HNTB Corporation monitored speeds after an HFST installation for the Florida DOT and found that speeds post-installation were actually lower. The report can be found at: https://fdotwww.blob.core.windows.net/sitefinity/docs/default-source/research/reports/bd500-v3-rpt.pdf?sfvrsn=d0ae33a5_2
While increasing superelevation does increase driver comfort, and improving driver comfort usually does increase speeds, there is no evidence that installing HFST leads to increased speed. HFST only satisfies friction needed to help the vehicle stay on the road.
Regardless of speed considerations, there have not been notable increase in crashes on treated segments. All of the crash evaluations to date have shown remarkable crash reductions, which is the bottom line.
Because HFST is such a thin overlay, generally less than 1/4-inch in thickness, the effect from snow plows has been minimal, even where “bare pavement” policies are followed in locations such as Illinois, Vermont, and Michigan.
Calcined bauxite aggregate wears very well under heavy snow plowing, and no deterioration from steel-tipped plows has been observed. HFST has been placed in many areas that see heavy snowplowing and winter weather, including Alaska.
In general, HFST can be applied over painted lines, but thermoplastic lines should be removed prior to HFST installation. If the existing pavement markings are in good condition, it is recommended that the markings be retained by masking them off prior to HFST placement. Always refer to resin binder manufacturer recommendations before applying over any surface treatment like paint lines.