U.S. Department of Transportation
Federal Highway Administration
1200 New Jersey Avenue, SE
Washington, DC 20590
202-366-4000
Federal Highway Administration Research and Technology
Coordinating, Developing, and Delivering Highway Transportation Innovations
| REPORT |
| This report is an archived publication and may contain dated technical, contact, and link information |
 |
| Publication Number: FHWA-HRT-14-065 Date: February 2015 |
Publication Number: FHWA-HRT-14-065 Date: February 2015 |
HTML Version of Errata for FHWA-HRT-14-065
PDF files can be viewed with the Acrobat® Reader®
As of July 2015, this online document was modified in the following way:
The following changes were made to the document after publication on the Federal Highway Administration Web site:
| Location | Corrected Values | URL |
| Page i, TECHNICAL REPORT DOCUMENTATION PAGE, Item 15 for Supplementary Notes |
FHWA Contract Task Managers: Roya Amjadi, Office of Safety Research and Development, and Jim Sherwood, Office of Infrastructure Research and Development at Turner-Fairbank Highway Research Center, 6300 Georgetown Pike McLean VA 22101 |
/publications/research/safety/14065/index.cfm#errata01 |
The research documented in this report was conducted as part of Phase VI of the Federal Highway Administration (FHWA) Evaluation of Low-Cost Safety Improvements Pooled Fund Study (ELCSI–PFS). The FHWA established this pooled fund study in 2005 to conduct research on the effectiveness of the safety improvements identified by the National Cooperative Highway Research Program Report 500 Guides as part of the implementation of the American Association of State Highway and Transportation Officials Strategic Highway Safety Plan. The ELCSI-PFS studies provide a crash modification factor (CMF) and benefit-cost (BC) economic analysis for each of the targeted safety strategies identified as priorities by the pooled fund member states.
The intent of the study was to isolate the effects of various low cost pavement treatments on roadway safety. This was a retrospective study for pavement safety performance, looking back at crash data both before and after treatments were installed. Both flexible and rigid pavement treatments were analyzed, with the majority typically used for pavement preservation or minor rehabilitation purposes. Although state highway agencies recognize that most of these treatments generally improve pavement friction, they are not typically installed explicitly for safety improvement. The one exception is high friction surfacing, which is typically applied as a spot safety treatment. Under this effort, CMFs and BC ratios were developed for various low-cost pavement treatments.
Monique R. Evans
Director, Office of Safety
Research and Development
Notice
This document is disseminated under the sponsorship of the U.S. Department of Transportation in the interest of information exchange. The U.S. Government assumes no liability for the use of the information contained in this document. This report does not constitute a standard, specification, or regulation.
The U.S. Government does not endorse products or manufacturers. Trademarks or manufacturers’ names appear in this report only because they are considered essential to the objective of the document.
Quality Assurance Statement
The Federal Highway Administration (FHWA) provides high-quality information to serve Government, industry, and the public in a manner that promotes public understanding. Standards and policies are used to ensure and maximize the quality, objectivity, utility, and integrity of its information. FHWA periodically reviews quality issues and adjusts its programs and processes to ensure continuous quality improvement.
| Form DOT F 1700.7 | Reproduction of completed page authorized |
SI* (Modern Metric) Conversion Factors
Figure 1. Illustration. Key mechanisms of pavement-tire friction
Figure 2. Graph. Pavement texture categories and their effect on surface characteristics (adapted from Henry)
Figure 3. Photo. Microtexture provided by aggregates on an asphalt pavement
Figure 4. Photo. Macrotexture for an asphalt pavement surface (left) and concrete surface from tining (right).
Figure 5. Photo. Placement of thin asphalt overlay (top) and surface texture of new (bottom left) and worn (bottom right) dense graded asphalt surfaces.
Figure 6. Photo. Surface texture of OGFC
Figure 7. Placement of an UTBWC using a self-priming paver (top) and surface texture of an UTBWC (bottom)
Figure 8. Photo. Placement of a chip seal (top) and surface texture of a single layer chip seal (bottom)
Figure 9. Photo. Placement of a slurry seal (top) and surface texture of a cured slurry seal (bottom)
Figure 10. Microsurfacing placement (top) and surface texture of cured microsurfacing treatment (bottom)
Figure 11. Photo. Diamond ground concrete pavement surface.
Figure 12. Photo. Grooved concrete pavement surface (top) and Next Generation Concrete Surface (bottom)
Figure 13. Photo. Micro-milled asphalt pavement surface
Figure 14. Photo. Shotblast asphalt pavement (top) and concrete pavement (bottom)
Figure 15. Photo. Emulsion material is scrubbed into the pavement surface for a scrub seal surface treatment
Figure 16. Photo. Installation of HFS (top) and finished surfaces (bottom)
Figure 17. Equation. Change in safety for a given crash type at a treated site.
Figure 18. Equation. Estimate of the expected number of crashes before treatment
Figure 19. Equation. Estimate of weight
Figure 20. Equation. Estimate of the index of safety effectiveness
Figure 21. Equation. Standard deviation of the estimated index of safety effectiveness
Figure 22. Equation. Model form for Pennsylvania SPFs
Figure 23. Equation. Model form for North Carolina SPFs
Figure 24. Equation. Model form for California SPFs
Figure 25. Equation. Model form for Minnesota SPFs
Figure 26. Photo. Example of wear in wheelpaths over time for chip seal treatments, reducing surface texture and friction
Figure 27. Equation. Estimated number of crashes that would have occurred in the after period with no treatment in the naïve study
Figure 28. Equation. Estimated variance of B in the naïve study
Figure 29. Equation. Estimated CMF in the naïve study.
Figure 30. Equation. Estimated CMF variance in the naïve study
Figure 31. Equation. Estimated number of crashes that would have occurred in the after period with no treatment in the C-G study
Figure 32. Equation. Estimated variance of B in the C-G study
Figure 33. Equation. Estimated CMF in the C-G study
Figure 34. Equation. Estimated CMF variance in the C-G study.
Figure 35. Equation. Annualized cost pavement treatment.
Figure 36. Equation. Model estimated for total crashes on thin HMA treatments on freeways.
Figure 37. Equation. Model estimated for total crashes on OGFC treatments on two-lane roads.
Figure 38. Equation. Model estimated for total crashes on diamond grinding treatments on freeways
Table 1. Summary of results from NYSDOT skid-accident reduction program analysis
Table 2. Flexible and concrete pavement treatment strategies considered in Phase VI
Table 3. Typical macrotexture depth for various pavement treatments
Table 4. List of potential data collected for treatment sites.
Table 5. Treatment strategies and quantities provided, by State, for asphalt pavements.
Table 6. Treatment strategies and quantities provided, by state, for concrete pavements
Table 7. Summary statistics for Pennsylvania treatment site geometry
Table 8. Summary statistics for Pennsylvania treatment site AADT and crashes
Table 9. Summary statistics for Pennsylvania reference sites.
Table 10. Summary statistics for North Carolina treatment site geometry
Table 11. Summary statistics for North Carolina treatment site AADT and crashes.
Table 12. Summary statistics for North Carolina reference sites
Table 13. Summary statistics for California treatment site geometry
Table 14. Summary statistics for California treatment site AADT and crashes.
Table 15. Summary statistics for California reference sites
Table 16. Summary statistics for Minnesota treatment site geometry
Table 17. Summary statistics for Minnesota treatment site AADT and crashes
Table 18. Summary statistics for Minnesota reference sites
Table 19. SPF parameter estimates and standard errors for Pennsylvania treatment sites.
Table 20. SPF parameter estimates and standard errors for North Carolina treatment sites
Table 21. SPF parameter estimates and standard errors for California treatment sites.
Table 22. SPF parameter estimates and standard errors for Minnesota treatment sites
Table 23. Summary of pilot test results of including climatic data
Table 24. Estimates of CMFs for chip seal treatment
Table 25. Estimates of CMFs for diamond grinding treatment
Table 26. Estimates of CMFs for thin HMA treatment.
Table 27. Estimates of CMFs for open OGFC treatment
Table 28. Estimates of CMFs for grooving treatment
Table 29. Estimates of CMFs for microsurfacing treatment
Table 30. Estimates of CMFs for slurry seal treatment
Table 31. Estimates of CMFs for UTBWC treatment
Table 32. Estimates of CMFs for chip seal treatment for wet-road crashes on two-lane roads by period after treatment.
Table 33. Estimates of CMFs for single and multi-layer chip seal treatment for wet-road crashes (NC and PA only) by period after treatment.
Table 34. Estimates of CMFs for diamond grinding treatment for wet-road crashes on freeways by period after treatment
Table 35. Estimates of CMFs for OGFC treatment for wet-road crashes on freeways and two-lane roads by period after treatment
Table 36. Summary statistics of HFS treatment site data collected
Table 37. Summary statistics of HFS comparison site data collected.
Table 38. Results for the naïve before-after study based on all sites.
Table 39. Results for the before-after C-G study for treatment sites for which comparison sites were available
Table 40. Results of BC analysis for conventional treatment groups with statistically significant crash reductions
Table 41. Results for model for total crashes on thin HMA treatments on freeways
Table 42. Results for model for total crashes on OGFC treatments on two-lane roads
Table 43. Results for model for total crashes on diamond grinding treatments on freeways.
Table 44. Treatment sites by State, part 1
Table 45. Treatment site by State, part 2.
| AADT | Average Annual Daily Traffic |
| AASHTO | American Association of State Highway and Transportation |
| BC | Benefit-Cost |
| Caltrans | California Department of Transportation |
| CDOT | Colorado Department of Transportation |
| C-G | Comparison Group (study) |
| CMF | Crash Modification Factor |
| CMFunction | Crash Modification Function |
| CPI | Consumer Price Index |
| EB | Empirical Bayes |
| ELCSI-PFS | Evaluation of Low-Cost Safety Improvements Pooled Fund Study |
| FHWA | Federal Highway Administration |
| GLM | Generalized Linear Modeling |
| GP | Groove Pavement |
| HFS | High-Friction Surfacing |
| HIS | Highway Information System |
| HMA | Hot Mix Asphalt |
| HSIS | Highway Safety Information System |
| KDOT | Kansas Department of Transportation |
| KTC | Kentucky Transportation Cabinet |
| MDOT | Michigan Department of Transportation |
| MDT | Montana Department of Transportation |
| MnDOT | Minnesota Department of Transportation |
| NCDC | National Climatic Data Center |
| NCDOT | North Carolina Department of Transportation |
| NCHRP | National Cooperative Highway Research Program |
| NYSDOT | New York State Department of Transportation |
| OGAC | Open Graded Asphalt Concrete |
| OGFC | Open-Graded Friction Course |
| PennDOT | Pennsylvania Department of Transportation |
| R-OGAC | Rubberized Open Graded Asphalt Concrete |
| ROR | Run-Off Road |
| RTM | Regression to the Mean |
| SCDOT | South Carolina Department of Transportation |
| SCRIM | Sideway-Force Coefficient Routine Investigation Machine |
| SEAHC | Surface Enhancements at Horizontal Curves |
| SHRP2 | Strategic Highway Research Program 2 |
| SPF | Safety Performance Function |
| TDOT | Tennessee Department of Transportation |
| TRIMS | Tennessee Information Management System |
| UTBWC | Ultra-Thin Bonded Wearing Course |
| WisDOT | Wisconsin Department of Transportation |
