USA Banner
  U.S. flag
              An official website of the United States government Here's how you knowOfficial US Government Icon
              **Official websites use .gov**A **.gov** website belongs to an official government organization in the United States.
            Secure Site Icon
              **Secure .gov websites use HTTPS**
                  A **lock** ( A locked padlock ) or **https://** means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites. 
 U.S. Department of Transportation Icon United States Department of Transportation
 Search DOT
            Search
                    About FHWAFHWA Organization
                Headquarters Offices
                Field Offices
                Strategic Plan
                Business Opportunities
                Staff Directories
                Careers
                Highway History
                Contact UsProgramsAcquisition Management
                Civil Rights
                Federal Lands Highway
                Infrastructure
                Innovative Program Delivery
                Operations
                Planning, Environment, and Realty
                Policy
                Research, Development, and Technology
                Safety
                Browse by TopicsResourcesCore Highway Topics
                Federal Aid Essentials
                Automation
                Complete Streets
                Laws and Regulations
                Policy & Guidance Center
                Section 508
                Publications and Statistics
                Professional Development
                National Highway Institute
                Resource Center
                Accessibility Resource Library
                FHWA Research LibraryNewsroomPress Releases
                Speeches & Testimony
                Photos
                Videos
                Media ContactsMenu FHWA Highway Safety Programs Home
                        Safety
                        Learn Safety
                        Noteworthy Practices


            
            In This Section
        Learn Safety
                About RSPCB
                Road Safety Fundamentals
                Roadway Safety Noteworthy Practices
                                Search Noteworthy Practices
                Resources
                Training and Education
                                Overview
                Training Opportunities
                Road Safety Course Finder
                NHI Courses
                Roadway Safety Champions
                Get Help
                                Overview
                Technical Assistance Guidelines
                Technical Assistance Online Application
                Safety Data Dashboard
                
                A Life-Saving and Cost-Effective Solution For An Environmentally Sensitive Location
**Publication Year:** 
            2015
    
        Original publication: Case Study: Northern California US 199-Del Norte County; FHWA-SA-15-055; 2015 (PDF, 2.3MB)

"Visitors to the national park admiring a stand of red wood trees. Photo: National Park Service."Northern California, near the Oregon State line is home to the Redwood National and State Parks, which span over 200 square miles and are some of the most environmentally diverse areas in the United States. Accordingly, transportation construction projects that disturb existing conditions within the parks' limits are subject to stringent environmental restrictions and long permitting processes.

Background

Over the last decade, a horizontal curve within the parks' limits experienced a high frequency of wet crashes. This curve, shown in Figure 1, is located on US 199, a two-lane, rural highway in Del Norte County, approximately one mile east of the South Fork Road intersection. It has a radius of 280 ft. and an advisory speed of 30 miles per hour (mph). Between 2006 and 2009, this site experienced 26 wet crashes and exhibited total and severe (fatal + injury) crash rates that were 7.3 and 4.3 times, respectively, greater than the statewide average for similar facilities. Crash types included run off road, head-on, and opposite direction sideswipe.

"US 199 in Del Norte County on the approach to a horizontal curve with curve warning signs, chevrons, and advisory speed placards. Photo courtesy of Caltrans."Figure 1. US 199 in Del Norte County

Caltrans previously installed several low-cost safety countermeasures at the site including center line rumble strips, speed warning signs, double stacked chevron signs, and one inch open grade asphalt concrete (OGAC) overlay. Yet, these treatments did not lead to the crash reductions Caltrans desired. They began to consider larger scale countermeasures, specifically roadway realignment. However, the realignment process would require a lengthy environmental review and mitigation of wetland impacts before the improvement could begin reducing crashes. As an alternative to realigning this curve, Caltrans began to investigate a High Friction Surface Treatment (HFST) and looked to other States for guidance and successes.

Factors Affecting the Final Decision

"A marbled murrelet, photo courtesy of the National Park, and a northern spotted owl, photo by Larry Meade."Figure 2. Threatened Species

Most critical for Caltrans at this location was mitigating environmental impacts. US 199 parallels the Smith River, the most pristine and environmentally sensitive river in California, protected by a full spectrum of environmental entities and regulations. The surrounding area sustains California's most diverse ecology, including the Marbled Murrelet and Northern Spotted Owl, as shown in Figure 2, both threatened species protected by the Federal Endangered Species Act. The area also contains over 400 separate species of plant life and a large number of active, very small wet lands.

Due to endangered species and water quality concerns, a roadway realignment project within the parks' limits would require Caltrans to spend six months acquiring environmental permits. Further, the North Coast Regional Water Quality Control Board requires Caltrans to mitigate construction effects upon the wetlands, even when impacts are only a few square feet. Wetland and impervious area mitigation ratios can range from 1:1 to 1:4 depending on several factors. If the replacement is to take place within another roadway project, it could be years before Caltrans is able to begin work on the initial project as crashes continue to occur. In contrast, HFST environmental impact and associated review is minimal and requires only a Categorical Exemption/Exclusion (CE/CE) document. 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 within the Parks limits.

In addition, any geometric improvement that involves construction incurs time restrictions (i.e., environmental windows) aimed at not disturbing wildlife. This would force Caltrans to either perform large-scale construction projects in stages or to use an accelerated/restricted schedule, both of which have significant effects upon the project. Conversely, HFST has the distinct advantage of an installation time period of just 10 working days.

*HFST could be implemented quickly compared to alternatives, satisfying Caltrans environmental concern, construction time schedule, and window of opportunity.*

Lastly, a feasible detour route for the realignment is not available because a network of local county roads that connects the lower and upper portions of the county does not exist. A detour around US 199 could take longer than 8 hours, which is estimated to cost upwards of $450 million a year in associated economic losses. HFST can be installed one lane at a time and therefore does not require a detour at any point during construction.

Table 1 summarizes and compares each countermeasure's environmental review and design time frames, construction duration, costs, and need for a detour.
"Diagram shows that the environmental review and design timeframe is 4 to 6 months for HFST, compared with 2 to 5 years for curve realignment. Construction duration is 10 working days for HFST compared to 6 months or more for curve realignment. The cost is $250,000 for HFST compared to more than $14 million for realignment. A detour is not necessary for HFST because the treatment can be installed one lane at a time. For curve realignment, the road must be closed and a detour would be required during construction."Table 1. Comparison of Factors between HFST and Curve Realignment on US 199

Selecting HFST

In summer 2012, Caltrans opted for the simpler, but still very effective, alternative. They installed 850 ft. of HFST at this horizontal curve on US 199, shown in Figure 3. The treatment consisted of a double layer of epoxy-resin binder with calcined bauxite aggregate, which filled in the surface voids from the previously installed OGAC and added protection against water penetration. With a peak hour volume of approximately 600 vehicles per hour (vph), Caltrans estimated only a 5 minute travel time delay during active construction. Caltrans is unaware of any crashes at this location since the HFST implementation.

To date, 139 sites on State maintained roadways in California have received HFST or will receive the treatment in the near future. Caltrans continually encourages and tries to educate its districts about the benefits of HFST. The agency believes that HFST is one of the best tools in its toolkit for challenging curves and should be the primary “go-to” friction enhancing countermeasure, even before OGAC.
""Aerial photo of US 199 depicting the application area between PM 8.24 and PM 8.32, a 0.8 mile segment. Staging areas are indicated both in advance of the application area and along the final one third of the treated segment. A line along the center of the roadway throughout the treatment area indicates that the roadway here was treated with grinding/AC fill to create rumble strips. Photo courtesy of Caltrans.Figure 3. US 199 HFST Application Area

What criteria does Caltrans use to install HFST?

Caltrans believes HFST is an appropriate safety countermeasure for both wet and dry locations, high and low volume roadways, and tangents as well as curves. It is effective at mitigating crashes involving large changes in speeds (acceleration/deceleration), low skid numbers, tight horizontal curves, and roadway departure. As a result, Caltrans has implemented HFST on a large variety of locations including horizontal curves, bridges, wet crash locations, signalized intersections, on- and off-ramps, and short freeway segments.

Are there any locations where HFST is not appropriate?

Caltrans does not apply HFST in cold/icy locations where heavy trucks frequently use chains in winter, as the chains significantly decrease HFST's lifespan. Further, in long tangent sections with intense rainfall, OGAC is preferred.

Contacts

Joseph Cheung
FHWA Office of SafetyJoseph.Cheung@dot.gov

Frank Julian
FHWA Resource CenterFrank.Julian@dot.gov U.S. DEPARTMENT OF TRANSPORTATION

**Federal Highway Administration**

1200 NEW JERSEY AVENUE, SE

WASHINGTON, DC 20590

202-366-4000Subscribe to email updates
                    About
  

        
              About FHWA
                Careers
                Org Chart
                Staff Directories
                Work with UsPrograms
  

        
              Acquisition Management
                Civil Rights
                Federal Lands Highway
                Infrastructure
                Innovative Program Delivery
                Operations
                Planning, Environment, and Realty
                Policy
                Research, Development, and Technology
                SafetyPolicies, Rights, Legal
  

        
              About DOT
                Accessibility
                Budget and Performance
                Civil Rights
                FOIA
                Information Quality
                No FEAR Act
                Office of Inspector General
                Privacy Policy
                USA.gov
                Web Policies and Notices
                Web StandardsNews & Events
  

        
              Newsroom
                Press Releases
                Speeches & Testimony
                Media Contacts
                Connect with Us