Attachment #2

Examples of state practices as derived from their published guidance relative to median barriers on high-
volume, high-speed roadways, regardless of access type:

Arizona: Barrier breaks for necessary crossings or turn lanes must be restricted to areas with acceptable
sight distances for both mainline and side roads.

California: Access openings on expressways, multilane conventional highways and two-lane and three-
lane conventional highway facilities present sight distance issues with respect to installation of a median
barrier. All access openings must be studied to maintain both corner sight distance at approach
intersections and stopping sight distance on the specific facility types themselves.

Maryland: Median barrier may be required on divided highways that lack full access control as justified
by accident experience or other special circumstances. Where a section of highway is less than one mile
in length that does not meet the requirement for median barrier is bordered on each end by a section
where median barrier is required, the barrier should be extended through the subject section if the ADT
for the subject section meets three quarters of the ADT criteria (i.e., the width of the median in the subject
section is less than 50’ and the ADT is 30,000 or greater; the width of the median in the subject section is
less than 75’ and the ADT is 60,000 or greater). Openings in the median barriers may be provided when
necessary for authorized vehicle crossovers and routine maintenance operations, in which case proper end
treatment is required.

Minnesota: The terminal points in barrier systems are generally critical elements in the performance of
the system. An unprotected median barrier terminal is essentially a fixed-object hazard to a motorist. For
this reason, the use of median barriers is generally restricted to full access-controlled facilities where there
are no median crossings requiring discontinuities in the barrier. Special designs may be required where at-
grade crossings are permitted and median barrier is used.

Missouri: Analysis of crashes on a candidate corridor should focus on cross-median crashes on that route
and, even more so, on those crashes resulting in fatalities and disabling injuries. It is important this data
analysis is robust, particularly on expressways. Due to at-grade intersection crashes on these routes, a
simple query of cross-median crashes may include unwanted events and exclude necessary ones.
Accuracy of these data is vital in decision-making.

New Jersey: Careful consideration should be given to the installation of median barriers on land service
highways ( i.e., highways with less than full control of access) or other highways with partial control of
access. Problems are created at each intersection or median crossover because the median barrier must be
terminated at these points.

An evaluation of the number of crossovers, crash history, alignment, sight distance, design speed, traffic
volume and median width should be made before installation of median barriers on land service highways
Each location should be looked at on a case-by-case basis.

Pennsylvania: Utilizing the Roadside Design Guide’s median barrier guidelines on roadways that do not
have full access control requires the need for engineering analysis and judgment, taking into consideration
such items as, right-of-way constraints, property access needs, number of intersections and driveway
openings, adjacent commercial development, sight distance at intersections, barrier end termination, etc.


Attachment #1

SHOULDER

MEDIAN WIDTH

TRAVELED
WAY

° Sw
Y

30 »
2 el. (ZZ
é.. pape BARRIER é s BARRIER BARRIER
Eas RECOMENDED + ERE ey eee fee AECOMMENDED BARRIER cD BARRIER
i: OPTIONAL z i LMU
aio Sw Z
g 3 & Z
3 x » a
2 oe

2 2

° se °

o a $ 0 15 2
MEDIAN WIDTH (tt) MEDIAN WIDTH (m)

Figure 6-1. Guidelines for Median Barriers on High-speed, Fully Controlled-Access Roadways

Source: AASHTO Roadside Design Guide, 4" edition, 2011



5
an Memorandum

Federal Highway
Administration

Subject: ACTION: Median Barriers on Divided Date: JUL -9 2014
Highways Regardless of Access Type

From: Michael S. Griffith Wikao! 3. ffi, In Reply Refer To:

Director, Office Safety Technologies HSST
Office of Safety

To: Division Administrators
Safety Field
Federal Lands Division Engineers

Purpose

The purpose of this memo is to address a recommendation from the National
Transportation Safety Board (NTSB) regarding median barriers on divided highways with
less than full control of access. We are requesting that you share this memo with your
respective state DOT to implement NTSB’s recommendation.

Background
A NTSB Safety Recommendation to the Federal Highway Administration (FHWA) states:

H-06-12 - Work with the American Association of State Highway and
Transportation Officials (AASHTO) to establish evaluative criteria for determining
when to install median barriers on high-volume, high-speed roadways, regardless of
access type.

The AASHTO Roadside Design Guide (RDG) Figure 6-1 (See Attachment 1) provides
guidelines for placing barriers in the medians of high speed, fully controlled access
highways based on median width and traffic volumes. The following general, qualitative
guidance is provided in the RDG Section 6.2 for installing median barriers on partially-
controlled or un-controlled access divided highways:

Median barriers are sometimes used on high-volume facilities, which do not have
fully controlled access. As indicated in Figure 6.1 [“Suggested guidelines for median
barriers on high-speed roadways”’], these median barrier guidelines were developed for
use on high-speed, fully controlled-access roadways. Utilizing these guidelines on


roadways that do not have full access control requires the need for engineering analyses

and judgment, taking into consideration such items as, right-of-way constraints, property
access needs, number of intersections and driveway openings, adjacent commercial
development, sight distance at intersections, barrier end termination, ete.

Therefore, trying to apply these guidelines to roadways that do not have full access
control can be rather complex in many locations.

We discussed with NTSB staff the challenge of developing objective, evaluative criteria
that would be applicable nationwide. They agreed that a review of design practices could
provide useful guidance to supplement the RDG.

Division Office Survey and State Practices

To better understand State practices used for addressing divided highways, we surveyed
our Division Offices to determine what factors the state DOTs are using when assessing
the need for a median barrier.

Seventy-five percent of those states that responded indicated they do install median
barriers on highways with partial control of access, while fifty percent responded they do
install barriers on divided highways with no access control. Because of the significant
number of factors that need to be considered on these facilities, many states do not have
published guidance beyond that in the RDG; rather they only consider median barriers on
a case-by-case basis.

The primary factors that states have recognized to consider for determining when to install
median barriers on high-volume, high-speed divided highways that lack full access control
include:

Traffic volume, design speed, and vehicle mix

Highway alignment

Median width and terrain features

Crash history, focusing on severe and fatal cross-median crashes
Right-of-way constraints, property access needs, number of intersections and
driveway openings, and adjacent commercial development

e Traffic operations including truck turning at intersections

Other specific considerations that states have in their published guidance include:

e Will the number of intersections and other median crossings hamper the
effectiveness of a median barrier?

Will sight distance at median crossings be a problem if a barrier is installed?
If most of the route warrants a barrier [i.e., meeting a state’s specified warranting
condition], should it be extended through all portions of the route that do not meet


the warrant?

e Acrash cushion or barrier terminal will likely be needed for both ends of the
barrier when it is interrupted for a median crossing.

¢ Median bridge piers, culvert headwalls, non-traversable ditches, trees, and other
fixed-object hazards in medians should be removed, redesigned, or shielded with
barrier just like hazardous elements on any roadside. When barriers are placed to
shield these features, the potential for impact from vehicles coming from the
opposite side of the highway should be considered.

Attachment #2 is a list of the design practices that we drew from the States’ published
guidance.

Action
Please share this information with your State and suggest they have written guidance on
factors to consider when evaluating the need for median barriers on high-speed divided

highways regardless of access control.

Attachments