Temporary Pavement Markings Placement and Removal Practices in Work Zones (2021)

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16 Literature Review is chapter presents the results of the literature review for temporary pavement markings in work zones and pavement marking removal. Sources compiled for the literature review include guides; research reports; journal articles; and DOT policies, manuals, specications, and standards. e chapter is organized into the following sections: literature for temporary pavement markings and literature for pavement marking removal. Literature for Temporary Pavement Markings General guidance for temporary pavement markings is supplemented by DOT guidance, standards, and specications. In addition, some research studies have evaluated the eec- tiveness of temporary pavement markings, including temporary pavement markings for wet, nighttime conditions and markings using special colors. An overview of literature pertaining to temporary pavement markings is provided in the following sections. General Guidance for Temporary Pavement Markings Some general guidance for temporary pavement markings is available through the MUTCD (FHWA 2009) and other resources. Standards and guidance provided in the MUTCD for temporary pavement markings include the following: • Placement and removal of pavement markings should allow for minimal disruption to trac (Section 6F.77). • Maintenance of the existing pavement markings is required, or temporary pavement markings should be provided (Section 6F.77). • e duration for temporary pavement markings to remain aer placement of the nal pavement surface is limited to a maximum 14 days (Section 6F.78). • Reviews of pavement markings and other devices used to delineate the path of travel should be performed during both daytime and nighttime (Section 6F.78). • “Do Not Pass,” “Pass with Care,” and “No Passing Zone” signs may be used to delineate no-passing zones in lieu of markings for durations of 14 days or less. e duration may be extended for low-volume roads (Section 6F.78). • TRPMs may be used in lieu of other marking types, but their color and pattern must emulate the other marking types (Section 6F.79). • Markings are required to be retroreective for long-term (duration) stationary work zones (Section 6G.02). In addition to the MUTCD, other resources for direction on temporary pavement markings include guides from the ATSSA and a research study to develop a methodology for the selection C H A P T E R 2

Literature Review 17   of pavement marking materials for work zones. An ATSSA guide on temporary pavement markings (ATSSA 2014) includes information regarding marking materials, retroreectivity standards, and factors typically considered during material selection for work-zone pavement markings. e ATSSA guide also describes some of the pros and cons of dierent types of temporary pavement markings, as shown previously in Table 1. ATSSA also provides guidelines for monitoring TTC devices, including temporary pavement markings and TRPMs, in its Quality Guidelines for Temporary Trac Control Devices and Features (ATSSA 2017). ese evaluation guidelines are summarized in Table 5. A methodology for the systematic selection of four types of pavement marking materials (paint, thermoplastics, temporary tapes, and trac buttons) for work zones was developed in a prior research study (Ullman et al. 2008, Songchitruksa et al. 2011). Charts to guide the selec- tion of marking material based on annual average daily trac (AADT), project phase duration, conditions (expected, worse than expected, or better than expected), and pavement surface type were generated using simulation based on data from multiple sources such as retroreectivity measurements from the 2002 National Transportation Product Evaluation Program (NTPEP) Mississippi test deck. An example chart is shown in Figure 13, which allows for selecting pavement marking materials for work zones based on project phase duration and AADT per lane under expected conditions. For example, the use of Figure 13 would lead to selecting thermoplastic for asphalt pavement in a work zone with a project phase duration of 360 days and an AADT per lane of 15,000 vehicles per day (vpd). e chart generally prescribes the selection of paint for work zones of short duration, while thermoplastic and buttons may be chosen for higher durations and AADT values. DOT Guidance, Specications, and Standards for Temporary Pavement Markings A review of DOT guidance, specications, and standards for temporary pavement mark- ings in work zones was undertaken. Tabular summaries of the results are provided in Appendices D, E, and F, respectively. Some highlights from this review are described in the following sections. Rating Criteria for Temporary PavementMarkings (Tape and Paint) Criteria for TRPMs Acceptable • All tape or paint in place • In conformance with material specifications • All TRPMs in place • In conformance with material specifications Marginal • Absence of 10% or less of tape, message, or symbol • Absence of two or less consecutive skip lines • Absence of 50 ft or less of continuous solid stripe • Absence of 10% or less of TRPMs • Absence of three or fewer consecutive TRPMs Unacceptable • Absence of more than 10% tape, message, or symbol • Absence of more than two consecutive skip lines • Absence of more than 50 ft of continuous solid stripe • Absence of more than 10% of TRPMs • Absence of more than three consecutive TRPMs Source: ATSSA 2017. Table 5. ATSSA evaluation guidelines for temporary pavement markings and TRPMs.

18 Temporary Pavement Markings Placement and Removal Practices in Work Zones DOT Guidance for Temporary Pavement Markings In general, DOTs follow the guidance of the national MUTCD (FHWA 2009) with respect to temporary pavement markings in work zones. However, as shown in Figure 14, 23 states and the District of Columbia developed their own supplement to the national MUTCD, while 10 states adopted their own MUTCD. State MUTCD manuals and supplements oen follow the requirements of the national MUTCD. In other cases, guidance that supersedes or supple- ments the national MUTCD is provided. Examples of such guidance are listed as follows: • In California, 4-in. by 24-in. lines are used for temporary lane lines and center lines. Raised markers may be used instead of lines (Caltrans 2019). Source: Adapted from Ullman et al. 2008 Figure 13. Selection chart for pavement marking material in work zones from research study (expected conditions): (a) asphalt pavement and (b) concrete pavement.

Literature Review 19   • In Delaware, the use of temporary markings is limited to 30 days (Delaware DOT 2011). • In Idaho, temporary edge lines and temporary channelizing lines are required for interstate highways and expressways but optional for other roadways (Idaho Transportation Depart- ment 2020). • In Minnesota, the use of signs instead of pavement markings is allowed for up to 14 days on roads with average daily trac (ADT) of less than 400 vpd, provided that appropriate signage (including “No Center Stripe” signs every mile and at major intersections) is provided (Minnesota DOT 2011). • In New Hampshire, all temporary markings are required to be oset 1  from the location of the nal striping (New Hampshire DOT 2019). • Both West Virginia and Delaware allow the use of signs instead of markings to identify no-passing zones for durations of three or fewer calendar days (West Virginia DOT 2006, Delaware DOT 2011). • Illinois provides guidance for short-term markings with abbreviated patterns that are required at the end of each day (Illinois DOT 1990). • Washington requires that temporary markings meet the requirements for permanent markings set forth in Chapters 3A and 3B of the national MUTCD (Washington State Legislature 2019). DOT Specications for Temporary Pavement Markings DOT specications include requirements for various aspects of temporary pavement mark- ings, such as materials and construction, time considerations, method of measurement and basis for payment, and inspection and monitoring. Some of these requirements are highlighted in the following sections, and additional details may be found in Appendix E. Source: FHWA 2020 Figure 14. Map showing adoption of national MUTCD, state supplements, or state MUTCD by DOT.

20 Temporary Pavement Markings Placement and Removal Practices in Work Zones Materials and Construction Requirements. DOT specifications provide a variety of require- ments for materials and construction of temporary pavement markings, such as geometric layouts, allowable marking types, material specifications, and application instructions. For geometric layouts, California prescribes a minimum lane line/centerline delineation that uses TRPMs every 24 ft. Options for edge line markings in California include 6-in.-wide tape, cones, delineators, channelizers placed at 100-ft maximum intervals, or TRPMs at 6-ft intervals (left edge line) (Caltrans 2018c, Caltrans 2020). Hawaii prescribes spacing for TRPMs of 20 ft for solid lines, with 5-ft sections spaced 20 ft on center (Hawaii DOT 2005a). Most DOTs use a 4-in. marking for work zones, although some DOTs use a 6-in. marking. In some cases, DOTs specify the allowable types of temporary markings. For example, Arkansas requires retroreflective tape for asphalt pavements and Type 4 retroreflective pliant- polymer preformed tape for concrete pavements. Arkansas also allows the use of paint or retroreflectorized raised-pavement markings as alternates (Arkansas State Highway and Trans- portation Department 2014). South Dakota permits the following types of temporary pavement markings: temporary paint, TRPMs, temporary flexible vertical markers (tabs), and temporary tape (South Dakota DOT 2015). In Alaska, only TRPMs are allowed as interim markings on seal coat and surface treatment pavements (Alaska Department of Transportation and Public Facilities 2017). South Carolina mandates the use of thermoplastic markings for asphalt pavements and epoxy markings for concrete pavements when the work zone duration is 4 to 6 months or greater (South Carolina DOT 2007). DOT specifications also include provisions for material requirements and installation instruc- tions such as application rates or thresholds for weather conditions. For example, Maryland prescribes that temporary paint must comply with manufacturer formulations along with supplemental requirements for viscosity, pigment for yellow paint, and color and appearance. In addition, tape must be installed in accordance with the manufacturer’s recommendations (Maryland DOT State Highway Administration 2018). Idaho requires temporary paint mark- ings to meet the materials specifications for permanent paint markings (Idaho Transportation Department 2018). For application rates, Kentucky mandates 24.8 gal/mi for 6-in. paint, 16.5 gal/mi for 4-in. paint, and 6 lb/gal for glass beads (Kentucky Transportation Cabinet 2019). Alabama’s required application rates for paint are 10 gal/mi and 18 gal/mi for rough surfaces (Alabama DOT 2018). New Jersey specifies a paint thickness of 5 to 7 mils with glass beads applied at a rate of 12 lb/gal. In addition to the application rate, New Jersey only allows paint to be placed when the air temperature is above 45°F and the pavement temperature is below 140°F (New Jersey DOT 2019). Louisiana includes weather restrictions for thermoplastic markings that cannot be applied within 12 h of rain, to wet surfaces, or when temperatures are below 50°F (Louisiana Depart- ment of Transportation and Development 2016). South Carolina prohibits installing thermo- plastic, epoxy, or tape within 24 h after rainfall (South Carolina DOT 2007). In some DOTs, material requirements also include minimum values for retroreflectivity. In Delaware, temporary pavement markings must meet the retroreflectivity requirements shown in Table 6. Maryland’s minimum retroreflectivity requirements for temporary pave- ment markings are 250 mcd/m2/lx for white markings and 150 mcd/m2/lx for yellow markings (Maryland DOT State Highway Administration 2018). Details regarding retroreflectivity requirements for Colorado, Florida, Illinois, Michigan, Missouri, North Carolina, and Oregon may be found in Chapter 4. In Indiana, temporary markings must meet the performance specifications of permanent markings with two exceptions: the contractor does not need to measure retroreflectivity of temporary markings and quality adjustments are not made (Indiana DOT 2020).

Literature Review 21   Time Considerations. DOT specications for temporary pavement markings in work zones include various time-related elements, such as classication based on duration, deadlines for installation or removal, and material requirements based on duration or time of year. For example, Ohio categorizes work zone markings as Class I (Full Pattern, Full Rate) for surfaces exposed to trac for more than 14 days before nal markings are installed, Class II (Abbreviated, Full Rate) for short-term use, and Class III (Full Pattern, Low Rate) for surface courses when thermoplastic, spray thermoplastic, or epoxy nal markings will be placed within 30 days (Ohio DOT 2019). Louisiana’s specications include a table of temporary pavement-marking patterns for short-term (durations shorter than 7 days or durations between 7 and 30 days) and long-term (durations greater than 30 days) markings. DOTs oen require installation or removal of temporary pavement markings within a specied time frame. For example, multiple DOTs such as North Dakota and Rhode Island require that temporary pavement markings be installed by the end of the workday (North Dakota DOT 2014, Rhode Island DOT 2018). Idaho mandates that temporary markings should be applied as soon as possible on newly placed pavement (Idaho Transportation Department 2018). In South Carolina, TPMs must be placed within 7 days of application of an asphalt pavement course, unless another asphalt pavement course is scheduled within 30 days (South Carolina DOT 2007). Pennsylvania allows the use of “No Pavement Markings” signs at 0.5-mi intervals in lieu of temporary pavement markings for 7 to 14 days on seal coats and surface treat- ments and for 3 to 7 days on slurry seals, heat scarication, and microsurfacing operations (Pennsylvania DOT 2019). Once temporary markings are placed, some DOTs place limits on how long they can remain in place. For example, Arkansas species that interim markings must be replaced by permanent or construction markings or covered with another pavement layer within 3 days (high-volume roads) or 14 days (low-volume roads) (Arkansas State Highway and Transportation Depart- ment 2014). In Colorado, full compliance markings must be installed within 2 weeks of nal surfacing (1 week for seal coat projects) or when pavement work is suspended for at least 2 weeks (Colorado DOT 2019b). In New York, the contractor must place the next pavement course or apply remaining temporary pavement markings (edge lines, stop bars, and crosswalks) within 14 days of placement of temporary pavement markings (New York State DOT 2020a). Delaware limits the use of temporary pavement markings to 30 days (Delaware DOT 2016), while Oregon allows 28 days for the installation of permanent markings once temporary markings have been applied (Oregon DOT 2018). In Massachusetts, the maximum duration for temporary pavement markings is 90 days (Massachusetts DOT 2020b). In some instances, DOT specications mandate the implementation of certain types of temporary pavement markings based on the time of year. For example, paint must be used for Pavement Marking Material Pavement MarkingColor Minimum Retroreflectivity – 1 mcd/ft2/footcandle = 1mcd/m2/lx Latex paint (temporary or permanent) White 150 Latex paint (temporary or permanent) Yellow 125 Temporary tape White 750 Temporary tape Yellow 450 Source: Delaware DOT 2016. Table 6. Delaware retroreectivity requirements for temporary latex paint and temporary tape from Section 1071 of standard specication.

22 Temporary Pavement Markings Placement and Removal Practices in Work Zones temporary markings in service from December 1 to March 31 in Indiana (Indiana DOT 2020). Michigan requires paint or nonremovable tape for temporary markings that are placed from November 1 through April 15 (Michigan DOT 2012). Method of Measurement and Basis for Payment. DOTs typically measure field quantities for temporary pavement markings for payment based on units of linear foot for striping and each for TRPMs and symbol markings. However, there are some exceptions. For instance, Texas uses plan quantities for both temporary pavement markings and pavement marking removal, and South Dakota also bases payment for pavement marking removal on plan quantities (Texas DOT 2014b, South Dakota DOT 2015). In addition, South Dakota performs only one centerline measurement for payment of all temporary pavement markings. Montana measures temporary pavement markings by linear mile (Montana DOT 2014). For measurement units for striping, Colorado uses gallon for paint, epoxy, and methyl methacrylate (including glass beads) and linear foot for thermoplastic and preformed markings and tape (Colorado DOT 2019b). Wyoming includes temporary pavement markings in the cost of TTC, and additional striping or tape not included in the contract is paid for by length as Category IV Traffic Control Device (TCD) Units (Wyoming DOT 2010). Hawaii does not provide direct payment for temporary pavement markings (Hawaii DOT 2005a). Additional information regarding basis of payment for temporary pavement markings and pavement marking removal may be found in Chapter 3, Survey Results, of this synthesis. Monitoring and Inspection. DOT specifications include different approaches to monitoring and inspecting temporary pavement markings, such as requirements for standards and personnel and mandatory inspections. ATSSA’s Quality Guidelines for Temporary Traffic Control Devices and Features (ATSSA 2017) is frequently used in DOT specifications as a standard for monitoring and inspecting TTC devices. For example, New Hampshire mandates that all TTC devices meet the acceptable criteria in the ATSSA guidelines and that TTC devices in unacceptable con- dition must be replaced (New Hampshire DOT 2016). North Dakota specifies that short-term pavement markings will be rated by the engineer in accordance with the ATSSA guidelines, and markings rated as unacceptable must be replaced within 24 h (North Dakota DOT 2014). Other specific examples of DOT practices for monitoring and inspecting temporary pave- ment markings are provided as follows. • Mississippi specifies that the contractor is responsible for maintaining temporary pavement markings (Mississippi DOT 2017b). • Delaware and New Hampshire require the contractor to maintain TTC devices, including temporary pavement markings, in accordance with the Delaware MUTCD and national MUTCD, respectively (Delaware DOT 2016, New Hampshire DOT 2016). • In Arkansas, the contractor must certify weekly that TTC devices were inspected daily, including at least one inspection at nighttime (Arkansas State Highway and Transportation Department 2014). • In Ohio, the engineer evaluates markings according to performance parameters, and markings receiving unsatisfactory numerical ratings must be replaced immediately (Ohio DOT 2019). • New Mexico mandates daily inspections of TTC devices, and the contractor must appoint at least one traffic control supervisor with ATSSA or other certification in charge of maintaining and replacing TTC devices (New Mexico DOT 2019b). • In Kentucky, the contractor must replace missing or damaged TRPMs within 3 days and missing or damaged stripes or tape within 24 hours (Kentucky Transportation Cabinet 2019). • Maryland requires the contractor to monitor and replace (at no additional payment) tape for 180 days and paint for 60 days (Maryland DOT State Highway Administration 2018). • Virginia directs the contractor to fill out a daily log for both permanent and temporary markings and markers (Virginia DOT 2016a).

Literature Review 23   DOT Standards for Temporary Pavement Markings A tabular summary of DOT standards by DOT for temporary pavement markings in work zones is provided in Appendix F. Many, but not all, DOTs provide information on temporary pavement markings in their standard drawings. is information can generally be categorized as follows: conditions under which temporary markings are required or not required, layouts of temporary pavement markings and other TTC devices for dierent work zone congurations, and dimensions for temporary pavement markings. In some instances, standard drawings prescribe conditions under which temporary pavement markings should be provided. For example, Arkansas provides tables, such as the one shown in Table 7, that show which types of TTC devices should be used for interstates and non- interstates based on vertical dierential, location, and speed. Oregon lists conditions (e.g., alignment shis or crossovers, high ADT, projects in place during winter months) under which dierent types of temporary pavement marking layouts should be used on its Standard Drawing TM810 (Oregon DOT 2019b). Various DOTs show layouts of temporary pavement markings and other TTC devices for dierent work zone congurations such as lane closures and crossovers. An example for a temporary crossover entrance from Indiana Standard Drawing E-801-TCCO-02 is shown in Figure 15, which shows locations for white and yellow temporary pavement markings, pave- ment marking removal, signs, drums, and a temporary concrete barrier. DOT standards oen show dimensions, including marking size and spacing, for temporary pavement markings based on marking type and use. For example, Kentucky Standard Drawing TTC-16-02 shows the layout of temporary pavement markings for two lane closure scenarios: a lane closure with duration of at least 4 days and ADT of at least 5,000 vpd (Arrangement “A”) and a lane closure with removal of existing pavement adjacent to trac (Arrangement “B”). e layout for Arrangement “A” shows a temporary edge line along with mono-directional white markers spaced at 20  in the taper, as shown in Figure 16. A review of DOT standards for temporary pavement marking shows that DOTs use dierent dimensions for size and spacing. Example marking layouts include a 4- marking with a 46- gap (Wisconsin), a 5- dashed line with a 45- gap (Minnesota), a 4- dashed line with a 12- gap (Oklahoma), and a 4.5- dashed line with a 15.5- gap (Texas). Sample marking layouts for one-way and two-way markings are shown in Figure 17 and Figure 18, respectively. ere are also dierences in TRPM layouts between DOTs, as shown in Figure 19. Interstate Vertical Differential Location Traffic Control 2 in. Centerline W8-11 and lane striping 2 in. Edge of traveled lane or edge of shoulder W8-9, edge line striping, and traffic drumsa > 2 in. 6 in. Edge of traveled lane or edge of shoulder W8-17, edge line striping, and traffic drumsa > 6 in. Edge of traveled lane or edge of shoulder Precast concrete barrier & edge lines NOTE: W8-11 = uneven lanes; W8-9 = low shoulder; W8-17 = shoulder drop-off (symbol). Source: Arkansas State Highway and Transportation Department 2019. aWhen there is insufficient width to place traffic drums on the remaining shoulder width, a stabilized wedge shall be used. Table 7. Trafc control requirements for interstates from Arkansas Standard Drawing TC-3.

Source: Indiana DOT 2019 Figure 15. Example layout of temporary trafc control devices for temporary crossover entrance from Indiana Standard Drawing E-801-TCCO-02.

Literature Review 25   Source: Kentucky Transportation Cabinet 2016 Figure 16. Example layout of temporary pavement markings for lane closure (Arrangement “A”) from Kentucky Standard Drawing TTC-160-02. Source: Wisconsin DOT 2020a Source: Oklahoma DOT 2009b Source: Texas DOT 2019 Figure 17. Example one-way temporary pavement marking layouts: (a) Wisconsin (Standard Drawing 15 C 8-19a); (b) Oklahoma (Standard Plan T521); and (c) Texas [Standard WZ (STPM)-13].

26 Temporary Pavement Markings Placement and Removal Practices in Work Zones Source: Minnesota DOT 2020a Source: Oklahoma DOT 2009b Source: Texas DOT 2019 Figure 18. Example two-way temporary pavement marking layouts: (a) Minnesota (Standard Plan 5-297.801); (b) Oklahoma (Standard Plan T521); and (c) Texas [Standard WZ (STPM)-13].

Literature Review 27   Figure 19. Example temporary pavement marking layouts for TRPMs: (a) New Jersey (Standard Construction Detail CD-159-2); (b) Oklahoma (Standard Plan T521); (c) Texas [Standard WZ (STPM)-13]. Source: New Jersey DOT 2016 Source: Oklahoma DOT 2009b Source: Texas DOT 2019

28 Temporary Pavement Markings Placement and Removal Practices in Work Zones Agency Practices for Temporary Pavement Markings A few studies have looked into DOT practices for temporary pavement markings. For example, survey responses from 20 states in a 2011 study indicated that paint was the most frequently used material for temporary pavement markings (Figure 20) (Cho et al. 2011). Results from a survey of southeastern state DOTs showed that the most frequently used marking types for work zones were paint, removable/temporary tape, and raised pavement markings (Jackson et al. 2001, Salem et al. 2002). In addition, one-third of the respondents indicated that they use thermoplastic. Results from a study to compare Utah’s practices for selection of permanent pavement markings with those of other agencies showed that most states employed an approach based on durability and cost (Eixenberger and Anderson 2016). Some states considered additional factors such as climate, crash history, snow removal, geometrics, work zones, and functional classication. Evaluations of Temporary Pavement Markings ere are a limited number of performance evaluation studies for temporary pavement markings. For instance, three temporary pavement-marking tape products and a removable paint were evaluated in an active work zone in Iowa (Hawkins et al. 2012). e markings were evaluated for performance with respect to presence, retroreectivity, and removal. e results indicated satisfactory performance of temporary pavement marking tapes except when the tape was placed on rough surfaces or when vehicles damaged the markings due to heavy wear (Figure 21). Failure of removable paint occurred aer 15 days, and latex paint was used to restripe those markings. A research study sponsored by the Illinois DOT assessed the performance of permanent pavement marking types and included development of a pavement- marking selection guide (Dwyer et al. 2013). A comparison of widths for edge lines for perma- nent markings found that wider markings resulted in total crash reductions of 15% to 30% and a benet cost ratio ranging from 33:1 to 55:1 (Carlson and Wagner 2012). Temporary Pavement Markings for Wet, Nighttime Conditions One challenge associated with the use of temporary pavement markings involves reduced visibility of the markings during wet, nighttime conditions. Research studies have evaluated Figure 20. Survey results for usage of temporary pavement markings from a prior study. Source: Cho et al. 2011

Literature Review 29   dierent products designed to address this challenge, including paint, tape, and permanent markings. For example, a two-phase project assessed the use of all-weather paint (AWP) for temporary pavement markings in work zones (3M 2008, Cunningham et al. 2013). e initial phase of the project included a prescreening process to reduce a pool of 24 pavement marking systems to three systems, which then underwent a human factors study. e human factors study found that the detection distances for the three AWP marking systems were statistically the same. In the second phase of the project, one of the three AWP systems was selected for further testing in active work zones at ve locations in North Carolina and Ohio. Example images of the AWP and standard marking are shown in Figure 22. e AWP marking was compared to a standard pavement marking based on four measures of eectiveness: retroreectivity, vehicle travel speed, rate of lane encroachments, and linear lane displacement. e results indicated that the retroreectivity values for the AWP markings were inconsistent but gen- erally higher than the retroreectivity values for the conventional markings. In addition, drivers generally used safer lane placements with the AWP markings. Another study inves- tigated three prototype optics-on-paint marking systems during dry, wet-recovery, and rain conditions (Higgins et al. 2009). e three prototype systems sustained 50% to 80% of their average dry detection distance, while conventional markings only maintained 17% to 28% of their average dry detection distance. Figure 21. Locations of heavy and minimal wear within the taper. Source: Hawkins et al. 2012 Figure 22. AWP (left) and standard pavement marking (right) in work zone on US-32/33/50 in Athens, Ohio. Source: Cunningham et al. 2013

30 Temporary Pavement Markings Placement and Removal Practices in Work Zones In 2017, Michigan was the rst DOT to implement a standard requiring the use of temporary wet reective tape and paint in work zones (Roads and Bridges magazine 2017). Prior to imple- mentation, testing was performed on 10 to 12 dierent paint applications and bead loads, and the paint with the best performance was chosen. e selected paint used an increased thickness of 18 mils (thousandths of an inch) along with 6 lb/gal of glass beads and 4 lb/gal of wet reective optic. Other research has addressed tape markings, including a study of two pavement-marking tape products over the course of three winters at two locations in Illinois (Hawkins et al. 2019). e installation on I-80 is shown in Figure 23. e retroreectivity of the tape markings was measured under dry, wet-recovery, and continuously wetted conditions. e results showed dierences in performance between the two tape products, and performance was reduced when the tapes were inlaid instead of recessed within a groove. Other studies have evaluated the use of all-weather materials for permanent pavement markings. In a project by Hawkins et al. (2015), 27 possible product combinations for all-weather markings were evaluated through laboratory and eld testing. Results from the eld testing showed that 44% of the product combinations had initial retroreectivity values greater than 50 mcd/m2/lx, while only 15% of product combinations had retroreectivity values greater than 50 mcd/m2/lx aer 2 years. Ohio sponsored a research project to assess the performance of AWP and wet retroreective durable tape to see if they could be used in lieu of snowplowable raised pavement markers (RPMs) (Abbas et al. 2014). e performance of AWP and wet retro- reective tape quickly degraded as a result of the eects of trac and snow plowing. Special Colors for Temporary Pavement Markings Another challenge associated with the use of pavement markings work zones concerns the ghost markings that sometimes remain aer old pavement markings are removed. ese ghost markings can cause confusion for drivers navigating through the work zone. One possible solution to this problem involves the use of special marking colors such as orange. ese special marking colors are oen used in the Canadian province of Ontario and in some European countries such as Switzerland, Slovakia, and Austria (Shaw et al. 2017). ere has been some experimentation with the use of special color markings in the United States through color recognition studies, driver surveys, and eld evaluations. For example, a color recognition study of Type 1 and Type 2 uorescent orange retroreective RPMs found that 100% of test subjects interpreted the marking color accurately during daytime, while the Source: Hawkins et al. 2019 Figure 23. Installation of temporary tape on I-80 in Illinois.

Literature Review 31   marking color was understood correctly during nighttime by 84% of test subjects for the Type 1 markings and 75% of test subjects for Type 2 markings (Finley 2007). Wisconsin evaluated orange pavement markings through eld studies and driver surveys at two locations. e rst location was the Zoo Interchange in Milwaukee, Wisconsin (DuPont and DeDene 2017). Wisconsin was generally pleased with the orange markings, although there were some issues with the formulation of paint materials and the conditions for paint applica- tion. Results from two public surveys indicated that the majority of respondents thought that the orange markings were more visible than the temporary white markings. Wisconsin also sponsored research to investigate the use of orange pavement marking tapes on a bridge redecking project on I-94 as shown in Figure 24 (Shaw et al. 2018). For comparison purposes, standard-color marking tapes were also installed on a bridge redecking project at another location. Results from eld testing showed that vehicle positioning and speeds were comparable for the orange and white colors. A driver survey found that approximately half of the respon- dents believed that the orange markings were more visible than the white markings. Considerations for Connected and Autonomous Vehicles Other considerations for temporary pavement markings in work zones involve connected and autonomous vehicles (CAVs), which are classied into six automation levels (0 = no auto- mation with driver warning systems, 1 = driver assistance, 2 = partial automation, 3 = conditional automation, 4 = high automation, and 5 = full automation) (U.S. DOT 2018). CAVs depend on machine vision technology to process pavement markings and signage and navigate the road- way (3M 2020), and vehicle manufacturers have identied pavement markings as an important infrastructure element necessary to attain the safety benets of CAVs (Carlson 2015). FHWA is in the process of updating the MUTCD to address CAVs (FHWA 2018). A policy document from ATSSA provides recommendations for changes to the MUTCD to accommodate CAVs, such as implementing a requirement for minimum retroreectivity values, using 6-in. markings on roads with a posted speed limit of 40 mph or higher, and applying 15- lane markings with 25- gaps (ATSSA 2019). Several research studies assessed the inuence of pavement marking properties on detection capabilities using machine vision. Davies (2017) investigated the eects of pavement marking width, color, and retroreectivity on the performance of machine vision systems. Whitney et al. (2018) suggested that lane detection could be improved by using pavement markings with Source: Shaw et al. 2018 Figure 24. Installation of uorescent orange pavement marking tape at I-94 over Golden Lake Road.

32 Temporary Pavement Markings Placement and Removal Practices in Work Zones appropriate size (based on viewing distance) and luminance values and gradients. A study by Pike et al. (2018) found that the use of a 6-in. width instead of a 4-in. width for preformed tape markings resulted in better machine vision performance during wet daytime conditions. Literature for Pavement Marking Removal e literature review for pavement marking removal included guidance documents, DOT specications and practices, and evaluations of pavement-marking removal methods, including new methods. e results of the literature review for pavement marking removal are presented in the following sections. General Guidance for Pavement Marking Removal Existing general guidance regarding pavement marking removal is limited. e MUTCD addresses pavement marking removal in Section 3A.02 and Section 6F.77 (FHWA 2009). e MUTCD prescribes that prior markings should be removed as soon as possible with minimal scarring to the pavement. e MUTCD allows that tape similar in color to the pavement may be used to cover existing markings on a temporary basis. However, the MUTCD indicates that black paint or asphalt spraying should not be used in lieu of marking removal. In addition to the guidance provided in the MUTCD, the ATSSA guide on temporary pavement markings in work zones includes a summary of several dierent marking removal methods (ATSSA 2014). A tabular summary of pros and cons of dierent removal methods is provided in a NCHRP study by Pike and Miles (2013) as previously shown in Table 3. A guidance document from AASHTO describes recommended environmental practices for pavement marking removal, including disposal of removed yellow thermoplastic and yellow paint at a Class 1 or Class 2 disposal facility, development of a project-specic Lead Compliance Plan to eliminate or limit worker exposure to lead when handling residue from removed yellow thermoplastic and yellow paint, and immediate removal of residue such as dust (AASHTO n.d.). DOT Specications for Pavement Marking Removal A tabular summary of DOT specications for pavement marking removal is shown in Appendix E. ese specications cover various aspects of pavement marking removal, such as removal methods, requirements for acceptance of removal, removal thickness limits, time considerations, width of removal, and equipment. Some highlights from these specications are described in this section. For removal methods, the DOT specications typically allow the use of any method that does not damage the surface or texture or pavement. Some DOTs impose limits on the allowable methods. Several DOTs, including Arizona, Oklahoma, and Oregon, do not allow painting over the markings or covering them with asphalt (Arizona DOT 2008, Oklahoma DOT 2019, Oregon DOT 2018). Kansas and North Carolina prohibit the use of water blasting on asphalt pavement (Kansas DOT 2015, North Carolina DOT 2018a). Nevada prescribes water blasting for pave- ment surfaces that will remain (Nevada DOT 2014). Kentucky only permits water blasting, but abrasive methods are allowed when the removal length is less than 1,000 feet (Kentucky Transportation Cabinet 2019). Grinding use in Utah requires approval of the engineer (Utah DOT 2017b). Tennessee species that the method that causes the least amount of damage to the pavement should be applied (Tennessee DOT 2015). Several DOTs limit the use of grinding in the specications. Maine and Ohio do not allow grinding on nal pavement surfaces (Maine DOT 2014b, Ohio DOT 2019). Pennsylvania

Literature Review 33   restricts the use of grinding to the removal of thermoplastic, cold plastic, or epoxy markings (Pennsylvania DOT 2019). Texas does not allow grinding under any circumstances, while Utah only permits grinding with the approval of the engineer (Texas DOT 2014b, Utah DOT 2017a). In some DOTs, an approval process for selecting the removal method is required. For example, in Colorado the contractor selects the removal method, and the engineer must approve the selected method (Colorado DOT 2019b). New Jersey requires approval by the Resident Engineer after the contractor provides a demonstration of the method’s effectiveness (New Jersey DOT 2019). Some DOTs prescribe minimum requirements for the amount of removal or limit the thickness of removal. When specified, the amount of pavement marking removal required is typically 90% (e.g., Iowa) or 95% (e.g., Missouri) (Iowa DOT 2015, Missouri DOT 2019c). Other DOTs such as Colorado specify that the pavement markings should be removed as much as possible (Colorado DOT 2019b). Removal thickness limits are sometimes specified to avoid pavement damage, with values such as ¼ in. (Texas), 1⁄8 in. (Ohio and Oregon), 1⁄16 in. (New Jersey), and 1⁄32 in. (Pennsylvania) (Texas DOT 2014b, Ohio DOT 2019, Oregon DOT 2018, New Jersey DOT 2019, Pennsylvania DOT 2019). Time restrictions are also sometimes included in the DOT specifications. Maryland and Ohio require that blackout tape must be removed within 14 days and 15 days, respectively (Maryland DOT State Highway Administration 2018, Ohio DOT 2019). New Jersey only permits removal of striping if it will be replaced on the same day (New Jersey DOT 2019). Washington State defines a time window of April 1 to September 30 when marking removal must be performed, and the pavement markings must be removed in the same time frame as paving (Washington State DOT 2020b). Several DOTs require collecting and removing residue and debris from the pavement during the process of removing pavement markings. In Georgia, vacuuming of sand and other debris must occur simultaneously with blasting (Georgia DOT 2013). Hawaii prescribes that removal material and debris must be sent to an authorized site for disposal (Hawaii DOT 2005a). New Jersey requires that marking materials be disposed of in accordance with applicable state regulations and a solid waste management plan (New Jersey DOT 2019). Arizona mandates compliance with 29 Code of Federal Regulations (CFR) (Lead Exposure in Construction, Interim Final Rule) for the removal of lead-based striping (Arizona DOT 2008). Other aspects of pavement marking removal addressed in DOT specifications include the removal width, equipment requirements, and repair of damage. Colorado establishes removal swath widths of 12 in. when the marking to be removed is 8 in. wide or less and 15 in. when the marking to be removed is more than 8 in. wide (Colorado DOT 2019b). Iowa and New Jersey require an additional 1 in. of pavement marking removal (Iowa DOT 2015, New Jersey DOT 2019). Michigan’s specifications state that self-propelled truck-mounted removal equipment must be used for more than 5,000 ft of removal (Michigan DOT 2012). Multiple DOTs, such as Missouri and Washington, require the contractor to repair damage caused by the marking removal (Missouri DOT 2019c, Washington State DOT 2020b). Agency Practices for Pavement Marking Removal Prior studies of agency practices for pavement marking removal found frequent use of grinding and water blasting and noted some of the agency and contractor concerns regarding different removal methods. For example, a survey conducted in a prior NCHRP study found that grinding was the marking removal method used most often by DOTs and local agencies (Pike and Miles 2013). Several respondents also indicated that they either used water blasting

34 Temporary Pavement Markings Placement and Removal Practices in Work Zones or were interested in trying water blasting. Agencies reported using shot blasting and sand- blasting for shorter removal sections. Results from a survey of 25 states in a previous study by Cho et al. (2011) showed that the most common removal methods were grinding and water blasting. In addition, respondents indicated that grinding and water blasting provided the most satisfactory performance (Figure 25). Concerns noted by the agency respondents included scarring of pavement for both grinding and water blasting and the higher cost of water blasting. Another earlier study included interviews with contractors who indicated that grinding was the most frequently used method to remove pavement markings because of its cost eectiveness and high speed (Jackson et al. 2001, Salem et al. 2002). e contractors were concerned about the suitability of water blasting for smaller work zones as well as its higher cost. Evaluations of Methods for Pavement Marking Removal Several previous studies evaluated various pavement-marking removal methods in both controlled and eld environments. For example, a eld study of marking removal methods on dierent types of pavement markings on 15 construction projects in New York found that sandblasting resulted in nearly complete removal of paint, thermoplastic, and epoxy markings with minimal pavement scarring (Bryden and Kenyon 1986). e research also concluded that grinding was ecient for multiple marking types except tape but resulted in extreme scarring of the pavement. A more recent eld evaluation of ve marking removal methods (diamond grinding, carbide grinding, water blasting, dry ice blasting, and soda blasting) on SH-202 in Utah concluded that water blasting was the most eective method and resulted in the lowest amount of pavement damage (Berg and Johnson 2009). e two grinding methods were found to be the most ecient for speed. Results for carbide grinding and water blasting on chip seal are shown in Figure 26. e soda blasting and dry-ice blasting methods resulted in minimal pavement damage, but the removal speeds for these methods were slow. In addition, the soda blasting created a signicant amount of dust. Pavement-marking removal methods have also been assessed in controlled environments. In a study by Cho et al. (2011), several marking removal methods (water blasting, dry ice blasting, grinding, shot blasting, heat scorching for tape, and chemical) were tested in a parking lot and asphalt yard in Nebraska. Assessment criteria included extent of removal, pavement surface condition aer removal, speed of removal, and cost. Digital image processing was also used to assess the pavement surface condition aer removal. e researchers concluded that chemical Source: Cho et al. 2011 Figure 25. Survey results from study showing number of states satised with pavement-marking removal methods.

Literature Review 35   removal was the most eective method as it did not leave any scars or residues (Figure 27). In addition, estimated unit costs for the dierent removal methods were provided as previously shown in Table 4. A NCHRP study of pavement marking removal included eld evaluations in both controlled environments and on actual highway construction or maintenance projects (Pike and Miles 2013). Testing was performed on paint, thermoplastic, and tape markings using grinding, water blasting, and a combination method of grinding and water blasting. Results showed that water blasting was eective at removing markings on concrete pavement but sometimes caused removal of some surface asphalt and nes on asphalt pavement. Grinding led to some pave- ment scarring. e water blasting speed was found to be comparable to the grinding speed. Source: Adapted from Berg and Johnson 2009 Figure 26. Chip seal after pavement marking removal in Utah study: (a) carbide grinding and (b) water blasting. Source: Cho et al. 2011 Figure 27. Condition of asphalt pavement for chemical removal in Nebraska parking lot study (a) before removal and (b) after removal.

36 Temporary Pavement Markings Placement and Removal Practices in Work Zones e combination method resulted in eective removal at high speed for concrete pavement but created some scarring on asphalt pavement. Innovations for Pavement Marking Removal Other research studies have investigated the use of innovative methods for pavement marking removal. In a study by Ellis et al. (2010), two alternative methods for marking removal, modied slurry-seal coat and modied sand-seal coat, were developed and evaluated. Results showed that both methods were eective for covering the markings and providing adequate friction. e results for the modied sand-seal coat are shown in Figure 28. However, only the modied sand-seal coating was recommended for possible use because the modied slurry-seal coating required several hours of time to set. A dra specication for the modied sand-seal method was developed, and the cost of the method was estimated as $1.15 per linear foot or $1.03 per square yard. As part of a capstone project at a university in South Korea, a semiautomated sandblast- ing system was developed and tested (Bernold et al. 2010). e testing showed that the system could potentially be used to remove pavement markings, but enhancements to the blasting hose and nozzle were recommended to increase the speed of removal. Another study tested a laser system for pavement marking removal and found that the rate of removal was slower than other methods such as sandblasting or grinding (Pew and orne 2000). In addition, the estimated cost of the prototype laser system was over $100,000. Reprinted by permission from Springer Nature Customer Service Centre GmbH: Springer, KSCE Journal of Civil Engineering, 2010. Figure 28. Modied sand-seal coat after 30 days of trafc.