Retroreflectivity What is it and Why Should I Care?
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DESCRIPTIONRetroreflectivity What is it and Why Should I Care?. Matheu J. Carter, P.E. T 2 Engineer Delaware T 2 Center October 15, 2009. Delaware T 2 Center. T 2 Centers or LTAPs located in all 50 states Funded by FHWA and state DOTs - PowerPoint PPT Presentation
RetroreflectivityWhat is it and Why Should I Care?Matheu J. Carter, P.E.T2 EngineerDelaware T2 Center
October 15, 2009Presented by Matt Carter as part of the October 15, 2009 Retroreflectivity Part 1 Click Listen & Learn Webinar by American Public Works Association.1
Delaware T2 CenterT2 Centers or LTAPs located in all 50 statesFunded by FHWA and state DOTsMission promote training, tech transfer, research implementation at local levelDelaware T2 hosted by University of Delaware, part of Delaware Center for Transportation
Many of you are probably familiar with the T2 Center or Local Technical Assistance Program in your state (or tribal region), which are funded by Federal Highway Administration, state DOTs, and often state universities. Our primary mission is to assist local agencies with transportation challenges through training, technology transfer, research, and all kinds of other creative means. Delawares center is based at the University of Delaware. 2
Matt CarterCurrently, Delaware T2 Engineer, Municipal Engineering Circuit Rider, Safety Circuit RiderProfessional Engineer, licensed in six states20+ year career, civil & env engineeringBridge, road, utility constructionDesign consultingPublic sector (Director, DPW, Cecil County, MD)
Just for a sense of my background, Im currently the T2 Engineer in Delaware with a focus on the Municipal Circuit Rider program and our Safety Circuit Rider program. Im a professional engineer with about 22 years or so of experience in heavy construction, design consulting, litigation support, and public sector administration. My most significant sign experience has been the 8 years or so I spent at Cecil County Government, mostly as Director of the Department of Public Works, and of course, my time here at the T2 Center. 3
OutlineWhat is retroreflectivity?What is the MUTCD and to whom does it apply?What is the origin of the retroreflectivity standards?What are the standards?What do you need to do and when?What are your options for compliance?What should you be doing now?Why should you take it seriously?
Heres a quick idea of the territory Ill cover before Ron takes us deeper into tort liability and other issues. 4
CautionThis is a big topicWhile a good start, this 2-hour webinar alone wont prepare youSo where else can you turn?The November 5 APWA CLL will be a big help alsoFHWA, APWA, ATSSA, NACE, and others have great web contentLTAP or T2 Centers in each state and tribal region many are conducting local training in your area
So, what is retroreflectivity?And what is it not?It is the ability of a material to return light back towards its sourceIt is not mirror-reflectivity, which bounces light off in the opposite directionIt is definitely not diffuse reflection, which scatters the light source think of a painted wall
So, what is retroreflectivity?These signs have varying retroreflective levels notice how brightly one returns the light versus the others
Which of the stop signs below do you want at the intersections as your teenage child or grandparent comes home on a rainy night?
Manual on Uniform Traffic Control DevicesThe MUTCD is the national standard for all traffic control devices installed on all roads that are open to public travelApplies to TCDs on any street, highway, or bicycle trail open to public travel 23 CFR Part 655 Subpart FMany states have their own MUTCD that meets or exceeds the federal manual
The MUTCD is incorporated by reference in 23 Code of Federal Regulations (CFR), Part 655, Subpart F and shall be recognized as the national standard for all traffic control devices installed on any street, highway, or bicycle trail open to public travel in accordance with 23 U.S.C. 109(d) and 402(a). 8
Origin of retroreflectivity standardsGeneral retroreflectivity standards have existed in the MUTCD for some time Section 2A.081993 DOT appropriations act required standardsMinimum retroreflective requirements established in Revision 2 of the 2003 Edition Section 2A.09Minimum requirements resulted from research targeted at the reduced reaction times and vision of some older drivers this becomes important with some of the compliance methodsSection 2A.08 - Standard: Regulatory, warning, and guide signs shall be retroreflective or illuminated to show the same shape and similar color by both day and night, unless specifically stated otherwise in the text discussion in this Manual of a particular sign or group of signs.Section 2A.09 - Standard: Public agencies or officials having jurisdiction shall use an assessment or management method that is designed to maintain sign retroreflectivity at or above the minimum levels in Table 2A-3.Revision 2 was published as a Final Rule December 21, 2007.9
The standards Table 2A-3
This is what all the ruckus is about. It looks very complicated if you arent already familiar with sheeting types and sign designations, but its not too bad if you begin by focusing on the top third, which addresses a lot of your signs; lets do that.10
The standards Table 2A-3Sheeting typesBeaded (Engineer Grade, Super Engineer Grade, High Intensity)Prismatic (High Intensity Prismatic, Diamond Grade, etc.)ExamplesEnd Detour (black on orange) orange 50Do Not Enter sign (white on red) white 35; red 7 and contrast of white to red 3:1 (wash out concern)
There thats better. Spend some time reading this part of Table 2A-3 at some point and it will become clearer. For example, you may know the sheeting types as Engineer Grade or Diamond Grade or DG3. Now, lets take a couple quick examples. An End Detour sign is black on orange and so the orange must be greater than 50 candela per lux per meter square, which is the unit of measure we use but hardly ever say, so dont worry about that term a whole lot right now. Now, why no requirement for the black that sits on the orange? Because the black legend isnt intended to be retroreflective indeed, its supposed to be non-reflective so there is a contrast with the orange. Now we could do all kinds of examples, but lets just consider one other slightly weird one because youll have so many of them white on reds. I chose to show a Do Not Enter sign here, but the normal example is a Stop sign. Notice with white on reds, we have an additional criteria note (#4) that requires a contrast of white to red no less than 3 to 1 thats because red tends to wash out, as you see in the ghost of a Stop sign shown here. Now we dont want to get too far in the weeds with this webinar so were going to leave the nuances of this table to Part 2 of this Click Listen and Learn series.11
Exempt signsParking/Standing/StoppingWalking/HitchhikingAdopt-A-HighwayBlue or Brown BackgroundsExclusive Use of Bikesor Pedestrians
Note: Must still meet otherrequirements in MUTCD(inspections, retroreflective,etc.)
12Welcome Module12Not all signs have to meet minimum levels, at least for now. For example, here is a list of exempt signs.
Although some Blue and Brown signs are just as important as those signs impacted by the new requirements, when the rule-making process was initiated, the research for minimum retroreflectivity levels for blue and brown signs was just beginning. That research has now been completed and if the recommendations are added to the MUTCD, then the process will have to go through rule-making, just like any change or addition to the MUTCD. The research report for blue and brown signs is available on the FHWA web page: fhwa.dot.gov/retro.
What to do and when?Develop and implement a method or methodsCompliance with theStandard is achieved by having a method in place and using the method to maintain the minimum levels established in Table 2A-3. Provided that an assessment or management method is being used, an agency or official having jurisdiction would be in complianceeven if there are some individual signs that do not meet the minimum retroreflectivity levels at a particular point in time. Section 2A.09Effective date of Final Rule January 22, 20081st compliance deadline January 2012 (4 yrs)2nd compliance deadline January 2015 (7 yrs)3rd compliance deadline January 2018 (10 yrs)Well, you start by selecting a maintenance method or management method or some combination of each and well talk about what those are in a very overview fashion in just a moment. But notice something terribly important in this excerpt of Section 2A.09 of the MUTCD it specifically tells you that you are in compliance with the retroreflectivity aspects of the MUTCD once you have a set of methods in place, even if some individual signs fail retroreflectivity. Now this is no get out of jail free card, but it underscores the notion that a structured and diligent program of sign maintenance is the real requirement here and, presumably, you wont be viewed as negligent if you have one or two signs in a hundred that dont meet the standards at any given time, provided you have an effective program underway.
These compliance dates seem like a long time from now, but theres some preparation that needs to be done and waiting until the last minute is a poor strategy. Lets talk about what these entail. 13
What to do and when?January 2012 Implementation & continued use of an assessment or management method designed to maintain retroreflectivity at or above established minimum retro levels (Table 2A-3)January 2015replacement of regulatory, warning, and ground-mounted guide (except street name) signs identified as failing to meet the minimum retro levelsJanuary 2018replacement of street name signs and overhead guide signs identified as failing to meet the established minimum levels.So, by January 2012, agencies must inventory their signs and select a management or maintenance method or combination thereof and put it into use to maintain retroreflectivity levels. Some form of formal adoption of methods should be made (such as policy statement or standard operating procedure) and then the implementation should be documented over time as part of the affirmative defense that you will hopefully never need for a court case. By 2015, regulatory, warning and most guide signs must meet the standards in Table 2A-3 and then in 2018, the additional guide signs must come into compliance. Beginning now will give you some time to develop funding for sign replacements by 2015 and 2018. 14
The methodsVisual Nighttime InspectionCalibration SignsComparison PanelsConsistent Parameters Measured Sign Retro
Expected Sign LifeBlanket ReplacementControl SignsFuture Method Based On Engineering StudyCombination Of Any
15In the new MUTCD language, Section 2A.09, there are a number of different methods listed that can be used to maintain traffic sign retroreflectivity. These are generally described as assessment methods, which are those listed on the left, and management methods, which are those listed on the right. Remember this slide, because it is essentially the menu well be working from for the next 15 minutes.
We will go through these very, very quickly, but Part 2 of this webinar series on November 5th will look much closer at these. 15
Visual nighttime inspectionTrained inspectorVisual inspection/assessment at nightNeed to tie to minimum values by usingCalibration signs procedure, orComparison panels procedure, orConsistent parameter procedure
16First up is a collection of Visual Assessment methods.
Note, there are three different procedures allowed within the Visual Assessment Method. Only one of the procedures needs to be used if a Visual Assessment Method is selected by your agency; not all three.
Of course, the procedures could be combined too.
However the Visual Assessment Method requires a Trained inspector and must be conducted at night. 16
Visual nighttime inspectionCommon elements of all visual assessment techniquesProperly aim inspection vehicle headlampshttp://www.automedia.com/Aiming_Headlights/ccr20010801ha/1http://www.coolbulbs.com/HID-VISUAL-HEADLIGHT-AIMING-PROCEDURE.pdf Two-person crew works bestHaving an inventory in advance is idealHave evaluation form and criteriaConduct evaluations at roadway speedUse low-beam headlamps
17Welcome Module17For any of the Visual Assessment methods, these will apply.
Dont assume the vehicle headlights are aimed properly calibrating them is easy and there are a number of websites to guide you through it, including those shown here.
Inspections are performed with low beams.
Because you perform the evaluations while driving at normal speeds in the travel lane, it is best to have a two person crew, to work from a sign inventory and to have evaluation forms that encourage consistent application of criteria.
[Option, if time: Generally, the driver should assess the signs and the passenger should navigate, complete forms, take notes, provide information from the inventory as to upcoming signs, etc. Because the passenger will need some form of light, it is best to sit in the backseat and utilize a book light or similar device to minimize the effect of internal light on the drivers assessment.]
You calibrate your eyes with calibration signsCalibration signs are near minimum retroYou then evaluate signs as compared to calibration signs
Calibration signs18Welcome Module18Using calibration signs is one of the three different procedures we saw about three slides back that meet the requirements of the Visual Assessment Method for maintaining sign retroreflectivity.
The trained inspector will calibrate his or her eyes to a sample of signs that have been pre-determined to be near the minimum levels.
Those shown here with arrows might be good candidates, although photographs do not show actual retroreflectivity well, so who knows.
But the key point here is that you dont want new signs as the calibration signs; you want signs just above the minimum retroreflectivity levels we saw in Table 2A.3.
The inspector looks at the sample signs at night, from a predetermined distance, in the inspection vehicle that will be used.
The inspector then drives the roads and documents those signs that appear to not meet the same brightness as the sample signs.
It is very important that the inspector be trained in the proper procedures for conducting the evaluation.
Comparison panelsTie to minimum values with comparison panelsPanels are near desired retroClipped to sign - viewed from distanceEvaluate signs compared to panels
19Welcome Module19The second of the three Visual Inspection procedures we saw four slides ago is called the comparison panel procedure.
As the name implies, this procedure consists of small panels at pre-determined retroreflectivity levels that are used to visually inspect signs identified as marginal during nighttime inspections.
A set of comparison panels is shown in the box on the lower right. The s...