Benefit–Cost Analysis of Florida High-Friction Surface Treatments

Abstract

High-friction surface treatments (HFSTs) are effective at reducing crashes on horizontal curves; however, HFST effectiveness on other roadway sections (e.g., tangents, intersections, intersection approaches) is not well documented. The crash reduction effectiveness of HFSTs in Florida was assessed, and the benefit–cost (BC) ratios for these section types were calculated. The researchers identified 23 HFST projects in Florida and attempted to collect data for each project, including bidding records, roadway geometry, and crash statistics. The cost data were based on the average comprehensive HFST unit cost and scaled by the size of the application. The benefit was estimated on the basis of 5-year extrapolations of average total and wet weather crash reductions. Savings were estimated on the basis of Florida Department of Transportation KABCO severity distribution of the crashes and an average cost per crash. On average, HFST applications on tight curves reduced the total crash rate by 32% and the wet weather crash rate by 75%. The average BC ratio on tight curve sections was between 18 and 26, depending on the benefit calculation method. Wide curve and tangents sections had few accidents initially, and HFST had negligible impact. From a crash perspective, wide curve and tangent HFST applications are not cost-effective. The effectiveness of HFST on intersection and approach applications is still inconclusive. Half the sections had good BC ratios and the other sections had negative benefit (increased crash rates). When considering the application of HFST, the engineer should consider whether there is an existing crash problem and whether it is skid related.

Life Cycle Cost Analysis of High Friction Surface Treatment Applications

“…The aggregates were tested for their degradation/polish resistances in the MD apparatus. The MD test was utilized to explore aggregates’ durabilities and resistances to polishing and grinding in the water ( 5, 9, 18 ). The coarse aggregate MD test was run following ASTM D6928 – 17 on aggregate size (passing from sieve 3/8′′ and retained on #4 [3/8′′–#4]).…”

“…HFST is determined to be a cost-effective safety treatment consisting of a polymer resin layer, that is used to bond the pavement with 3–4 mm maximum size high friction aggregates. These aggregates have high angularity, high texture, and high polishing resistance (e.g., calcined bauxite [CB], flint/chert, slags, or granite) ( 1, 2, 5–8 ). Resin binder, such as epoxy resin, polyester resin, polyurethane resin, acrylic resin, or methyl methacrylate, is spread over the pavement surface to bond this surface with the aggregate layer ( 2, 5, 6 ).…”

“…These aggregates have high angularity, high texture, and high polishing resistance (e.g., calcined bauxite [CB], flint/chert, slags, or granite) ( 1, 2, 5–8 ). Resin binder, such as epoxy resin, polyester resin, polyurethane resin, acrylic resin, or methyl methacrylate, is spread over the pavement surface to bond this surface with the aggregate layer ( 2, 5, 6 ). The most common resin binder in HFST is epoxy resin, a two-part binder that consists of a resin (extender) and an epoxy (hardener) ( 5 ).…”

Empirical Bayes Before-After Study to Develop Crash Modification Factors and Functions for High Friction Surface Treatments on Curves and Ramps

“…Rigorous safety evaluations have been elusive to date, largely because this is a relatively new treatment with limited applications, and partly because of methodological issues with larger-scale studies. An example of a larger-scale study with methodological limitations is one in Florida that concluded that HFST may not provide the desirable crash-reduction performance at wide curves/tangents, intersection approaches, and intersections; the only statistically significant change in crash rates was the decrease in wet weather accidents on tight curves (3). However, these results may not be reliable, since they were based on a naı¨ve before-after comparison that did not control for regression-to-the-mean and other changes in crashes that were unrelated to the treatment, for example, those because of differences in weather between the ''before'' and ''after'' periods.…”

Laboratory and Field Evaluation of Single Layer and Double Layer High Friction Surface Treatments

“…To ensure successful applications of HFST, the American Association of State Highway and Transportation Officials (AASHTO) has issued a provisional specification, i.e., AASHTO PP 79-14 ( 4 ). To date, considerable efforts have been made to evaluate the use of HFST across the United States (U.S.) ( 5 – 10 ). In particular, Izeppi et al evaluated the use of various proprietary high friction surfacing systems for both pavement and bridge deck in terms of friction performance and benefit-cost (BC) ratio ( 5 ).…”