Transcript
8/13/2019 Retro Workshop
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TrafficSignRetroreflectivity
Workshop
July12,2011
8/13/2019 Retro Workshop
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Traffic Sign Retroreflectivity
as cs o gn
Retroreflectivit
&
New Sign
Requirements
1
Todays Speaker
, ,
Texas Transportation Institute,
Research Engineer
Head Operations & RoadwaySafety Division
Member of FHWA
Retroreflectivity Team
Member:
ASTM, TRB, NCUTCD, ITE
2
Todays Schedule
Start StopDescri tion
Time Time
9:30 10:00 Check in / Registration
10:00 10:15 Welcome / Participant Introductions
: : as c e rore ec v y g me s y oncep s
10:45 11:05 Texas MUTCD Requirements and compliance dates
11:05 11:45 Sign Retro Maintenance Methods
11:45 12:15 LUNCH
12:15 12:45 Retroreflectometer Demo / Discussions
Open Floor Discussions:
Practical Implementation of new requirements
12:45 2:00
Life Cycle Costs and cost reduction
Around the room, what have you already
implemented, what are you still planning, how well is it
working, and what does it cost?
Other items?
3
Welcome
Importance has increased
Not a part of any educational
curriculum
OTJ training
Your agency is now
responsible to maintain sign
retroreflectivity
4
Texas MUTCDs
http://www.txdot.gov/Current TX MUTCD
5
Background Information
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Wh Do We Install Si ns?
Re uired b MUTCD?
NO
Engineering Decision?
YES!
Why?
To help drivers
7
Key Issue: Older Drivers
10.7 million drivers a e 70+ in 1990
+.
48% increase from 1990 to 2006
1990 8% of drivers were 70+ 2006 10.2% of drivers were 70+
Older driver population will continueto grow as baby-boomers age
8
TMUTCD Existing Reqs.
exas anua on n orm ra c on roDevices
Section 2A.06 Desi n of Si ns The basic requirements of a highway sign are that it
be legible to those for whom it is intended and thatit be understandable in time to ermit a ro erresponse. Desirable attributes include: High visibility by day and night; and
High legibility (adequately sized letters or symbols, and as or egen or qu c compre ens on y a roa userapproaching a sign).
9
TMUTCD Sign Maintenance
TMUTCD Section 2A.22 Maintenance
Maintenance activities should consider properposition, cleanliness, legibility, and daytime andni htt ime visibili t see Section 2A.09 . Dama edor deteriorated signs should be replaced.
To assure adequate maintenance, a schedule for, ,
replacing signs should be established.
Ste s should be taken to see that weeds, trees,shrubbery, and construction, maintenance, andutility materials and equipment do not obscure the
face of any sign.
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Night Travel and Crashes
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Nighttime Driving
Many cues availableMany cues available
Driver task relatively easyDriver task relatively easy
Few cues remainFew cues remain
Task more difficultTask more difficult
RetroreflectivityRetroreflectivity provides nighttime guidanceprovides nighttime guidance
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Why Create Minimums?
Daytime
Nighttime
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Typical Outdoor Durability Testing
T e III
45 degree south facing
le
ctivity
Retrorefl
Type II
Type I
0 10 20 30 40 50 60 70 80Age (months)
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Retroreflectivity
Concepts
15
RETROreflection
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Retroreflection
of light returned froma sign versus theamount hitting thesign
efficiency of a material
Light OUT of sign
Light INTO sign= Retroreflectivity
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Retroreflective Elements
Glass s heres and microsized risms arethe current technologies used to make sign
materials retroreflective
The light is returned to the source in a cone
shaped pattern
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Sign Sheeting Materials
Engineering Grade
Hi-Intensity
Beaded
Microprismatic
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Sheetin T es
(Type III e.g. High Intensity)
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Technical Terms
Retroreflective Si n(RAcd/lx/m
2)Luminance(cd/m2)
Illuminance (lx)
21
Basic Angles of Retroreflectivity
Observation An le Where in the coneis the measurement made (from the lightsource).
Entrance An le What is the orientationof the sign or pavement marking (is fromthe light source)
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Key Geometry Angles
Observation an leObservation an le Between source and receptorBetween source and receptor
(red and blue lines)(red and blue lines)
PerpendicularPerpendicular
to s gnto s gn
Entrance angle (Entrance angle ())Between source andBetween source and
target axistarget axis(blue and green lines)(blue and green lines)
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Sheeting Specification Geometry
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Rotational Sensitivit
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Rotation Marks
Microprismatic sheeting
Retroreflectivit can var with
rotation
Some rismatic sheetin hasorientation arrows
,
cutting, and fabricating signs
26
Rotational Sensitivit
y
oreflectivi
Retr
Minimum
Retro
0 degrees 45 degrees 90 degrees
27 28
Questions
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MUTCD Sign Retroreflectivity
Maintenance Requirements
New Requirements
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Congressional Legislation
1993 DOT A ro riations Act1993 DOT A ro riations Act
The Secretary of
revise the MUTCD to
include a standard for aminimum level of
maintained for traffic signs and
avement markin s which a l to all
roads open to public travel.
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Final Rule
Published on Dec 21, 2007
, .
Edition of the MUTCD
Effective Jan 22, 2008
32
New MUTCD Language.
an ar :
Public agencies or officials having jurisdiction
s a use an assessmen or managemen
method that is designed to maintain sign
levels in Table 2A-3
33
New MUTCD Language.
Su ort:
Compliance is achieved by having a method
in lace and usin the method to maintain the
minimum levels established in Table 2A-3.
Provided that a method is being used, an
agency would be in compliance even if there
are some individual signs that do not meet the
.
34
New MUTCD Language
One or more of the following assessment
or management methods should be used
Ex ected Si n Life
Inspection
Calibration Si ns
Blanket Replacement
Control Signs
Comparison Panels
Future Method BasedOn Engr. Study
Parameters
Measured Si n Retro
Combination Of Any
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New MUTCD Table 2A.3Minimum Maintained Retroreflectivity Levels
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What do the numbers look like?
c ures o no represen re rore ec v y we
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Exempt Signs
Parking/Standing/Stopping
Walking/Hitchhiking
Adopt-A-Highway
Blue or BrownBackgrounds
Exclusive Use of Bikesor Peds
Note: Must still meet other
requirements in MUTCD
(inspections,,
etc,)
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Clarification
fluorescent yellow -- > yellow
- --
fluorescent orange -- > orange
39
Compliance Dates
s a s an mp emen me o s
January, 2012
Replace identified regulatory, warning, ground-mounted guide signs (except street-name)
anuary,
Replace identified street name & overhead guidesigns
January, 2018
40
Summary of New Language
Public a encies or officials havin urisdiction shall usean assessment or management method that isdesigned to maintain sign retroreflectivity at or abovethe minimum levels in Table 2A-3
Compliance is achieved by having a method in place
established in Table 2A-3. Provided that a method isbeing used, an agency would be in compliance even
ere are some n v ua s gns a o no meethe levels at a particular point in time.
41
Can you see the sign?
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Questions
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MUTCD Si n Maintenance
Methods
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Can we decide to replace signs based on
45
- - -- - -
46
MUTCD Methods
Measured retroreflectivity
Expected sign life
Blanket replacement
Control signs
Combination of methodswww.fhwa.dot.gov/retro
47
Method: Visual Assessment
Com arison anels rocedure or
3 Techniques:
Calibration signs procedure, or
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Method: Visual Assessment
panels
Clipped to sign - viewed from distance
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Comparison Panels
have a retroreflectivity level
the MUTCD
done at night
These panels have retroreflectivity
levels at the levels in the MUTCD
minimum retroreflectivity table
Comparison Panel Procedure
50
Source of Comparison Panels
,
find in-service signs near the minimum
.
from service and cut into smaller pieces.
scrap yard.
very enn son us announce
availability comparison panels.
Comparison Panel Procedure
51
Field Procedure
Comparison Panel Procedure
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Method: Visual Assessment
Calibrate eyes with calibration signs
Calibration
minimum retro
va ua e s gns
compared to
ca ra on s gns
53
Calibration Signs
have a retroreflectivity
designated in the
The inspection has to be
Calibrated Signs Procedure
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Source of Calibration Signs
With a retroreflectometer an a enc canfind in-service signs near the minimumlevels. These signs can be removedfrom service and stored until nighttimesign inspections commence.
An agency can also look through theirscrap yard for representative signs.
Avery Dennison just announced
availability comparison panels.
Calibrated Signs Procedure
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Field Procedure
These signs have retroreflectivity
levels at the levels in the MUTCD
l lm n m um re r ore l ec v y a le
Calibrated Signs Procedure
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Visual Inspection Method:
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Overview
With this method a SUV or truck has to be used
with specific headlamps (described later) and
the inspector needs to be at least 60 years old.
The inspection occurs at highway speeds.
No calibration signs or comparison panels are
needed.
This method simulates the conditions of the
research which FHWA used as a foundation for
the minimum retroreflectivity levels.
Consistent Parameter Procedure
58
Field Technique
Preferable to use a two erson crew. Must have a SUV, pick-up, or similar vehicle
with VOA style headlamps.
Driver can be any age but inspector needs tobe at least 60 years old.
nspec on occurs a g way spee s.
Inspector concentrates on judging sign.
Example: adequate, marginal, poor (replace)
Driver concentrates on drivin safel .
Consistent Parameter Procedure
59
Method: Measure Sign Retro
Use a portable instrument
Receive proper training
Compare readings to minimum values
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Overview
This method includes si nretroreflectivity measurements of in-service signs
The measurements are made with
devices similar to cordless drills The measurement devices must be in
contact with the sign face
The measurements need to beperiodically repeated (e.g., annually orevery other year)
61
Examples of Sign Retroreflectometers
on ac
Devices:
Model GR3(Delta)
Model 922(Gamma Scientific)
Non-ContactExperimental concept,
but NOT etavailable.
Devices:
l l
SMARTS Van
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Field Procedure
Measure each color that is retroreflective
Multiple measurements should be made
to compute an average
A measurement protocol should be
developed
An extension pole or ladder will be
needed
63
64
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Measurement Protocol
,may require a minimum of
as shown to the left
measurements would be
condition of the sign
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Taking Measurements
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Method: Expected Sign Life
Find the life of the sheeting type in your area
Re lacement based on ex ected life for
individual signs
67
Indicating Sign Age
when fabricated or installed
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Determining Sign Life
Build and use a weathering rack
like the one shown
-
Use warranty information from
sheeting company
pec y s gn e
Measure existing signs with
known install date and compare to
min level
Use weathering data or nearbyurisdictions weatherin data
69
Using Warranty Information
Predicted si n a e could be rovided in a
warranty by sheeting manufacturers.
T ical warranties not t icall based on
minimum retroreflectivity levels
Agencies could develop specifications with
warranties based on minimum retroreflectivity
levels
Example: Warranty Type III sheeting for 15 years in
accordance to Table 2A-3 of the MUTCD
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Weathering Racks at TTI
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Method: Blanket Replacement
All signs in an area/corridor are replaced at the
same time at specified intervals
Specified intervals could be set based on
expected sign life
Some existing blanket sign replacement policies
exist using 10-12 years for Beaded High-
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Blanket Replacement
Divide a enc into Exam le
areas/corridors or zones
Relate number of areas toReplaceReplace
7th7thyearyear
replacement cycle
Replace all signs in an
this areathis areaduring 1stduring 1st
yearyeararea/ corridor each
replacement cycle
3rd3rdyearyear
yearyear
10 yr life, 10 areas
Annual replacement in each
City of Tempe AZ Maintenance Zones
73
Method: Control Signs
Sign life is estimated using a subset of signs
representing an agencys inventory.
Subset of signs is the control signs
--
maintenance yard.
Agency monitors control Example of Control Signssigns to estimate condition
of all their signs.
Periodically measure
retroreflectivity of control
.
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MUTCD Methods
Measured retroreflectivity
Expected sign life
Blanket replacement
Control signs
Combination of methods
www.fhwa.dot.gov/retro
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Method: Other Options
Flexibility is provided for
future advancements in
technology and methods
that have not been fully
developed
Must be based on an
engineering study
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Future Technologies
Mobile sign retroreflective
measurement technology
e ng eve ope y a
least 3 different companies
that measures pavement
highway speeds
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MUTCD Methods
Measured retroreflectivity
Expected sign life
Blanket replacement
Control signs
Combination of methodswww.fhwa.dot.gov/retro
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NCHRP Survey Participants
Survey conducted May 2011
Included 9 cities, 15 counties, 16 DOTs, and 9 others
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Agency Method Selection
MUTCD MethodsPrimary Sign
Replacement MethodSecondary or
Support Method
Measured Retro. 2 0
Expected Sign Life 17 16Blanket Replacement 7 4
Control Signs 2 10
Note: Table only includes agencies that operate and maintain
roadways that are open to the public
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Summary: Methods Allowed
Visual Ni httime Ins ection Calibration Signs
Comparison Panels
Consistent Parameters
Measured Sign Retro
Blanket Replacement
Future Method Based On Engr. Study
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ona n orma on
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More Information
ATSSA www.retroreflectivity.net
Primer on retroreflectivity
Common questions
FHWA fhwa.dot.gov/retro
Summar Brochure
Final Rule
Newsletter Articles
83
FHWA Supporting Material
www.fhwa.dot.gov/retrowww.fhwa.dot.gov/retro
-
s
Research Reports
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Thank You
au . ar son
paul-carlson@tamu.edu
- -
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