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SECTION V--DESCRIPTION OF STRATEGIES the application of increased fines through more frequent visible enforcement activities will help change driver perception about the likelihood of being cited for violations. In addition to the possibility of being cited a large fine, the driver needs to have the perception that the fine will be large and the sanction will be upheld by the courts. Otherwise, the sanction will be reduced to the inconvenience of the court visit. Forty-five states currently impose increased penalties for speed violations in work zones, and in some states those increased fines apply to all types of violations. Studies show that many drivers continue to violate the work zone speed limits in spite of these increased fines. Using a consistent approach to enforcing work zone traffic laws and adjudicating citations is a way to curb this trend. This will require seeking the cooperation of the judiciary. It can be facilitated by encouraging a partnership and making sure that judges understand the importance of this strategy for saving lives. More information on this strategy, with respect to use in work zones, is discussed in greater detail in NCHRP Report 500, Volume 17 (Work Zones) of this series. Doubling the fines in school zones may be one of the ways to improve compliance of speed limits in those areas. Signs may be posted around the school showing the message that speeding fines will be doubled. Public information campaigns may also be conducted to educate people about the penalty of speeding in school zones. Without proper enforcement, long-term effects may not be seen. More frequent enforcement activity may change drivers' perceptions and adherence to speed limits. Washington State enacted a state legislation in 1996 doubling the fines for speeding in school crosswalk and playground zones after a survey showed that 50 percent of drivers were not complying with reduced school zone limits and also speeds in excess of 50 mph were observed during the survey. One-half of the amount collected through doubling the fines was used for improving school zone safety like installation of signs, replacing existing school zone crossing signs with new fluorescent yellow-green signage. Similar strategies can be applied in problem locations in residential areas, hospitals and places with large elderly populations and numbers of pedestrians. Objective D--Communicate Appropriate Speeds through Use of Traffic Control Devices Traffic control devices are the primary means through which drivers are made aware of traffic laws. The most basic device is the speed limit sign, informing drivers of the maximum allowable safe travel speed, under any conditions. Variable message signs (VMS) provide more personalized, current information. Active speed warning signs display current travel speeds to drivers, and are intended to deter drivers from speeding and make them aware of the appropriate speed. In-pavement techniques can also be applied to the actual roadway to encourage safer speeds. The placement, visibility, and maintenance of all traffic control devices are important features in effectively communicating speed limits clearly. Poorly placed devices can have a negative effect on safety, and increase the chances of speeding-related collisions. Strategy D1--Improve Speed Limit Signage (T) The placement, visibility, and maintenance of speed limit signs are important features in effectively communicating speed limits clearly. A speed limit sign that has been misplaced, has low visibility, or is not properly maintained can result in ineffective communication of speed limits, which consequently can fail to encourage drivers to obey the speed limit. This can in turn have a negative effect on safety, and increase the chances of speeding-related collisions. V-48

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SECTION V--DESCRIPTION OF STRATEGIES Location and frequency of speed limit signs are two key elements to properly communicating the speed limit. Speed limit signs need to be consistently placed at the proper locations (for example, following major intersections), which will reinforce a driver's expectation of when to look for a speed limit sign. This is especially important if there is to be a change in the speed limit from one section of the roadway to the next. If a speed limit change occurs at a location where a driver may not be expecting one, then adding speed reduction signs should be considered. Along extended stretches of roadway where there are no changes in the speed limit, additional signing is still important as a reminder to drivers and also to inform drivers that may have entered the roadway at a minor intersection. In Minnesota, "Reduced Speed Ahead" signs are used to give advance notice of reduced speed limits when the reduction is 15 mph or more. In urban areas, where speed reductions to 55 mph or less are required, speed reductions signs are to be erected on both sides of the roadway. This is to be followed by supplemental speed limit signs mounted on both sides of the roadways through the reduced speed zone. Supplemental speed limit signs, through all reduced speed zones, should be placed at intervals approximately equal to 60 seconds of travel time at the posted speed limit. Signs may need to be spaced closer in urban areas due to the increased number of access points. Minnesota sets 10 miles as the maximum spacing between speed limit signs in rural areas. In urban areas a speed limit sign should be placed at each interchange for traffic entering the mainline (Minnesota DOT, 2004). As with placement, the driver's ability to see the sign is highly important if the driver is expected to obey the speed limit. Two factors that may affect the visibility include the mounting details (i.e., Is the sign properly mounted so that it is in a driver's field of vision?) and letter/border size (i.e., Was the appropriate letter and border size chosen for the speed limit such that a driver can easily read the sign?). For more information regarding the proper mounting and sizing of speed limit signs, refer to the current MUTCD. Often overlooked, the context of the environment around a sign can impact its visibility. In urban areas where traffic signs and commercial signs may be abundant, a driver may need additional assistance with locating the speed limit signs. This assistance may take on different forms, but possibilities include using larger signs and removing or relocating unnecessary signs. The issue of maintenance is an important factor in a sign's visibility. Poor maintenance can result in reduced visibility through many forms, including tree and shrub growth, vandalism, and reduction of the sign's retro reflectivity. See Exhibit V-12 for more information about improving speed limit signage. Strategy D2--Implement Active Speed Warning Signs (Including Truck Rollover Warnings) at High Risk Locations Where Excessive Speeds and Potential Conflicts Are Expected (T) Active speed warning signs, also known as radar speed displays, speed display signs or speed trailers, are similar to variable message signs (VMS), except they have radar technology that determines the traveling speed of vehicles. Active speed warning signs are intended to deter drivers from speeding and improve awareness that they need to obey the posted speed limit. Travel speeds are detected and then displayed on the message board. V-49

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SECTION V--DESCRIPTION OF STRATEGIES EXHIBIT V-12 Strategy Attributes for Improving Speed Limit Signage (T) Attribute Description Technical Attributes Target This strategy is targeted at providing improved signing to communicate speed limits clearly and effectively, especially to drivers that are unknowingly speeding. The proper sign type, location, and routine inspection and maintenance of signs can deter speeding and facilitate enforcement by effectively communicating the proper speed limit to drivers. All agencies can implement this strategy. This strategy may be especially important where there is a higher percentage of older drivers, or the visibility of signs is often obscured by adverse weather, such as drifting snow. Expected Effectiveness There is a lack of studies evaluating the effect of proper signage and routine maintenance on preventing speeding; however, the general principle is that there is a higher likelihood that speed limits may be exceeded if drivers are unaware of the actual speed limit. Furthermore, clear and unambiguous communication of the speed limit to drivers is an important role of effective enforcement and prosecution of speeders, especially if law enforcement and the courts are to view speeding as a significant and preventable safety risk. Keys to Success The consistent and correct placement of speed limit signs is the first step towards effective communication. Further, selecting the proper design standards (i.e., lettering size) for the roadway is a fundamental requirement. Following deployment, the upkeep of speed limit signs is necessary, especially if minimum retro reflectivity levels are adopted by the highway agency. A GIS-based road sign inventory with links to maintenance records is one possible tool that can be used to track and manage sign maintenance activities and needs. Another key to the success of speed limit sign improvements is that the posted speed limit is reflecting an appropriate speed limit for the roadway. See Strategy A1 for setting appropriate speed limits. Potential Difficulties The biggest difficulties associated with this strategy are maintaining a sign inventory and routine inspection and maintenance of signs. This is especially difficult in urban areas where there are many signs on the roads. Likewise, this can be a difficult task for rural areas, where highway mileage with associated signage is high. Lack of personnel to take inventory and provide maintenance and repairs to correct signs can also be a potential difficulty for agencies that are understaffed for such duties. Appropriate Measures Key process measures include the number of locations where poor signage was and Data replaced, and the related effect it had on speeding vehicles. Additional data might include identifying locations with improved signage and using this to compare to locations with undesirable signage. Observing any negative effects that the adverse signs have on safety and speeding may provide beneficial results in identifying the effects of improved signage on speeding. Associated Needs None identified. Organizational and Institutional Attributes Organizational, Highway agencies should review any policy concerning signage requirements to Institutional and Policy ensure that they meet the current MUTCD guidelines. Agreement among neighboring Issues jurisdictions as to the policy, sign requirements (placement, letter height, etc.), routine inspection, and maintenance should be coordinated to ensure uniformity. V-50

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SECTION V--DESCRIPTION OF STRATEGIES EXHIBIT V-12 (Continued) Strategy Attributes for Improving Speed Limit Signage (T) Attribute Description Issues Affecting Implementation time for this strategy is short to moderate. Taking inventory of speed Implementation Time limit signage can be time-consuming, depending on the size of the municipality or jurisdiction. Once the inventory is taken, routine inspection should be geared to those signs identified as priority for improvements. Costs Involved This strategy should have a low implementation cost. Costs with this strategy include personnel to take inventory, inspect, and provide maintenance to signs. Other costs include the acquisition and installation of new signs. Development of a sign inventory system would increase costs. Training and Other Additional personnel might be needed for jurisdictions where there is not adequate Personnel Needs staffing to take on duties related to sign design, erection, and maintenance. Staff should also be properly trained to ensure consistent and effective signing practices. Legislative Needs None identified. Other Key Attributes Compatibility of This strategy is compatible with and oftentimes necessary for enforcement, Different Strategies education, and engineering strategies to be effective. Effective speed limit signing is an important issue when informing drivers of reduced speed zones (Strategy E2). Other Key Attributes to None identified. a Particular Strategy Depending on the type of speed sign, some are capable of displaying additional text, such as "Slow," or they completely blank out when vehicles are driving at excessive speeds. This blank-out feature is intended to discourage drivers from speeding excessively to test the capabilities of the sign or their own driving audacity. Active speed warning signs are similar to variable message boards and photo radar devices. They are different from automated speed enforcement devices in that they do not take photos and are not used for enforcement purposes. These signs differ from variable message boards as they have the radar technology to detect actual vehicle speeds. Speed warning signs can be used permanently at a location, or mounted on trailers and moved to different locations for temporary use. Speed warning signs can be used permanently at a location, or mounted on trailers and moved to different locations for temporary use. One type of permanently mounted sign, used by King County in Washington, features a 12-inch high fluorescent yellow-green readout and is the same overall size and style as the existing speed limit sign. They are placed directly below the existing speed limit sign on the same post. These signs are ideal for neighborhoods as they are relatively small and do not stand out visually as much as a portable trailer would. A study of the effectiveness of speed warning signs on speeding (for a roadway with a 25 mph posted speed limit) was reported by TranSafety, Inc., in May 1998, in the publication, Road Injury Prevention and Litigation Journal. Conclusions from this report are based on the study, V-51

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SECTION V--DESCRIPTION OF STRATEGIES A Comparative Study of the Speed Reduction Effects of Photo-Radar and Speed Display Boards (Bloch, 1998). The use of a speed warning sign reduced the mean speed by 5.8 mph at the experimental site but had little effect 0.2 miles downstream (a 2.9 mph reduction in mean speeds). A speed warning sign used in conjunction with intermittent enforcement resulted in a 6.1 mph mean speed reduction at the experimental site and a 5.9 mph reduction in the mean speed downstream of the display. The study found that speed warning signs were the major contributing factor in reducing the number of vehicles traveling at "excessive" speeds (i.e., at least 10 mph above the posted speed limit) by 34.9 percent (Bloch, 1998). The study also found that when used in conjunction with intermittent enforcement, speed display boards reduced the number of vehicles at "excessive" speeds by 31.8 percent (Bloch, 1998). Speed display signs can be used as a deterrent to speeding, which may result in decreased speed-related crashes. Studies have found that these signs effectively contribute to decreased travel speeds while in place, with mixed long-term results. In combination with enforcement and other technology such as photo radar devices, speed display signs could have a greater potential to reduce speeding. The technology for detecting vehicle speeds and providing a real-time warning to drivers can be applied to locations where there is a potential for heavy vehicle rollovers, such as a sharp curve. In addition to speed, warning systems may need to collect other information such as vehicle height and weight to determine the potential of a rollover crash. For information specific to the issue of speed warning signs as part of an interactive truck rollover warning system, refer to Strategy 12.1 E2 in NCHRP Report 500, Volume 13: "A Guide for Reducing Collisions Involving Heavy Trucks." As in other community-wide solutions, such as traffic calming, highway and/or enforcement agency staff should host a neighborhood meeting to discuss the existing condition with interested parties and identify possible solutions. If active speed warning signs are the preferred mitigation method, an on-site investigation should be conducted to determine a physical range along the roadway where the signs would best meet the needs of the traveling public. See Exhibit V-13 for further discussion. EXHIBIT V-13 Strategy Attributes for Implementing Active Speed Warning Signs at High Risk Locations Where Excessive Speeds and Potential Conflicts are Expected (T) Attribute Description Technical Attributes Target The target of this strategy is drivers who are willing to change their behavior when given information on their actual travel speeds, and has the added advantage of letting drivers know their speed is being monitored. Speed warning signs can be used in locations where speeding has been observed or may pose a safety risk (i.e., prior to a sharp horizontal curve, school zone, roadway section with a lower speed limit, and any location with a history of speed-related crashes). This strategy can also be used in cooperation with law enforcement efforts or as a substitute for enforcement at locations that cannot be adequately patrolled due to a lack of personnel. V-52

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SECTION V--DESCRIPTION OF STRATEGIES EXHIBIT V-13 (Continued) Strategy Attributes for Implementing Active Speed Warning Signs at High Risk Locations Where Excessive Speeds and Potential Conflicts are Expected (T) Attribute Description Expected Effectiveness Studies on speed warning signs have found the technology to be effective at reducing vehicle speeds while the signs are in place, especially for vehicles that are 10 mph or more above the posted speed limit (see discussion in the strategy introduction). Significant speed reductions were not sustained after the devices were removed. However, it was noted that one long-term, statistically significant effect occurred with the unenforced speed display board: a 1.7-mph decrease in speed continued at an experimental site after the display board was removed. Meyer (2000) noted that changeable message signs are unlikely to be able to reduce speeds by 10 mph or more in A Literature Review of Perceptual Countermeasures to Speeding. Keys to Success A key to the success of this strategy is identifying the locations that will have the greatest benefit from active speed warning signs (whether permanent or temporary). Locations should have a history of speeding and/or speed-related collisions. Observations from concerned citizens and law enforcement officials are often good sources for this information. Selected locations will likely have the greatest potential for success if both highway agencies and law enforcement agencies are involved in the process of determining locations to deploy the signs. Another important key to success is educating the public on the need for and benefits from speed warning signs in order to gain their acceptance. Likewise, it is important for local agencies, such as law enforcement and highway agencies to initially accept the need for speed warning signs. Potential Difficulties The public may initially be resistant to speed display signs, especially those accompanied with photo-radar or traditional enforcement. Because of the possibility for negative opinion, public outreach is needed early in the process so that the public understands the reasons for using the signs. It is especially important to inform drivers of where speed display signs are used in conjunction with enforcement. Appropriate Measures A key process measure is the number of road segments where active speed warning and Data signs are installed. A more detailed measure includes observing any changes in the number of speeding vehicles and in the speed profiles. When used in conjunction with photo-radar enforcement, data concerning the number of citations issued should be collected. Changes in the crash history and severity of speed-related collisions are good indicators of safety effectiveness. Data on speed-related crashes at locations of the speed displays should be collected before and after the installation of the signs. It is also important to monitor the long-term performance of the speed display sign to ensure that it remains effective. Associated Needs Informing the public on the use of speed displays is important. Informational materials should include: Local issues with speeding Safety advantages to using active speed warning signs General locations where active speed warning signs are used V-53

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SECTION V--DESCRIPTION OF STRATEGIES EXHIBIT V-13 (Continued) Strategy Attributes for Implementing Active Speed Warning Signs at High Risk Locations Where Excessive Speeds and Potential Conflicts are Expected (T) Attribute Description Whether speed warning signs are used in conjunction with photo-radar or traditional enforcement (if so, use of revenue from automated enforcement) Conveying this information to the public may help extend the period of effectiveness of the signs. Organizational and Institutional Attributes Organizational, Highway and law enforcement agencies need to develop or review policy regarding Institutional and Policy the deployment of speed display signs, especially how the agencies will respond to a Issues neighborhood's request to address a speed problem (perceived or actual). In the situation where the request is being made by the public, policies should also address which type of display will be used (permanent or temporary), how long temporary displays will be used at the location, and what actions an agency may take if the sign displays prove not to be effective at a particular location. Agencies should also consider developing guidelines and criteria to help in the identification of locations where speed display signs (with or without enforcement) would be warranted. Issues Affecting Implementation time for active speed warning signs can typically be performed in Implementation Time less than 1 year (especially for portable signs), but can vary depending on the level of public involvement, acquisition of signs, and additional personnel or studies needed. Costs Involved Costs will vary, but are expected to be low. The main costs are those which include data collection for prioritizing locations, acquisition, installation (does not apply to portable signs which can be placed in locations temporarily via truck and trailer), and maintenance. The acquisition and installation cost of permanent active speed warning signs is much higher compared to mobile ones. Training and Other No significant training or increases in personnel should be needed for the Personnel Needs installation, operation and maintenance of a speed warning sign. Legislative Needs Local legislation might cover requirements that address local needs for active speed warning signs such as operating criteria, agency responsible for operation and maintenance of signs, and restrictive uses (such as using in conjunction with photo- radar enforcement). Other Key Attributes Compatibility of This strategy is compatible with the others discussed in this guide. This strategy Different Strategies relies on the similar technology discussed in Strategy C2 (automated speed enforcement); therefore, these two strategies can be used in conjunction. Other Key Attributes to None identified. a Particular Strategy V-54

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SECTION V--DESCRIPTION OF STRATEGIES Strategy D3--Use In-Pavement Measures to Communicate the Need to Reduce Speeds (T) This strategy relies on the use of perceptual and in-pavement techniques to encourage drivers to proceed at a safe travel speed. This strategy can be applied along a roadway segment as well as at locations such as intersection approaches, work zones, toll plazas, ramps, and so on. Perceptual Pavement Markings Perceptual pavement markings give the driver the illusion of traveling faster than his or her actual speed in order to decrease the driver's comfort at excessive speeds. At locations where drivers are expected to reduce their speed, such as the beginning of a school zone, approach to an intersection, entrance to a residential neighborhood, or prior to a sharp horizontal curve, a converging pattern of pavement markings can be used to give the perception to the drivers that they are increasing their speed if they fail to slow down at a sufficient rate. Pavement markings can also be used for other perceptual applications, such as to give the illusion of lane narrowing. This method is intended to reduce a driver's comfort at an excessive speed while proceeding through the markings, as a way to encourage deceleration. This type of treatment has potential applications along the entire length of a corridor. Perceptual pavement markings are good candidates for roads where speeding is known to play a role in either crash frequency or severity. Furthermore, perceptual techniques are expected to reduce travel speeds without the need for increased enforcement, and should be able to affect driver behavior regardless of whether a driver is intentionally or unintentionally speeding. Perceptual pavement markings can also encourage drivers to decelerate at an appropriate rate on the approach to an area with a reduced speed limit (i.e., school or work zone or intersection). Perceptual pavement markings have several advantages over traditional speeding countermeasures. First, the cost of applying perceptual pavement markings is very low; however, the pavement markings must be routinely maintained in order to prevent a decrease in their visibility. Second, perceptual techniques are also very flexible since they can be used to target speeding specifically in high-risk areas, or for the whole length of a corridor. Finally, this strategy can be used for areas where law enforcement is not readily available, or can be used in conjunction with law enforcement for increased speed reductions. There are several different types of perceptual techniques. The following are examples of different perceptual pavement techniques that have been in use. Transverse Lines: Transverse pavement mark- ings are dashed lines that span the width of a travel lane. These pavement markings can be used to create the illusion that lane widths are Source: Katz, 2004 V-55

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SECTION V--DESCRIPTION OF STRATEGIES decreasing or narrowing, an effect that is perceived when the driver is traveling at higher speeds. A study in Kansas found that using these pavement markings at work zones decreased speeds and reduced the variation in speeds, though the speed reductions were fairly small (Meyer, 2001). Peripheral Transverse Lines: Peripheral transverse lines are the same as the transverse lines discussed above but they are used at the edges of travel lanes rather than across the entire lane. A study, as cited in Katz's report Pavement Markings for Speed Reduction, found that peripheral transverse lines performed the same, and in some occasions better than, full-length transverse lines. Full-length transverse lines tend to decrease vehicle speeds upon entering the zone with transverse lines; however, vehicle speeds tend to rise again after time. Converging Chevrons: Chevrons can also be used in a converging pattern. This pattern is characterized by a series of chevrons on the pavement surface that are placed progressively closer together. The first chevrons encountered by a driver passing through the pattern are widely spaced; those later in the pattern are closer together. The intent of this pattern is to create the illusion that drivers are traveling faster than they really are and to foster the impression that the traffic lanes are narrow- ing. These are sometimes accompanied by a dashed edge line. This edge line may promote the perception in drivers that the traffic lane is narrower than it really is. This perception can encourage a driver to reduce his/her speed (Griffin and Reinhardt, 1995). Source: Katz, 2004 Speed reduction can be further enhanced when these perceptual pavement techniques are combined with other in-pavement measures like rumble strips--discussed later in this strategy. The Manual on Uniform Traffic Control Devices (2003) provides guidelines on the use of pavement markings as well as details concerning standard colors, dimensions, and placement. Additional information can be found on the use of perceptual pavement markings in the discussion for Strategy 15.1 A4 in NCHRP Report 500, Volume 6: "A Guide for Addressing Run-Off-Road Collisions." Rumble Strips In addition to perceptual pavement marking techniques, in-pavement strategies, such as rumble strips, can be deployed as a means to reduce vehicle speeds and/or prevent crash types where speeding may play a significant role, like a lane departure crash, or a transition from a high-speed zone to a low-speed zone. Rumble strips can also be used as a traffic calming tool in high pedestrian areas, such as neighborhoods and school zones. Rumble strips are grooves installed in the road surface intended to draw drivers' attention to the roadway environment--either that the vehicle is drifting out of the travel lane, or that V-56

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SECTION V--DESCRIPTION OF STRATEGIES there is a situation ahead that requires more attention or deceleration. When a vehicle travels over a rumble strip, the driver is warned through the vehicle vibrations and the noise it produces. There are three types of rumble strip applications. Continuous Shoulder Rumble Strips: This is the most common type of rumble strip that is typically applied to the shoulder of high-speed roads. These aim to prevent run-off- road accidents. The primary use of this type of rumble strip for speeding-related crashes is not to reduce vehicle speeds, but is instead to provide an additional warning to drivers leaving the roadway, especially those that are speeding. Centerline Rumble Strips: These are applied to the centerline of high-speed roads. Centerline rumble strips aim to prevent median crossing or head-on collisions. Again, this application's primary intent is not to reduce speeding (although they may provide the illusion of lane narrowing, which may slow drivers), but is instead to warn drivers they are crossing the centerline. Transverse Rumble Strips: These are used at intersection approaches, toll plazas, work zones, ramps, and extreme curves. The warning provided by the transverse rumble strips should help drivers recognize that they need to slow down, possibly even come to a complete stop depending on the situation. For more information, see FHWA Research and Technology's Priorities, Market-Ready Technologies and Innovations, Rumble Strips at http://www.fhwa.dot.gov/rnt4u/ti/ rumblestrips.htm. Rumble strips are commonly applied on the side of rural roads to deter vehicles from leaving the traveled way, and are increasingly used at the centerline of high speed roads. On low speed roadways, transverse rumble strips are used to alert drivers of a speed zone transition. On a state highway, speed reduction will typically occur in a transition from rural to downtown conditions. Transverse rumble strips can be used on approaches to a main street where a speed reduction is desired and where speed limit or warning signs are already in place. They are used to target drivers that are inattentive, drowsy/fatigued, careless, or distracted (FHWA Research and Technology). Rumble strips are also safety measures during adverse weather conditions. Fog, snow, rain and related weather events can reduce the visibility of pavement markings and road signs (FHWA Research and Technology). Rumble strips have the advantage in these types of conditions of not relying on visibility to be effective; however, some states paint rumble strips to increase their visibility during favorable conditions (FHWA Research and Technology). Intersections, work and school zones, neighborhoods, toll plazas, and freeway ramps are all locations that are vulnerable to speeding-related collisions and pose risks to drivers, workers, or pedestrians. Rumble strips are low-cost measures that can be taken to prevent collisions at these locations, by providing warning and increasing awareness of changes in the road environment to drivers. NCHRP Report 500, Volume 6: "A Guide for Addressing Run-Off-Road Collisions" provides supplemental information on the application of shoulder rumble strips to decrease run-off- road collisions, while NCHRP Report 500, Volume 4: "A Guide for Addressing Head-On Collisions" provides a review of centerline rumble strips to prevent head-on crashes. Both V-57

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SECTION V--DESCRIPTION OF STRATEGIES of these strategies are again reviewed in NCHRP Report 500, Volume 7: "A Guide for Reducing Collisions on Horizontal Curves." The use of transverse rumble strips was also reviewed in depth in NCHRP Report 500, Volume 5: "A Guide for Addressing Unsignalized Intersection Collisions." For additional information on the application and issues for rumble strips, refer to the mentioned guides. Traffic operation personnel should consider rumble strips that are compatible with motorcycle and bicycle use. An abrupt rise in the roadway can present problems to bicyclists and motorcyclists. For this reason, there should be provisions made for cyclists to safely traverse through or around raised rumble strips. See Exhibit V-14 for more detail on this issue. EXHIBIT V-14 Strategy Attributes for Using In-Pavement Measures to Communicate the Need to Reduce Speeds (T) Attribute Description Technical Attributes Target The perceptual pavement markings and transverse rumble strips are intended to give drivers a warning when entering a high-risk area at a potentially unsafe speed. Perceptual pavement markings can help a driver select a safe speed while transverse rumble strips are a warning that the driver is approaching a situation that requires more attention. Shoulder and centerline rumble strips are not intended as a speed reduction strategy, but instead will provide drivers with a warning when crossing the centerline or leaving the roadway, which are crash types in which speeding may play an important role. These strategies can be deployed on the approach to high-risk areas, such as sharp horizontal curves, intersections, school zones, work zones, neighborhoods, speed zone transitions and toll plazas, or can be deployed continuously along a high-speed corridor (such as freeway facilities and arterial highways). Expected Effectiveness It is expected that perceptual pavement marking techniques can reduce speeding and have the potential to reduce collisions. There are several studies on the effectiveness of perceptual pavement techniques that indicate successful applications in reducing vehicle speeds. Katz (2004a) reviewed the effects of perceptual techniques in the study, "Perceptual Pavement Marking Techniques as a Low-Cost Safety Improvement to Reducing Vehicle Speeds" at the 2004 Annual Meeting and Exhibit of the Institute of Transportation Engineers. His study indicated that perceptual techniques can provide results beneficial to safety and can also reduce speeding. Results from a study in Kansas indicated that optical speed bars cause reductions in mean speed, 85th percentile speed and speed variation (Meyer, 2001). A different study indicated that perceptual markings effectively decreased travel speeds where there was a high frequency crash history at a sharp curve in Kentucky (Agent, 1980). A study in Wisconsin found that chevron pavement markings that were placed at the exit ramp of a freeway reduced travel speeds by up to 17 mph after 20 months of installation (Drakopoulos & Vergou, 2003). However, the perceptual pavement markings have not always demonstrated the ability to reduce speeds over the long term. Furthermore, questions have been raised if the decrease in travel speeds was due to the speed illusion or simply because the drivers recognized the presence of pavement markings as a warning of a hazardous location (NCHRP Report 500, Volume 6 ). V-58

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SECTION V--DESCRIPTION OF STRATEGIES EXHIBIT V-14 (Continued) Strategy Attributes for Using In-Pavement Measures to Communicate the Need to Reduce Speeds (T) Attribute Description Perceptual techniques such as widening centerline markings (to provide the illusion of a narrower travel lane) and their effects have been studied in Europe. A study in the Netherlands found that applications along roads with posted speed limits of 80 kph (50 mph) produced speed reductions of 5 to 10 kph (3 to 6 mph). During this study a 36 percent reduction in crashes was observed for the roads where the application was used on a trial basis, while the control roads experienced an increase in crashes of 17 percent (FHWA, 1995). It can be expected that these speed reductions can be somewhat less on lower speed roads, depending on the severity of the speeding problem. Also, it should be considered that various pavement marking patterns may show relatively little effect on vehicle speeds but still serve to reduce the probability of traffic crashes. This is to say, even if perceptual pavement marking patterns do not dramatically reduce vehicle speeds, they may alert or rouse the driver into a heightened sense of awareness in which they are better prepared to avoid a crash (Griffin and Reinhardt, 1995). There are numerous studies that indicate the beneficial safety effects of the application of rumble strips in reducing run-off-road and head-on crashes. The FHWA has sponsored several studies that indicate rumble strips can reduce run-off- road collision by 20 to 50 percent (NCHRP Report 500, Volume 6). While there are many studies that indicate the safety benefits of shoulder rumble strips, there are also benefits to the application of transverse rumble strips. Portable rumble strips in rural work zones were found to have a positive impact on safety. Results from this study found that the average travel speed of passenger vehicles was reduced by 2 mph and the number of cars exceeding the speed limit decreased by up to 7 percent (Fontaine and Carlson, 2001). The same study found that rumble strips had a bigger impact on reducing average speeds of trucks, by up to 7 mph (Fontaine and Carlson, 2001). The Minnesota DOT reports that rumble strips have been used in work zones since the 1950's (Corkle, Marti, and Montebello, 2001). The study indicates that rumble strips in construction zones are typically used in conjunction with warning signs, flagging, and barricades. These devices likely add to the effectiveness of rumble strips. Keys to Success A key to the success of this strategy is identifying and prioritizing locations that can benefit from perceptual pavement markings, rumble strips or other in-pavement strategies. Identification of roadways for this application includes those where enforcement is not available, speeding is a problem at high speed limits, and there is a history of speed-related collisions. Provided that the use of transverse rumble strips is as effective as studies indicate, states should install them at locations as suggested. Further proof of effectiveness, through observing nationwide studies, is important prior to future installation of transverse rumble strips at intersections, school and work zones, neighborhoods, ramps, and toll plaza locations. A key to success for installation of transverse rumble strips is identifying locations where they would be most effective. In order to identify and prioritize these locations, it is important to look at crash history and severity, as well as travel speeds. V-59

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SECTION V--DESCRIPTION OF STRATEGIES EXHIBIT V-14 (Continued) Strategy Attributes for Using In-Pavement Measures to Communicate the Need to Reduce Speeds (T) Attribute Description Another key to success for the implementation of transverse rumble strips is using them properly and in conjunction with other safety measures. For example, rumble strips can be more effective when used with proper flagging and signage in work zones. Potential Difficulties The biggest issue for perceptual pavement markings is identifying locations where perceptual pavement techniques should be applied. Also, careful consideration needs to be given to the design of the pavement markings, especially converging patterns, in order to produce the desired effect and be consistent with requirements and guidelines in the MUTCD. Incompatibilities and issues may exist between rumble strips and certain motor bikes and bicycles. It is possible for cyclists to lose control while traveling over rumble strips (e.g. wheel catching in rumble strip). It is recommended by the FHWA in Technical Advisory on Roadway Shoulder Rumble Strips that they not be used in locations where there are bicycle paths or a high number of cyclists (FHWA, 2001). This is an issue since the transportation community encourages the use of bicycles. This strategy, therefore, targets toll plazas and freeway ramps, which are locations where bicycling is prohibited. Another possible issue with rumble strips is that they can produce additional risk. It has been found that it is common for drivers to merge into opposing lanes or swerve abruptly to avoid the rumble strips. This poses alarming risks to safety by providing exposure to head-on collisions or severely injuring workers at toll plazas or in work zones, or putting pedestrians and bicyclists at risk in downtown and residential areas. There are issues regarding adverse weather and rumble strips. Rumble strips can be ineffective when ice or snow builds up in them. Likewise, snow removal is difficult with conventional plows as they cannot pick up snow packed in the grooves of rumble strips. Rumble strips also can be a noise nuisance when placed in close proximity to residential areas. This may not be a well accepted alternative by residents. Public involvement must take place before rumble trips are installed in a residential area. Appropriate Measures One key process measure is the number of corridors and locations where and Data perceptual pavement markings and other in-pavement countermeasures have been applied. Identifying average travel speeds and crash history before and after the installation of the countermeasure can be used to determine the overall effect. Road characteristics should be noted, to indicate areas where this strategy might be more useful or at locations where it is not as successful, for the use of future applications. Other appropriate measures include gathering information and feedback from the public. For example, it is important to listen to concerns from the public on issues with rumble strips such as noise or use with bicycles. Associated Needs Information campaigns may be needed to inform the public of the purpose of the markings prior to the installation of pavement markings. As identified in NCHRP Report 500, Volume 6, there have been reports of persons mistaking the noise produced from rumble strips as car problems. Public information and educational campaigns can be used to reduce these misinterpretations. V-60

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SECTION V--DESCRIPTION OF STRATEGIES EXHIBIT V-14 (Continued) Strategy Attributes for Using In-Pavement Measures to Communicate the Need to Reduce Speeds (T) Attribute Description Organizational and Institutional Attributes Organizational, Highway agencies should have a design policy for perceptual pavement markings Institutional and and other in-pavement countermeasures that can be used for speed zone transitions, Policy Issues neighborhoods, work and school zones, freeway ramps, toll plazas, and intersections. If highway agencies do not have a policy concerning these countermeasures, then these need to be developed first before the strategy is implemented. Many states have specific design and placement criteria concerning conventional rumble strip applications (shoulder rumble strips). Policy for transverse rumble strips should be implemented with design and placement criteria for speed zone transitions, neighborhoods, work and school zones, freeway ramps, toll plazas, and intersections. Issues Affecting Implementation time for this strategy is expected to be low. The process of Implementation identifying and prioritizing locations may lengthen implementation time. Time Costs Involved Costs for perceptual pavement markings will vary depending on the length of corridor to which the markings will be applied. The overall cost of perceptual pavement techniques is rather low compared to other speed reducing techniques, as pavement markings are inexpensive to install and maintain. Due to advances in construction technology and increased applications of rumble strips, the cost of installation has been on the decline. NCHRP Report 500, Volume 6 reported that the New York Department of Transportation paid approximately $6.18 per linear meter of rumble strip in 1990. This decreased to only $0.49 per linear meter in 1998. The costs associated for transverse rumble strips, as described for applications in this strategy, would be much lower because ramps, toll plazas, work zones, and intersections do not require continual rumble strips at extensive lengths. Costs for maintenance of rumble strips are generally minimal. Training and Other No additional training or personnel should be needed for this strategy. Personnel Needs Legislative Needs None identified. Other Key Attributes Compatibility of Use of enforcement with these countermeasures may help increase their effectiveness Different Strategies at reducing speeding and speeding-related crashes. Also, perceptual pavement markings can be used to help control speeds on approaches to reduced speed zones (Strategy E2) and can also be combined with geometric design elements to control speeds (Strategy E1). Other Key Attributes to None identified. a Particular Strategy V-61

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SECTION V--DESCRIPTION OF STRATEGIES Strategy D4--Implement Variable Message Signs to Display Information on Appropriate Speeds for Current Conditions, As Well As Technologies to Monitor Conditions (High Speed Only) (T) Variable message signs (VMS) are used to provide drivers information concerning the current and expected driving conditions. VMS display messages to drivers that will inform or warn them of conditions ahead that may prove beneficial to their safety or travel time. Examples of information commonly displayed by VMS are: Traffic conditions Work zone/construction areas Weather and surface conditions Detour/direction information Crashes and incidents Appropriate speed limits There are several different types of VMSs, such as flip disk, light emitting diode (LED), and fiber optic displays (Wisconsin DOT, 2000). LED and fiber optic are two of the more common technologies in use today for the display of messages. VMS can be either permanent fixtures often mounted over the roadway or can be smaller, trailer mounted displays which are placed on the roadside. Both forms have a limited space for long messages with multiple text items; therefore, they are programmed to flash one item after another. The messages displayed on some VMS can be programmed on-site or remotely. This allows for a rapid update of information on current and expected travel conditions. VMS displays provide advanced technology to indicate safe travel speeds to drivers. For certain conditions (i.e., congested roadways or inclement weather), the posted speed limit may not be a safe travel speed; however, drivers will often attempt to drive at the posted speed limit despite the safety problems this may create. A key element to this strategy's effectiveness is the support from enforcement and adjudication when speed limits are decreased due to conditions. In addition to using ITS to display a safe speed for the driving conditions, ITS technology is needed to collect information on current conditions so that speed limits can be accurately set. Traffic conditions can be observed using video cameras and/or pavement loop detectors. Video can also be used to observe weather conditions, along with weather stations. Furthermore, in-pavement sensors are available for collecting information on actual pavement conditions, including pavement surface condition and temperature. Often this information can be gathered and then sent to a central location, such as a traffic management center in a large metropolitan area, for processing and display on VMS. See Exhibit V-15 for more information on how to use VMS. V-62

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SECTION V--DESCRIPTION OF STRATEGIES EXHIBIT V-15 Strategy Attributes for Implementing Variable Message Signs to Display Information on Appropriate Speeds for Current Conditions As Well As Technologies to Monitor Conditions (T) Attribute Description Technical Attributes Target This strategy is targeted at reducing crashes related to traveling at speeds faster than what is appropriate for current conditions. Real-time communication of current conditions is provided to help drivers make better choices concerning their speed. VMS technology is ideal for high-speed roads such as freeways and arterials that have a history of speeding-related crashes (especially during congested conditions or adverse weather). Expected Effectiveness It is difficult to determine the effectiveness of this strategy in reducing crashes related to speeds higher than appropriate for conditions, as there are a variety of other factors that can affect the occurrence of crashes that are difficult to measure. There are a few studies which quantify the actual effectiveness of VMS presence and its ability to deter speeding. Studies indicate that VMS are effective in gaining travelers' attention. One particular study indicates that drivers feel VMS is reliable and provides them with helpful information while traveling (Ran et al., 2004). A survey by the Wisconsin DOT was administered to determine if VMS displays are effective ways to communicate information to travelers. Results from the survey (sample of 200+ respondents) indicated that the majority of the drivers are familiar with VMS, with 70 percent of the respondents indicating viewing VMS on their routine routes (Ran et al., 2004). From the total respondents, the collective attitude was positive, indicating that drivers feel the information displayed is reliable. They indicated that VMS were particularly informative concerning weather and traffic condition updates. Keys to Success The Wisconsin DOT's Intelligent Transportation Systems Design Manual identifies criteria that are useful for successful deployment of a VMS system (Wisconsin DOT, 2000). The manual indicates the following criteria for determining the use of VMS: Data Collection: Data collection to determine where VMS would be most effective includes mapping of area, road alignment information, crash history, an inventory of existing signs, locating power sources along the road (to provide electricity to VMS). Determine Type of VMS: Determining the type of VMS depends on the intended purpose for the signs. For displaying speed information it is important to consider VMS technology that is capable of displaying several lines of information. Some VMS signs are limited in the information that can be displayed. It is important to obtain a sign that is capable of displaying several lines of information concerning appropriate speed limits, traffic conditions, weather conditions and other related items that would have an effect on safe traveling speeds. Identify Locations to Install VMS: Once data are reviewed, locations for VMS should be identified. This should be based primarily on the need for the signs. High-priority locations where VMS would be effective should be identified and exact locations to install the signs should be determined. Data collection is needed to know if a speed adjustment is warranted; this data is equally important to the effective and efficient location of VMS. Without timely and accurate data, drivers are more likely to disregard the suggested driving speeds. V-63

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SECTION V--DESCRIPTION OF STRATEGIES EXHIBIT V-15 (Continued) Strategy Attributes for Implementing Variable Message Signs to Display Information on Appropriate Speeds for Current Conditions As Well As Technologies to Monitor Conditions (T) Attribute Description Potential Difficulties Convincing drivers that they need to obey the suggested speeds could be one of the biggest difficulties. As with any speed limit or speed advisory sign, drivers will not necessary obey them, especially if the information is not up-to-date. Another potential problem may be legibility of the messages. Also drivers should not be overwhelmed with too much information which may cause distraction by taking too much reading time and causing vehicles to slow down. Another identified difficulty of this strategy is the costs associated with VMS. The acquisition, installation, and routine maintenance of variable message displays and the data collection equipment can be very costly. Appropriate Measures As mentioned previously, data collection is important to determine effective and Data locations to install VMS. Measures and data appropriate to determine the effectiveness of VMS at those locations include obtaining historical and current data concerning speeding at locations where VMS is installed. Crash data concerning speeding and various conditions such as weather and congestion are also important to identify, if available. These data items should be observed for current and future conditions after the VMS is installed, to determine the effectiveness of VMS. Associated Needs A public information campaign may be needed to inform drivers of the intent of VMS, especially if use of them in this manner is new to an area. A survey or other method of obtaining feedback from drivers can be a good way to gain information on the use, location, and other issues related to the signs. Technology to detect adverse conditions (high winds, snow, rain, fog, etc.) contributes to success in providing updated information displayed on variable message signs. Organizational and Institutional Attributes Organizational, Policy guidance regarding the installation of VMS should be considered with the Institutional and MUTCD as a reference. Policy Issues Issues Affecting Implementation time can vary depending on the process to identify proper locations Implementation Time and type of VMS to install. The data collection process is likely the longest task for this strategy. Acquiring and installing the VMS should not take long, especially if there is infrastructure to accommodate the signs (e.g., power supply or bridge to hang sign). In addition, the installation of data collection equipment can vary based on the size of the network observed and the technology selected. Costs Involved Costs for this strategy can be moderate to high, due to the detection and communication equipment needed. There are several different costs associated with this strategy. The major costs include the acquisition, installation, and routine maintenance of the VMS and data collection equipment. The costs are much higher if infrastructure to mount the signs (such as a bridge overpass) and a power supply does not exist. V-64