This poster on wrong-way driving countermeasures was presented at the 95th Annual Transportation Research Board (TRB) meeting in January 2016.

1. Operational Field Studies of Two Wrong-Way Signing Countermeasures (16-1827)
Melisa D. Finley, P.E., Research Engineer, Texas A&M Transportation Institute (m-finley@tti.tamu.edu)
Yang Ouyang, P.E.,PTOE, Traffic Operations Engineer, North Texas Tollway Authority (youyang@ntta.org)
Research Sponsored by: Research Conducted by:
Steven P. Venglar, P.E., Research Engineer, Texas A&M Transportation Institute (s-venglar@tti.tamu.edu)
INTRODUCTION BORDER-ILLUMINATED SIGNS, CONT. LOWERED SIGNING LOWERED SIGNING, CONT.
Background
• In 2009, the North Texas Tollway
Authority (NTTA) considered the use of
lowered DO NOT ENTER and
WRONG WAY signs.
• Approved 3-ft mounting height:
• Unable to locate any crash tests to
verify that signs mounted at 3-ft
would not be hazardous to an errant
Data Analysis
• San Antonio Police Department WWD event data (crashes
and non-crashes) from January 2011 to April 2014.
• Before-after evaluation of WWD events with a comparison
group used to determine device effectiveness.
• Study area: 15-mile US 281 corridor.
• Comparison group: All other freeways in San Antonio.
• Before period: 14 months.
• After period: 22 months.
Primary Computations
𝑬𝑬𝑬𝑬𝑬𝑬𝑬𝑬 𝑻,𝑨 = 𝑶𝑶𝑶𝑶𝑶𝑶𝑶𝑶 𝑻,𝑩 ×
𝑶𝑶𝑶𝑶𝑶𝑶𝑶𝑶 𝑪,𝑨
𝑶𝑶𝑶𝑶𝑶𝑶𝑶𝑶 𝑪,𝑩
= 𝟕𝟕. 𝟔𝟔
𝑬𝑬𝑬 =
𝑶𝑶𝑶𝑶𝑶𝑶𝑶𝑶 𝑻,𝑨
𝑬𝑬𝑬𝑬𝑬𝑬𝑬𝑬 𝑻,𝑨
𝟏 +
𝑽𝑽𝑽𝑽𝑽𝑽𝑽𝑽𝑽𝑽𝑽𝑽𝑽𝑽𝑽𝑽 𝑻,𝑨
𝑬𝑬𝑬𝑬𝑬𝑬𝑬𝑬 𝑻,𝑨
𝟐
= 𝟎. 𝟔𝟔
𝟗𝟗𝟗 𝑪𝑪 = 𝑬𝑬𝑬 ± 𝟏. 𝟗𝟗 × 𝑬𝑬𝑬 𝑺𝑺𝑺𝑺𝑺𝑺𝑺𝑺 𝑬𝑬𝑬𝑬𝑬 = 𝟎. 𝟑𝟑 𝒕𝒕 𝟎. 𝟖𝟖
Results
• Event modification factor (EMF) indicates a 38% reduction in
the WWD events on US 281 after the installation of border-
illuminated WRONG WAY signs. This percent change was
statistically significant at 5% significance level.
• The 95% confidence interval (CI) was −13% to −63%.
Problem Statement
Since the 1950s, wrong-way crashes have posed a problem for
transportation officials. Although research has focused on
quantifying the wrong-way driving (WWD) problem and
summarizing implementation information about traditional and
innovative countermeasures, little is known about the
effectiveness of the innovative strategies. Recently, Texas A&M
Transportation Institute (TTI) researchers assessed the
effectiveness of two innovative WWD countermeasures in actual
operational environments.
Objectives
• The first study evaluated the effectiveness of WRONG WAY
signs with flashing red light-emitting diodes (LEDs) around the
border.
• The second study assessed the effectiveness of lowered
DO NOT ENTER and/or WRONG WAY signs.
BORDER-ILLUMINATED SIGNS
CONCLUSIONS
Background
• Between March 2012 and June 2012, the
Texas Department of Transportation
(TxDOT) installed WRONG WAY signs
with flashing red LEDs around the border
at every exit ramp along a 15-mile
corridor on US 281 in San Antonio.
• The purpose of the LEDs was to increase
the conspicuity of the signing at night.
Time Period
US 281 Corridor (T)
(n=96)
Comparison Group (C)
(n=1073)
Before (B) 46 396
After (A) 50 677
• When deciding how to mitigate wrong-way movements on
freeways, agencies should consider the use of either
countermeasure studied.
• The 2-ft sign height examined is lower than currently allowed
in the MUTCD. A request to experiment would be needed
before installing signs at this height.
Primary Computations
𝑬𝑬𝑬𝑬𝑬𝑬𝑬𝑬 𝑻,𝑨 = 𝑶𝑶𝑶𝑶𝑶𝑶𝑶𝑶 𝑻,𝑩 ×
𝑶𝑶𝑶𝑶𝑶𝑶𝑶𝑶 𝑪,𝑨
𝑶𝑶𝑶𝑶𝑶𝑶𝑶𝑶 𝑪,𝑩
= 𝟓𝟓. 𝟓𝟓
𝑬𝑬𝑬 =
𝑶𝑶𝑶𝑶𝑶𝑶𝑶𝑶 𝑻,𝑨
𝑬𝑬𝑬𝑬𝑬𝑬𝑬𝑬 𝑻,𝑨
𝟏 +
𝑽𝑽𝑽𝑽𝑽𝑽𝑽𝑽𝑽𝑽𝑽𝑽𝑽𝑽𝑽𝑽 𝑻,𝑨
𝑬𝑬𝑬𝑬𝑬𝑬𝑬𝑬 𝑻,𝑨
𝟐
= 𝟎. 𝟒𝟒
𝟗𝟗𝟗 𝑪𝑪 = 𝑬𝑬𝑬 ± 𝟏. 𝟗𝟗 × 𝑬𝑬𝑬 𝑺𝑺𝑺𝑺𝑺𝑺𝑺𝑺 𝑬𝑬𝑬𝑬𝑬 = 𝟎. 𝟏𝟏 𝒕𝒕 𝟎. 𝟕𝟕
Results
• EMF indicates a 56% reduction in WWD events after the
installation of lowered signing. This percent change was
statistically significant at a 5% significance level.
• The 95% CI was −27% to −85%.
• Regression-to-the-mean may have occurred since lowered
signing installed at some ramps with high number of wrong-
way entries.
Time Period
Treatment Ramps (T)
(n=44)
Comparison Group (C)
(n=169)
Before (B) 15 34
After (A) 29 135
vehicle that was traveling the right way.
• Concerns on how a sign mounted at 3-ft would perform
using the latest crash test criteria.
• Proposed 2-ft mounting height:
• A height with the potential to catch an impaired driver’s
attention while still being able to alert unimpaired drivers
of restricted movements and meeting current
crashworthiness criteria.
• In spring 2011, NTTA, in cooperation with the TxDOT,
requested experimentation to mount
36-inch by 36-inch DO NOT ENTER and
24-inch by 36-inch WRONG WAY signs at 2 ft.
• Request to experiment approved by the Federal Highway
Administration on July 14, 2011.
Data Analysis
• NTTA WWD event data (crashes and non-crashes) from
January 2010 to June 2015.
• Before-after evaluation of WWD events with a comparison
group used to determine effectiveness of lowered signing.
• Study area: 28 exit ramps.
• Comparison group: 114 exit ramps.
• Before period: 18 months.
• After period: 47 months.
• The LEDs continually flashed under low ambient light
conditions (i.e., not detection-based).
• This method of operation was used to catch the attention
of wrong-way drivers on the frontage road prior to
entering the ramp.