Urban Road Safety How to deal with complexity? D. Fleury – INRETS Conference Physics and the City. Bologna December 2005

Department of Accident Mechanisms (INRETS)  Research in the field of Road Safety  A multidisciplinary team (cognitive psychology, ergonomics, civil engineering, town planning, law, political science, vehicle engineering)  The “system” 'approach as a theoretical framework  Interdisciplinary modelling In Depth Accident Investigation (IDAI) Études détaillées d’accidents (EDA)

Complexity in the traffic system  The result of situational heterogeneity and multiple retroactions  The most common modelling of the road traffic system: [man]-[vehicle]-[road environment] Specific research issues based on system analysis

Micro-regulation of the traffic system Man (driver-pedestrian) regulates the (M/V/R) system in real time Macro-regulation and social management of safety Regulation performed in “response” delay time, with the observation of user behaviour (driving speeds, accidents, perceived risks, opinions, etc.)

Accidents are the symptom of a dysfunctional situation in the interactions between components in the M/V/R system

Simplified functional model for the analysis of safety (INRETS) Information input Processing Choice and decision-making ActionConse- quences

Example of a functional model (MDAI project)

Phased models Baker and Fricke (1986)

Phase analysis and space analysis General conditions Driving situation Accident situation Emergency and collision situations network and choice of itineraries characteristics of the carriageway and section break related to a section or particular location (intersection, for example) fine characteristics of the location

Consistency (between the different levels) of the layout in question  Improve the overall consistency of the entire (socio-technical) traffic system to improve safety.  Parallel between individual user control and actions on space. Accident analysis, not restricted to immediate interaction, leading to actions for treating black spots as well as town planning and transportation policy.

A field of research: the notion of typical scenarios as “road pathologies" Example Wide through road, problems of visibility (night, wetness, age, advertising, etc.) Driving situation High speed, low attention Pedestrian preparing to cross outside a pedestrian crossing Accident situation View obstructed by a standing vehicle, the pedestrian crosses Emergency situation No manoeuvre (surprise) Collision situation Pedestrian hit

Example of research on accident scenarios : from IDAI (EDA) to intelligent safety diagnosis 1. Construction of “scenarios” on a panel of accidents 2. Scenarios recognition through police reports (and accident files) Structure of the knowledge field Symptoms (data) for recognition Statistical inferences 3. Links between road environment and accident scenarios Road types Scenarios profiles (% of each scenario)

Modelling Micro-regulation Systems with decision-making and memory centres (ref.: Boulding )

Models coming from psychology and safety diagnosis of large socio-technical systems On the role of memorisation. Rasmussen model (1980), level of cognitive operation: problem, procedural and automation resolution. On decision-making and motivation. Risk models:  risk homeostasis (Wilde, 1988),  zero risk (Näätänen and Summala, 1974),  threat avoidance (Fuller, 1984).

Macro-regulation and social management of safety

To improve safety, we have to understand the Functional descriptions of the system and the regulation goals  Understanding how the system operates (functions)  Understanding the process of action  Analysing the implicit models on which this action is based

Research example: Urban Travel Plan design (Plans de Déplacements Urbains) Obligations in: Law on the Air and Rational Energy Use – 1996 Law on Solidarity and Urban Renewal – 2000 Follow-up work meetings for nearly one and a half years

Design Process

The “Relatiogram” – Frédérique Hernandez

The Urban Travel Plan as a scene for actors Construction of a “reference project” by clustering "operational projects":  technical objects (tramway…)  technical layout concepts (traffic calming…)

Marseille Urban Travel Plan (Hernandez, 2000) Three main scenarios:  “town centre” scenario grouping together projects such as "pedestrian priority hypercentre", "tramway" and "cycling",  “periphery” scenario with secondary centres, 30 km areas, Southern Urban Boulevard, etc.  “cluster” scenario with the “regional express rail network” and the “Blancarde Aubagne route" Referring to an "island strategy" concerning automobile traffic

Some conclusions: Safety research entails modelling Different levels of representations of unsafe situations Both aspects: techniques and decision making How to make explicit the models of action Stressing the “unspokens” of planning (importance of Ring roads, forgetting mopeds and motocycles, etc.) The possible consequences on safety (accident scenarios)