Median Barriers

Median barriers are longitudinal barriers that separate opposing traffic on a 

divided highway and are designed to redirect vehicles striking either side of 

the barrier. Median barriers significantly reduce the number of cross-median 

crashes, which are attributed to the relatively high speeds that are typical 

on divided highways. AASHTO’s Roadside Design Guide (RDG) recommends 

guidelines for the use of median barriers on high-speed, fully controlledaccess roadways for locations where the median is 30 ft in width or less and 

the average daily traffic (ADT) is greater than 20,000 vehicles per day (vpd). 

For locations with median widths greater than 50 ft and where the ADT is less 

than 20,000 vpd, a median barrier is optional. For locations where the median 

is between 30 and 50 feet, the RDG suggests an analysis to determine the 

cost effectiveness of median barrier installation. Median barriers can be 

cable, metal-beam, or concrete.

• Cable barriers are flexible barriers,

made from steel cables mounted

on weak steel posts, resulting in

less occupant impact force as it

absorbs energy from the crash,

capturing or redirecting the

vehicle. Due to larger deflection,

median width is an important

consideration. These barriers are

more adaptable to slopes typically

found in medians. Cable barriers

tend to require more frequent

maintenance and repair than

other barrier types.

• Metal-beam guardrails are

considered semi-rigid barriers,

where the W-beam or box-beam

is mounted to steel or timber

posts. When impacted, they are

designed to deform and deflect,

absorbing some of the crash

energy and redirecting the vehicle.

Metal-beam guardrails often do

not require maintenance after

minor impacts. They deflect less

than cable barriers, so they can

be located closer to objects where

space is limited.

• Concrete barriers are usually rigid

and result in little to no deflection.

They redirect rather than absorb

energy from the impact. Rigid

concrete barriers seldom require

repair or maintenance. Some

agencies have used portable

concrete barriers as median

barriers. These barriers require

repositioning after an impact but 

are typically less maintenance than 

a post mounted barrier.

To reduce cross-median crashes, 

transportation agencies should 

review their head-on crash history 

on divided highways to identify hot 

spots. Agencies should also consider 

implementing a systemic approach 

to median barrier placement based 

on cross-median crash risk factors. 

Potential risk factors include:

• Traffic volumes.

• Vehicle classifications.

• Median crossover history.

• Crash incidents.

• Vertical and horizontal alignment.

• Median terrain configurations.

FHWA-SA-21-037

Median cable barrier prevents a 

potential head-on crash. 

Source: Washington State DOT

1 Fatality Analysis Reporting System.

2 (CMF ID: 7040) NCHRP Report 794: Median Cross-Section Design for 

Rural Divided Highways, (2011).

OFFICE OF SAFETY

Proven Safety 

Countermeasures

8%

of all fatalities on divided 

highways are due to 

head-on crashes.1

Safety Benefits:

Median Barriers Installed

on Rural Four-Lane

Freeways

97%

 reduction in 

cross-median crashes.

For more information on this 

and other FHWA Proven Safety 

Countermeasures, please visit 

https://highways.dot.gov/

safety/proven-safety-counter 

measures and https:// 

highways.dot.gov/safety/

rwd/reduce-crash-severity.

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