Contribution of Infrastructures upon Road Safety: Modeling and

Regulation of Operating Vehicle Speeds

Nicolas Hautière

Marie-Line Gallenne

Overview

• Context and Motivations

• Range of Infrastructure-Based Solutions

• Underlying technical processes– Collection and update of road characteristics– Monitoring and modeling of road usage– Computation of adaptive speed limits

• Perspectives

Context and Motivations

• Speed enforcement led to a drastic reduction of accidents on the different road networks

• Inspection and audit procedures have been standardized at the EU level, but are restricted to main roads

• The proportion of accidents is increasing on the secondary road network

• Solutions must be found for this network which has the following particularities:

Vehicle dynamics more demanding Less traffic density Bigger diversity of vehicles: LV, HGV, PTW, bikes,

agricultural vehicle, etc.

Range of Infrastructure-Based Solutions

• Road design and maintenance

• Static road signs

• VMS

• Embedded VMS

Intrusive

Interactive

Underlying Processes

• Diagnostic Monitoring and modeling of road usage Collection and update of road characteristics

• Operation Detection of safety-critical events Computation of relevant speed limits

• Regulation and standardization for deployment

Photo credit: tasosk

Vehicle Infrastructure Integration

• The development of ITS offers a relevant solution for secondary road networks

• ITS allows interconnecting maintenance centers, OBU, sensors using ITS Stations (RSU).

Monitoring of Road Usage Instrumentation and measurement of trajectories

• Static devices, e.g. the OdT system:

• Instrumented vehicles

Perspectives: data fusion between the different methods.

Collection and Update of Road Characteristics

• Today, data collection is performed by maintenance vehicles

• Tomorrow, the use of probe vehicles will emerge

• Development of cooperative Decision Support Systems (DSS)

Modeling of Road Usage

Perspectives • Deployment of reference

speeds on a road network

• Update of posted speed limits

• Still open questions• Only in normal conditions?• Single speed?• Pessimistic or realistic?

• Calibration of reference speed models, e.g. the SAVV model:

OperationData

Speed estimated by SAVV model, V85th speed and legal speed limit

Spe

ed

Curvilinear abscissa (m)

Toward adaptive speed limitsDetection of Safety-Critical Events

• Development of in-vehicle or roadside devices, e.g. camera-based detection of rain or fog episodes

• Development of prediction models, e.g. water layer thickness (WLT) or skid resistance (SR) models

• Speed computation– Solve speed to get a

the same risk as in normal conditions

Toward Adaptive Speed LimitsComputation of Relevant Contextual Speeds

• Highway risk

Probability of occurence x gravity

risk

Braking distance (m)

Braking distance (m)

Braking distance (m)

Pro

bab

ility

of

fata

l in

jury

(%

)

Pro

bab

ilit

y o

f fa

tal

inju

ry (

%)

Pro

bab

ilit

y o

f fa

tal

inju

ry (

%)

Spe

ed

Perspectives• Advisory speed limits or

standardized advisory speed limits? HMI?

• Traffic and vehicle class, • Driver profile estimation

Toward Adaptive Speed LimitsComputation of Contextual Speeds

Curvilinear abscissa (m)

Spe

ed

Reference speed, advisory speed and stopping distance speedwith reduced friction and visibility

Global System Overview

ITS Framework Architecture

Conclusion and Perspectives

• Validation of legal and adaptive speed limits computation tools on a panel of drivers

• Standardization and deployment on networks• Agenda

2005-2010: Scientific foundations 2011: Technical consolidation 2012-2015: Deployment and validation at a medium scale 2015+: Standardization and deployment at bigger scale

The DRAVIA project“Advanced Diagnostic of Networks for Relevant Speeds”

Diagnostic de Réseau Avancé pour des VItesses Adaptées