Robert Thomson Chalmers University of Technology Division of Vehicle Safety/SAFER

1. Robert Thomson Chalmers University of Technology Division of Vehicle Safety/SAFER Rankers Field Studies of Infrastructure Performance

2. Outline • Motivation for Field Studies • Partners • Field Study Objectives • Infrastructure Monitoring • Countermeasure Effectiveness • Methods • Results • Future Activities

3. Motivation What approach do we need for improving traffic safety? 1) Identify locations with traffic safety problems • What indicators can we use to predict safety problems? • Do we need to wait for fatal accidents to accumulate before we identify problem areas? 2) Identify suitable candidate solutions • Identify potential solutions for review • Conduct field evaluations of selected countermeasures • Provide information for ranking suggested countermeasures

4. Motivation • Road Safety Index • Use existing road information to find signals of safety problems • Traffic data • Accident data • Maintenance data • Road Surface properties • Road Geometry • Roadside layout • Identify important indicators for monitoring trends in road safety • Eliminate need for Black Spot developments

5. Motivation • Safety Countermeasures must be evaluated and compared with the following considerations: • What type of safety problem is of most concern? • What are the installation / implementation costs? • What are the maintenance and operations costs? • What is the effectiveness of the countermeasure? • How will this affect future safety / traffic conditions?

6. RANKERS Scenarios • A review of a detailed database developed in RANKERS identified several accident types • Main accident types • Run off road without driver reaction • Run off road with driver reaction • Rear end impacts 15% • Lane change accidents 13% • Wild life 3% • Pedestrians • Wrong way entrance to motorway / Tunnels 46% RANKERS Field Studies primarily focus on items 1-4

7. Partners • Five partners are involved in the Infrastructure field studies: • Chalmers University of Technology (Sweden) • Swedish Road Administration • Helsinki University of Technology (Finland) • Autostrade (Italy) • CETE (France) • DARS (Slovenia)

8. Objectives

9. Field Study Objectives • The Infrastructure Field Studies can be divided into two groups based on the type of activity • Monitoring: What are the relationships between road characteristics and accidents (numbers and types) • Countermeasure Performance: How does a given countermeasure perform in real world conditions

10. Objectives: Monitoring • Studies related to accident analysis and contributions of the road infrastructure focus on the following variables: • Road Geometry (vertical and horizontal alignment, width, cross slope, etc.) • Road Surface (roughness, wheel ruts) • Speed • Analysis requires accident and infrastructure databases, common for road operators but not necessarily combined • Link accident information and road information by accident location

11. Objectives: Countermeasure Performance • Different countermeasures in before-after studies were evaluated • Countermeasures were selected which have a connection to the main accident scenarios presented earlier • Specific topics comprise: • Curves • Aquaplaning • Rear end / lane change • Passive Safety Devices • Wildlife • Speed reduction • Sign/Lighting

12. Methods

13. Methods: Safety Monitoring • A linked dataset to analyze the contibution of road characterisics to safety • A national accident database • Road network database • Pavement Management System (PMS) • Accident locations were connected to road sections with a 200 m accuracy • Swedish data included all accident types, Finnish data included only Run-off-Road accidents • Swedish road sections were physically divided (median barrier) and were 2+1, 2+2, motorway designations • Finnish data covered motorways with different construction dates (old/new designs)

14. Road data: Laser RST Sketch of the 17 laser measurement points

15. Methods PMS (Pavement Management System) Super elevation Unevenness Wheel rut Curvature Carriageway width Grade Measuring date Measuring direction Link ID Speed limit Traffic volume Road type

16. Methods: Period of Investigation • Sweden: • Six-year period, from 2000 to 2005 accidents with personal injury. • No property damage reported to the accident databases. • 2912 accidents collected including 54 fatal, 29 severe and 3877 light injuries. • Finland: • Six-year period, from 2000 to 2005 accidents with personal injury • 437 accidents been collected including 31 fatal, 406 personal injuries.

17. Mehtods: Statistical Analysis • Accident and Infrastructure data were analyzed using a regression analysis to identify the relationships between different parameters • Accident data were expressed in Accident Rates (AR): • Where: N=number of accidents; AADT= Annual Average Daily Traffic; L=Length of section;L=Length of investigation period (km), T=period of study (years) • This allowed a normalised value for comparing different infrastructure elements • Road sections with similar characteristics were lumped together

18. Methods: Countermeasure Evaluation • Countermeasures studied were implemented and investigated in the period 2000-2007. • The before – after period of interest varied depending on date of implementation • The number of accidents in the before period were often limited to a limited road segment length (1-5 km). • May involve only 1-2 accidents for a given location • Higher accident rate than network average • Results are the influence of countermeasure at the area of implementation and may not represent their global performance

19. This presentation will only discuss 4 countermeasures Mehtods: Countermeasure Types • The countermeasure types can be grouped in the following categories and partners

20. Results

21. Results: Monitoring Most interesting results related to curvature, cross slope, road surface • Accident rate increases with decreasing radius, below 400 dealing with ramps and urban sections of motorway (lower speeds)

22. 100.00 80.00 L L L 60.00 L R R L Accident Type Contribution (%) R R 40.00 R 20.00 Rear End Run-off-Road Overtaking 0.00 < 250 400 700 1000 >1000 Curve Radius [m] Results: Monitoring L=Left R=Right Accident distribution changes with curvature, overtaking accidents increase significantly in right curves with curve radii 700-1000m Right curves have higher risk for overtaking accidents

23. 0.80 Positive Cross-slope Negative Cross-slope 0.60 Accident Rate 0.40 0.20 0.00 0-1.5 1.5-2.5 2.5-3 3-4. 4-5. >5 Cross Slope (%) Results: Monitoring • Higher risk for negative 3%-4%

24. 0,6 0,5 - 0,4 - 0,3 Accident rate 0,2 + 0,1 0 Left curves Left curves Right curves Results : Super elevation Accident rate for (3-4)% cross slopes for left and right curves • Positive cross slope is twice as safe as negative in left curves. • Explanation needed for higher risk for negative cross slope in right curves

25. Results: Monitoring • Road Condition Both IRI and Rut depthaffect accident rate, almostdoubling in the first 2 intervals

26. Results: Monitoring • Other Results: • Relationship between carriageway width and accident rate • Average curvature of a road network appears to influence the accident rate • Old motorways had higher accident rate • Average curve radius under 3000 m(old) compared to 4000 m (new) • Relationship between speed and accident rate

27. Results: Safety in Curves • Two studies on safety in curves and countermeasures • A: Speed Cameras • B: Adjust crossfall • Both sites are characterised by 400 m radius curves counter-acting crossfall (ie –ve slope for left curves) • Both curves are preceded by curves R>500m and the driver is “surprised” with a tighter curve

28. Results: Safety in Curves • Countermeasures investigated • Speed Cameras mounted at the site with information signs • Reconstruction of crossfall in left curve (-2.5% changed to +2.5%)

29. After Results: Speed Cameras Case A Posted Speed 90 km/h Before

30. Before After Effectiveness ratio Injury accidents 6 in 20 months 0 in 1 year 100% Safety in Curves • Case A: Speed Cameras Installed

31. Results: Crossfall Change • Case B

32. Before After Effectiveness ratio Non-injury accidents 20 in 1 year 1 in 9 months 93% Injury accidents 5 in 2 years 0 in 1 year 100% Video footages 6 in 2 months 0 in 4 months 100% Effectiveness on accidents Case A • Accident follow-up 9 months later: • 0 injury accident • 1 non-injury accident

33. Vehicle motionbefore Reconstruction of road shifted traffic left Results: Reconstruction of Curve Before After

34. Aquaplaning • Two aquaplaning issues were identified in France and Slovenia • Two different countermeasures investigated • Rehabilitation (France+Slovenia) • Grooving (Slovenia) • Both cases involve low crosslopes values with low grades • Identify a monitoring condition: • -1% <crossfall<1% and -1% <grade<1%

35. Before After Effectiveness ratio Injury accidents 12 in 7 months 0 in 4 years 100% Results Aquaplaning • Results – Reconstruction France

36. Aquaplaning Aquaplaning: accident before / after: Slovenia

37. Speed Control – Influence of System Speed Measurement • Identification of road sections suitable for improvements (scenario definition), • Identification of the PISM and collection of the accidents data in the period 1999-2005 of the A14 motorway sections, • Case study A • Installation of safety tutor, • Data collection, • Analysis of the performance in terms of real average speed reduction. • Case study B • Installation of a combined safety system (camera and inductive loops), • Data collection, • Analysis of the performance in terms of real average speed reduction.

38. Six-month period September 2005 April 2006 Six-month period September 2006 April 2007 ∆ Accident rate 52.35 40.73 -22.2 % Injury rate 20.76 15.94 -23.2 % Death rate 0.71 0.44 -38.1 % Speed Control – Influence of System Case study A • In the eight-month period September 2006 - April 2007, the accident rate and the consequences for persons on sections covered by Tutor registered a decline. This can be attributed to the following factors: • Average speeds on the sample day were in constant reduction (-16 km/h) • An even greater reduction concerned the top speeds (-23 km/h on the average of the ten top speeds) • This favourable trend in driving behaviour is reflected in the tickets issued by the constantly operating system, which also recorded a reduction (Highway Police data)

39. Speed Control – Influence of System Case study B • Data have been acquired for the following two monthly periods by a speed monitoring systems including loop system and camera box • October 2nd-29th, 2006 (without camera box) • January 29th-February 25th, 2007 (with camera box) • In order to verify the influence on vehicle speed of put off effect of speed monitoring system by camera box, more than 9,000 data of average speed (km/h) on a 5 min base, box have been acquired. • From data analysis appears that the average speeds on the sample month are in constant reduction on both carriageway (of -10 km/h on right and of -5 km/h on left).

40. Summary

41. Summary • Accident Data provides some possibilities to identify critical infrastructure conditions • Sufficient data needed for analysis • New motorway designs may have sufficiently high standard limiting black spot analysis • An alternative to black spot analysis - critical infrastucture properties - may be useful for monitoring road safety • Countermeasures • Several countermeasures were investigated addressing run-off road accidents, rear-end, and lane change accidents • Speed control was shown to be an effective approach in 3 different studies

42. Future Work

43. Connections between Infrastructure and Human Factors Studies • Behaviour in Curves • Influence of curve direction on overtaking accident risk (right curves more dangerous) • Influence of cross fall (-ve cross slope more dangerous, even for right curves) • Lane keeping tendencies in smaller radius curves (400-500) • Speed Control • What is the mechanism to reduce accident risk • Speed distribution (V15-V85) • Lateral handling capacity (skid resistance)

44. Future Work • Data from the field studies needs to be analysed and presented in a form to • Develop a set of recommendations for a safety problem • Cost (Benefit) information • Maintenance information • Influence on traffic • Develop a diagnostic tool (Road Safety Index) • Help point put critical infrastructure elements • Support ongoing monitoring of traffic safety

45. Further Information • Results of the RANKERS project will be implemented into an “e-Book” that will provide information on countermeasures for a variety of road safety issues • Further information on the field studies can be found at the RANKERS website www.rankers-project.com (Or contact the indiviudal partners)

46. Acknowledgements • The RANKERS project is thankful for the support of the European Commission (DG-TREN) • Partners are also indebted to national and regional road authorities for their support and assistance in the project