MUTCD Retro Rule: How to be
Compliant without Busting
Budgets Using a
Retroreflectometer
Learn how the use of a retroreflectometer as a safe
and efficient method for monitoring traffic signs to
ensure they meet established minimum
retroreflectivity standards set forth in the MUTCD
can help save budgets by enabling allocation of
resources by sign performance and priority.
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MUTCD Retro Rule: How to be Compliant without
Busting Budgets Using a Retroreflectometer
Understanding the MUTCD “Retro Rule”
Starting with the publishing of the 2009 edition of the Manual on Uniform Traffic Control Devices
(MUTCD) agencies have been scrambling to understand what they need to do to be compliant with the
rules governing retroreflectivity minimums of their traffic signs in use.
Simply put, the retroreflectivity requirements state that every agency with signs under their jurisdiction
is required to implement an assessment or management method designed to maintain sign
retroreflectivity at or above the established minimum levels.
Recent changes passed on May 14, 2012 adjusted the compliance date for this mandate to June 2014 to
have a program in place that covers at minimum regulatory and warning signs by the new compliance
date. While the new MUTCD compliance date does not require inclusion or replacement of other signs
by a particular date, the FHWA has instructed agencies to add other sign types to their selected
management method as resources and competing priorities allow.
Regardless of the established compliance date, agencies are still liable for all signs under their
jurisdiction that do not meet minimums should a tort liability situation arise. Being protected in that
instance is the main driver for agency compliance, however, Federal and State funding could also be
affected down the road if a sign monitoring program is not in place.
The Approved Methods for MUTCD Retro Rule Compliance
There are currently five approved methods for meeting the MUTCD requirements of monitoring and
maintaining retroreflectivity minimums of traffic signs. Agencies can use a matrix of methods as
necessary to ensure minimums are met within their means. The five approved methods consist of:
1. Blanket Replacement of every sign in a particular region on a set schedule (typically
every 10 years)
2. Scheduled replacement at the end of the Manufacturer’s Suggested Sign Life
(typically 10 years)
3. Replacement as determined by Control Signs in a sign yard whose useful life is
determined by periodic readings with a retroreflectometer
4. Nighttime Inspections by a Trained Sign Inspector that meets specific qualifications
in a specific vehicle setup with a dedicated driver and supplemented by the use of
control panels
5. Use of a Retroreflectometer to do periodic assessments of individual signs and
replace once the sign is close to or falls under the established minimum levels
Regardless of what method(s) is implemented, at the backbone of a successful program is having proper
processes and data management methods established to ensure no sign goes unattended for any
extended period of time opening the potential for expensive tort liability.
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MUTCD Retro Rule: How to be Compliant without
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Considerations when Choosing a Method
While each method has its benefits and drawbacks, there is a misperception that employing a
retroreflectometer to gather actual retroreflectivity readings is an expensive and timely endeavor in an
economic time when resources are incredibly tight. The truth could not be further from this opinion.
The use of a handheld sign retroreflectometer is arguably the most proficient method available for
determining a sign’s field performance and need for replacement. Retroreflectometers provide a
scientific reading that represents a sign’s nighttime performance in a single scientific reading without
subjectivity while simultaneously allowing for a safe daytime physical inspection of the post, hardware,
and general sign condition.
Agencies currently utilizing a retroreflectometer to determine sign performance often find that their
signs are significantly outperforming the manufacturers’ expectations, often by as much as 10-20 years.
Using a retroreflectometer to determine sign performance has actually provided a cost savings of 3040% annually over the blanket replacement, suggested sign life, and control signs methods simply by
extending the usable service of a significant portion of existing signs in the field.
Based on the national average of loaded sign replacement cost at $150 per sign,
the initial cost of a retroreflectometer is typically paid for by saving less than 65
signs that would have been replaced using another method.
Another consideration of the blanket replacement, suggested sign life, and control signs methods is the
increase in odds of tort liability due to signs in need of early replacement not being individually
monitored for performance degradation.
Visual nighttime inspection is another popular method because of the perception of relatively low
startup costs and the appeal of inspecting individual signs for retroreflectivity performance degradation.
However, visual nighttime inspection has several hidden costs that range from approved vehicle
specifications to typically higher resource pay and training costs to posing a higher safety risk for
employees having to drive around at night to high subjectivity that may not withstand tort scrutiny.
The use of retroreflectometer to get actual retroreflectivity readings of individual signs is the only
method where all signs are truly inventoried, actively monitored using hard data, and enables physical
inspection during the safety of the day while performing other duties in the field.
Overview of the Sign Lifecycle Management Process
The bottom line is that the MUTCD calls for a sign maintenance program that addresses retroreflectivity.
It is not enough to do a one-off project where you purchase a retroreflectometer and send your crew
out to measure every sign in the field and then the unit sits on the shelf the next five years. You will
quickly have signs fall out of compliance if you do that. The data collected should be incorporated into
either an existing asset management program or used to create one that will help formulate annual
budgets for sign replacements and schedule periodic re-assessment of signs in the field.
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MUTCD Retro Rule: How to be Compliant without
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Out of 498 agencies surveyed between January 2011 and April 2012, a mere 47.9% of agencies reported
utilizing full blown GIS software systems to manage their traffic sign assets. An agency with over 10,000
signs under their jurisdiction is 17.8% more likely to utilize a GIS system than smaller agencies.
While utilizing a GIS system to manage the sign lifecycle process is convenient it is not entirely
necessary, especially for smaller agencies, as long as the proper process and procedures are in place.
Initial Data Collection
The initial data collection process is the most time intensive aspect of becoming compliant with the
retroreflectivity aspect of the MUTCD. Sign inspections as part of a Pilot or Feasibility Study will take
significantly longer, likely 2-3 times longer, than they will once all the kinks in the process has been
worked out.
Agencies who have an existing GIS system that incorporates signs for work orders and inventory
management, typically already have typical sign attributes collected in their systems and simply are
looking to add retroreflectivity measurements to their existing databases to be incorporated in reports
for budgeting and maintenance decisions. Such agencies typically will make short order of adding
retroreflectivity to their program and may even contract a third party to do the initial inventory readings
to add them to their systems for future management.
An agency without a formal sign asset system in place should take the extra time to collect additional
sign attributes such as the GPS location, sheeting type, size, MUTCD sign code or sign type description,
direction facing, mounting specifics, and others as well as the signs’ retroreflectivity measurements to
make monitoring the inventory for performance a much easier task.
Post Processing
After the initial data collection of taking actual measurements of the signs in the field, there is a certain
level of post processing that must take place. For agencies with an existing sign asset program in place,
this is typically a matter of preparing the data for upload. For agencies just getting started, this is the
step in which they marry the data gathered with the
retroreflectometer to other sign attributes collected.
Putting the Data to Work
The next step is to create an initial action plan and start
putting the data to work. The data collected from the
physical inspections and retroreflectivity measurements
should be used to identify high priorities for sign repair and
replacement. Upon repair or replacement, the inventory
would need to be updated. Retroreflectivity measurements
of signs without issue will allow for creating work plans and
scheduling periodic re-assessment for signs as they near
the minimums set forth in the MUTCD.
Figure 1: Sign Management Lifecycle
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Understanding Your Needs
Before selecting a retroreflectometer, agencies should have a firm grasp of what other information they
plan to collect during their initial and subsequent inspections. The ease of use of the retroreflectometer
itself to easily collect and reconcile sign data points can greatly impact the success of the
implementation and periodic assessments.
Ask yourself these questions:





Do you need a full inventory or just appending your GIS with retroreflectivity readings?
What is missing? What do you not already know about your signs in the field?
Do you already utilize barcodes or will they need to enter a stencil/sticker asset ID?
Do your workers need the ability to add custom comments or select preprogrammed
comments? Or will a notepad suffice? Who will data enter handwritten notes?
Will they need laptops? Trimble units? Cameras?
Approved Retroreflectometers in the
United States
As of June 2012, only two manufacturers have sign retroreflectometer devices that are currently
approved for use in the United States: RoadVista (USA) and Delta (Denmark). Each manufacturer makes
a retroreflectometer device approved for field-use, the RoadVista 922 and Delta RetroSign GR3
respectively.
Though the devices made by these two companies may accomplish the same end result of being MUTCD
compliant, there are several notable differences between their form and function that sets them apart.
This is why it is important for agencies to understand the sign management lifecycle and what their
unique data collection needs are to ensure they choose the most practical, efficient option for their
agency.
Side-by-side Comparison: RoadVista 922 vs. the Delta RetroSign GR3
Both retroreflectometers resemble a gun and are activated by placing the front of the unit flush against
the sign and pulling a trigger to take the reading. Pulling the trigger without the unit pressed against a
flat surface will activate the barcode readers; note, however, that the barcode reader on the Delta GR3
is actually an external attachment (not pictured below). Both units come equipped with internal GPS
and Bluetooth.
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MUTCD Retro Rule: How to be Compliant without
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Figure 2: RoadVista 922
Figure 3: Delta GR3
The largest difference in the units is the user interface and data display. The Delta GR3 has an array of
symbol buttons and a black and white LCD screen on the side of the unit that is difficult for the
untrained eye to interpret the results of the reading. The RoadVista 922 has a color touch screen with
intuitive onscreen button navigation and the ability to enter custom comments and up to six pre-loaded
standard comments per sign. This allows for more information to be collected on the unit on the same
data record as the sign’s measurements instead of being recorded separately by other means as it would
have to be with the Delta units.
Figure 4: RoadVista 922 Touch Screen and Delta GR3 Screen Shots
Use in the Field
Both units have significant internal memory capacity that allow for long periods in the field before
having to clear data off of the units. The RoadVista unit utilizes standard 12V tool batteries found in any
local hardware store that can be recharged while the included second battery is in use. The Delta on the
other hand has a semi-permanent battery and cannot easily be used in the field while recharging.
Software
Each manufacturer includes data integration software with each purchase that enables the agency to
easily get the retroreflectivity readings off the retroreflectometers to prepare it to be used in the sign
management lifecycle.
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Delta’s RSC software will export data for Microsoft Excel and Google mapping (.xls, .txt, .kml).
RoadVista’s 922 Download Manager exports data for Microsoft Excel, Access, Google mapping, and ESRIbased GIS systems utilizing Shapefiles (.csv, .kml, .shp).
Because of the limitations of the Delta’s on-unit controls, their RSC software is necessary to perform
several management functions for the actual retroreflectometer that is handled on-unit with the
RoadVista 922.
Figure 5: 922 Download Manager Screenshot
Figure 6: Delta RSC Screenshot
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MUTCD Retro Rule: How to be Compliant without
Busting Budgets Using a Retroreflectometer
Annular vs. Point Technology
Retroreflective materials, such as traffic signs, appear at night to a driver almost exactly as they would in
broad daylight when a beam of light is emitted from the vehicle’s headlights because of the materials’
ability to concentrate light reflection back to the source of the light with minimal diffusion.
Very simply put, a retroreflectometer is a device that simulates retroreflectivity of a surface by
triggering an encapsulated light source and measuring how much of the light was returned to that light
source.
Point Retroreflectometer Technology
A point retroreflectometer will measure a single point along a 360⁰ circumference directly above the
light source. This is a simplified representation of a driver and vehicle’s headlights.
Because of the nature of microprismatic retroreflective materials (such as ASTM Types VII, IX, XI) and the
fact that drivers in the real-world will view signs at many different angles, ASTM measurement
specifications for a point device call for two point readings at a 90⁰ rotation from each other (i.e. one at
0⁰ and one at 90⁰) to be taken and then averaged together to get a retroreflectivity reading that more
accurately represents how a sign will perform in the real world as
individual point measurements can differ significantly based on
orientation.
Annular Retroreflectomer Technology
An annular retroreflectometer takes an infinite number of
ANNULAR DEVICE
POINT DEVICE
measurements simultaneously along the same 360⁰ circumference
Figure 7: Annular vs. Point Instruments
surrounding the light source emitted and essentially averages the
measurements along that entire circumference to produce a single reading that accurately represents
laboratory reference measurements and how a sign will perform in the real world.
Practical Application Considerations
Point devices are ideal for lab use as a perfect 90⁰ rotation for the second point measurement is a near
impossible feat in the field, especially with extension pole operation which does not allow for a change
in instrument orientation; thus an annular device is arguably a safer, more efficient, and accurate
retroreflectometer for use in the field.
The RoadVista 922 is an annular device. It takes a mere second for a single annular reading. The Delta
GR3 is a point device. It takes a second for a single point reading; however, to obtain measurements that
will correlate to laboratory reference measurements, the unit should be rotated 90⁰ to take a second
point reading taken and the two measurements averaged together. When operated correctly, the
measurements of both instruments should produce the same or similar results.
When reading traffic signs in the field, measurements of each quadrant of the sign’s background and
non-black legend should be taken and averaged together respectively. With an annular device, that is
four readings of the background and four readings of non-black legend to get one measurement per sign
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color; with a point device that is eight point readings per color to get one measurement per color. Black
is non-reflective so signs using black legend only require the four measurements of the background. It is
that average of each color that needs to meet the retroreflectivity minimums laid out in the MUTCD.
The RoadVista 922 has separate data collection for legend and background and averages the
measurements of each automatically with the ability to add comments on the unit as a single sign
record without additional software or hardware.
At-a-Glance Comparison of US Approved Retroreflectometers
Manufactured In
Device Type
Angles
Inventory System
Battery
Display
Reading Time
GPS
Bluetooth
RoadVista 922
USA
Annular – Single Measurement per
Reading on Prismatics
US Patent 7,961,328
2 angles: .2, .5
Built-in Barcode Reader
Standard 12V Rechargeable Power Tool,
~$70
Touchscreen facing User
1 Second Per Reading
Standard Internal
Standard Internal
Delta RetroSign GR3
Denmark
Point – Two Measurements per Reading
on Prismatics are Required
(at 0⁰ and 90⁰)
3 angles: .2, .5, 1.0
Attachable RFID Reader or Attachable
Barcode Reader
Bosch Special Order, ~$330
LCD on side of unit
2 Seconds Per Reading
Standard Internal
Standard Internal
1
FHWA
Real World Use of Retroreflectometers
Should your agency decide to utilize retroreflectometers to ensure MUTCD compliancy and limit your
tort liability, you will not be alone. In that same survey of 498 US agencies, 16.1% responded as using
retroreflectometer readings as their primary method of sign inspection. 67.7% responded as using visual
inspection as their primary method, but over half of those agencies (54%) responded as not doing any
nighttime visual inspections thus are not MUTCD compliant. Fact is that retroreflectometers are not as
scary as they may seem and are growing in popularity.
What we are seeing from the agencies that are paving the way is that the established retroreflectivity
levels are so low that a sign is far more likely to require replacement due to physical damages before it
reaches a level of retroreflectivity failure.
1
Federal Highway Administration. Retro Tool Kit. Guidelines for Conducting Retroreflective Measurements of Traffic Signs.
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MUTCD Retro Rule: How to be Compliant without
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It is also notable that introduce laptops and GIS/Mapping in the field for reference and data collection
are seeing an increase in productivity as much as 50% over traditional paper-based manual reference
systems.
Another common concern agencies have is the amount of time it will take to perform inspections of the
entire sign inventory. Most agencies using a retroreflectometer are reporting that one person with a
retroreflectometer can take 8-19 readings in an hour; however, consultancies report a much higher rate
of 15-30 an hour. Both report the biggest determinant of signs per day is the distance between signs –
rural areas obviously require more travel time between signs. Signs per day rates also appear to be
significantly lower during Pilot or Feasibility Studies.
If your agency wishes to perform a Pilot or Feasibility Study, it is recommended that you focus on the
regulatory and warning signs within your jurisdiction first. This is typically 25-35% of total sign inventory,
the main reason the FHWA kept a compliance date associated with them in the recent MUTCD revisions.
Select Case Studies
Pilot Study: Iowa Region XII Council of Governments
Region XII is a multi-community collaboration that spans five counties of Iowa. In 2010, they decided to
purchase a RoadVista 922 retroreflectometer and hire two summer interns from the IDOT’s Urban Youth
Corps Program to do a pilot study in one of the counties of the feasibility of a wider roll out for all of the
Region XII participating agencies.
The interns were instructed to inventory an estimated 6,000 – 7,000 signs in the selected Guthrie
County including retroreflectivity measurements, sign type, height of the sign, distance off the road,
direction facing, sheeting type and GPS location. The interns averaged 140 signs a day and at the end of
two months, Guthrie County had a highly accurate sign inventory database complete with mapping.
Overall, the biggest challenge they faced was the pressure to read so many signs in such a short amount
of time.
Pilot Study: Portland Oregon
In 2011, Portland, OR embarked on a random sampling of 398 warning and regulatory signs to see what
kind of work they had ahead of them in their efforts to become MUTCD compliant. Their study
suggested that a sign in their jurisdiction was 33x more likely to need replacement due to physical
damage (graffiti, missing, knocked down) than it would be due to low retroreflectivity. With only a 1.5%
retroreflectivity failure rate as determined by a retroreflectometer, they observed no correlation
between visual inspection results and retroreflectivity readings.
Upstate NY Project
A consultancy was hired to append existing Cartegraph GIS system with retroreflectivity data of 8,000
signs along 600 miles of rural roads. Only 10% of the signs failed due to not meeting retroreflectivity
minimums.
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MUTCD Retro Rule: How to be Compliant without
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NYC Overhead Sign Project
The majority of signs in New York City are overhead signs. In 2011, a consultancy was hired to inspect
the overhead structures to ensure safety. It made perfect sense to add retroreflectivity readings of the
2,000 signs on the 1,283 overhead structures to the scope of the project. The majority of the signs had
been replaced during a blanket replacement project in 1997, yet at 500 signs read, the average
retroreflectivity readings were at 115% higher than MUTCD minimums with only a 1% failure rate.
Anderson Passe & Associates
In 2009, Anderson Passe & Associates added retroreflectivity measurements to their portfolio of
services. Most of their clientele is rural townships, parks and forests. Over a two year period, they
inspected over 7,000 signs for client agencies. Of those 7,000 signs, 68% of the signs failed due to
physical damage or substandard sheeting while only 5.1% failed due to not meeting retroreflectivity
minimums. On average, clients of Anderson Passe & Associates have seen a 35% savings over blanket
replacement.
What Data Should you be Considering?
A March 2012 survey of 129 agencies asked what attributes they collect as part of their sign
management lifecycle database and how they use that data. An overwhelming response was that
agencies were dying to know where their signs actually are located. Mapping was the number one data
use, followed closely by the ability to create prioritized maintenance and replacement lists and
estimating field sign life for budgeting decisions. No other method makes this information easier to
obtain or analyze than physically inspecting and taking actual retroreflectivity measurements with a
retroreflectometer.
Figure 8: Sign Attributes Survey Results
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MUTCD Retro Rule: How to be Compliant without
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In Summary
In an age where technology is so prevalent in our lives, actual retroreflectivity readings of traffic signs
with a retroreflectometer is the option that makes the most sense. It is the only method that provides a
safe opportunity to routinely inspect individual signs while producing hard, scientific data so agencies
can effectively allocate resources based on actual sign performance and priority.
The retroreflectometer method is as useful for agencies that have never actively tracked their sign
inventory and are effectively starting from scratch as it is for agencies with full blown GIS systems that
are only missing retroreflectivity readings in their data set.
The real decision comes down to whether to purchase a RoadVista 922 or Delta GR3 to implement a sign
management lifecycle that monitors retroreflectivity readings.
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About Professional Pavement Products, Inc
Professional Pavement Products (PPP) is a leading provider of maintenance and construction products for the improvement of
safety and effectiveness of our roadways and parking areas. Established in 1996, the company currently provides over 800
products online and through six warehouse outlets in the Southeastern USA and Texas. PPP is the exclusive distributor of the
RoadVista Model 922 in North America and is highly recognized as experts for retroreflectivity matters, retroreflectometers
and the associated safety concerns that led to retroreflectivity standards inclusion in the MUTCD. PPP currently serves the
following associations in various capacities concerning retroreflectivity matters: American Traffic Safety Services Association
(ATSSA), American Society for Testing and Materials (ASTM), Transportation Research Board (TRB), and Local/Tribal Technical
Assistance Program (LTAP/TTAP). For more information on PPP, please visit www.pppcatalog.com – for more information
regarding the RoadVista 922 or to request a demonstration, please visit www.ppcatalog.com/922.
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