1. DI V AS ANR Safe Highways of the Future, 12-13-14 February 2008, Brussels, Belgium, Improving the Credibility of, and Compliance with, Speed Limits: a Real-World Approach N. Hautière 1, P. Charbonnier 2, E. Dumont 1, S. Glaser 1, E. Violette 3 DI V AS ANR 1 LCPC, Paris 2 LRPC de Strasbourg, ERA 27, Strasbourg 3 CETE Normandie-Centre, ERA 34, Rouen

2. DI V AS ANR Safe Highways of the Future, 12-13-14 February 2008, Brussels, Belgium, 2 Presentation Outline  Introduction  Rough points  Our position  Speed limits computation: state of the art  How to improve drivers’ compliance with speed limits?  Process  Examples  On-board solution: ARCOS  Roadside solution: SARI  Cooperative solution: DIVAS  Perspectives

3. DI V AS ANR Safe Highways of the Future, 12-13-14 February 2008, Brussels, Belgium, 3 Introduction  Fact There is a strong link between accidentology and speed.  Problem Permanent speed limits (signs) do not help road users to adapt their speed in case of transient difficulties - Meteorology: rain, fog, wet road, ice on the road - Traffic, road works, lack of maintenance…  Solution Adaptive and customized speed limits. 110 light rain 90 strong rain

4. DI V AS ANR Safe Highways of the Future, 12-13-14 February 2008, Brussels, Belgium, 4 Introduction: Rough Spots (at least in France)  The duality of speed limits  Speed limits have different functions, e.g.: to ensure homogeneous behaviours,to ensure homogeneous behaviours, to ensure coherence with road related risks.to ensure coherence with road related risks.  To comply with speed limits, road users must be aware that speed limits are related to the risk and not only to speed enforcement.  Problem: do we communicate on the speed or on the risk?  Compliance  Prior to the introduction of automatic speed enforcement, speed limits were designed knowing that they would not be respected.  Today, posted speed limits are no longer suitable because they are complied with.  Liability  Legal issues are problematic for adaptive speed limits.

5. DI V AS ANR Safe Highways of the Future, 12-13-14 February 2008, Brussels, Belgium, 5 Introduction: Our Position  We focus on the scientific aspect of the problem.  We seek to compute credible safe* speed limits. (*) i.e. risk-related  We consider isolated vehicles, only interacting with the infrastructure.

6. DI V AS ANR Safe Highways of the Future, 12-13-14 February 2008, Brussels, Belgium, 6 Speed Limits Computation: State of the Art  Empirical approach   Actual speeds are measured in nominal conditions  all the parameters are integrated    Problem: only applies in nominal conditions  not adaptive  not credible  Computational approach   Based on physical models for specific situations  many parameters are omitted: driver, car, visibility...    Problem: not customized  needs to be pessimistic  not credible

7. DI V AS ANR Safe Highways of the Future, 12-13-14 February 2008, Brussels, Belgium, 7 How to Improve Drivers’ Compliance with Speed Limits?  Hypothesis Credible speed limits are better complied with.  Question How to make speed limits credible?  Answer By making them adaptive and customized.

8. DI V AS ANR Safe Highways of the Future, 12-13-14 February 2008, Brussels, Belgium, 8 Process  Combine empirical and computational approaches Usual approach: Our approach: with SL = Speed Limit MSL = Mandatory Speed Limit NSL = Nominal Speed Limit  empirical model f(p i ) = speed decrement needed to maintain nominal risk level p i = transient risk factor  computational approach

9. DI V AS ANR Safe Highways of the Future, 12-13-14 February 2008, Brussels, Belgium, 9 Examples On-board solution  We make it customized (on-board = more credible),  ARCOS Project First use of risk functions  Example: the SAVV (speed warning in curves)  Website: http://www.arcos2004.com/ Source: ARCOS Project

10. DI V AS ANR Safe Highways of the Future, 12-13-14 February 2008, Brussels, Belgium, 10  We make it adaptive  SARI / IRCAD (roadside = addresses all drivers)  Problem: drivers are not aware of the risk in bad conditions (particularly with skid resistance)  We must set a warning threshold in the speed distribution.  Website: http://www.sari.prd.fr/ Examples Roadside solution Source: Lacroix Traffic Alert threshold Risk function

11. DI V AS ANR Safe Highways of the Future, 12-13-14 February 2008, Brussels, Belgium, 11 Examples Cooperative Solution  We make SLs both adaptive and customized.  We generalize road-related risks by adding meteorological risks, and by combining risk factors (with ranking, rather than simply decrementing).  This is one objective of the DIVAS Project. Source: PReVENT Maps&Adas Source: ARCOS Project

12. DI V AS ANR Safe Highways of the Future, 12-13-14 February 2008, Brussels, Belgium, 12  Type of project: French ANR 2006  Promoted by PREDIT GO9  Timeframe: May 2007-May 2010  Cost budget: 4 M€ (ANR funding 1.3M€)  Coordinator: LCPC  Philippe Lepert  Nicolas Hautière  Consortium: 15 partners Industrials Research institutes Local actors Universities Competitiveness clusters DIVAS: Dialog between Infrastructure and Vehicles to Improve the Road Safety (1) Source: LARA (ENSMP/INRIA)

13. DI V AS ANR Safe Highways of the Future, 12-13-14 February 2008, Brussels, Belgium, 13  The DIVAS project is building a global a vehicles – infrastructure information exchange system  It aims at preparing its implementation, in terms of:  technology,  acceptability,  credibility.  The project is focussed on the role of:  the infrastructure characteristics  the role of the road operators in the deployment of such systems.  It aims at providing each vehicle with an individualized safety indicator along a route,  It mainly takes into account the road geometry, the road surface conditions and the visibility conditions.  Web site: http://or.lcpc.fr/divas-fr/  Reference:  N. Hautière, P. Lepert. “Infrastructure - Vehicles Dialogue to Improve Road Safety: The DIVAS Approach”. To appear in Transport Research Arena (TRA), Ljubljana, Slovenia, April 21 – 25, 2008 DIVAS: Dialog between Infrastructure and Vehicles to Improve the Road Safety (2)

14. DI V AS ANR Safe Highways of the Future, 12-13-14 February 2008, Brussels, Belgium, 14 DIVAS Measuring Actual Speeds (empirical approach)  “Reference” drivers with instructions, in nominal conditions.  Record the speed profile along the road (and other information also) with an instrumented vehicle.  Calibrate speed profiles using roadside speed measurements at different spots.  Build a nominal speed profile.  Infer nominal risk for a specific situation (e.g. “brick wall”) Source: LAVIA Project

15. DI V AS ANR Safe Highways of the Future, 12-13-14 February 2008, Brussels, Belgium, 15 1 st Level Application: Consolidation of Vertical Signalling  Signs provide the permanent speed limits, posted by the road operator (or police).   Posted speed should be coherent with nominal speed in order to be credible  Discrepancies should be studied, baring in mind the duality of posted speed limits.

16. DI V AS ANR Safe Highways of the Future, 12-13-14 February 2008, Brussels, Belgium, 16 2 nd Level Application: Adaptation of Speed Limits to Keep Constant Risks (computational approach)  Risk models are chosen with respect to the studied risk factor  The  V is computed to have a constant risk (R) compared to the nominal risk (R N )  Example: brick wall risk model and wet road  Nominal risk: we compute the gravity of an accident at impact speed S N into a wall at t=2s  S N   A N  EES N *  R N  Wet road leads to a reduction of skid resistance  S   A  EES  R > R N  Knowing the actual road surface conditions, we can compute   S / S’=S-  S  R’=R N  Assumption: computing S’=S-  S is more credible than computing S’=f(skid resistance), which was used for example in ALZIRA project. *EES = Equivalent Energy Speed (cf. LAB PSA/RENAULT)

17. DI V AS ANR Safe Highways of the Future, 12-13-14 February 2008, Brussels, Belgium, 17 Perspectives  We argue that credible risk-related speed limits would be better complied with.  We proposed an approach to compute credible speed limits by making them adaptive and customized.  We are testing the approach in the framework of DIVAS project dealing with cooperative systems.  In the coming next months, we will see if our approach is relevant or not. May 2010 November 2008 Mid-term seminar Q1Q2Q3Q4Q5Q6Q7Q8Q9Q10Q11Q12 Time(Quarter) May 2007 DIVAS agenda Today