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                Media ContactsMenu OFFICE OF RESEARCH, DEVELOPMENT, AND TECHNOLOGY AT THE TURNER-FAIRBANK HIGHWAY RESEARCH CENTER Home
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   Ana Maria Eigen
      Ana Maria Eigen
      
                    
            Research Highway Safety Specialist
      
                    
            Office of Safety and Operations Research and Development
      
                    
            Turner-Fairbank Highway Research Center6300 Georgetown PikeMcLean, VA 22101United States
      
          
    **Email:**ana.eigen@dot.gov**Phone:** (202) 493-3168
    If you are deaf, hard of hearing, or have a speech disability, please dial 7-1-1 to access telecommunications relay services.
                
                HSIS Summaries
    

    
    
    
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HSIS Summary Reports are two to eight pages in length and include a brief description of the issue addressed, data used, methodology applied, significant results, and practical implications.

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**Safety Effects of Horizontal Curve and Grade Combinations on Rural Two-Lane Highways**

dataThe safety effects of horizontal curves and grades on rural two-lane highways have been quantified in the American Association of State Highway and Transportation Officials (AASHTO) Highway Safety Manual (HSM), but it was not previously known whether and how the safety performance of horizontal curves and grades interact. Furthermore, there are no established safety effects for crest and sag vertical curves, and it is unknown whether and how the safety performance of crest or sag vertical curves is affected by the presence of horizontal curves.

The objective of this study was to quantify the combined safety effects of horizontal curves and grade combinations and express the results as crash modification factors (CMFs) that can be considered for use in the AASHTO HSM.

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**Safety Evaluation of Converting Traffic Signals from Incandescent to Light-Emitting Diodes**

Across the Nation, many agencies have been replacing conventional incandescent light bulbs in traffic signals with light-emitting diodes (LED). LEDs are primarily installed to reduce energy consumption and decrease maintenance. In addition, LEDs are expected to last much longer compared with incandescent bulbs and tend to age gradually. However, a recent study revealed several potential problems with LEDs, including their inability to melt snow and issues related to visual discomfort caused by glare at night.

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**Safety Evaluation Of Discontinuing Late-Night Flash Operations at Signalized Intersections**

During late-night flash (LNF) mode (from late night to early morning hours), traffic signals flash yellow for one road (typically, the major road), requiring caution but no stopping, and flash red for the other road (typically, the minor road), requiring drivers to stop and then proceed through the intersection after yielding to the traffic on the major road. The intent of LNF is to reduce energy consumption and delay during periods of low traffic demand. However, in recent years, many agencies have begun replacing LNF with normal phasing operation because of safety concerns.

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            Expand All
      Collapse All
        **2014**
        Title
			Publication Date
			Author
			Report NumberSafety Effects of Horizontal Curve and Grade Combinations on Rural Two-Lane Highways
			January
			
			FHWA-HRT-13-078
  


      **2013**
        Title
			Publication Date
			Author
			Report NumberSafety Evaluation of Converting Traffic Signals from Incandescent to Light-Emitting Diodes
			August
			Raghavan Srinivasan, Daniel Carter, Sarah Smith, Bo Lan
			FHWA-HRT-13-070Safety Evaluation Of Discontinuing Late-Night Flash Operations at Signalized Intersections
			August
			Bo Lan, Raghavan Srinivasan
			FHWA-HRT-13-069
  


      **2012**
        Title
			Publication Date
			Author
			Report NumberSafety Evaluation of Transverse Rumble Strips on Approaches to Stop-Controlled Intersections in Rural Areas
			May
			Srinivasan, R., J. Baek, and F. Council
			FHWA-HRT-12-047
  


      **2011**
        Title
			Publication Date
			Author
			Report NumberSafety Evaluation of the Safety Edge Treatment
			January
			Graham, J., K. Richard, M. O’Laughlin, and D. Harwood
			FHWA-HRT-11-025
  


      **2010**
        Title
			Publication Date
			Author
			Report NumberEvaluation of Lane Reduction "Road Diet" Measures on Crashes
			June
			Persaud, B. and C. Lyon
			FHWA-HRT-10-053Factors Contributing to Pedestrian and Bicycle Crashes on Rural Highways
			June
			Carter, D. and F. Council
			FHWA-HRT-10-052Development of a Speeding-Related Crash Typology
			May
			Council, F.M., R. Srinivasan, S. Masten, D. Carter, and M. Reurings
			FHWA-HRT-10-039
  


      **2005**
        Title
			Publication Date
			Author
			Report NumberSafety Effects of Using Narrow Lanes and Shoulder-Use Lanes to Increase the Capacity of Urban Freeways
			June
			Bauer, K.M., D.W. Harwood, K.R. Richard, and W.E. Hughes
			FHWA-HRT-05-001
  


      **2004**
        Title
			Publication Date
			Author
			Report NumberAn Examination of Fault, Unsafe Driving Acts, and Total Harm in Car-Truck Collisions
			June
			Council, F.M., D.L. Harkey, D.T. Nabors, A.J. Khattak, and Y.M. Mohamedshah
			FHWA-HRT-04-085
  


      **2001**
        Title
			Publication Date
			Author
			Report NumberReview of the Impacts of the Towaway Reporting Threshold on a Highway Safety Program
			July
			Lacy, K., C. Zegeer, and R. Schneider
			FHWA-RD-01-114
  


      **2000**
        Title
			Publication Date
			Author
			Report NumberAssociation of Selected Intersection Factors with Red-Light-Running Crashes
			May
			Yusuf M. Mohamedshah, Li Wan Chen, and Forrest M. Council
			FHWA-RD-00-112
  


      **1999**
        Title
			Publication Date
			Author
			Report NumberSafety Evaluation of Rolled-in Continuous Shoulder Rumble Strips Installed on Freeways
			December
			Michael S. Griffith
			FHWA-RD-00-032Safety Effects of the Conversion of Rural Two-Lane Roadways to Four-Lane Roadways
			November
			Forrest M. Council and J. Richard Stewart
			FHWA-RD-99-206Using GIS in the Analysis of Truck Crashes
			June
			David Harkey
			FHWA-RD-99-119GIS-Based Crash Referencing and Analysis System
			February
			David L. Harkey
			FHWA-RD-99-081
  


      **1998**
        Title
			Publication Date
			Author
			Report NumberEffects of a Towaway Reporting Threshold on Crash Analysis Results
			August
			Charles V. Zegeer, Herman F. Huang, J. Richard Stewart, Ron Pfefer, Jun Wang
			FHWA-RD-98-114Investigation of National Highway System Roadways in the HSIS States
			April
			Charles V. Zegeer, Herman F. Huang, J. Richard Stewart, and Carolyn Williams
			FHWA-RD-98-080The Effects of Airbags on Severity Indices for Roadside Objects
			February
			Forrest M. Council, J. Richard Stewart, and Yusuf M. Mohamedshah
			FHWA-RD-98-056
  


      **1997**
        Title
			Publication Date
			Author
			Report NumberSafety Effects of Cross-Section Design on Rural Multilane Highways
			June
			Jun Wang, Warren E. Hughes, and Richard Stewart
			FHWA-RD-97-027
  


      **1996**
        Title
			Publication Date
			Author
			Report NumberInvestigation of Highway Work Zone Crashes: What We Know and What We Don't Know
			October
			Jun Wang, Warren E. Hughes, Forrest M. Council, and Jeffrey F. Paniati
			FHWA-RD-96-100Accident Analysis of Older Drivers On Freeways
			August
			David L. Harkey, Herman Huang, and Charles V. Zegeer
			FHWA-RD-96-035
  


      **1995**
        Title
			Publication Date
			Author
			Report NumberComparison of the Safety of Lighting Options on Urban Freeway
			May
			Michael S. Griffith
			FHWA-RD-94-188Investigation of Crashes with Animals
			March
			Warren E. Hughes and Reza Saremi
			FHWA-RD-94-156Accident Analysis of Older Drivers at Intersections
			February
			
			FHWA-RD-94-021
  


      **1994**
        Title
			Publication Date
			Author
			Report NumberThe Magnitude and Severity of Passing Accidents on Two-Lane Rural Roads
			November
			
			FHWA-RD-94-068The Application of an Improved Accident Analysis Method for Highway Safety Evaluations
			October
			Jun Wang
			FHWA-RD-94-082Truck Accident Models
			August
			
			FHWA-RD-94-022Accident Relationships of Roadway Widths on Low-Volume Roads
			June
			Charles V. Zegeer
			FHWA-RD-94-023
  


      **1993**
        Title
			Publication Date
			Author
			Report NumberThe Association of Median Width and Highway Accident Rate
			August
			Matthew W. Knuiman, Forrest M. Council, and Donald W. Reinfurt
			FHWA-RD-93-046
  


      **1992**
        Title
			Publication Date
			Author
			Report NumberAnalysis of Commercial Bus Crashes
			November
			Charles V. Zegeer (HSRC)
			FHWA-RD-93-018

    
          Last updated: Tuesday, July 18, 2023 U.S. DEPARTMENT OF TRANSPORTATION

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