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
                        Speed Management Safety


            
            In This Section
        Speed Management Safety
                USLIMITS2
                                Overview
                Create a New Project
                Revise an Existing Project
                Frequently Asked Questions
                Technical Support
                Facts & Statistics
                Engineering Speed Limits
                Traffic Calming ePrimer
                Ongoing Research
                Reference Materials
                Related Web Site Links
      
   Contact Us
      Guan Xu
      
                    
            Program Contact
      
                    
            Office of Safety Programs
      
                
    **Email:**Guan.Xu@dot.gov**Phone:** (202) 366-5892
    If you are deaf, hard of hearing, or have a speech disability, please dial 7-1-1 to access telecommunications relay services.
                
                Memorandum – Guidelines for the Use of Variable Speed Limit Systems in Wet Weather
    

    
    
          **US Department of Transportation**

Federal Highway Administration

**Subject:** **INFORMATION**: Guidelines for the Use of Variable Speed Limits Systems in Wet Weather

**Date:** September 26, 2012

From:
			Tony Furst
			Associate Administrators for Safety**In Reply Refer To:** HSST

To:
			Division Administrators
			Safety Field
			Federal Lands Highway Program AdministratorThe purpose of this memorandum is to issue the guidelines on the use of variable speed limit (VSL) systems in wet weather. In response to a motorcoach crash on Interstate 35 near Hewitt, Texas on February 14, 2003, the NTSB recommended that FHWA issue guidance on the use of VSL systems during wet weather conditions at locations where the operating speed exceeds the design speed and the stopping distance exceeds the available sight distance (NTSB recommendation H-05-14).

The guidelines cover the design, installation, operation, maintenance, and enforcement of VSL systems used for wet weather conditions such as snow, rain, and ice. They were developed based on a thorough review of the state-of-the-practice of VSL installations in the United States. The guidelines are intended for a broad range of audiences from the transportation policy professionals who are considering whether or not their agency should use VSL systems to the engineers who are actually designing VSL systems. The guidelines also provide examples of the challenges and issues that organizations have encountered when implementing VSL systems so that future implementers can develop practices that will increase their likelihood of success.

The successful use of VSL systems during wet weather conditions should take into account factors such as traffic volume, operating speeds, sight distance, and roadway surface condition when posting appropriate speed limits. Some of the information provided in the guidelines may also be adapted for other VSL applications such as for work zones and congested freeways.

Please share these guidelines with your respective State and local transportation agencies and encourage the use of VSL systems for wet weather applications where appropriate. The guidelines are available on FHWA's website at http://safety.fhwa.dot.gov/speedmgt/ref_mats/fhwasa12022/. For further information, please contact Ms. Guan Xu at (202) 366-5892, or at guan.xu@dot.gov.

Page last modified on October 15, 2014
              
      
    
          Last updated: Wednesday, October 15, 2014 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