use of the device.
Apprehending the rules
A road user faces perpetually a jungle of road signs. There are about 400 official
European road signs. They are not independent but respect a grammar [7], [8]. Each
road sign can be divided into primitives: the shape (circle, triangle or square), the
frame and font color, the icon in the centre of the sign; each element has its own
meaning. The combination of those different elements allows a great amount of
possible messages.
Bazire, Brézillon, Cambon de Lavalette et Tijus
Figure 1: The making of a road sign.
Figure 1 presents the realization of a road sign: the “cow icon” (which stands for
any cattle) combined with (b) a red bordered triangle means that there is a danger
because of the eventual presence of cattle on the road, or with (c) a red bordered
circle, would mean that this way is forbidden to domestic animals. Note that (b) could
be “Danger for cows” and (c) could be “forbidden because of cows”.
Do the users know about this combinatory? Are they capable of deducting the
meaning of an unknown sign, using the combinatory rules supposed to be known? We
think that it is the context in which appear road signs which determines our decision
about the meaning of road signs.
Rules and driving
Data [9] show that a good expertise level is associated with a bad knowledge of the
(theoretical) Highway Code. The knowledge of the meaning of road signs decreases
with the number of years of practice but the knowledge of the correct action to
perform improves. For instance, we found that correct interpretation of road signs
seen in isolation was of .42 for people driving cars more than 10 years vs. .9 for
people driving cars less than 2 years. Thus, more people drive, the more the gap
between procedures and practices increases. In other words, the way in which a
practice diverges from the official procedure is an indicator of the expertise level. We
reasoned that this is so because an expert will take into account more of the driving
Gaps between rules and uses of the road
situation than prescribed by the Highway code rules : the whole situation, including
contextual knowledge.
If there is a knowledge transformation along with the practice of driving, from a
theoretical knowledge to an operational knowledge, then practice as the
contextualization of Highway Code rules, i.e. rules put into context, rules and context
being judged globally as a whole. Then, with the acquisition of expertise, road signs
lose their rule codification function to become one of the elements that entail the
process of contextualizing a driving situation.
Practices formalization
The fundamental role of contextualization when driving is to unify driver’s goal
and decision making with the environment. This can be shown in the following
example (figure 2).
Figure 2: The road sign “dangerous bend on right” in 3 different contexts.
Even if the “Danger because of a left turn” is the same in the three images of
Figure 2, these 3 different situational contexts will not produce the same decision-
making and subsequent behaviors from road users: the first case incites effectively to
reduce speed immediately (the road sign is almost in the bend), the second has a more
doubtful effect: (1) It could distract the user from the concrete situation (where it’s the
other cars being stopped that requires to reduce speed) and (2) Is the bend dangerous
only in case of slippery road? In the last picture, the utility of the road sign (fixed
whereas variable messages road signs exist) on a road that must be often blocked by
traffic, then where speed isn’t very high, is debatable (and probably intervene as a
distractor).
Therefore, it is necessary to take explicitly the context of practices into account, if
we want to explain and formalize them.
Contextual graphs [10,11] allow producing a representation of practices based on
context. They are oriented graphs, acyclic and with a general structure in spindles. A
contextual graph is made of nodes and arcs and, more particularly, actions (noted A),
contextual nodes (NC), recombination nodes (RC) and groups of parallel actions.
We show the theoretical contextual graph that could be built from the road sign
“Dangerous bend on right”:
Bazire, Brézillon, Cambon de Lavalette et Tijus
A1
NR1
NC1 A7
NR2 NC3 NR3
A4
NC2 A3 A6
A5
A2
NC1 Do I see the road sign?
NC2 Yes. Do I recognize it?
NC3 What about the distance to obstacle?
NR1 I have to…
NR2 I do recognize the road sign.
A1 No, then I keep the same behavior.
A2 No, then I have to identify it from the situation.
A3 I have to find the situation corresponding to the road sign.
A4 Obstacle is close, then I focus on it immediately.
A5 Obstacle is far, I postpone first other actions.
A6 I reduce my speed in order to …
A7 … Turn right.
Figure 3: Contextual graphs associated to the road sign “Dangerous bend on right”
presenting the set of possible actions.
Contextual Graphs make it possible to describe practices (figure 3) as well as the
strict application of the prescribed procedure of the Highway Code (the black way in
the Contextual Graph displayed in figure 4).
A1
NR1
NC1 A7
NR2 NC3 NR3
A4
NC2 A3 A6
A5
A2
Figure 4: Description of the prescribed procedure derived from the Highway Code for the road
sign “Dangerous bend on right”
Thus, prescribed procedures derived from the Highway Code do not capture the
complexity of the driving activity and deny the diversity of possible behaviors when
facing road signs. We state that it is thanks to a study of practices in context that we
can touch the nature of the spread between procedures and practices, and then, some
law transgressions.
Gaps between rules and uses of the road
Conclusion
We have pointed out that there is a gap between driving rules prescribed by the law
and users practices. This is a gap that increases with years of experience as shown by
data. We reasoned that the main difference between young and expert drivers lies in
an appropriation of road signs by expert drivers as contextualization of road signs that
allows to identify, not only the road sign itself (as young driver), but the occurring
situation as other situations already encountered in a “situation based reasoning
process” approach.
The uncertain interpretation of a road signs message allows us to take the context
into account, giving information regarding to the circulation context (traffic jam in 5
km) and to the individual contexts of users (traffic jam in 5 km, reduce your speed
from 120 to 80 km/h).
References
[1] Lagarde, E., Chiron, M., Lafont, S. (2004) Traffic ticket fixing and driving behaviours in a
large French working population. Journal of Epidemiology and Community Health, 58: 562-
568.
[2] Cambon de Lavalette, B. (1999) La signalétique dans le réseau des déplacements routiers:
histoire et fonction. La signalétique: conception, validation, usages. Actes INRETS n°73:
15-29.
[3] Allen, T.M., Lunenfeld, H. & Alexander, G.J. (1971) Driver information needs. Highway
research record, n°366, p.102-115.
[4] Norman, D.A. (1983) Some observation on mental models. In Gentner D. & Stevens A.L.
(Eds.), Mental Models Hillsdale N.J: Lawrence Erlbaum Associates, pp. 7-14.
[5] Richard, J. F. (1983). Logique du fonctionnement et logique de l'utilisation. Rapport de
recherche INRIA N° 202.
[6] Brézillon, P. (2003) Representation of procedures and practices in contextual graphs. The
Knowledge Engineering Review, 18(2): 147-174.
[7] Brézillon, P. (2003) Focusing on context in human-centered computing IEEE Intelligent
Systems, 18(3): 62-66. [4] Droste, F.G. (1972) The grammar of traffic regulations.
Semiotica, 5 (6): 257-262.
[8] Meunier, J.G. (1988) La structure générique des systèmes sémiotiques. Recherches
Sémiotiques. Vol. 8: 75-107.
[9] Tijus, C., Barcenilla, J., Cambon de Lavalette, B., Lambinet, L. & Lacaste, A. (To appear)
Conception, compréhension et usages de l’information iconique véhiculée par les
pictogrammes, In JM Cellier, Production, compréhension et usages des écrits techniques au
travail, Octarès.
[10] Brézillon, P. (2005) Modeling users' practices in contextual graphs. ISKO-France, INIST-
France. (To appear)
[11] Brézillon, P. and Tijus, Ch. (2005) Une représentation basée sur le contexte des utilisateurs
à travers leurs pratiques. Proceedings of the EGC-2005 Workshop on "Modélisation de
l'Utilisateur et Personnalisation". (To appear)