Helping Drivers See at Night: Maintaining Sign Retroreflectivity

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Helping Drivers See at Night Maintaining Sign
Retroreflectivity

• Paul Carlson
• Texas Transportation
• Institute

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Presentation Overview

• Why address retroreflectivity?
• Nighttime needs (eliminate bad signs)
• Congressional legislation
• Initial research
• Stakeholders views
• Recent research
• Agency workshops
• Current status

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Why Address Retroreflectivity?

• Provides ability to see signs at night
• Comfort and convenience
• Older driver concerns
• Nighttime conditions are a safety concern
• Safety is FHWA Vital Few goal
• Congressional mandate

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Nighttime Driving
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Night Travel and Crashes
Source National Safety Council
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Current MUTCD Language

• 2A.06 basic requirements legible for whom
  intended high visibility by day and night
• 2A.08 shall be retroreflective show same
  shape and color day and night
• 2A.23 should have adequate retroreflectivity
  should establish schedule for inspecting (both
  day and night)

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Congressional Legislation
1993 DOT Appropriations Act The Secretary
of Transportation shall revise the MUTCD to
include a standard for a minimum level of
retroreflectivity that must be maintained
revise the MUTCD
include a standard
must be maintained
for traffic signs and pavement markings which
apply to all roads open to public travel.
all roads open to public travel
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Key Activities

• 1993 initial research recommendations
• 1995 agency workshops
• 1998 revised values
• 1998 AASHTO task force
• 2000 AASHTO resolution
• 2001 overhead and street name values
• 2002 agency workshops
• 2003 updated values
• 2003 developing proposed rule

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Initial Research

• 1993 values
• Paniati Mace (FHWA-RD-93-077)
• Developed using CARTS
• 1995 workshops
• McGee Taori
• Initial agency input
• 1998 revisions
• McGee Paniati (FHWA-RD-97-052)
• Changes to initial (1993) values

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Example of Values
White Background Signs
RA, cd/lux/m2 Geometry 0.2 / -4.0 degrees
Similar tables for yellow/orange, red, and green
signs
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AASHTO Task Force

• 1998 - AASHTO requested FHWA suspend rulemaking
  on minimum retro until a Task Force could
  evaluate the issues
• AASHTO resolution on sign minimums in December
  2000
• AASHTO Position Paper in November 2002

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AASHTO 2000 Resolution

• Desirable to assure adequate night visibility for
  signs
• Regular assessments of retroreflectivity or
  planned replacements of signs is necessary

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AASHTO 2002 Position

• Reauthorization recommendations
• Levels should not be in MUTCD
• Agencies should establish a process
• Signs markings should be replaced
• Concern over agency liability
• Congress should reconsider prior action

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Stakeholders Views

• Other organizations have positions/policies
• American Traffic Safety Services Assoc
• Support minimum retroreflectivity standard
• Institute of Transportation Engineers
• Support retroreflectivity efforts
• National Assoc of Counties
• Repeal Congressional legislation
• National Assoc of County Engineers
• Oppose Congressional legislation

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Recent Research

• 2002 overhead guide signs and street name signs
• Carlson et al (TRR 1794)
• Identified shortcomings with initial levels
• 2002 workshops
• Hawkins et al (FHWA-SA-03-002)
• Solicited agency input on MUTCD language
• 2003 updated values
• Carlson et al (FHWA-RD-03-081)
• Basis for future rulemaking

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Effort to Update Levels

• Basis for updates
• Older drivers
• Vehicle headlamps
• Newer materials
• Vehicle sizes
• Consolidated values
• Fewer minimum values

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Updated Values
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Agency Workshops

• Key agency concerns
• Tort
• Costs
• Agency preferences
• No values in MUTCD
• Values in support document
• Exclude certain signs
• Options for implementation methods

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Workshop Information
http//tcd.tamu.edu
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Implementation Methods

• Assessment methods
• Visual inspections
• Calibration signs
• Comparison panels
• Measured retroreflectivity
• Management methods
• Expected sign life
• Periodic replacement
• Control signs

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Current Status

• FHWA is in process of developing
• Proposed rule language
• MUTCD language
• Support document
• Impacts analysis
• Training activities
• LTAP and DOT training

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Questions
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