HIGH FRICTION SURFACE TREATMENT
High Friction Surface Treatments (HFST) is the application of specialty coatings that improve traction in dangerous sections of highways. A major advancement in transportation safety for severe curves and breaking areas, sharp corners, areas entering intersections, bridges, highway off ramps–there are many areas where traction conditions vary and yet the ability to maintain friction between the tires and the road surface in wet and dry conditions is critical for driver safety.
A research report published by FHWA shows HFST is estimated to reduce
wet crashes by 83 percent and total crashes by 57 percent.
Our HFST trucks are high production, fully automated and specifically designed for High Friction Surface Treatment.
This technology reduces errors and inaccuracies which allows for more consistent results and guarantees you will meet your target specifications. HFST more than doubles the existing friction value on the roadway surface.
HFST can be a viable long-term answer for not only highly traveled roads and bridges, but also on rural dangerous curves, providing consistent durable and high friction levels that have been proven to reduce crashes and increase roadway safety while at the same time, maintain a cost-effective strategy.
HFST’s nominal effect on the surrounding environment is due to the treatment’s application between existing pavement edges, resulting in no net increase of impervious areas. HFST can be implemented quickly eliminating most environmental concerns. The quick installation also minimizes the time of direct impact to the traveling public.
Benefits of Fully Automated Application
The applicator truck is continuously mixed, metered, and monitored when applying the resin binder and high friction aggregate in one continuous application pass.
The automated applicator will have continuous pumping and portioning devices that blend the epoxy resin binder within a controlled system ensuring a 1:1 mixing ratio.
The vertical placement of the Calcined Bauxite eliminates the possibility of displacement of the epoxy resin, providing a uniform aesthetically accepted and smooth finished ride on the roadway surface.
Installs up to 14' full lanes widths at 26 linear ft./minute.
Installs up to 3000 sq. yards per hour before requiring to be refilled.
Analyzing HFST Benefits
HFST places a layer of highly durable, anti-abrasion and polish-resistant aggregate over a thermosetting epoxy resin binder. The mineralogical and physical properties of these aggregates make the overlay exceptionally resistant to wear and polishing by traffic. The epoxy resin binder locks the aggregate firmly in place, creating an extremely durable surface capable of withstanding even the most extreme roadway demands, from cornering and heavy braking to excessive snowplowing in cold climate areas. HFST restores, and, in most cases, significantly enhances, pavement surface friction where traffic has worn down existing pavement surface aggregates. HFST can also help compensate for inadequate geometric designs, such as sharp curves and substandard super elevations.
The greatest benefit from HFST is often gained where friction demand exceeds the available friction of a roadway surface. These areas are often interchange ramps, rural curves, steep grades, and intersections. HFST has also been successful when used in lieu of costly roadway realignments, which can take years to complete due to delays associated with lengthy planning phases and budget constraints. While HFST has been proven successful in preventing crashes under dry roadway conditions, installing HFST where clusters of wet weather crashes have occurred may demonstrate the greatest benefit. Some agencies have made a determination to install HFST systemically as a preventive safety countermeasure based on specific roadway characteristics and friction at various locations. HFST can increase roadway friction significantly in locations with these common characteristics, thus increasing roadway safety.
Several States have found HFST to be an ideal alternative to horizontal curve realignment, saving 90 to 98 percent in project costs. The treatment offers many advantages over large roadway realignment projects and other pavement treatments. These advantages include:
Relatively inexpensive treatment. HFST is a low-cost crash reduction treatment capable of providing greater safety benefits than other low-cost safety measures such as advanced curve warning signs, advisory speed plaques, pavement markings, chevrons, open-graded friction course (OGFC), open graded asphalt concrete (OGAC), and guardrail when installed in appropriate locations.
Quick implementation. Agencies can expect a relatively short planning process and installation timeframe, compared to other alternatives. Some agencies have reported installation in as little as 10 days for small applications or 6 months for larger projects.
Minimal impact to traffic. HFST implementation requires only one lane to be closed at a time, most likely eliminating the need for a detour and most applications require only and 8-hour lane closure. Once cured and excess bauxite is removed, the product can immediately be open to traffic.
Negligible environmental impacts. The treatment is only applied between existing pavement edges and does not require disturbances to surrounding ground. This can result in shortened environmental review periods and lessen environmental mitigation. Being a topical application, so sub surface utilities are affected.
Durable and long lasting. HFST has excellent pavement surface functional durability, having an estimated service life from 5 to 8 years for 15,000 vehicles per day, and up to 5 years with 50,000 vehicles per day.
"HFST's coefficient of friction lasts longer and reduces friction-related crashes better than any other pavement treatment."
Compared to conventional pavement maintenance treatments, this seems quite expensive. What must be considered is that HFST is NOT a pavement maintenance treatment, and the costs being saved are the prevention of crashes and fatalities. The alternative to HFST is actually roadway geometric corrections, which are considerably more expensive and time consuming. Looking at the costs saved by reducing total crashes and fatalities, the average 5-yr benefit-cost ratio for HFST on tight curves is 24.5. So, for a typical 1,500-sy application, costing roughly $92,000, the agency could estimate savings of $2.2M over a 5-yr period. The actual service life of HFST can be as long as 10 years. —FloridaDOT
WHERE TO USE HFST
High traffic volume areas.
On and Off Ramp transition lanes.
Moisture ponded areas on the roadway surface.
Areas with poor water runoff/ hydroplaning prevention.
Interstate and State Route Lane Reduction Zones
•The resin overlay should not be placed on concrete that is less than 28 days in place.
•An overlay on concrete may call for two applications or courses depending on the state specification.
•Concrete surface should be abrasively cleaned by shot blasting to remove oils, dirt, rubber, curing compounds, paint, and other potentially detrimental contaminates which may interfere with the bonding or curing of the overlay.
•A brush broom/mechanical vacuum sweeper should be utilized to clean all surfaces of dust and ensure proper adhesion of the epoxy resin binder to the roadway surface.
•For applications on new asphalt pavements, it is recommended to wait a minimum of 30 days after paving before placement of HFST.
•Before placement of HFST on asphalt, the surface needs to be cleaned to remove oils, dirt, rubber, curing compounds, thermoplastic paint, and other potentially detrimental contaminates which may interfere with the bonding or curing of the overlay.
•A high-pressure air lance, or a vacuum sweeper should be used to remove all dust and other loose material.
•In some circumstances, an asphalt surface may need to be shot blasted prior to installing the overlay. This will be determined by the state specification.
POST HFST APPLICATION
ACCIDENT REDUCTION %
HWY 17 AT LAUREL CANYON
100 SITES (2010-2012)
PA SR 6 11