US.Departmeni 

of Tronspor lotion 

Memorandum 

Federal Highway 

Admlnlsl ration 

Subject: ACTION: State Guidelines for Cable 

Median Baniers 

Date: p a5 2016 

From: MichaelS.Griffith 

Director, Oftlce of Safety Technologies 

Jn Reply Refer To: 

To: Division Administrators 

Directors of field Services 

Federal Lands I lighway Division Directors 

IISST-1 

Purpose: To address Recommendation H-1 5-4 1 issued by the National Transportation 

Safety Board (NTSB) to the Fl I WA n11d to clari l'y cable barrier crash test criteria in the 

American Association of State 11 ighway and Transportation Officials (AASHTO) Manual 

for Assessing Safoty l-fardware. 

Action: Please share this information \Yi th your State partners and ask then1 to review 

this information in light of their own guidance on the use of median barriers on high 

speed divided highways. 

Background: The Board has issued numerous recommendations regarding the use or 

median barriers on divided highways. In its investigation of a cross-median crash in 

Davis, Oklahoma, the NTSB recognized the Oklahoma Department of Transportation's 

median cable barri er guidelines as more adva11ced lhan those in tl1c /\ASJ ITO Roadside 

Design Guide (ROG) or those in use by most State departments of transportation. The 

Board recommended the rHWA share this information with the States. 

Disseminate information to the State departments of transportation about the 

circumstances of the Davis. Oklahoma. crash and the Oklahoma Department 

of Transportation revised median cable barrier guidelines that resulted in the 

installation of a median cable barrier at the crash site. (H-15-4 1) 

The Oklahoma median barrier guidelines are included as Attachment I to this 

memorandum. 

The Board notes that certain States, including Oklahoma, have developed more advanced 

guidelines for the install ation of median cable barriers to reduce crossover crashes nnd 

fatalities. Such guidelines and the circurnstanccs of the Oklahoma crash can provide 

critical information in the development of comprehensive State or national guidelines for 

the installation of median barriers. The Office of Safety recommends that States review 

lhe attached Oklahoma Median Cable Barrier Guidelines as one example of expanding 
the guidance in the RDG. Additional factors that may be considered are included as 

Attachment 2. 

The NTSB also reiterated the followinf.! two recommendations regarding median barriers. 

Work with the AASHTO to identify cross-median crash rates that call for 

special consideration when selecting median brmicrs. (H-1 1-22) 

Work with lhe AAS I ITO lo ·define the criteria for median barrier selection, 

including heavy vehicle traffic volume. (H- 11-23) 

2 

The NCJ IRP Project 22-31, titled, ··Recommended Guidel ines for the Selection and 

Placement of Test Levels 2 through 5 Median Barriers" is expected to provide additional 

guidance covering Lhese topics but will not be completed for another 3 years. The f-HWA 

has worked closely with the AASTHO Technical Committee on Roadside Sarety in 

support ofNCJ IRP Project 22-3 1 which will look nt cross-median crash rates as we ll as 

barrier test levels for heavy vehicles. States should examine their crash record system to 

ensure that cross medinn crashes can readily be identified through their crash database. 

This will aid development and deployment of new barrier guidelines in the ruture. 

IJ you have any questions or comments, please contact Nicholas Artimovich in the Office 

of Safety at (202) 366- 133 I. 

2 Attachments 
Attachment I 

Oklahoma Median Cable Barrier Guidelines 

The Oklahoma Department of Transportation adopted its median cable barrier 

guidelines on October 28, 2014. The first stage contains the following seven requirements, 

each of which should be met to begin considering a median cable barrier at a particular 

location: 

0 Posted speed limit of 55 mph or greater. 

0 At least two through travel lanes in each direction of travel. 

0 No existing barrier in the median, except short overlaps at transitions or where 

the existing barrier protects a fixed object. 

[J All cable baJTier median openings located not less than 0.4 mile from each other 

and from any interchange overpass or underpass. 

0 No uninteJTupted length of cable baJTier longer than 2 miles without a 

median opening or interchange overpass or underpass permitting crossing of the 

median by emergency vehicles. 

0 An achievable 6: I median cross slope, unless cable barrier is to be placed on 

both sides of the median. 

• At least 0.2-mile uninterrupted length of any median cable barrier installation. 

The second stage of requirements consists of four primary guidelines: 

0 G11ideli11e 1 (Co11trolled Access): (1) All fully controlled access highways with 

a median width of 80 feet or less; (2) all partially controlled access highways with 

annual average daily traffic (AADT) of 3,500 vehicles or greater and a median 

width of 80 feet or less. 

0 Guideli11e 2 (Crasll History and AADT): The entirety of any portion of a 

highway, not less than I mile, with substantially similar characteristics of traffic 

flow, speed, median width, access density, terrain, and geometrics, within which 

0.23 or more crossovers per mile have occurred within a 5-year period, and having 

an average AADT of 10,500 vehicles or greater. 

• Guideli11e 3 (Higll Speed, Narrow Medi011): Any highway with a speed limit of 

65 mph or greater, AADT of 3,500 vehicles or greater, and median width less than 

35 feet. 

0 Guideline 4 (Gaps): Any portion of highway up to 1 mile long, adjacent to a 

portion of the same highway that is provided with median cable barrier, 
which has substantially similar characteristics of traffic flow, speed, median 

width, access density, terrain, and geometrics. 

Meeting any one of these second-stage requirements could justify the installation of a 

median cable barrier as long as that highway segment also meets all of the first-stage 

requirements. 
Attachment 2 

Each State should have design guidnnce for median barrier selection and placement on all 

divided highways. That guidance may consider the following factors: 

• Traffic 

o Speed* 

o Volumes* or Highway Functional Classification 

o Truck percentage 

• Geometry 

o Median width* 

o Spacing of crossovers, intersections** or other gaps in the barrier 

o Median slopes I grading 

• Level of access control 

o Fully controlled access 

o Partial control. or uncontrolled access *** 

• Crash history  

o Overall crashes 

o Cross median crashes 

o Run-off-road into median (non-crossover) 

o Crash proximity to interchanges or intersections 

• Barrier type** *** 

o flexible (cable, weak-post w-beam) 

o Semi-rigid (MGS, strong post w-beam, weak-post box beam) 

o Rigid (F-Shape, Constant Slope) 

* Guidance on design speed, median width. and traffic volume is in the AAS! ITO 

Roadside Design Guide. Chapter 6. 

**Sight distance over or through median barriers may be an issue at intersections. 

***NTSB Recommendation 11-06-12 recommended that States provide guidance on Lhe 

use of median barriers on divided highways regardless of access type. 

 See NCHRP Report 790 '·factors Contributing to Median Encroachments and 

Cross-Median Crashes" 

** ***Cable median barriers can be placed on slopes as steep as 1H:6V. W-beam, 

Box-beam. and concrete barTicrs should be used on slopes no steeper than IV: 1 OH. 

NCH RP Project 22-22(02) ··Effectiveness oCTraCfic Barriers on Non-Level Tl.!rrain'' is 

researching the effect of terrain on barrier placement and will provide additional 

guidance for longitudinal barriers on slopes.