The National Academies Press

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From page 25... ... 25 C H A P T E R 3 3.1 Survey Method A survey of state highway agencies concerning their median design practices was conducted in 2003 as part of NCHRP Project 17-14. This previous survey was updated by a survey conducted as part of the current research. Read the entire page →
From page 26... ... 26 Agencies responding to both 2003 and 2006 surveys Agencies responding to the 2003 survey only Agencies responding to the 2006 survey only Alabama Alaska Idaho Arkansas Arizona Kentucky California Colorado New Mexico Connecticut Hawaii Oregon Delaware Kansas Tennessee Florida Massachusetts Texas Indiana Michigan Iowa New Hampshire Maine North Dakota Maryland Minnesota Mississippi Missouri Montana Nebraska Nevada New Jersey New York North Carolina Ohio Pennsylvania South Carolina South Dakota Virginia Washington West Virginia Wisconsin Wyoming Table 3-1. State highway agencies that responded to one or both surveys. Read the entire page →
From page 27... ... 27 they use the AASHTO median barrier warrants. Ten of the 30 responding states (33.3 percent) Read the entire page →
From page 28... ... 28 Agency Response Median width Median side slopes Other Alabama (2003) Use AASHTO Guidelines California (2003) Read the entire page →
From page 29... ... 29 Minimum median width (ft) Number of state highway agencies 26 1a 36 1 40 4 42 2 46 2 48 1 60 3 64 3b 76 3 20 a Minimum 26-ft width used only for flush median with median barrier. Read the entire page →
From page 30... ... 30 Agency Does your agency use the 2002 AASHTO median barrier warrants? Alabama (2003) Read the entire page →
From page 31... ... 31 Agency Response Median barrier criteria California (2003) Conduct study if median width is 0 to 20 ft and ADT exceeds 20,000 veh/day Conduct study if median width is less than 75 ft and ADT exceeds 60,000 veh/day Study any median with 0.5 cross-median crashes per mile per year or 0.12 fatal crashes per mi per year Florida On Interstate, install barrier if median width less than 64 ft; 50 ft on other freeways On Interstates and expressways, median barrier is required within 1 mi of exit/entrance gore with one or more cross-median crashes within 5 years Maine (2003) Read the entire page →
From page 32... ... Median barrier types currently approved for use on rural divided highways Weak-post W-beam guardrail Box-beam barrier Blocked-out W-beam guardrail (strong post) Blocked-out Thrie-beam guardrail (strong post) Read the entire page →
From page 33... ... 33 Median barrier type Range of minimum median widths (ft) for use of specific median barrier types Weak-post W-beam guardrail 18 Box-beam barrier 10 to 14 Blocked-out W-beam guardrail (strong post) Read the entire page →
From page 34... ... Agency Minimum median width (ft) for use of specific barrier types Weak-post W-beam guardrail Box-beam barrier Blocked-out W-beam guardrail (strong post) Read the entire page →
From page 35... ... Agency Most common placement location for each barrier type Weakpost, Wbeam guardrail Box-beam barrier Blocked-out W-beam guardrail (strong post) Blocked-out Thrie-beam guardrail (strong post) Read the entire page →
From page 36... ... Agency Most common placement location for each barrier type Weakpost, Wbeam guardrail Box-beam barrier Blocked-out W-beam guardrail (strong post) Blocked-out Thrie-beam guardrail (strong post) Read the entire page →
From page 37... ... Agency Most common placement location for each barrier type Weakpost, Wbeam guardrail Box-beam barrier Blocked-out W-beam guardrail (strong post) Blocked-out Thrie-beam guardrail (strong post) Read the entire page →
From page 38... ... Agency Maximum median side slope on which the specified barrier is installed Weakpost Wbeam guardrail Box-beam barrier Blocked-out Wbeam guardrail (strong post) Blocked-out Thrie-beam guardrail (strong post) Read the entire page →
From page 39... ... Agency Maximum median side slope on which the specified barrier is installed Weakpost Wbeam guardrail Box-beam barrier Blocked-out Wbeam guardrail (strong post) Blocked-out Thrie-beam guardrail (strong post) Read the entire page →
From page 40... ... Agency Current agency usage (percent) of each of the approved barrier types Weak-post W-beam guardrail Box-beam barrier Blocked-out W-beam guardrail (strong post) Read the entire page →
From page 41... ... Agency Response Width (ft) Slopes Depth (ft) Read the entire page →
From page 42... ... Agency Dimensions used in typical median cross sections Median width (ft) Median shoulder width (ft) Read the entire page →
From page 43... ... 43 3.4 In-Service Performance Evaluations and Unpublished Reports The Iowa Department of Transportation and the Ohio Department of Transportation submitted reports of the use of the Brifen Wire Rope Safety Fence (WRSF) Read the entire page →
From page 44... ... * Denotes opposite direction impactAverage Daily Traffic (ADT) Read the entire page →
From page 45... ... 45 when medians are 15 m (50 ft) or less and ADTs are over 20,000 vehicles per day. Read the entire page →

From page 25...

... 25 C H A P T E R 3 3.1 Survey Method A survey of state highway agencies concerning their median design practices was conducted in 2003 as part of NCHRP Project 17-14. This previous survey was updated by a survey conducted as part of the current research.