Practice of Rumble Strips and Rumble Stripes (2016)

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7 tion on the roadway. Overall, results show that rumble strips are mostly applied in rural settings and that installation varies by the type of rumble strip considered. Urban Versus Rural Rumble strips are much more prevalent in rural settings, which typically have less dense housing and roadways with a higher frequency of single-vehicle run-off-road and cross-center line crashes. As shown in the “None” column in Table 3, all but one of responding agencies use some type of rumble strip on rural roadways. In contrast, 59% report not installing rumble strips on urban multilane divided highways, 73% do not use them on urban multilane undivided roadways, and 76% do not use rumble strips on urban two-lane roadways. Common Practice by Rumble Strip Type Agency practices show that a right shoulder rumble is the most common in rural settings, followed by left shoulder rumbles on rural multilane divided roadways and then center line rumble on two-lane rural roads. Additional discussion from Table 3 shows that: • The right shoulder/passenger side rumble on rural multi- lane divided highways has the highest use of any rumble strip type, by 95% of responding agencies. Use of this rumble type is consistent with efforts to address single vehicle run-off-the-road crashes, particularly in rural settings. This is followed by 85% usage on both rural multilane undivided and rural two-lane roadways. • Left shoulder/driver side rumble strips are most often installed by agencies on multilane roadways, especially on rural multilane divided highways (88% usage). In addition, 37% reported using left shoulder rumbles on urban multilane divided highways, which is within set- tings that allow for the balance between crash prevention and noise. Last, 39% reported installing left shoulder rumbles on rural multilane undivided roadways and rural two-lane roads, responses that may reflect some confusion concerning the question or special roadway conditions. • Center line rumble strips were applied on rural two-lane roads by 71% of respondents, which is consistent with efforts to reduce cross-center line crashes. This chapter presents the results from the survey to which 41 state DOTs responded. The survey consisted of six main sections: 1. Rumble strip practices (three questions) 2. Selection criteria (three questions) 3. Design and installation practices a. General (nine questions) b. Shoulder rumble strips (seven questions) c. Center line rumble strips (six questions) d. Rumble stripes (seven questions). 4. Maintenance practices (10 questions) 5. Benefits (eight questions) 6. Issues (11 questions). The survey questions are included in Appendix A. RUMBLE STRIP PRACTICE Rumble strips are a low cost safety countermeasure used to reduce roadway/lane departure crashes. Table 1 shows that all of the 41 responding agencies reported that they use rumble strips. Table 2 shows that 37 (90%) of these agencies have a policy or guidance specific to the application of rumble strips. Unlike most traffic control devices, where shape, size, and installation criteria are established, rumble strip installations can vary by the types of roads, the shapes and patterns used to install them, and the maintenance practices which keep them effective. RUMBLE STRIP SELECTION CRITERIA The variation in rumble strip practice is often a result of influ- encing factors including roadway features, user groups, traffic volume, speed limit, pavement condition, available lane and shoulder widths, and other impact factors including sensitiv- ity to noise generated within residential areas. State feedback on these influencing factors for rumble strip installations is explored here. Rumble Strip Practice by Roadway Type Table 3 provides a summary of DOT practices for installing rumble strips by the type of roadway and rumble strip posi- chapter three SURVEY RESULTS

8 Conditions Influencing Rumble Strip Installation Given that all 41 responding state DOTs use rumble strips, it is important to understand the factors that influence installation guidelines, and policies that contribute to variation in practice. The survey listed some common influencing factors, includ- ing shoulder width, pavement condition, and speed limit; and requested that states report their minimum required values for each applicable factor. Table 4 shows those results by shoulder and center line. Shoulder Rumble Strip Installation Table 4 indicates that having sufficient shoulder width is the most frequent criterion considered, with 37 agencies reporting a range in width of between two and eight feet. Speed limit was the second most frequently listed factor; 25 agencies reported installing shoulder rumbles on roadways having a posted speed higher than 40 mph and as high as 55 mph. Other common factors were reported by 19 agencies, includ- ing consideration of lane width, bicycle use, adjacent home locations, and roadway type. Agencies are also con sidering the quality of the pavement surface before installing rumble strips, as reflected by the 18 agencies noting that the pave- ment must be in “good” condition and typically asphalt rather than concrete or treated surfaces. Only 11 agencies, just over a quarter, use crash frequency or rate as a criterion for installation. Center Line Rumble Strip Installation Table 5 shows that having sufficient lane width is the most common criterion considered in center lane installations, with 22 agencies reporting a range in width of between 10 and 12 feet. Twenty (20) agencies identified the presence of homes, noise, functional classification, and urban versus rural setting as other factors. Speed limit is considered by 18 agen- cies, with the majority listing a minimum of a posted speed of 45 mph and the range being from 35 to 55 mph. As with shoulder rumble strips, agencies are looking to install on pave- ment in “good” condition. However, in contrast to shoulder rumbles, 13 agencies noted considering crash frequency for locations which either have a crash history or more than aver- age head-on collisions. TABLE 1 AGENCY USE OF RUMBLE STRIPS (survey question 1) Does Your Agency Use Rumble Strips? Number of Agencies Percent Yes 41 100 No 0 0 41 responding agencies. TABLE 2 APPLICATION GUIDELINES AND POLICIES (survey question 2) Does Your Agency Have a Written Policy/Guidelines Concerning the Application of Rumble Strips? Number of Agencies Percent Yes 37 90 No 4 10 41 responding agencies. TABLE 3 RUMBLE STRIP INSTALLATIONS BY ROADWAY TYPE AND RUMBLE STRIP LOCATION (survey question 4) Type of Roadway None Left Shoulder (median) Center Line Right Shoulder (outside) Responses Urban Multilane Divided Highways 59% 37% 5% 41% 41 Urban Multilane Undivided Highways 73% 7% 12% 27% 41 Urban Two-Lane Roads 76% 5% 15% 22% 41 Rural Multilane Divided Highways 5% 88% 5% 95% 41 Rural Multilane Undivided Highways 5% 39% 59% 85% 41 Rural Two-Lane Roads 5% 39% 71% 85% 41 41 responding agencies.

9 DESIGN AND INSTALLATION PRACTICES These questions focused on understanding the state of practice for rumble strips and stripes in terms of how, when, and under what conditions they are used. The questions were asked, and are reported here, by category (general, shoulder rumble strips, center line rumble strips, and rumble stripes). General Agencies were surveyed regarding general rumble strip and stripe installation practices including the use of a sealant over the rumble, whether they measure in-place rumble dimensions, and if they have performance targets for rumble performance. Use of a Sealant over Rumble Strips Rumble strips can allow water to pool and increase the exposed pavement surface area. Some agencies address this through the application of a sealant over the rumble. Figure 1 shows the current state of practice, with 44% of agencies reporting using a sealant; however, of these, 15% note that this is not standard practice. More than half, 56%, do not use any sealant. Of the agencies that use a sealant, the common reasons were to slow pavement deterioration and protect against moisture. Field Measurement of Installed Rumble Strip Dimensions Establishing rumble strip dimensions is critical in producing the audible and tactile ranges necessary for their effectiveness. Given that construction practices include tolerances and that installation techniques and contractor quality processes can vary, agencies were asked if they measure post-construction rumble strip dimensions. Figure 2 shows that more than two- thirds of agencies, 28 or 68%, do measure these field dimen- sions; however, only eight of that 28, or 20% or respondents, reported having a fully defined method to check these dimen- sions. Figure 3 shows that the most common field measure- ments are spacing, depth, and width, at 96%, 96%, and 93% respectively. Electronic Database of Rumble Strip Locations Having an accurate record of rumble strip locations, patterns, and dimensions is critical towards evaluating the impact these Influencing Factor Number of Agencies Percent Minimum Required Values/Explanation Lane Width 22 58 Between 10 and 12 ft Other (please specify) 20 53 Factors include homes, noise, functional class, and rural Speed Limit 18 47 Between 35 and 55 mph with the majority at 45 mph Pavement Condition 17 45 Good condition Crash Frequency/Rate 13 34 Locations with a crash history or above average head-on crashes Pavement Type 9 24 Mostly asphalt ADT 4 11 Alignment 1 3 38 responding agencies. ADT = average daily traffic. TABLE 5 INFLUENCING FACTORS FOR CENTER LINE RUMBLE STRIP INSTALLATION (survey question 6) Influencing Factor Number of Agencies Percent Minimum Required Values/Explanation Shoulder Width 37 93 Between 2 and 8 ft Speed Limit 25 63 Between 40 and 55 mph with the most common answer at 45 mph Other (please specify) 19 48 Factors include lane width, bicycle presence, home locations, roadway type Pavement Condition 18 45 Good condition Crash Frequency/Rate 11 28 Pavement Type 10 25 Mostly asphalt and no treated surfaces (microsurface, seal coat, and chip seal) ADT 3 8 Alignment: 1 3 40 responding agencies. ADT = average daily traffic. TABLE 4 INFLUENCING FACTORS FOR SHOULDER RUMBLE STRIP INSTALLATION (survey question 5)

10 FIGURE 1 Use of a sealant over rumble strips (survey question 7). FIGURE 2 Field measurement of rumble strip dimensions (survey question 8).

11 FIGURE 3 Measuring rumble strip dimensions in the field (survey question 11). FIGURE 4 Specification for rumble strip pattern (survey question 16). countermeasures are having on safety. When this information is tied to an agency’s location referencing system, it allows for integration with other data sets such as crash experience. The survey found that 17 agencies (42%) have an electronic database of their installed rumble strip locations, but that 24 agencies do not. Of the 17 agencies responding affirma- tively, 13 have tied the information to their location refer- encing system. This could provide the basis for conducting a national study on the effectiveness of rumble strips and stripes on safety. Specifications for Desired Audible and Tactile Ranges Agencies were asked if they use audible and tactile specifica- tions that an installed rumble strip should produce. Thirty- nine (39) agencies reported having no specific ranges; one reported using a specification for interior sound warnings (Arkansas, which uses a ½-inch rumble depth to produce 6 db at 65 mph); and one agency reported a standard for exterior sound (Delaware, which measures noise outside the vehicle at a distance of 275 to 350 feet). Specifications for Rumble Strip Pattern Agencies were asked if they have a specification regard- ing the pattern to be used when installing rumble strips (Figure 4). Thirty-eight (38) agencies, 93%, reported using a specification for rumble strip patterns. The patterns (loca- tions where rumbles are omitted) are applied to bicycle- friendly areas as well as intersections, bridge decks, and residential areas.

12 Shoulder Rumble Strips Shoulder Rumble Strip Placement Location Agencies were asked how close to the pavement edge line they install shoulder rumble stripes. Table 6 shows that the reported results range from 0 (i.e., directly on the edge) to 18 inches, with the most common answer being 6 inches (12 responses, or 29%). Types of Rumble Strip Patterns Installed Rumble strip pattern affect the sound levels produced; for example closely-spaced rumble strip patterns are expected to have a higher sound level difference than patterns spaced further apart. Agencies were asked what types of rumble strip patterns they install, between the choices of continuous, pat- tern (gap/cycle), or bicycle gap pattern. The findings show that 34 agencies, 83%, use the continuous pattern (mostly on divided highways), 14 agencies use the gap/cycle pattern, and 24 agencies use the bicycle gap pattern. Specific to the bike pat- tern, half of the states use a 12-foot gap with 48 feet of rumble. The smallest bike gap was 10 feet and the widest was 16 feet. Intermittent Gaps Installed for Rumble Strips Agencies routinely create intermittent gaps between continu- ous applications of the rumble line for pre-determined situ- ations such as intersections, major driveways, bridge decks, and noise sensitive areas. Agencies were asked to identify if they used intermittent gaps, and if so, what factors determined where used. Table 7 shows the reasons gaps are created, the most common responses being bridges, “other,” and noise, at 30, 29, and 22 agencies, respectively. For the gaps categorized as “other,” the most common answers included urban areas (high driveway densities), poor pavement, horse and buggy areas, railroad crossings, and pedestrian crossing areas. Typical Dimensions for Shoulder Rumble Strips Rumble strip dimensions vary by agency, as shown in the sur- vey of practice results in Table 8, which is based on the dimen- sions defined by Figure 5. The survey found the following most common values (bolded and shaded in a darker color): • Length of 16 inches (15 agencies) followed closely by 12 inches (14 agencies) • Width of 7 inches (29 agencies) • Spacing of 12 inches (27 agencies) • Depth of 0.5 inches (15 agencies). Typical Dimension Variation by Roadway Type Given the range of dimensions used, agencies were asked if any of these shoulder rumble strip dimensions varied by road- way type (Figure 6). As shown, all dimensions do vary by roadway type, and length appears to vary more than width, spacing, or depth. Agencies noted that these changes are influ- enced most often by roadway type, functional class, and pave- ment type (concrete versus asphalt). Center Line Rumble Strips Center Line Placement Location Agencies were asked where they install the center line rum- ble strip relative to the roadway center line and the pavement marking. The possible answer choices were rumble stripes, rumble strips, both, or other (with a required answer). Table 9 shows that 32 of the states (78%) are using rumble stripes (strips with the pavement marking on the rumble); five agencies are not using any center line rumbles. Types of Center Line Rumble Strips Installed Agencies were asked what types of center line rumble strip patterns they install; the choices were continuous, pattern (gap/cycle), or bicycle gap pattern. Thirty (30) agencies use the continuous pattern where there is no need to provide gaps for intersections; nine agencies use the gap/cycle pattern, mostly for passing on two-lane roads; and two agencies use the bicycle gap pattern. Inches from Edge Line Number of Agencies Percent 0 7 17 4 7 17 6 12 29 12 3 7 16 2 5 18 1 2 Varies 9 22 41 responding agencies. TABLE 6 SHOULDER RUMBLE STRIP LOCATION FROM EDGE LINE (survey question 17) Gaps Created For: Number of Agencies Percent Bridge Decks 30 79 Other 29 76 Noise 22 58 Bicycles 17 45 Special Users 6 16 38 responding agencies. TABLE 7 REASONS AGENCIES CREATE INTERMITTENT GAPS WITHIN SHOULDER RUMBLE STRIPS (survey question 21)

13 Length in Inches Inches No. of 6 7 8 9 10 11 12 13 14 15 16 Agencies 6 to 16 1 7 3 8 to 12 1 8 to 16 2 12 to 16 2 12 14 16 15 18 1 30 1 40 responding agencies. Width in Inches Inches No. of 4 5 6 7 8 Agencies 4 1 5 5 6 1 7 29 36 responding agencies. Spacing in Inches Inches No. of 5 6 7 8 9 10 11 12 13 14 15 Agencies 5 7 7 2 9 1 10 1 12 27 14 1 39 responding agencies. Depth in Inches Inches No. of 0.25 0.30 0.35 0.40 0.45 0.50 0.55 0.60 0.65 0.70 0.75 Agencies 0.25 to 0.5 1 0.375 9 0.375 to 0.625 5 0.5 15 0.5 to 0.75 2 0.75 1 33 responding agencies. TABLE 8 SHOULDER RUMBLE STRIP DIMENSIONS (survey question 22)

14 Intermittent Gaps Installed for Rumble Strips Agencies were asked whether if they used intermittent gaps on center line rumble strips, and if so, what factors determined where (Table 10). Bridges, “other,” and noise were the most common responses, at 27, 23, and 20, respectively. Among “other” factors, the most common were intersections, urban areas (high driveway densities), pavement condition, and pass- ing lanes. Typical Dimensions for Center Line Rumble Strips Rumble strip dimensions vary by agency, as shown in the sur- vey of practice results in Table 11 based on the dimensions defined by Figure 6. The survey found the following most common values (bolded and shaded in a darker color): • Length of 12 inches (18 agencies) • Width of 7 inches (22 agencies) • Spacing of 12 inches (19 agencies) • Depth of 0.375 inches (18 agencies). Typical Dimension Variation by Roadway Type Agencies were asked if any of these center line rumble strip dimensions varied by roadway type. The answers are summa- rized in Figure 7. In contrast to shoulder rumble strips, the cen- ter line dimensions have little variation by roadway type, with at least 30 agencies reporting no variation in each category. Agencies noted that these changes are influenced most often by pavement type (open graded thin asphalt), narrow road- ways, and by higher functional class of roadway. Rumble Stripes Rumble Stripe Usage Agencies were asked if they use edge and/or center line rum- ble stripes. Figure 8 shows that 29 agencies (70%) install edge line rumble stripes and that 35 (85%) install center line rumble stripes. Measuring Retroreflectivity Agencies were asked if they measure the pavement marking retroreflectivity of their rumble stripes. The results show that the majority, 29, do not; however, 15 agencies are measur- ing retroreflectivity. Of these 15, 12 agencies measure under FIGURE 5 Shoulder rumble strip dimensions referenced. Center Line Rumble Type Number of Agencies Percent Rumble Stripe 32 78.0 Rumble Strip 2 4.9 Both 2 4.9 None 5 12.2 41 responding agencies. TABLE 9 CENTER LINE RUMBLE LOCATION (survey question 24) FIGURE 6 Do shoulder rumble strip dimensions vary by roadway type (survey question 23)?

15 Gaps Created For: Number of Agencies Percent Bridge Decks 27 79.4 Other 23 67.6 Noise 20 58.8 Special Users 6 17.6 Bicycles 3 8.8 34 responding agencies. TABLE 10 REASONS AGENCIES CREATE INTERMITTENT GAPS WITHIN CENTER LINE RUMBLE STRIPS (survey question 27) Length in Inches Inches No. of 7 8 9 10 11 12 13 14 15 16 17 Agencies 4 1 7 2 8 2 10 1 12 18 14 1 16 11 36 responding agencies. Width in Inches Inches No. of 4 5 6 7 8 Agencies 4 1 5 6 6 2 7 22 7.5 2 33 responding agencies. Spacing in Inches Inches No. of 4 6 8 10 12 14 16 18 20 22 24 Agencies 4 1 5 6 12 19 14 2 24 6 34 responding agencies. Depth in Inches Inches No. of 0.2 5 0.27 5 0.30 0 0.32 5 0.35 0 0.37 5 0.40 0 0.42 5 0.45 0 0.47 5 0.50 0 Agencies 0.25 1 0.375 18 0.25 to 0.5 2 0.5 13 0.5 to 0.75 1 35 responding agencies. TABLE 11 CENTER LINE RUMBLE STRIP DIMENSIONS (survey question 28) dry conditions, three include wet recovery, and two agencies include continuous wetting measurements. Pavement Marking Materials Agencies were asked to identify the pavement marking prod- ucts being used for rumble stripes. Table 12 shows that the most common is standard acrylic waterborne paint (17 agen- cies, or 42%) followed by epoxy at 16 agencies (39%). In addition, 11 agencies reported using wet reflective media to enhance wet night visibility of the rumble stripes. Another nine DOTs reported using some wet reflective media but that

16 FIGURE 7 Do center line rumble strip dimensions vary by roadway type (survey question 29)? FIGURE 8 Rumble stripe use by line type (survey questions 30 and 32). Ag en ci es 29 Shoulder Rumble Stripes Center Line Rumble Stripes 12 Yes No 35 6 5 10 15 20 25 30 35 40 The results show that 30 agencies (73%) replace rum- ble strips based on pavement surface rehabilitation as opposed to tactile/audible effectiveness. • Winter maintenance—Agencies were asked if winter maintenance operations vary based on the presence of rumble strips (snow removal, sanding, salt and brine applications). Thirty-nine (39), 95%, do not alter winter maintenance practice as a result of the presence of rumble strips. One agency noted that districts typically place some amount of melting material near the center line joint with the expectation that the material will work its way down the cross slope. Some districts use more material with the expectation that the center line rum- ble will “catch” some of the material. Another agency reported that salting practices are adjusted when center line rumble strips are present to avoid the salt collecting in the rumble strip rather than being distributed. • Maintaining the pavement marking within the rumble— Agencies were asked how they maintain the pavement marking within the rumble stripe. The results show that 85% paint over the existing marking, while the rest remove the existing marking prior to reapplication. When asked about experiencing differences in retroreflectivity by direction of travel for center line rumble stripes, only 20% (eight agencies) noticed any difference. One agency com- mented that this has been addressed through establishing minimum retroreflectivity in both directions and another reported painting center line stripes in both directions. BENEFITS This section focused on the benefits of using rumble strips and stripes as experienced by state DOTs. The questions focus on crash modification factors (CMFs), pavement marking performance, and other benefits. this was not a standard practice; and 21 agencies reported using no wet media. MAINTENANCE These questions focused on DOT maintenance practices when rumble strips and stripes are present. The questions were asked, and are reported here, by category: sealant, life expectancy, winter maintenance, and maintaining the pavement marking within the rumble. • Sealant—Agencies were asked whether over time they re-apply sealant over the rumble strip. Only five agen- cies re-apply, and this is based on a pavement condition assessment with no standard frequency for re-application. • Life expectancy—Agencies were asked if they have determined a life expectancy for rumble strips (in terms of tactile and audible effectiveness) or whether their replacement is based on pavement surface rehabilitation.

17 Crash modification factors—A CMF is a multiplicative factor used to compute the expected number of crashes after implementing a given countermeasure at a specific site (CMF 2015). Agencies were asked whether they have established crash modification factors for installing rumble strips. Ten (10) of 41 agencies, 25%, reported crash reduction values, which are shown in Table 13. For those agencies using CMFs from the CMF Clearing House, it is advisable that they use the studies that are rated 4 or 5 stars, as these studies have had a more rigor- ous evaluation. Cost-effectiveness—Agencies were asked whether they have established a cost-effectiveness value for install- ing rumble strips based on safety benefits. The results show that 11 agencies (27%) have established values ranging from 7:1 to 75:1, with multiple states currently conducting research projects to determine these values. Rumble stripe longevity—It was noted in the survey that anecdotal evidence suggests installing a pavement marking over the rumble strip extends the life of the marking. Agencies were asked for their expectations of the results of this procure given the following choices: providing similar strip performance, extending a strip’s life by less than one year, or extending it by more than a year. Fifteen (15) agencies reported expecting similar performance, two agencies expect that the life would be extended by less than 1 year, and six agencies antic- ipate that pavement marking life would be extended by more than one year (the average was 3–4 years) when installed within a rumble (see Figure 9). However, comments indicated that agencies do not have enough experience monitoring pavement markings within the rumble to have a good idea on what impact this has on life expectancy. Visibility—The survey asked if rumble stripes were being used as a wet night visibility solution, and 11 agencies (27%) confirmed that they are. Additional benefits—Agencies were asked if there are other benefits not touched on in the survey that they consider from using rumble stripes. Some of the com- ments are summarized here in three general categories. Winter weather conditions: • Rumbles help snow plow operators maintain their posi- tion in the lane during winter weather events. Pavement Marking Material Used Number of Agencies Percent Standard Acrylic Waterborne Paint 17 46 Epoxy 16 43 Other (required) 15 41 High Build Acrylic Waterborne Paint 11 30 Sprayed Thermoplastic 11 30 Polyurea 6 16 Urethane 1 3 37 responding agencies. TABLE 12 PAVEMENT MARKING MATERIALS USED FOR RUMBLE STRIPES (survey question #5) State CMF for Rumble Strips Note Shoulder Center Line AK CRF: -20% on rural two-lane hwy > 50 mph -10% on four-lane rural hwy > 50 mph CO 0.70 CMF GA Refer to the Highway Safety Manual and CMF Clearinghouse. MI 0.53 to 0.45 MO 0.75 CMF NC https://connect.ncdot.gov/resources/safety/Pages/Safety-Evaluation.aspx OR CRF: -12% for centerline, all crashes; -22% for shoulder RS PA 0.96 to 0.57 0.94 to 0.55 TX 0.65 Centerline: milled 0.50, profile 0.40 VA 0.71 0.56 TABLE 13 CMF AND CRASH REDUCTION FINDINGS BY AGENCY (survey question 47)

18 • Rumbles help snow plow operators to locate the center line of the roadway during snow storms. • Vibrations from rumbles help plow drivers detect the edge of the lane when snow covers the pavement markings. Safety: • Rumble strips potentially reduce speeds in some areas. • Rumbles help with road navigation in bad weather and low-light conditions, especially as a result of vibrations from center line rumbles. • Even in non-storm conditions, the vertical face of the rumble indentation makes the stripe more visible to the driver at night. Vibrations from the rumble strip can also aid in navigation under extremely low visibility conditions. • Rumble strips provide a more clear shoulder distance for cyclists, especially where roadside barriers or other obstructions exist. • Beyond the improved road departure safety performance involving distracted, fatigued, impaired and drifting motorists, there have been some instances where highway workers and emergency responders on the road shoulder were alerted to an errant vehicle by the audible warn- ing created when encroaching vehicles tires engaged the rumble strip. Service Life: • Rumbles protect some pavement markings from snow plow damage and reduce maintenance costs by eliminat- ing plowable raised markers. ISSUES The survey included a section asking agencies to identify the relative importance, on a scale of 1 to 5 (with 5 being the most important) of specific issues faced when using rumble strips or stripes. Table 14 shows the rated issues and scores. Noise and bicycle complaints had the highest average score in terms of issue importance, with 24 agencies (58%) giving noise a score of 4 or 5; bicycle complaints were the most important, rating 4 or 5, to 21 agencies (51%). The next issue in terms of importance was related to pavement FIGURE 9 Pavement marking longevity (survey question 51). Issue 5 4 3 2 1 Average Bicycle Complaints 12 9 10 9 1 3.5 Noise Complaints 9 15 4 10 3 3.4 Pavement Deterioration (center line joint) 10 7 6 8 10 3.0 Rumbles on Challenging Surfaces 4 10 8 10 9 2.8 Pavement Deterioration (edge line) 4 7 9 10 11 2.6 Pavement Marking Performance 4 2 12 8 15 2.3 Motorcycle Complaints 0 5 12 13 11 2.3 Winter Maintenance Issues 0 1 6 15 19 1.7 Ranking: 5 = Most Important Issue Faced. TABLE 14 ISSUES FACED WHEN USING RUMBLE STRIPS AND STRIPES (survey question 55)

19 deterioration owing to the rumble or the inability to place a rumble on challenging surfaces (microsurfaces, thin asphalt, seal coat, chip seal, etc.). When it comes to pavement dete- rioration, perspectives can be quite different. For example, center line joint pavement deterioration was ranked a 5 (most important) by 10 agencies, while the same number ranked it a 1 (least important). State DOTs did not view winter mainte- nance as an important issue, with 33 states (80%) rating this either a 1 or 2. Other issues reported include: • Added wear and tear on snow plowing equipment • How many chip seals can be applied before it is neces- sary to regrind the rumble strip • Maintenance of pavement markings in rumble stripes • Installation accuracy (particularly on edge line rumbles stripes) improving on the method of controlling lateral alignment • Schedule of upcoming resurfacing • Future use of the pavement as a travel lane [and] issues with future work zone phases and staging (may have to fill in the rumble and overlay to use) • Need to consider impact to agency and vehicles on shoulder operations • Ability to effectively restripe without having to blast/ remove markings in the rumble stripe (most would be expected to survive until next resurfacing) • What needs to be done when it is time to resurface to avoid reflection through thin overlays. Noise issues—Agencies were asked if their rumble strip policy/guidance addresses noise concerns. Table 15 shows that 27 agencies (66%) are addressing noise con- cerns, as described in more detail in chapter four: Case Examples. Various agencies address noise by installing strips away from urban areas, eliminating roads with speeds less than 45 mph, and being sensitive to com- munity needs. Bicycle issues—Agencies were asked if their rumble strip policy/guidance addresses bicycle concerns. Table 16 shows that 34 agencies (83%) are addressing bicycle concerns, as detailed in chapter four. Of these, 15 agen- cies reported that this impacts installation practices by location selection. In addition, 10 agencies noted that this impacts rumble strip design in terms of bicycle gap selection. Pavement deterioration issues—Agencies were asked if their rumble strip policy/guidance addresses pavement deterioration concerns. Table 17 shows that 18 agen- cies (44%) do address deterioration, as described in chapter four. Of those 18 agencies, 10 reported that this impacts installation practices by location; three said it affects rumble strip design. Public complaints—Agencies were asked to rate the level of public complaints specific to issues commonly asso- ciated with rumble strips. Table 18 shows that DOTs are primarily receiving complaints regarding bicycles— Address Noise Concerns Number of Agencies Percent Yes 27 66 No 7 17 Not Applicable 7 17 41 responding agencies. TABLE 15 ADDRESSING NOISE CONCERNS (survey question 57) Address Pavement Concerns Number of Agencies Percent Yes 18 44 No 19 46 Not Applicable 4 10 41 responding agencies. TABLE 17 ADDRESSING PAVEMENT DETERIORATION CONCERNS (survey question 63) Address Bicycle Concerns Number of Agencies Percent Yes 34 83 No 4 10 Not Applicable 3 7 41 responding agencies. TABLE 16 ADDRESSING BICYCLE CONCERNS (survey question 59) Level Of Public Complaints Complaints Regarding: Low Medium High Noise 18 16 7 Bicycle Related 17 11 13 Motorcycle Related 33 6 1 Pavement Deterioration (center line joint) 36 3 2 Pavement Deterioration (edge line) 35 5 1 Winter Maintenance Issues 38 3 0 Pavement Marking Performance 35 6 0 Rumbles on Challenging Surfaces 34 5 2 TABLE 18 PUBLIC COMPLAINTS BY TOPIC (survey question 67)

20 13 agencies rating these as “high”—followed by noise. Both of these issues have the highest ratings in the medium complaint level category as well. Public outreach materials—Agencies were asked if they had developed fact sheets/brochures regarding the benefits of rumble strips. There results show that only eight agencies have developed outreach materials while 29 agencies have not. Specific resources agencies reported using included FHWA materials, NCDOT documentation materials, and in Delaware, brochures given out during state DOT public events. Five agencies also provided specific links: • http://www.ct.gov/dot/cwp/view.asp?a=3199&q=526532 • http://www.dot.state.mn.us/trafficeng/safety/rumble/ • http://www.dot.state.wi.us/safety/motorist/roaddesign/ rumblestrips/how-they-work.htm • http://www.maine.gov/mdot/safety/docs/rumblestrip- brochure-general.pdf • http://www.dot.state.ak.us/stwddes/dcstraffic/rumble/ index.shtml. Public service announcements (PSAs)—In addition to fact sheets, agencies were asked if they had developed PSAs (web, radio, television) to communicate the ben- efits of rumble strips; the answer options were yes, no, and other. Only two agencies, the Michigan and North Dakota DOTs, said they have developed PSAs using web and traditional media, in contrast to the 36 agencies that have not. For example, Michigan DOT developed a PSA in response to vehicles not wanting to cross the center line to pass a bicycle when rumble strips were present. In addition, three agencies reported “other” with expla- nations of using national campaign materials (North Carolina and New York DOTs) and having conducted a public education and information campaign when first starting to use rumble strips (South Carolina DOT in 2008). These links refer to existing web/media pro- vided by Michigan DOT, MnDOT, and FHWA: • Michigan Rumble Strips Save Lives https://www.youtube.com/watch?v=EEQXuu6ITjA • Michigan DOT Share the Road. https://www.youtube.com/watch?v=MUL8l9_65Ic • Minnesota DOT noise video (traditional rumble vs. sinusoidal rumble) https://www.youtube.com/watch?v=W3-uPGb1nmM • FHWA Video “Sound Investment” https://www.youtube.com/watch?v=bug-KDhu2Ec