Evaulation of Pavement Friction
Evaluation of Pavement Friction FHWA Development Of Crash Modification Factors Task B9: High Friction Surface Treatments David Merritt, The Transtec Group, Inc. ATSSA HFS Council Midyear Meeting 24 August 2016
Task Order B9 Objectives
Develop reliable Crash Modification Factors (CMFs) and Benefit/Cost (B/C) ratios for High Friction Surface Treatments (HFST). Provide guidance on the use of HFST to reduce roadway departure crashes. • Materials and specifications • Appropriate locations and conditions
Why HFST?
HFST has been demonstrated to be a proven safety countermeasure. • ELCSI-PFS Phase VI CMFs: Total Crashes Methodology
Wet Road Crashes
Naïve
Curves 0.628
Ramps 0.484
Curves 0.373
Ramps 0.211
Comparison Group
0.759
0.653
0.481
0.139
• Kentucky HFST Evaluation (70 curves): Annual Reduction
Ramps
Curves
Wet Avg.
90%
84%
Dry Avg.
77%
79%
Total Avg.
89%
83%
HFST Usage (Dec. 2015)
Courtesy: Frank Julian, FHWA
Task Order B9
Reliable CMFs and B-C Ratios will provide Safety Engineers with tools for deploying HFST. Guidance is needed on when and where to use HFST most effectively.
DCMF Task B9 Project Team
FHWA • Roya Amjadi • Joseph Cheung
Contract Lead: • VHB (Kim Eccles, Jon Soika)
Technical Team: • The Transtec Group (David Merritt, Helga Torres) • Persaud & Lyon (Dr. Bhagwant Persaud, Craig Lyon)
States with active HFST programs
Technical Activities
Task 2: Literature Review
Task 3: Identify HFSTs
Task 4a: Data Collection Plan
Task 4b: Data Collection Effort
Task 5: Determine Statistical Methodologies
Task 6: Data Analysis
Task 7: Technical Report and Quick Reference Guide Task 8: Build to Evaluate
Phase I: COMPLETE
Phase II: IN PROGRESS
Task 3: Identify HFSTs
Two Categories • HFST installations already in place. • HFST installations planned for the next ~6-8 months
Sites with Calcined Bauxite aggregate
Curves, Ramps, Intersections • On grade (bridges excluded)
Task 3: Identify HFSTs
Initial HFST Site List
Task 3: Identify HFSTs
HFST Site “Short List” for Curves
Task 3: Identify HFSTs
HFST Site “Short List” for Ramps and Intersections
Task 4: Data Collection
Crash Data
Roadway and Traffic Data
Pavement File Data (including previous friction measurements)
Climatic Data
Friction Data Collection • Examine any relationship between friction and crash reduction. • Monitor friction change over time.
Task 4: Data Collection
GripTester and FHWA Highway Friction Tester (HFT) continuous friction measurement device to be used for all sites to be evaluated.
For existing HFSTs, estimate pre-HFST friction data from lead-in and leadout pavement. For new HFSTs (installed in 2016), collect pre- and post-HFST installation friction data at these sites.
Questions?
Task Order B9 Objectives
Develop reliable Crash Modification Factors (CMFs) and Benefit/Cost (B/C) ratios for High Friction Surface Treatments (HFST). Provide guidance on the use of HFST to reduce roadway departure crashes. • Materials and specifications • Appropriate locations and conditions
Why HFST?
HFST has been demonstrated to be a proven safety countermeasure. • ELCSI-PFS Phase VI CMFs: Total Crashes Methodology
Wet Road Crashes
Naïve
Curves 0.628
Ramps 0.484
Curves 0.373
Ramps 0.211
Comparison Group
0.759
0.653
0.481
0.139
• Kentucky HFST Evaluation (70 curves): Annual Reduction
Ramps
Curves
Wet Avg.
90%
84%
Dry Avg.
77%
79%
Total Avg.
89%
83%
HFST Usage (Dec. 2015)
Courtesy: Frank Julian, FHWA
Task Order B9
Reliable CMFs and B-C Ratios will provide Safety Engineers with tools for deploying HFST. Guidance is needed on when and where to use HFST most effectively.
DCMF Task B9 Project Team
FHWA • Roya Amjadi • Joseph Cheung
Contract Lead: • VHB (Kim Eccles, Jon Soika)
Technical Team: • The Transtec Group (David Merritt, Helga Torres) • Persaud & Lyon (Dr. Bhagwant Persaud, Craig Lyon)
States with active HFST programs
Technical Activities
Task 2: Literature Review
Task 3: Identify HFSTs
Task 4a: Data Collection Plan
Task 4b: Data Collection Effort
Task 5: Determine Statistical Methodologies
Task 6: Data Analysis
Task 7: Technical Report and Quick Reference Guide Task 8: Build to Evaluate
Phase I: COMPLETE
Phase II: IN PROGRESS
Task 3: Identify HFSTs
Two Categories • HFST installations already in place. • HFST installations planned for the next ~6-8 months
Sites with Calcined Bauxite aggregate
Curves, Ramps, Intersections • On grade (bridges excluded)
Task 3: Identify HFSTs
Initial HFST Site List
Task 3: Identify HFSTs
HFST Site “Short List” for Curves
Task 3: Identify HFSTs
HFST Site “Short List” for Ramps and Intersections
Task 4: Data Collection
Crash Data
Roadway and Traffic Data
Pavement File Data (including previous friction measurements)
Climatic Data
Friction Data Collection • Examine any relationship between friction and crash reduction. • Monitor friction change over time.
Task 4: Data Collection
GripTester and FHWA Highway Friction Tester (HFT) continuous friction measurement device to be used for all sites to be evaluated.
For existing HFSTs, estimate pre-HFST friction data from lead-in and leadout pavement. For new HFSTs (installed in 2016), collect pre- and post-HFST installation friction data at these sites.
Questions?
