|
Minimum Sign Retroreflectivity RequirementsDownloadable Version
|
|||||||||||||||||||||||||||||||||||||||||||||||||||||||
Slide #1 - New MUTD Standard
Required by MUTCD? NO
| Sign Color | Sheeting Type (ASTM D4956-04) (1) | Additional Criteria |
|||
|---|---|---|---|---|---|
| Beaded Sheeting | Prismatic Sheeting | ||||
| I | II | III | III, IV, VI, VII, VIII, IX, X | ||
| White on Green | W* G ≥ 7 |
W* G ≥ 15 |
W* G ≥ 25 |
W ≥ 250; G ≥ 25 | Overhead |
| W* G ≥ 7 |
W ≥ 120; G ≥ 15 | Ground- mounted |
|||
| Black on Yellow or Black on Orange |
Y*; O* | Y ≥ 50; O ≥ 50 | (2) | ||
| Y*; O* | Y ≥ 75; O ≥ 75 | (3) | |||
| White on Red | W ≥ 35; R ≥ 7 | (4) | |||
| Black on White | W ≥ 50 | — | |||
| (1) The minimum maintained retroreflectivity levels shown in this table are in units of cd/lx/m2 measured at an observation angle of 0.2° and an entrance angle of -4.0°. (2) For text and fine symbol signs measuring at least 1200 mm (48 in) and for all sizes of bold symbol signs (3) For text and fine symbol signs measuring less than 1200 mm (48 in) (4) Minimum Sign Contrast Ratio ≥ 3:1 (white retroreflectivity ÷ red retroreflectivity) * This sheeting type should not be used for this color for this application. |
|||||
Speaker's Notes:
The numbers are also in the MUTCD (this was somewhat controversial)
- The chart is a little complex, so Example 1: a curve warning sign
- black on yellow
- *Type I (eng grade) should not be used
- Any other type okay and should have a yellow retro level of 50 or 75
- (2) Since curve is not text or fine symbol, should meet 50
- Black not retroreflective, so don’t have to measure it.
- Example 2: Stop Sign
- Any type sheeting meets initially
- Both white and red have to meet retro levels: White >35, Red>7
- (3) Need contrast ratio > 3:1 (e.g. red=20, white must >60)
Slide #8 - Methods to Maintain Retro
- Visual Nighttime Inspection
- Calibration Signs
- Comparison Panels
- Consistent Parameters
- Measured Sign Retro
- Expected Sign Life
- Blanket Replacement
- Control Signs
- Future Method Based On Engineering Study
- Combination Of Any
Methods Intro
So those are the numbers you need to meet, but remember the requirement is to have a method that maintains those minimums.
The rule provided much versatility - many methods available
Basics are in brochure (http://safety.fhwa.dot.gov/roadway_dept/retro/sa07020/sa07020.pdf),
Research details are in "Methods Report" on-line at FHWA nighttime visibility site.
Each method has some advantages and disadvantages that should be considered. Combining methods can help minimize the concerns/disadvantages.
Keep in mind the goal is to have visible signs that at least meet the needs of drivers during nighttime.
Slide #9 - New MUTCD Language
Section 2A.09 Maintaining Minimum Retroreflectivity
- "Support:
Compliance. is achieved by having a method in place and using 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. levels at a particular point in time.
This support statement helps to limit an agency's liability: compliance is by implementing a maintenance method, even if some signs do not meet levels at a particular time.
It is not meant as an easy out: the maintenance method must be designed to maintain the minimum requirements fro sign retroreflectivity.
Slide #10 - Exempt Signs
- Parking/Standing/Stopping
- Walking/Hitchhiking
- Adopt-A-Highway
- Blue or Brown Backgrounds
- Exclusive Use of Bikes or Peds
Note: Must still meet other requirements in MUTCD (inspections, retroreflective, etc,)
Several signs are exempted from the minimum retro requirements because they are primarily for daytime or non vehicular use, or there is not adequate research currently to select appropriate minimums.
Slide #11 - Compliance Period
From "Effective" Date of Final Rule (January 22, 2008):
- 4 yrs (January, 2012)
Establish and implement method(s) - 7 yrs (January, 2015)
Replace identified regulatory, warning, ground-mounted guide signs (except street-name) - 10 yrs (January, 2018)
Replace identified street name & overhead guide signs
These are important dates to keep in mind for compliance.
Slide #12 - What do the numbers mean for selecting sheeting type?
(just read as intro to next several slides)
Slide #13 - Types that meet Minimums
All prismatics currently on the market may be used for all signs.
High-Intensity Beaded and Super Engineering Grade may be used for all signs except white legend on overhead guide signs.
Engineer Grade may be used for all signs except for:
- White legend on guide signs
- White legend on street name signs
- All warning signs
Even though a particular type of sheeting might initially meet the minimum retro level when it is new, it might quickly degrade to below the minimum, thus losing its effectiveness at night and requiring replacement during next assessment. The use of higher performance sheeting, even though it has a higher initial cost, might provide a better life-cycle cost for the agency.
Slide #14 - Types that meet Minimums (cont'd.)
New Yellow Material: Type I doesn't meet, Type II is a little above min, Type III better, prismatics generally much better (this is an average),
So.
Slide #15 - Types that meet Minimums (cont'd.)
Speaker's Notes:
This graph shows how different sheeting types may last. In general, those with higher initial retroreflectivity will take longer to degrade to the minimum values. NOTE: this is a generalized graph, not based on data. Agencies may want to determine the length of life for their sign, and using this concept develop a life cycle cost. THIS IS AN IMPORTANT CONCEPT THAN CAN SAVE $$.
Slide #16 - EXAMPLE of Life/Cycle Costs
(using invented numbers)
- Assume $160 to replace a sign with EG sheeting
(substrate, sheeting, labor) - If so, then
- SEG might be $164
- HI might be $168
- Pris might be $192
- Cost per year might look like:
EG: $160 / 0 = Can not calculate
SEG: $164 / 12?* = $14 / yr ??
HI: $168 / 12?* = $14 / yr ??
Pris: $192 / 16?* = $12 / yr ?? - Add in potential cost of traffic hazard
* Generalized numbers based on information from sign test racks
Speaker's Note
NOTE: this example has invented numbers. Go through calcs.
So based on this, you might determine the most cost-effective sheeting is not necessarily the one with the lowest initial cost, especially if you consider the risk to your crews out replacing signs more frequently. As you develop your assessment or management method, you may want to collect this life cycle information to help you make better decisions in the future.
Slide #17 - More Information
- FHWA fhwa.dot.gov/retro
- Summary Brochure
- Final Rule
- Power Point Presentations
- Newsletter Articles
- TTI tcd.tamu.edu
- Research Reports
- ATSSA www.retroreflectivity.net
- Q&A
Here are some sources that you can easily access to gain further information on retroreflectivity.
(Recommend handing out copies of the summary brochure: http://safety.fhwa.dot.gov/roadway_dept/night_visib/policy_guide/fhwasa07020/fhwasa07020.pdf at any live presentation.)
Program Contact
Cathy Satterfield
Cathy.Satterfield@dot.gov
708-283-3552
What's New
Sign Retroreflectivity Toolkit
Sign Upgrade Guide Specification
