Performance Criteria for Retroreflective Pavement Markers (2022)

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33   Survey and Review of State Practices The research team sent surveys to representatives of all 50 states to identify the current state of use of RPMs. The survey was administered in two phases. An initial survey was sent in 2015. The survey in 2015 initially queried states on whether they had RPMs. For those states that had RPMs, a more detailed survey was sent (see Figure 2 for a list of questions sent as part of this survey). This initial survey was meant to collect information regarding the use and main- tenance of RPMs in addition to state preference on willingness to provide RPM data for safety evaluation. A follow-up survey was conducted in 2018. In the follow-up survey, three different sets of questionnaires were sent to three different groups of states: • Group 1: States that responded YES to using RPMs in the initial survey. • Group 2: States that did not respond to the initial survey. • Group 3: States that responded NO to using RPMs in the initial survey. The set of questions sent to each of these groups can be found in Figure 3 through Figure 5. These surveys were used to re-collect information regarding the use and maintenance of RPMs with detailed questions on the types of RPMs used, the cost associated, and maintenance and roadway issues attributable to RPMs. In addition to conducting surveys on the use of RPMs in all 50 states, a review of state prac- tices and policies was also conducted by reviewing documents available on state DOT websites. In order to determine what current state policies were regarding RPMs, the following process was followed for all 50 states; Washington, DC (DC); and Puerto Rico (PR): • Check official MUTCD documentation for any references to RPMs and record aberrations, alterations, and additions in comparison to the national MUTCD policies. • Check the state DOT website for standard drawings and standard specifications relating to RPMs. • Search DOT website for any other documents (bulletins, memos, guides, etc.) that mention RPM policies in any way. – Sample keywords: RPMs, raised pavement, pavement markers, standard plans, standard specifications, standard drawings, pavement markings, snowplowable markers, MUTCD, RPM maintenance, SRPM [snowplowable RPMs], plowable markers. • Download all documents that are found to have some relevance to RPMs. • Download all documents that have a conspicuous absence of RPM-mentions despite normally being a source of related information. • Distill and record information. C H A P T E R 3

34 Performance Criteria for Retroreflective Pavement Markers Figure 2. Questionnaire for initial survey conducted in 2015. Figure 3. Group 1 questionnaire for follow-up survey conducted in 2018.

Survey and Review of State Practices 35   Figure 4. Group 2 questionnaire for follow-up survey conducted in 2018. Figure 5. Group 3 questionnaire for follow-up survey conducted in 2018.

36 Performance Criteria for Retroreflective Pavement Markers 3.1 Use of RPMs Information regarding the use of RPMs was collected using both the state survey and the review of state policies regarding RPMs. Table 9 and Table 10 provide the survey responses from both the initial and follow-up surveys conducted in 2015 and 2018 and a summary of RPM usage for all 50 states. As Table 9 indicates, in the initial survey conducted in 2015, 27 states reported using RPMs, while 11 states reported not using RPMs, and 12 states did not respond to the survey. In the follow-up survey conducted in 2018, each of these three groups of states was sent a different questionnaire meant to reconfirm and update the initial responses. Of the 27 states that reported using RPMs in the initial survey, 11 states responded to the follow-up survey. Of the 12 states that did not respond to the initial survey, four states responded to the follow-up survey, with two states reporting using RPMs and two states reporting not using RPMs. Overall, at the end of the follow-up survey, the responses (see Table 10) indicated that 29 states use RPMs and 13 states do not use RPMs. Due to the lack of responses, RPM usage for eight states could not be determined from the surveys. Table 11 provides RPM usage as identified from the review of state policies for all 50 states; Washington, DC; and Puerto Rico. As Table 11 shows, documentation of state policies from 35 states strongly indicates the use of RPMs. All states with minimal snowplowing use RPMs. All states that do not use RPMs receive significant snowfall and would have to install either snowplowable or recessed RPMs if they were to use RPMs. Some inconsistencies can be observed between the survey responses (Table 9 and Table 10) and the state policies (Table 11) regarding the use of RPMs. • Colorado, Connecticut, Maine, and Montana reported not using RPMs in the surveys; how- ever, this was not confirmed or disproven by their current state documentation. (Maine responded in the survey to using RPMs in the past.) • Hawaii, New Hampshire, and Wyoming reported using RPMs in the surveys; however, RPMs are not present in their standard drawings. • South Dakota reported not using RPMs in the survey; however, respondents did mention temporary use of RPMs from traffic control, as was confirmed in the review of their state documents. Status Quantity States States surveyed in 2015 responding that RPMs are used (Group 1). 27 AL, AR, AZ, CA, DE, GA, HI, IL, IN, KY, LA, MD, MS, NC, NH, NM, NV, NY, OH, PA, SC, TN, TX, VA, WA, WV, WY States surveyed in 2015 that did not respond to the survey (Group 2). 12 AK, FL, MA, ME, MN, MO, ND, NJ, OR, RI, SD, UT States surveyed in 2015 responding that RPMs are not used (Group 3). 11 CO, CT, IA, ID, KS, MS, MT, NE, OK, VT, WI Group 1 states that responded to the follow-up survey in 2018. 11 AR, AZ, DE, HI, KY, MS, NH, OH, PA, SC, WV Group 2 states that responded to the follow-up survey in 2018 stating that RPMs are used. 2 FL, MA Group 2 states that responded to the follow-up survey in 2018 stating that RPMs are not used. 2 ME, SD Group 3 states that responded to the follow-up survey in 2018. 9 CO, CT, IA, MI, MT, NE, OK, VT, WI Table 9. Survey responses from 2015 and 2018 on the use of RPMs.

Survey and Review of State Practices 37   • Idaho and Oklahoma reported not using RPMs in the surveys; however, their state docu- mentation indicates the use of RPMs. (Oklahoma responded in the survey to using RPMs in the past and mentioned that the existing RPMs are being removed with a very low priority.) • New Jersey, North Dakota, and Oregon did not respond to the surveys; however, their state documentation indicates the use of RPMs. Table 12 shows a summary of RPM usage by state, as was confirmed using the surveys and/or the review of state practices. Twenty-six states were confirmed as using RPMs from both surveys and the review of state practices. An additional three states were confirmed as using RPMs from the surveys, and six states (plus Washington, DC, and Puerto Rico) were confirmed as using RPMs from the review of state practices. Fifteen states were not using RPMs (confirmed by either the surveys or the review of state practices) or did not respond to the surveys (but could also not be confirmed as using RPMs from the review of state practices). Status Quantity States States surveyed in 2015 and 2018 responding that RPMs are used. 29 AL, AR, AZ, CA, DE, FL, GA, HI, IL, IN, KY, LA, MA, MD, MS, NC, NH, NM, NV, NY, OH, PA, SC, TN, TX, VA, WA, WV, WY States surveyed in 2015 and 2018 that did not respond to the survey. 8 AK, MN, MO, ND, NJ, OR, RI, UT States surveyed in 2015 and 2018 responding that RPMs are not used. 13 CO, CT, IA, ID, KS, ME, MI, MT, NE, OK, SD, VT, WI Table 10. Summary of the use of RPMs based on survey responses. Status Quantity States, DC, and PR States explicitly stating in documentation that RPMs are not used. 5 MN1,2; MO3; UT4; VT5; WI6 States surveyed in 2015 and 2018 that either did not respond or responded that RPMs are not used, but not confirmed or disproven by current documentation. 5 CO7,8; CT7; ME7,9,10; MT7,11; RI7,12,13 States where RPMs are absent from standard drawings or limitation of RPM-mentions in documentation to temporary or other special and limited uses. 7 HI14,15; IA16,17; KS18,19,20; NE21,22,23; NH24,25,26,27,28,29,30,31,32,33,34; SD35; WY36 States that did not respond to the surveys in 2015 and 2018, but current documentation seems to strongly indicate the use of RPMs. 4 AK7,37,38,39; NJ40,41,42; ND43,44; OR45,46,47,48,49,50 States with documentation indicating use of RPMs. 31 AL51,52; AZ53,54,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71; AR72,73,74; CA75,76,77,78,79,80,81,82; DE83,84,85; FL86,87,88; GA89,90,91,92; ID93,94; IL95,96,97; IN98,99,100; KY101,102,103,104,105,106,107,108,109,110,111,112,113; LA114,115,116,117,118; MD119,120; MA121,122,123,124; MI125,126,127,128,129,130; MS131,132; NV133,134,135; NM136,137; NY138,139,140; NC141,142,143,144; OH145,146,147,148,149; OK150,151; PA152,153,154; SC155,156,157; TN158,159,160,161; TX162,163,164,165,166,167; VA168,169,170; WA171,172,173,174,175,176,177,178; WV179,180,181,182; DC183; PR184 Table 11. Use of RPMs based on review of state policies.

38 Performance Criteria for Retroreflective Pavement Markers The following sections focus on summarizing data from only the 35 states (plus Washington, DC, and Puerto Rico) with either the survey responses or state documentation indicating the current use of RPMs. 3.2 Types of RPMs Used Information on the types of RPMs used by states was collected from the surveys and the review of state practices. Table 13 provides information from the survey responses on the types of RPMs used. Table 14 provides information extracted from the review of state practices on the types of RPMs used. The data in Table 13 and Table 14 were categorized under different types of RPMs used by states. These included raised, snowplowable, and recessed RPMs individually and in combina- tion. The survey responses from 19 states indicated the type of RPMs used, whereas the review of state practices led to information on the type of RPMs used by 35 states. Status Quantity States Raised RPMs only 4 FL, HI, MS, OH Snowplowable RPMs only 4 IN, PA, TN, VA Snowplowable and recessed RPMs 6 KY (snowplowable RPMs were used in the past, currently only using recessed RPMs), MA (snowplowable RPMs were used in the past, currently only using recessed RPMs), MD, NH, NY, WV Raised and snowplowable RPMs 3 AR (snowplowable RPMs were used in the past; currently only using recessed RPMs), DE, SC Raised and recessed RPMs 2 AZ, WA Table 13. Types of RPMs used based on survey responses. Table 12. Summary of the use of RPMs based on surveys and review of state practices. Status Quantity States States using RPMs (confirmed from both surveys and review of state practices) 26 AL, AR, AZ, CA, DE, FL, GA, IL, IN, KY, LA, MA, MD, MS, NC, NM, NV, NY, OH, PA, SC, TN, TX, VA, WA, WV States using RPMs (confirmed from surveys but could not be confirmed from the review of state practices) 3 HI, NH, WY States (plus DC and PR) using RPMs (confirmed from review of state practices but could not be confirmed from surveys) 8 AK, ND, NJ, ID, MI, OKa, DCb, PRc States not using RPMs (confirmed from either surveys or review of state practices) or did not respond to the surveys (could also not be confirmed as using RPMs from the review of state practices) 15 CO, CT, IA, KS, ME, MN, MO, MT, NE, OR, RI, SD, UT, VT, WI NOTE: aOklahoma responded to the surveys as having used RPMs in the past, with some RPMs still existing without maintenance. bWashington, DC, was not sent survey questionnaires. cPuerto Rico was not sent survey questionnaires.

Survey and Review of State Practices 39   Some inconsistencies can be observed between the survey responses (Table 13) and the state policies (Table 14) regarding the types of RPMs used. • Ohio responded to the survey as using raised RPMs; however, a review of its state documents suggested that it uses snowplowable RPMs. • Tennessee responded to the survey as using snowplowable RPMs; however, a review of its state documents suggested that it uses both raised RPMs and snowplowable RPMs. • Massachusetts and Maryland responded to the survey as using both snowplowable and recessed RPMs; however, a review of their state documents suggested that they only use recessed RPMs. • Delaware responded to the survey as using both raised RPMs and snowplowable RPMs; how- ever, a review of its state documents suggested that it only uses snowplowable RPMs. • Some differences may be due to the timeframe between the surveys and modifications to state practices that may not have been published when the documents were reviewed. In the survey, the states were also asked about their typical costs for RPM installation. A total of eight states gave responses regarding their costs of RPM installation. The responses are shown in Table 15. Status Quantity States, DC, and PR Raised RPMs only 7 AL51; FL88; GA92; LA114,118; MS131; SC156,157; PR184 Snowplowable RPMs only 13 DE85; ID94; IL97; IN100; KY113; MI130; ND44; NJ42; NY139,140; OH147,148; OK151; PA (recessed RPMs expressly prohibited for new installations)154; VA168,169 Recessed RPMs only 3 AK38,39; MA123; MD120 Snowplowable and recessed RPMs 1 DC183 Raised and snowplowable RPMs 6 AR (snowplowable RPMs removed from standard drawings in 2010)72,73; NC142; NM136; TN159,160,161; TX165,166; WV182 Raised and recessed RPMs 5 AZ54,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70; CA79,80; NV135; OR45,50; WA176 Table 14. Types of RPMs used based on review of state practices. States Costs Associated Arizona Arizona uses raised RPMs and recessed RPMs. They typically cost $2.50–$3.00 each. Arkansas Arkansas currently only uses raised RPMs. The contract price of an RPM ranges from about $6.50–$11.50 per marker. Using state forces, the price is about $4.00 per marker. Delaware Delaware uses raised RPMs and snowplowable RPMs. Each RPM costs approximately $70.00. Hawaii Hawaii uses raised RPMs. Cost of Type A (nonreflective) is $6–$8 per each; Type C, D, and H (reflective) cost $7–$10 each. Kentucky Kentucky uses recessed RPMs and snowplowable RPMs. RPM costs are as follows: recessed (2 markers, 1 groove)—$35; snowplowable lenses only—$6; snowplowable markers and lenses—$21. Mississippi Mississippi uses raised RPMs. They typically cost about $4.00–$5.00 each. Ohio The installed, raised RPM cost is about $22.57 each. Pennsylvania Pennsylvania uses snowplowable RPMs. Costs typically range from $30–$50 for a new RPM. Table 15. Costs associated with the types of RPMs used based on survey responses.

40 Performance Criteria for Retroreflective Pavement Markers As Table 15 indicates, there is no uniformity in costs of RPMs among the eight states that responded. The cost of an RPM ranges from approximately $2.50 to $70.00 per marker. This large range is due to the different types and application methods for the RPMs. 3.3 Installation of RPMs This section provides information regarding (a) RPM installation guidelines collected from the survey responses (information about system-wide installations) and the review of state policies (detailed guidelines on where RPMs should be installed), and (b) RPM placement (spacing) criteria as extracted from the survey responses and the review of state policies. 3.3.1 RPM Installation Guidelines Information regarding RPM installations was collected both from the state survey and the review of state policies regarding the use of RPMs. The state survey mainly focused on whether RPMs are implemented system-wide or only for certain sections based on the crash history or other parameters. The responses from the survey are presented in Table 16. The review of state policies focused mostly on extracting detailed guidelines on where RPMs should be installed. This information is presented in Table 17. As Table 16 shows, the majority of the states that responded to the survey install RPMs system- wide across different categories of roadways, with some exceptions where RPM installations are based on a request from the district engineers or police officers. Another point to note here is that only three survey responses from states (Delaware, Hawaii, and Pennsylvania) specifically mentioned using RPMs on bridge decks. As Table 17 indicates, the review of state practices showed that there is no uniformity among the states regarding where RPMs should be installed. The state DOTs do not use the same cate- gories, nor do they use the same criteria within each category for evaluating where RPMs should be installed. Sixteen states in the analysis group have at least a partial guideline. However, since these guidelines are not standardized and many guidelines combine criteria from different categories (e.g., an AADT threshold and the presence of overhead lighting), a summary table outlining states with specific category values would not be of much use. Instead, Table 18 summarizes a variety of criteria put forth by the states. As Table 18 illustrates, there are numerous categories of consideration between the states that list at least a partial installation location guideline, in addition to the states with nonselective blanket installation policies (New Jersey, Ohio, and Texas). 3.3.2 RPM Placement (Spacing) Criteria Information regarding RPM placement (spacing) criteria was collected from both the state survey and the review of state policies regarding the use of RPMs. The state survey mainly focused on typical RPM placement criteria. The responses from the survey are presented in Table 19. The review of state policies provided a more detailed overview of RPM placement criteria for centerlines, edge lines, ramps, curves, and gore areas. These results are presented in Table 20 through Table 27. Table 19 shows that the majority of states surveyed use 80-ft spacing, while two states (Arizona and Florida) primarily use 40-ft spacing. In Hawaii, 20-ft spacing is commonly used for center- lines, whereas 40-ft spacing is used for edge lines. The following sections provide information about longitudinal RPM spacing and transverse RPM placements extracted from the review of state practices.

Survey and Review of State Practices 41   States Condition Alabama RPMs are used system-wide on all interstate, federal, and state routes. Some counties and cities also use RPMs, but it is not widespread. Arizona RPMs are installed system-wide on the state highway system. Arkansas RPMs are used for certain road types unless condition warrants on other roads (see policy). Policy is not different in different parts of the state. California RPMs can be used on any roadway. There is a statewide policy and standards for districts on RPM use. District engineers can determine where and when to use them on the state roadway system. Delaware RPMs are implemented system-wide and have been since 2007. They also install RPMs on bridge decks. Florida RPMs are installed system-wide. Hawaii RPMs are installed system-wide. They also install RPMs on bridge decks. Illinois RPMs are installed system-wide A policy lists specific situations where RPMs should be used, but these situations encompass most of their highways. Indiana RPMs are implemented system-wide on all freeways. RPMs should also be installed on nonfreeways if rumble strips are not installed and the AADT exceeds 2,500 for two-lane roads or 6,000 for multilane roads. Kentucky RPMs are installed system-wide on multilane roadways (median and no median). Maryland RPMs are installed system-wide. Massachusetts RPMs are implemented system-wide since 2004. Mississippi RPMs are implemented system-wide as a part of new overlay projects or occasionally as district-wide RPM replacement projects. Nevada RPMs are used in the southern part of the state (Las Vegas area), where they are standard on most roadways including the interstate system. New Hampshire RPMs are installed only in areas where the town’s police chief requests their installation due to higher-than-normal crash rates. New Mexico RPMs are only implemented at the request of the district traffic engineer (mostly by preference instead of data- or classification-driven approach). New York RPMs are used only as temporary supplemental markings in work zones. North Carolina RPMs are used in every division except in areas with heavy snowplowing. There is no official policy to use RPMs. However, divisions use them on most of their two- lane, two-way roadways. Each division is a little different on its use with regard to AADT. Most divisions will not install them with an AADT less than 4,000 while others set the mark at 6,000. Ohio RPMs are system-wide on all interstates, U.S. routes, and state routes that are maintained by Ohio DOT. Pennsylvania RPMs are installed system-wide. They also install RPMs on bridge decks. South Carolina RPMs are installed system-wide on all state-maintained roads with ADT ≥ 500. Tennessee RPMs are installed system-wide with a focus on (but not limited to) four-lane divided highways and higher classification routes. Virginia RPMs are installed on all interstates and other limited access highways where the speed limit is ≥ 55 mph; for all roadways with speed limit ≥ 60 mph; for all two- lane roadways with ADT ≥ 15,000 and no roadway lighting; and for unlit multilane roadways with ADT ≥ 25,000 and speed limit ≥ 45 mph. There is an exception that RPMs may be omitted on some very short (< 2 mi) sections of limited access highways (for example, a short bypass around a small town) if the adjacent sections do not have RPMs. Washington RPMs are used at the discretion of the region traffic engineer. West Virginia RPMs are used system-wide on expressways, typically with a 65 mph speed limit. There is no policy for RPM installation on two-lane roads, where they are handled on a case-by-case basis. Table 16. System-wide installations of RPMs based on survey responses. 3.3.2.1 Longitudinal RPM Spacing Based on the Review of State Practices 3.3.2.1.1 White Broken Lane Line. A summary of longitudinal RPM spacing along the white broken lane lines is presented in Table 20. As Table 20 shows, a majority of states use 80-ft spacing, while most of the remaining states use 40-ft spacing. Three states (California, Michigan, and Idaho) have unique spacing require- ments. Three states (Ohio, Mississippi, and Idaho) have longer spacing specified for freeways. For four states (New York, North Dakota, Oklahoma, and Puerto Rico), no specific data were found. Certain states like Alabama51 and Florida87 make use of black lag lines in conjunction with white broken lane lines to enhance the white lines’ visibility. However, RPM spacing is based entirely

42 Performance Criteria for Retroreflective Pavement Markers States Condition Arizona • Type E (edge line) pavement markers should not be installed in areas of continuous illumination or where mechanical sweeping is routinely performed.68 • Pavement markers can be installed in the rumble strip if necessary.68,70 • Raised RPMs at elevations < 4,000 ft, recessed RPMs > 4,000 ft.54,55,56,58,59,60 Delaware • Always: interstates, freeways, expressways, and principal arterials. • Sometimes: conventional roads with posted speed limits of 45 mph or greater; horizontal/vertical curves; and areas of low lighting, a history of roadway departure crashes, advisory speed postings, or where a barrier/parapet is < 6 ft from the edge of the travel lane. • Never: surface-treated roadways.83 Idaho Any roadway where justified by engineering judgment or by an engineering study.93 Indiana Two-way white-red RPMs within 200 ft of all public road intersections.99 Kentucky • Always: all sections of roadway that are identified in the Raised Pavement Marker System (system inclusion criteria not defined) and sections of road with a two-way left-turn lane. • Never: bridge decks.101 Louisiana • Edge lines: all multilane roadways, two-lane roadways with a traveled way width ≥ 20 ft and ADT ≥ 6,000 vehicles per day. • Centerlines: roadways with a traveled way width ≥ 16 ft. • Narrow bridges: on edge lines at 20-ft centers.114 Massachusetts All state-owned highways that meet the following criteria: • Along the lane lines on freeways. • Along the lane lines of all multilane, nondivided highways with posted speed limits of 40 mph or greater. • Along the centerlines of nondivided highways with posted speed limits of 40 mph or greater. • Along channelizing lines of freeways at exit and entrance ramp gores. • Along the left edge lines of exit and entrance ramps. • Never: bridge decks.122 Michigan Always: all freeways without lighting along lane lines and ramp gores.127 New Jersey Regardless of the lighting conditions, designers should include RPMs on all HMA surfaces to supplement traffic stripes.40 North Dakota Recommended for locations with unusual or unexpected geometry that requires a greater degree of delineation than average.44 Ohio RPMs should be used on Ohio DOT-maintained highways. They should be included in new construction and resurfacing projects on Ohio DOT-maintained highways. They may also be included in the plans at other locations.149 Oregon • Raised pavement markers should be used in accordance with the region RPM plan. Contact the region traffic engineer for guidance. • Never: bikeways.45 Pennsylvania • All interstate highways, freeways, and expressways. • As funding is available, install RPMs on high-volume National Highway System roadways, and on sections of other roadways where there is a higher-than-normal incidence of nighttime run-off-the-road crashes. • All bridges that are 200 ft or longer when RPMs are on the adjacent sections of roadway.154 Texas All roadways with centerlines.167 Virginia Always: • Limited access highways ≥ 2 mi in length and posted speed limit ≥ 55 mph. • Limited access highways < 2 mi in length and with posted speed limit ≥ 55 mph and where adjacent approaching or departing nonlimited access sections are marked with SRPMs. • Roadway facilities with posted speed limit ≥ 60 mph. • Two-lane, two-way roadways with AADT ≥ 15,000 and no roadway lighting. • Multilane roadways with AADT ≥ 25,000 and posted speed limit ≥ 45 mph and no roadway lighting. Sometimes (implementation is up to engineering judgment): • Multilane roadways with 15,000 ≤ AADT < 25,000 and posted speed limit 45 mph–55 mph. • Two-lane, two-way roadways with 5,000 ≤ AADT < 15,000 and only if the sections do not have multiple horizontal curves with posted speed limit < 55 mph. • Two-lane, two-way roadways with AADT ≥ 15,000 and roadway lighting present. • Multilane roadways with AADT ≥ 25,000 and posted speed limit 45 mph–55 mph and roadway lighting present. • High crash locations demonstrating significant crash proportions due to roadway departures, complex intersection configurations, detours, fog-prone areas, and highway segments with wet and nighttime crash histories that could be alleviated with snowplowable RPMs.168 • Never: bridge decks.169 Washington Not recommended for continuously illuminated sections of highway, but may be used. Note that recessed RPMs may be obscured by the groove on curves and fill with water on flat grades.177 Table 17. Detailed guidelines on where RPMs should be installed based on the review of state practices.

Survey and Review of State Practices 43   Category States All DOT-maintained roads (minimal exclusions) NJ, OH, TX All roads in a state-specific system KY, OR All freeways, highways, expressways, and similar DE, MA, MI, PA, VA Illumination (presence of roadway lighting) AZ, DE, MI, VA, WA Number of lanes LA, MA, VA Accident history DE, PA, VA Traffic volume (AADT) LA, PA, VA Normal speed limits (mph) DE, MA, VA Advisory speed limits (mph) DE Curves DE, VA Ramp and gore areas LA, MI Unusual roadway geometry ND, VA Traveled way width (ft) LA Existence of street-sweeping activities AZ Presence of median divider MA Existence of barriers near roadway DE Surface type DE Bridges (guidance on use or nonuse) KY, LA, PA, VA Bicycle paths/lanes OR Fog areas VA Engineering judgment ID, VA Proximity to intersection IN Note: States may appear in more than one category. States appearing within the same category do NOT necessarily have the same criteria within each category. See the previous table for sources. Table 18. Categorical summary of RPM guidance based on the review of state practices. States RPM Placement Criteria Arizona For lane dividing lines and on centerlines, 40-ft spacing is used. On striped medians, they are placed 6 ft inside the yellow striping at the edge of the lanes. Arkansas Varies from 80-ft spacing on freeways to 40-ft spacing on Arkansas’ primary highway network. Delaware Typically, 80-ft spacing is used. Florida Markers are installed at the midpoint of skip lines at 40-ft intervals. Hawaii Typically, 20-ft spacing is used except for edge lines, where 40-ft spacing is used. Illinois Typically spaced every 80 ft (every other skip dash) but may also be spaced at 20 ft or 40 ft for locations such as lane reduction transitions, freeway exit ramps, bidirectional turn lanes, etc. Indiana Generally placed at 80-ft intervals on tangent sections. Kentucky Markers installed at the midpoint of skip lines at 80-ft intervals on both divided and undivided highways. Massachusetts Markers installed at the midpoint of successive skip lines at 80-ft intervals. Mississippi In urban areas, the spacing is always 40 ft; however, in rural areas, it is 80 ft on tangent sections and 40 ft on curves. New York At the end or beginning of each skip line in some work zones. Ohio Generally, 80-ft spacing is used for both centerlines and edge lines. Pennsylvania Typically, 80-ft spacing is used. However, in some cases (such as curves and approaches to intersections), 20-ft and 40-ft spacings are also used. South Carolina For two-lane roads (most common), one raised marker is placed on the centerline every 80 ft. On interstate routes, clear/red bidirectional markers are placed on the lane lines at 80-ft spacing. On 12-inch gore markings, they are placed using 20-ft spacing along the outside edge of the marking. The vast majority of markers are applied using bituminous adhesive. Tennessee RPMs are primarily installed at 80-ft intervals; however, they are placed at 40-ft intervals on curves. Virginia Markers are generally placed at 80-ft spacing on tangent sections, at 40-ft spacing on curves with ≥ 3 degrees of curvature, and at 20-ft spacing when adjacent to freeway interchange on- or off-ramp gore areas. When markers are placed adjacent to double-yellow lines, the markers may be placed either between the double- yellow line or “doubled up” with pairs of markers outside of the double-yellow line. The latter is done when the pavement joint is between the double-yellow lines, and there are concerns about putting the SRPMs directly on the joint. Table 19. RPM placement (spacing) criteria based on survey responses.

44 Performance Criteria for Retroreflective Pavement Markers Center-to- Center Distance Quantity States, DC, and PR 80 ft 18 AK38; AL51; DE83; IL96; IN99; KY102,103,104,105,106,107,108,109,110,111; MA123; MD119; NC142; NJ41; OH (120 ft on freeways)146; PA153; SC156; TN159; TX163; VA168,169; WA173,175; WV180 40 ft 10 AR73; AZ68; FL87; GA89,90; LA (4x in a row spaced 2 ft apart on centerline for urban interstates)114; MS (80 ft on rural freeways)131; NM136; NV134; OR45; DC183 48 ft 1 CA75,76 100 ft 1 MI127,128 25 ft (< 40 mph) / 50 ft (> 45 mph) 1 ID (150 ft on freeways)93,94 No data/Not explicitly defined outside of standard MUTCD language 4 ND, NY, OK, PR Table 20. Longitudinal RPM spacing along white broken lane lines. Center-to-Center Distance Quantity States, DC, and PR 80 ft 14 AK38; AR72; DE83; IL (40 ft for undivided multilane)96; KY103,106; MD119; NC142; NJ41; OH146; PA (40 ft for fog or high accident areas)153; SC156; TN159; VA169; WA163 40 ft 10 AL51; AZ67; FL87; GA89; IN99; MS131; NM (20 ft on multilane roads)136; OR45; TX (80 ft on multilane)163; WV180 20 ft 3 LA114,116,117; NV134; DC183 24 ft 1 CA76 100 ft 1 MI127,128 25 ft (< 40 mph) / 50 ft (> 45 mph) 1 ID93,94 No data/Not explicitly defined outside of standard MUTCD language 5 MA, ND, NY, OK, PR Table 21. Longitudinal RPM spacing along yellow double-solid centerlines. on the position of the white lines and remains unaffected by the presence or absence of the black lag lines. Louisiana specifies groupings of four markers spaced 2 ft apart, with lead marker to lead marker spacing set at the normal 40 ft per placement for urban interstates.114 3.3.2.1.2 Yellow Double-Solid Centerline. A summary of longitudinal RPM spacing along the yellow double-solid centerlines is presented in Table 21. As Table 21 indicates, a plurality of states use 80-ft spacing, while most of the remaining states use 40-ft spacing. Three states (Louisiana, Nevada, and DC) have only 20-ft spacing. Three states (California, Michigan, and Idaho) have unique spacing requirements. Two states (Illinois and New Mexico) have shorter spacing at half the normal distance for multilane roads. Texas has longer spacing at double the normal distance for multilane roads.163 Pennsylvania halves the spacing for fog areas or areas with a high incidence of head-on or sideswipe crashes.153 For five states (Massachusetts, New York, North Dakota, Oklahoma, and Puerto Rico), no specific data were found. 3.3.2.1.3 Yellow Double-Solid Centerlines on Curves. A summary of longitudinal RPM spacing along the yellow double-solid centerlines on curves is presented in Table 22.

Survey and Review of State Practices 45   Table 22 shows that, with a total of nine states, the most common spacing along yellow double- solid centerlines on curves is 40 ft. Except for Florida,87 all states having a guideline for closer RPM spacing on curves have an original tangent spacing guideline of 80 ft or longer. Guidelines giving curvature by the length of the radius in feet were converted to degrees of curvature using the following equation: ( ) ( )° = × ° π × 100 360 2 [1]Degrees of Curvature ft Radius of Curvature ft An opportunity for further research exists in terms of determining how much (and if) RPMs should be rotated on curved one-way sections to face approaching traffic instead of having the reflective face in the direction parallel to the tangent at the RPM’s location along the curve. Orienting RPMs toward approaching traffic may benefit drivers by allowing greater preview time prior to a curve. Oregon’s standard drawings specify that RPMs placed on curves on one-way sections should be oriented to face the marker placed three markers behind.47 This potential benefit is limited to one-way sections since rotating markers on two-way sections would have an obvious detrimental effect on opposite-direction traffic. For 22 states, no specific data were found. Mississippi expressly noted the same 40-ft spacing on curves and tangents. 3.3.2.1.4 Yellow Broken Centerline. A summary of longitudinal RPM spacing along yellow broken centerlines is presented in Table 23. As Table 23 shows, a plurality of states use 80-ft spacing, while most of the remaining states use 40-ft spacing. Three states (California, Michigan, and Idaho) have unique spacing requirements. Two states (Illinois and New Mexico) have shorter spacing, at half the normal distance for multi lane roads. Oregon is one of the states that uses 40-ft spacing, but its guidelines allow for 80-ft spacing at the engineer’s discretion.45 For eight jurisdictions (Delaware, Maryland, Massachusetts, New York, North Dakota, Oklahoma, Washington, DC, and Puerto Rico), no specific data were found. Center-to- Center Distance Degrees of Curvature Range Tangent Spacing Quantity States, DC, and PR 40 ft 80 ft 9 >6° (954.93-ft radius) 80 ft 1 NC142 >5.730° (1,000-ft radius) 80 ft 1 PA153 >3.820° (1,500-ft radius) 80 ft 1 WA163 >3.581° (1,600-ft radius) 80 ft 1 AK38 >3° (1,910-ft radius) 80 ft 2 NJ41, VA169 No range given 80 ft 2 DE83, MD119 Multilane: where advisory speeds are 10+ mph less than posted speeds; Two-lane: where posted or advisory speeds are 45 mph or less 80 ft 1 IL96 40 ft, 20 ft 5° < curve < 10°, > 10° 80 ft 1 OH146 50 ft, 25 ft 3°30 ft < curve < 7°, > 7° 100 ft 1 MI127 May be reduced No range given 40 ft 1 FL87 40 ft No reduction 40 ft 1 MS131 No data/Not explicitly defined outside of standard MUTCD language 22 AL, AR, AZ, CA, GA, ID, IN, KY, LA, MA, ND, NM, NV, NY, OK, OR, SC, TN, TX, WV, DC, PR Table 22. Longitudinal RPM spacing along yellow double-solid centerlines on curves.

46 Performance Criteria for Retroreflective Pavement Markers Center-to-Center Distance Quantity States, DC, and PR 80 ft 15 AK38; AL51; AR72; IL96; IN99; KY106; NC142; NJ41; OH146; PA153; SC156; TN159; TX163; VA169; WA163 40 ft 9 AZ67; FL87; GA89; LA114; MS131; NM136; NV134; OR (80 ft optional)45; WV180 48 ft 1 CA76 100 ft 1 MI127,128 25 ft (< 40 mph) / 50 ft (> 45 mph) 1 ID93,94 No data/Not explicitly defined outside of standard MUTCD language 8 DE, MA, MD, ND, NY, OK, DC, PR Table 23. Longitudinal RPM spacing along yellow broken centerlines. Center-to-Center Distance Quantity States, DC, and PR 24 ft 7 Single 5 AL51; FL86; GA90; KY102,109,110; NC142 Double 2 AZ55,56,57,59,60,69; OR [12 ft (2) optional]46 48 ft 2 Single 1 IN99 Unknown 1 DE83 6 ft Double 1 NV134 30 ft Double 1 CA78 36 ft Double 2 AR73; MD119 40 ft Single 1 NJ41 60 ft Single 1 TN160 Solid Line Between Gore and Dotted ONLY 20 ft 3 Single 1 LA115 Double 2 PA153; VA169 40 ft Double 1 TX164 No data/Not explicitly defined outside of standard MUTCD language 16 AK, ID, IL, MA, MI, MS, NM, NY, ND, OH, OK, SC, WA, WV, DC, PR Table 24. Longitudinal RPM spacing along white dotted lane drop at exit ramps. 3.3.2.1.5 White Dotted Lane Drop at Exit Ramps. A summary of longitudinal RPM spacing along the white dotted lane drop at exit ramps is presented in Table 24. As Table 24 indicates, a weak plurality of states have a spacing guideline of 24 ft, and there is no semblance of a consensus on the spacing guidelines for RPMs on white dotted lane drops at exit ramps. Of the seven states that have a spacing guideline of 24 ft (Alabama, Arizona, Florida, Georgia, Kentucky, North Carolina, and Oregon), five recommend using a single RPM per placement (Alabama, Florida, Georgia, Kentucky, and North Carolina), while two recommend using two RPMs per placement (Arizona and Oregon). Oregon also allows the option of reducing the spacing from 24 ft to 12 ft.46 Of the 19 states with a guideline for spacing on white dotted lane drops at exit ramps, nine recommend using single RPMs per placement, nine recommend using two (side-by-side) RPMs per placement, and one (Delaware)83 does not explicitly define the number of RPMs per placement. Each state that has a guideline for RPM spacing on white dotted lane drops at exit ramps has a guideline that is lesser in value than the state’s guideline for white broken lane line spacing. For 16 states, no specific data were found. 3.3.2.1.6 White Theoretical-to-Physical Gore Area. A summary of longitudinal RPM spacing along the white theoretical-to-physical gore area is presented in Table 25.

Survey and Review of State Practices 47   As Table 25 shows, a weak plurality of states have a spacing guideline of 20 ft, and there is no semblance of a consensus on the spacing guidelines for RPMs in gore areas. Each state that has a guideline for RPM spacing in gore areas has a guideline that is lesser in value than the state’s guideline for white broken lane line spacing. Eleven of these states have a guideline that is exactly 50% of the state’s value for white broken lane line spacing (50 ft/100 ft: Michigan; 40 ft/80 ft: Illinois, Indiana, Kentucky, Ohio, and Tennessee; 24 ft/48 ft: California; 20 ft/40 ft: Arizona, Florida, Georgia, and DC). Eleven states have a guideline that is less than 50% of the state’s value for white broken lane line spacing (20 ft/80 ft: Delaware, Maryland, North Carolina, Pennsylvania, Texas, and Virginia; 12 ft/80 ft: West Virginia; 10 ft/40 ft: Arizona, Louisiana, and Nevada; 3 ft/80 ft: Alabama). Only one state (New Mexico) has a guideline that is more than 50% of the state’s value for broken lane line spacing.136 New Jersey is the only state with a variable guideline based on the length of the gore area.41 For 11 states, no specific data were found. 3.3.2.2 Transverse RPM Placement Based on the Review of State Practices 3.3.2.2.1 White Broken Lane Line. A summary of transverse RPM placement along the white broken lane lines is presented in Table 26. Table 26 shows that a majority of states recommend a single marker centered on the center- line of the striping for each RPM placement. Louisiana also specifies groupings of four markers spaced 2 ft apart per placement for urban interstates.114,115,116,117 Only one state, Michigan, speci- fies an offset placement.126,127 For six states, no specific data were found. 3.3.2.2.2 Yellow Double-Solid Centerline. A summary of transverse RPM placement along the yellow double-solid centerlines is presented in Table 27. Center-to-Center Distance Quantity States, DC, and PR 20 ft 10 AZ54,55,56,58,59; DE83; FL86; GA90; MD119; NC142; PA153; TX164; VA169; DC183 40 ft 5 IL96; IN99; KY102,108,109,110; OH146; TN160 10 ft 3 AR73; LA115; NV134 3 ft 1 AL51 12 ft 1 WV180 24 ft 1 CA78 30 ft 1 NM136 50 ft 1 MI126,127 10 ft when length < 80 ft, 20 ft at 80 ft < < 200 ft, 40 ft at > 200 ft 1 NJ41 No data/Not explicitly defined outside of standard MUTCD language 11 AK, ID, MA, MS, NY, ND, OK, OR, SC, WA, PR = length. Table 25. Longitudinal RPM spacing in the white theoretical-to-physical gore area. Placement Quantity States, DC, and PR Single marker on centerline of striping 28 AK38; AL51; AR73; AZ68; CA76; DE (at least 2 in. from construction joint)83; FL87; GA90; ID94; IL96; IN99; KY102,103,104,105,107,108,109,110,111; LA (4x in a row spaced 2 ft apart on centerline for urban interstates)114,115,116,117; MD119; MS131; NC142; NJ41,42; NM136; OH146,147; OR45; PA153; SC156; TN159,160; TX163; VA169; WA163; WV180; DC183 4 in. offset left of centerline 1 MI126,127 No data/Not explicitly defined 6 MA, ND, NV, NY, OK, PR Table 26. Transverse RPM placement along the white broken lane line.

48 Performance Criteria for Retroreflective Pavement Markers As Table 27 illustrates, a majority of states recommend a single marker centered between the two stripes for each RPM placement. Three of these states specify an exception for multilane roads; two states (South Carolina and Texas) specify using two markers, one offset on each side for multilane roads; and one state (Louisiana) specifies using two markers, side-by-side, between the two stripes for multilane roads.114,116,117 One state (Virginia) specifies using two markers, one offset on each side if the road seam is in between the lines.168,169 Six states (California; Florida; Georgia; Michigan; New Mexico; and Washington, DC) recommend using two markers, one offset on each side of the two stripes. For eight states, no specific data were found. 3.4 Using Red RPMs to Delineate Wrong-Way Traffic Flow This section provides information regarding the use of red-colored RPMs to delineate wrong- way traffic as extracted from the review of state practices. A summary of findings is presented in Table 28. Placement Quantity States, DC, and PR Single marker centered between both lines 21 AK38; AL51; AZ67,70; DE83; IL96; IN99; KY103,106; LA (two markers between lines for multilane)114,116,117; MD119; MS131; NC142; NJ41,42; OH146,147; OR45; PA153; SC (pair offset on each traffic side for multilane)156; TN159; TX (2 in. offset on each traffic side for multilane)163; VA (unless road seam between lines, then two markers 3 in. offset on either side)168,169; WA173; WV180 Two markers, one offset on each side 6 Offset: 1 in. 1 FL87 Offset: 2 in. 3 CA76; NM (2 in.–3 in.)136; DC183 Offset: 4 in. 1 MI127 Offset: 5 in. 1 GA89 No data/Not explicitly defined 8 AR, ID, MA, ND, NV, NY, OK, PR Table 27. Transverse RPM placement along the yellow double-solid centerline. Attribute Quantity States, DC, and PR Red expressly used to delineate wrong-way traffic flow 24 AK38; AL51; AR73; AZ54,55,56,57,58,59,60,62,68,69; CA75,76,78; DE83; FL87; GA89,90,91; ID94; IN99; KY102,104,108,109,110; LA114,115,116,117; MA123; MS131; NC142; NM136; NV134; OH146,147; PA153; SC156; TN160; TX163; VA168,169; WV180 Red expressly used to delineate wrong-way traffic flow as well as truck escape ramps 1 MD119 Red expressly used to delineate wrong-way traffic flow as well as symbols and transverse lines 1 NY138 Not mentioned in documentation, and monodirectional crystal markers used at intersection approaches 3 MI127,128; NJ41; WA173,174,175 Not mentioned in documentation, and monodirectional crystal markers used at intersection approaches, but observation shows that red is used to delineate wrong- way traffic flow in practice 1 IL96 Not mentioned in documentation 5 ND, OK, OR, DC, PR Table 28. Use of red RPMs to delineate wrong-way traffic.

Survey and Review of State Practices 49   As Table 28 indicates, a majority of states expressly recommend using red RPMs to delin- eate wrong-way traffic flow. Maryland specifies in its state MUTCD that red markers can also delineate truck escape ramps.119 New York specifies in its MUTCD supplement that red RPMs can be used to delineate symbols and transverse lines in addition to wrong-way traffic flow.138 However, no other documentation concerning these alternate implementations was found. Four states (Michigan, New Jersey, Washington, and Illinois) did not expressly confirm or deny that red RPMs are used to delineate wrong-way traffic flow. These four states also have documenta- tion indicating that monodirectional crystal (white) markers are used at intersection approaches [common areas for the utilization of bidirectional crystal (white)-red markers]. For five states (North Dakota; Oklahoma; Oregon; Washington, DC; and Puerto Rico), no specific data were found. 3.5 Reflectivity of RPMs This section provides retroreflectivity guidelines of RPMs as extracted from the review of state practices. The retroreflectivity of an RPM is expressed as the coefficient of luminous intensity (RI), also referred to as SI, and is measured in units of candelas per lux (cd/lux) or candelas per foot-candle (cd/fc). A summary of findings is presented in Tables 29 through 34. The standard guidelines, ASTM D4280 (nonplowable RPMs) and ASTM D4383 (plowable RPMs), recommend that reflectivity be tested after conducting a steel wool abrasion procedure with reflectivity values no less than 50% of the values outlined for new, nonabraded markers.185,186 Arizona and Hawaii adopted the steel wool abrasion procedure for testing markers without adopting the 50% reflectivity reduction factor. For these states, minimum SI levels after a steel wool abrasion procedure are the same as the ASTM D4280 and ASTM D4383 standard values for nonabraded markers: 0 degrees (White—3.0, Yellow—1.8, Red—0.75) and 20 degrees (White—1.2, Yellow—0.60, Red—0.30).71 Additionally, Hawaii has reflectivity guidelines for measurements taken after 1 year of field evaluation (requirements: White—0.30, Yellow—0.15, Red—0.08).15 However, Hawaii is not included in this analysis because no other documentation could be found indicating the current use of RPMs in permanent applications. West Virginia previously had nonstandard values for minimum reflectivity (cd/fc): 0 degrees (White—4, Yellow—2.4, Red—1) and 20  degrees (White—1.6, Yellow—0.96, Red—0.4).181 However, these guidelines were superseded by the January 1, 2016, supplement182 to the 2010 Standard Specifications for Roads and Bridges,181 in which the guidelines were changed to meet the standards set forth in ASTM D4383. Alabama is the only state with a guideline not based on cd/fc or millicandelas per lux (mcd/ lux) reflectivity values. Its guideline is subjective, stating that RPMs must be visible at night from a distance of 320 ft with low beams from a passenger vehicle. The documentation does not specify criteria for what is considered to be visible.52 Attribute Quantity States, DC, and PR 3.0 (ASTM D4280 and ASTM D4383)185,186 19 AK39; AR74; AZ71; CA82; DE85; FL88; GA92; IL97; IN100; LA114,115,116,117,118; NC144; NM137; NV135; NY139,140; OK151; SC157; TX (snowplowable RPMs: 3.0 at 4° entrance angle)165,166; VA170; WV182 Visible at night from 320 ft with low beams from a passenger vehicle 1 AL52 Not mentioned in documentation 15 ID, KY, MA, MD, MI, MS, ND, NJ, OH, OR, PA, TN, WA, DC, PR Table 29. Minimum reflectivity, new white RPMs, 0-degree entrance angle (SI, cd/fc).

50 Performance Criteria for Retroreflective Pavement Markers Attribute Quantity States, DC, and PR 1.8 (ASTM D4280 and ASTM D4383)185,186 15 AK39; AR74; AZ71; DE85; FL88; GA92; IL97; IN100; LA114,115,116,117,118; NC144; NY139,140; OK151; SC157; VA170; WV182 2.0 1 TX (snowplowable RPMs: 2.0 at 4° entrance angle)165,166 1.5 3 CA82; NV135; NM137 Visible at night from 320 ft with low beams from a passenger vehicle 1 AL52 Not mentioned in documentation 15 ID, KY, MA, MD, MI, MS, ND, NJ, OH, OR, PA, TN, WA, DC, PR Table 30. Minimum reflectivity, new yellow RPMs, 0-degree entrance angle (SI, cd/fc). Attribute Quantity States, DC, and PR 0.75 (ASTM D4280 and ASTM D4383)185,186 18 AK39; AR74; AZ71; CA82; DE85; FL88; GA92; IN100; LA114,115,116,117,118; NC144; NM137; NV135; NY139,140; OK151; SC157; TX (snowplowable RPMs: 0.4 at 4° entrance angle)165,166; VA170; WV182 0.7 1 IL97 Visible at night from 320 ft with low beams from a passenger vehicle 1 AL52 Not mentioned in documentation 15 ID, KY, MA, MD, MI, MS, ND, NJ, OH, OR, PA, TN, WA, DC, PR Table 31. Minimum reflectivity, new red RPMs, 0-degree entrance angle (SI, cd/fc). Attribute Quantity States, DC, and PR 1.2 (ASTM D4280 and ASTM D4383)185,186 18 AK39; AR74; AZ71; CA82; DE85; FL88; GA92; IL97; IN100; LA114,115,116,117,118; NC144; NM137; NV135; NY139,140; OK151; SC157; VA170; WV182 1.5 1 TX165,166 Visible at night from 320 ft with low beams from a passenger vehicle 1 AL52 Not mentioned in documentation 15 ID, KY, MA, MD, MI, MS, ND, NJ, OH, OR, PA, TN, WA, DC, PR Table 32. Minimum reflectivity, new white RPMs, 20-degree entrance angle (SI, cd/fc). Attribute Quantity States, DC, and PR 0.72 (ASTM D4280 and ASTM D4383)185,186 14 AK39; AR74; AZ71; DE85; FL88; GA92; IN100; LA114,115,116,117,118; NC144; NY139,140; OK151; SC157; VA170; WV182 1.0 1 TX165,166 0.7 1 IL97 0.6 3 CA82; NM137; NV135 Visible at night from 320 ft with low beams from a passenger vehicle 1 AL52 Not mentioned in documentation 15 ID, KY, MA, MD, MI, MS, ND, NJ, OH, OR, PA, TN, WA, DC, PR Table 33. Minimum reflectivity, new yellow RPMs, 20-degree entrance angle (SI, cd/fc).

Survey and Review of State Practices 51   Guidelines giving reflectivity values in mcd/lux were converted to cd/fc using the following equation, with the result rounded to the nearest tenth: cd fc cd fc mcd lux 1 1000 mcd 10.76391 lux 1 [2]= × × Per ASTM D4280 and ASTM D4383, mcd/lux is the SI and accepted worldwide unit norm.185,186 However, the vast majority of states list these values in the inch-pound units of cd/fc, so it is in cd/fc that they are listed here. For 15 states, no specific data were found. While some states had varying guidelines, most with guidance conformed to the guidelines set forth by ASTM D4280 and ASTM D4383. The minimum reflective surface area extracted from the review of state practices is presented in Table 35. Twenty-five states analyzed do not have a minimum surface area explicitly defined in their documentation. Of the 10 states that do have a value defined, no two agree on a particular value. 3.6 RPM Replacement Criteria This section provides information regarding the (a) issues attributable to the use of RPMs from the survey responses and (b) RPM replacement criteria as extracted from the survey responses and the review of state policies. A summary of issues attributable to the use of RPMs from the state surveys is in Table 36. Attribute Quantity States, DC, and PR 0.3 (ASTM D4280 and ASTM D4383)185,186 18 AK39; AR74; AZ71; CA82; DE85; FL88; GA92; IL97; IN100; LA114,115,116,117,118; NC144; NM137; NV135; NY139,140; OK151; SC157; TX (snowplowable RPMs: 0.2)165,166; WV182 0.25 1 VA170 Visible at night from 320 ft with low beams from a passenger vehicle 1 AL52 Not mentioned in documentation 15 ID, KY, MA, MD, MI, MS, ND, NJ, OH, OR, PA, TN, WA, DC, PR Table 34. Minimum reflectivity, new red RPMs, 20-degree entrance angle (SI, cd/fc). Minimum Reflective Surface Area (in.2) Quantity States, DC, and PR 3.25 1 AK39 3 1 AZ71 2.5 1 SC156,157 1.87a 1 TN161 1.6 1 IL97 1.43 1 NY139,140 1.4 1 VA170 1 1 ND43 Raised RPM: 2; Snowplowable RPM: 1.44 1 NC142 4 in. width, area not specified 1 WV182 Not mentioned in documentation 25 AL, AR, CA, DE, FL, GA, ID, IN, KY, LA, MA, MD, MI, MS, NJ, NM, NV, OH, OK, OR, PA, TX, WA, DC, PR a Rhode Island also has a value of 1.87 in.² in its Bluebook. However, other documents indicate that this information may be outdated, and Rhode Island may no longer use RPMs in nontemporary situations. Table 35. Minimum reflective surface area.

52 Performance Criteria for Retroreflective Pavement Markers As Table 36 shows, a major issue that states using snowplowable RPMs face is the snowplowable casing dislodging from the roadways. Three states (Arizona, Arkansas, and Kentucky) have discontinued the use of snowplowable RPMs over this issue. Few states have a written, publicly available guideline stating the conditions for which RPMs require replacement. The states that do have guidelines have extremely different guidelines. There appears to be no attempt at standardization between states toward obtaining uniform RPM replacement criteria. The RPM replacement criteria from the state surveys and the review of state practices are shown in Table 37 and Table 38, respectively. 3.7 Summary of the Survey and Review of State Practices The research team surveyed and reviewed policies and state practices from all 50 states, Puerto Rico, and Washington, DC. The survey responses and review of state practices and policies revealed similarities in some areas of how RPMs are implemented but also differences in many areas. Key aspects of the results are outlined below: • Survey responses indicated 29 states use some form of RPM, 13 do not use RPMs, and eight states did not respond. State policies indicated 35 of the 52 agencies reviewed use RPMs. • Some states use only the standard surface-applied, raised RPM; some states only use snow- plowable RPMs or recessed RPMs, and some states use combinations of different types of RPMs. • Typical costs reported ranged from $2.50-$70 per RPM. The large range is due to the different types and application methods for the RPMs. • Most states using RPMs indicate system-wide usage. Use is more frequent on higher-volume roadways. Areas with snowplowing activities use RPMs less frequently. Several states indi- cated areas with continuous roadway lighting may be excluded from implementing RPMs. Each state has slightly different practices for where to implement RPMs. State Issue Arizona Arizona has used SRPMs in the past and had cases where the snowplowable casings got dislodged from the roadway since they do not work well with snowplows. Currently, they use recessed RPMs in snow areas. Arkansas Arkansas has used SRPMs in the past and had cases where the snowplowable casing got dislodged from the roadway. Another factor that led to the discontinued use of SRPMs was that they were more difficult to install on chip-sealed routes. The glue dissipates into the voids created by the chips, and the RPM does not stick as well. Delaware Delaware had cases where the snowplowable casing of the RPMs got dislodged from the roadway, resulting in multiple pavement repairs needing to be done in the same area. Kentucky Kentucky has used SRPMs in the past and had cases where the snowplowable casing got dislodged from the roadway. They also experienced massive delamination of the markers to the pavement about halfway into the life cycle of the pavement. Currently, they are using recessed RPMs. New Hampshire New Hampshire’s biggest issue with raised RPMs is the delamination related to removal of the epoxy-affixed reflectors and complaints from plow operators reporting premature damage to the plow blades and discomfort in the cab when they hit SRPMs. Pennsylvania Pennsylvania has had several cases of the snowplowable casing getting dislodged and going through the front of vehicles or windshields. West Virginia West Virginia has had cases where the snowplowable casing of the RPMs got dislodged from the roadway. NOTE: SRPMs = Snowplowable RMPs. Table 36. Issues attributable to the use of RPMs based on survey responses.

Survey and Review of State Practices 53   Table 37. RPM replacement criteria based on survey responses. State Replacement Criteria Alabama There is no defined replacement cycle or policy. Replacement done on an as-needed basis. Arizona There is no guidance for the replacement cycle for RPMs. However, they are targeted to be replaced every 3 years when there is a pavement preservation project or chip seal project. Arkansas RPMs are generally replaced at 2-year intervals. However, based on the availability of state funds, a decision can be made at a district level to replace them annually due to damage during the snow season. California Replacement of RPMs depends on the traffic volumes of the roadway. Usually they last 3–5 years. Delaware RPMs are usually replaced on a 3-year cycle. Florida RPMs are replaced when maintenance of pavement markings is done. The cost of replacing RPMs is included in the cost of pavement markings. Hawaii There are no set criteria for RPM replacement. Judgment is used to replace markers when a sufficient number of markers is missing. Illinois RPMs are inspected for replacement after the winter performance period after they are first installed. Inspection occurs 4 years after their initial installation and then again 7 years after their initial installation. After this, if they are still in place, they should be inspected annually. These schedules are shortened/adjusted if certain sections are showing a propensity to fail. Indiana Replacement frequency depends (to a large extent) on the type of roadway and AADT. INDOT issues separate maintenance contracts for RPM refurbishment. Each of INDOT’s six district offices typically issues one RPM maintenance contract per year. Kentucky Replacement occurs either during resurfacing or by an annual marker maintenance contract in which the routes experience systemic replacement every 2–3 years. Massachusetts RPMs are not maintained. Mississippi RPMs are replaced every year based on survival rate inspections conducted at nighttime to determine nighttime reflectivity. They are replaced either by state forces or by contract, depending on the scope/size of the project. The RPM projects are not related to any other maintenance project; they are stand-alone. Nevada RPMs usually last 2–5 years depending on traffic volumes. Other maintenance is taken into consideration if it will affect the markings (things like overlays, chip seals, etc., that will result in complete removal and replacement of the RPMs). New Hampshire RPMs are usually replaced in conjunction with pavement maintenance operations, which generally are well beyond the useful life of markers. New Mexico RPMs are mostly used to supplement striping. They are usually replaced when the striping is replaced. New York RPMs are replaced as they come off in work zones. Not used for long term, only during summer and spring since snowplows will rip them off in the fall and winter. North Carolina RPMs are generally replaced every 2–3 years. However, due to any unexpected snow or ice, they may only last one season. RPM replacement is related to maintenance other than resurfacing. Ohio Once the RPM castings are installed in the pavement, they last for the life of the pavement (approx. 10–12 years). RPM reflectors are replaced after every 3 years of installation. They replace 1/3 of RPM reflectors every year statewide. Missing RPM castings are also replaced, while RPM reflectors are replaced under the district-wide program. Pennsylvania RPMs are inspected every 2–3 years, and this cycle is unrelated to maintenance. The guidance used for inspections includes at least 50% of the reflective surface visible at night; at least 90% of RPMs exist and are visible at night; and, on expressways and freeways, at least five RPMs are continuously visible at night using low beams. South Carolina RPMs are replaced on a regular cycle. The current replacement cycle on interstates is yearly. On primary and secondary routes, the replacement cycle is 3 years. Tennessee RPMs are replaced or relensed every 3 years under a maintenance contract. All lenses are replaced if necessary. Virginia Typically, markers get replaced at the time the road is resurfaced. This is presumably on a ≤ 12-year cycle for the types of higher-volume roads that get snowplowable RPMs. However, it should be noted that if a road is overlaid with a latex emulsion, then it is possible to do so when leaving the existing markers in place (as long as they are properly protected). Washington Typically, RPMs get 2–4 years of service before they are replaced. West Virginia Reflectors are replaced once every 3 years under a maintenance contract. They also have the contractor replace missing castings unless the roadway is in poor condition, and they cannot install a new one in a location where there is no cracking.

54 Performance Criteria for Retroreflective Pavement Markers • Most states space RPMs at 40 ft or 80 ft (80 ft is most common) when supplementing centerline or broken lane line markings. Some states have different spacing criteria for different roadway classifications or based on the number of lanes. Some states reduce spacing in curves depending on the degree of curvature. • Gore area RPMs are generally spaced closer than other locations. Most states indicate 20 ft spacing for gore area RPMs. • Most states use white RPMs with a red back to indicate wrong-way driving. • Most states use ASTM retroreflectivity values for initial retroreflectivity requirements (ASTM D4280 and ASTM D4383)185,186. Most states do not specify a minimum surface area of the RPM face that must be reflective. • Several snowplow states mentioned snowplowable RPMs being dislodged from the roadway. Some of these states have moved away from snowplowable RPMs, and have implemented recessed RPMs. • Few states have a written guideline stating the conditions for which RPMs require replace- ment. The states that do have guidelines have varying criteria for replacement. Most states indicate replacing RPMs on a 2–3 year cycle. Some states indicate yearly replacement, whereas others indicate RPMs are replaced when the road surface is replaced. Replacement cycles are impacted by traffic volumes in many states. Some states have performance-based criteria for replacement. The performance criteria are typically the number of markers visible at night or the percent remaining on the roadway. These findings indicate the most common practices among states but highlight differences as well. Consistency of application and replacement may be beneficial to provide a more uniform environment for drivers while maintaining the asset at an adequate level of visibility. Consis- tency of application is difficult when policies can vary within an individual state. These policy differences generally relate to snowplow activities and restricted usage of raised RPMs or snow- plowable RPMs in these areas. Review of and modifications to current state practices may be beneficial to ensure RPMs are being applied and maintained in a cost-efficient and uniform manner. State Replacement Criteria Alabama Three consecutive markers (or two at 80-ft centers) are considered damaged (missing or < 50% lens area remaining). If 50% of markers are missing in a section, the entire area is replaced. Replacement must occur within 30 days from inspection. Inspections occur annually.52 Illinois Ninety-seven percent intact during the inspection period of 180–195 days after November 30 of the installation year (for newly placed markers only).97 Mississippi Survival rate is less than 60% in a 500-ft sampling zone.132 North Carolina Three consecutive markers of seven in three sections of road or 20% of all markers are missing, crushed, or nonreflective.143 Ohio 2–4 year replacement cycle depending on roadway volume.149 Pennsylvania Fewer than 90% exist, fewer than five consecutive RPMs are visible (> 50% of reflective surface intact).154 Texas < 2 markers visible at 80-ft spacing or < 3 markers visible at 40-ft spacing; 1 year cycle for > 50,000 ADT; 2–3 year for >10,000 and < 50,000 ADT; 3–4 yr for < 10,000 ADT.167 Washington Non-yellow: every 2 years; yellow supplementing edge lines on divided highways: every 4 years; islands: three consecutive markers missing.176 Table 38. RPM replacement criteria based on the review of state practices.