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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 Training and Other No extensive training or additional personnel should be needed to implement this Personnel Needs strategy. Personnel may need to be trained, however, concerning installation and maintenance of VMS and technologies used to collect field conditions. Also, an increase in law enforcement may be needed to improve compliance with the suggested driving speeds. Legislative Needs None identified. Other Key Attributes Compatibility of This strategy will generally be compatible with other countermeasures. Different Strategies Other Key Attributes None identified. to a Particular Strategy Objective E--Ensure Roadway Design and Traffic Control Elements Support Appropriate and Safe Speeds While drivers have a responsibility to drive at a safe speed, they need to be able to receive clues from the roadway environment on what that speed should be. The design of a roadway and its traffic control devices should consider the speeds at which the agency wishes people to drive, as well as the speeds that can reasonably be expected. A key element in safety is that road design and traffic control elements effectively communicate appropriate and safe speeds to ensure the safety of road users. This objective observes several different design and traffic control elements that are vital in providing safe travel at high speeds, and aims at correcting locations where current design elements are not appropriate. Strategies for this objective include: Combinations of geometric elements to control speeds Safe speed transitions through design elements Adequate sight distance for expected speeds Speeds on approaches to reduced speed zones Appropriate intersection design for speed of roadway Adequate clearance intervals at signalized intersections Appropriate operation of traffic signals for speed of intersections and corridors Protected-only signal phasing for left turns at high-speed signalized intersections V-65

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SECTION V--DESCRIPTION OF STRATEGIES Lighting at high speed intersections and high volume pedestrian/bicycle crossings Reduction of traffic speeds and volumes with traffic calming and other related counter- measures Strategy E1--Use Combinations of Geometric Elements to Control Speeds (Horizontal and Vertical Curves, Cross Section), Including Providing Design Consistency along an Alignment (T) Designing a roadway to influence drivers to travel at a particular "controlled" speed, and discourage them from traveling at an excessive or inappropriate speed, helps to prevent crashes from occurring and can also reduce severity when they do occur. Geometric elements, such as horizontal and vertical curves, affect operating speeds, and these elements can be designed in combinations to encourage appropriate speeds. This strategy aims at providing consistency in the design of roadway elements and selecting design elements that can be used to control vehicle speeds while providing for safe travel. Such road design elements may include the alignment, number of lanes, and width of lanes and shoulders. The provision of design consistency leads to roadway elements that meet drivers' expectations and result in consistent speeds along an alignment and fewer unexpected speed changes, factors which contribute to a reduced likelihood of crash occurrence. Of the several design factors that influence driver speed and perception, two of the primary ones are the curve radius and the tangent length. Other important parameters include the length of spirals, the vertical grades and curves, the available sight distance, and the cross- section features. Historically, the horizontal curve is the most critical geometric design element that influences driver behavior and has the most potential for crashes, and research has indicated that the average accident rate for horizontal curves is about three times the average accident rate for highway tangents and the average run-off-the-road crash rate for highway curves is about four times that of highway tangents (Lyles and Taylor, 2006). Reasons for this increased crash frequency include restricted sight distance, driver inatten- tiveness, and speed estimation errors. To mitigate errors by the driver, it is important to convey a message to the driver as to what is the appropriate speed of the roadway. This can be done by providing a roadway that conforms to what a driver expects (from previous experience) and also provides clear clues as to what is expected of her/him on a particular roadway. This strategy thus aims at being consistent in the design of the roadway elements and selecting design elements that positively influence driver behavior and expectations, resulting in safer driving speeds and thus a reduced risk of collision. The concept of design consistency is well documented and it is recognized that a consistent alignment will enable most drivers to operate safely at their desired speed along the entire alignment. Designs should thus strive to provide alignments that meet driver expectations, and avoid or minimize unexpected, unusual, or inconsistent design or operational situations. For example, large differences and sudden changes in horizontal alignment should be avoided, as these tend to increase driver workload and increase the likelihood of crashes. This includes situations such as the unexpected introduction of a relatively sharp curve at the end of a long tangent, where the higher speeds that may be encouraged by the long straight alignment could lead to driver error when the curve is encountered. One strategy is V-66

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SECTION V--DESCRIPTION OF STRATEGIES to flatten the curve so that a driver can negotiate it at a higher speed which reduces the likelihood of someone over driving the curve. Research by Zegeer et al. (1992) indicated that curve flattening may reduce crash frequency by as much as 80 percent, depending on the central angle and the amount of flattening. Alternatively, providing a consistent design by the occasional introduction of a series of gentle curves may prevent speeds from getting too high on the tangent sections. This idea builds off the concept that is called a self-organizing road (Keith et al., 2005). Other design considerations include providing consistency in terms of sight distance availability, particularly to horizontal curves, again ensuring that the roadway meets the driver's expectations and does not surprise them (see Strategy E8). A self-organizing road is essentially defined as a road that ". . . increases the probability that a driver will automatically select appropriate speed or steering behavior for the roadway without depending on road signs. The geometric features of the road encourage the desired driver behavior, and do not rely on the driver's ability or willingness to read and obey road signs." (Keith et al., 2005). The concept of a self-organizing, self-enforcing road is therefore to select distinctive features such that the appearance of the road leaves drivers in no doubt as to what sort of facility they are on. By providing a roadway that is planned and designed in such a way, an appropriate and "consistent" speed for each road category can be achieved. Distinctive features that "explain" the road include items such as number of lanes and lane width, presence or lack of cyclists and pedestrians, width of sidewalks, presence of medians, provision of on-street parking, and frequency of access. Simply, a self-organizing road is designed utilizing an aesthetic approach so that drivers will select an appropriate speed because it is comfortable and safe. In this way, the roadway environment provides positive enforcement by encouraging the driver to stay within the desired speed limit. In addition to curvilinear alignments, other examples of a self-organizing road that can be used on low-speed roadways include lane width reduction (or lane narrowing), traffic calming measures, and roundabouts (Keith et al., 2005). Narrower lane widths tend to reduce speeds since drivers are "encouraged" to slow down to maintain a comfortable position within the available lane width. Research carried out by an OECD Scientific Experts Group in 1990 reviewed impacts of lane width upon driver behavior and consistently found a reduction in speed with decreases in lane width and vice versa. Yagar and Van Aerde (1983) found that increasing lane width from 3.3 to 3.8 m was associated with a 2.85 km/h increase in speed. More recent work (Fitzpatrick et al., 2000) has corroborated these findings of very modest changes in speed associated with lane width. Narrower lane widths can be implemented either by physically creating narrower travel lanes or by visually decreasing the available width, and may be supplemented by other measures within the driver's peripheral vision, such as landscaping and transverse lane markings, to reinforce the "slow down" message. This treatment may be a more effective tool for reducing speeds on rural roads and roads where there are more visual cues within the driver's periphe- ral vision. As previously noted, the roadway width can be visually narrowed by such techniques as painting wider edge lines. The intention is that the driver will reduce speed to maintain a comfortable position within the narrower painted lanes. However, a study in a residential area by Lum (1984) indicated no impact on free speeds of narrowing lane widths from 5.5 m and 4.25 m to 2.7 m; thus, simply narrowing lane width without other measures, such as transverse V-67

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SECTION V--DESCRIPTION OF STRATEGIES lane markings that have the effect of attracting the driver's peripheral vision, may not be particularly effective. Regardless of the design technique used, the key is a consistent design so that the driver is not presented with an unexpected situation; Exhibit V-16 illustrates this point. EXHIBIT V-16 Strategy Attributes for Using Combinations of Geometric Elements to Control Speeds, Including Providing Design Consistency Along an Alignment (T) Attribute Description Technical Attributes Target This strategy targets low-speed roads with inconsistencies in the alignment that may be a contributing factor to crashes, especially crashes where speeding plays a prominent role. Other components of this strategy also address using design elements to convince drivers to travel at a safe and reasonable speed. Providing consistent design and the appropriate use of design elements to reduce speeds and improve safety can be effective on low-speed roads. Expected Effectiveness Design inconsistencies, such as a sharp horizontal curve following a long tangent section, are known to have poor safety records. In this case, one of the best options would be to flatten the curve. The safety benefit from curve flattening was discussed above and reviewed in Strategy 15.1 A5 of the run-off-the-road guide (NCHRP Report 500, Volume 6). NCHRP Project 3-61, "Communicating Changes in Horizontal Alignment," indicates that the average crash rate for highway curves is 3 times higher compared to tangent highway alignments. The average rate of run-off-the-road crashes is four times higher at highway curves compared with the rate on straight alignments (Lyles and Taylor, 2006). Keys to Success Keys to success depend on the road type, traffic characteristics, traffic control devices, and safety elements. It is important to identify low-speed roads with inconsistent alignment or unsafe geometric elements. Improvements to these roads to reduce speeding is also most successful in reducing collisions when used in conjunction with traffic control devices, medians, barriers, and increased enforcement. Potential Difficulties One issue with this strategy is the cost of improvements. Roadway improvements requiring construction on new alignment can be costly. Costs will vary depending on the length of road segment to be improved and type of improvements being made. Appropriate Measures Appropriate measures include the number of locations where geometric road and Data improvements are made and the type of improvements (i.e., curve flattening or addition of gentle horizontal curves to a long tangent section). Vehicle speeds should be recorded before and after the project in order to determine if the project was successful in lowering vehicle speeds and making them more uniform. Impact measures also include the frequency or rate of collisions and severity of crashes that occur at these locations, especially those with speeding listed as a contributing factor. Comparison of crash data before and after improvements can help to identify the effectiveness of modifying different geometric design elements. Other measures include gaining public feedback to determine if the public is in favor of the revised road geometry. V-68

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SECTION V--DESCRIPTION OF STRATEGIES EXHIBIT V-16 (Continued) Strategy Attributes for Using Combinations of Geometric Elements to Control Speeds, Including Providing Design Consistency Along an Alignment (T) Attribute Description Associated Needs Needs associated with this strategy include informing the public that the road geometry will be improved. Signage and media announcements should indicate any changes prior to construction. Organizational and Institutional Attributes Organizational, Highway agencies should have a current policy or adopt new policy on guidelines Institutional and Policy and criteria for road alignment. The AASHTO Green Book provides information on Issues road design for reference. Issues Affecting Implementation time for this strategy will depend on the design selected. Minor Implementation Time improvements and changes (i.e., pavement markings) can often be implemented in 1 year or less. Major construction projects such as curve flattening and introducing occasional flat horizontal curves into a long tangent section will require several years to implement. Costs Involved Implementation costs will vary depending on the design alternative selected and the size of the area to be treated. For example, flattening a curve or series of curves can have a high cost due to design, right-of-way (ROW), and construction; whereas lane narrowing with pavement markings is a low-cost strategy. Training and Other Highway personnel should receive training on the safe and proper use of design Personnel Needs elements to control speeds. Such strategies have to be implemented carefully so as not to create a safety hazard while trying to address excessive speeds. Legislative Needs None identified. Other Key Attributes Compatibility of This strategy is one aspect addressing the overall design of a roadway. Other Different Strategies aspects of design specific to speed transitions, intersections, and sight distance are discussed in Strategies E2, E5 and E8 of this report. Other Key Attributes to None identified. a Particular Strategy Strategy E2--Effect Safe Speed Transitions through Design Elements and on Approaches to Lower Speed Areas (T) Reduced speed zones are areas where posted speed limits are reduced to safely accommodate traffic, pedestrians, and road conditions because there is a risk increase (perceived or actual) if traffic continues to travel at higher speeds. Reduced speed zones are generally used in school zones, high pedestrian areas, work zones, intersections and highway transitions from rural to urban areas. Work zones and rural to urban transitions are the most common type of reduced speed zones on high speed roads (45+ mph) such as freeways or major arterial highways. Reduced speed zones further lower speeds on low speed roads; typical applications include school zones, high pedestrian areas, work zones, and in residential or commercial neighborhoods. V-69

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SECTION V--DESCRIPTION OF STRATEGIES This strategy aims at methods to encourage safe and effective speed transitions on the approaches to (and within) areas with a reduced speed limit. It may not be possible to ensure that all vehicles drive at or below the reduced speed limit; however, there are several methods and countermeasures that can be deployed to deter speeding in these zones. To increase the effectiveness of speed transitions, signing, enforcement, pavement markings, and other safety elements should be used appropriately to deter drivers from speeding in these zones. Further, roadway designs sensitive to the context in which they will be located can encourage appropriate speed choice by drivers. Elements of the roadway, such as curvature and lane width, along with landscaping and other roadside features, can communicate the context of the roadway. For example, areas with high pedestrian activity may include raised or otherwise marked crosswalks and other physical features that draw drivers' attention to the nature of the area, which can both reduce their speeds and increase their awareness of pedestrians in the area. Visual cues that may encourage drivers to reduce vehicle speeds on approaches to lower speed areas include the introduction of sidewalks and curb and gutter, raised medians, landscaping, ornamental lighting, pedestrian signs, textured crosswalks or intersection pavement, banners and decorations, and other forms of street furnishings. Enforcement: There are different enforcement measures that can be taken and the best type of enforcement to implement depends on factors such as the extent of the speeding problem and the resources available for implementation. Enforcement methods to control speeds at these locations include: Increasing law enforcement presence More frequent ticketing of violators Increasing fines (doubling or tripling fines in reduced speed zones) Employing enforcement technology such as automated speed devices (e.g., photo radar which can be used in conjunction with speed display signs) Transverse rumble strips: Rumble strips are used to gain a driver's attention by produc- ing an alarming noise and vibration throughout the vehicle. The use of transverse rum- ble strips in reduced speed zones may not efficiently control driver speeds; however, rumble strips used in conjunction with traffic control devices can provide an increased awareness of the importance of reducing speeds. Depending on the topography and the ambient noise levels, rumble strips can generate con- siderable noise over a large area. Consequently, they can be a more appropriate application in a rural environment and have only limited use in urban areas. Speed reductions from the use of transverse rumble strips alone are likely to be small and probably erode over time. Advance warning signs: It is important to use signs to provide drivers with advance warning of reduced speed locations. Previous versions of the MUTCD used a regulatory sign informing drivers of decreases in the posted speed limit ahead. The 2003 MUTCD allows a yellow diamond warning sign with either text or an arrow to show a reduced speed zone is ahead and what the speed limit is in that zone. Variable message signs used to display messages informing drivers of reduced speed zones and other relevant information are good to use in construction zones. Active speed feedback display signs can also be used to control speeds at reduced speed zones, as they typically gain a driver's attention, especially when the signs are used in conjunction with photo radar devices for enforcement. V-70

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SECTION V--DESCRIPTION OF STRATEGIES Road design: Changes can also be made to the alignment and cross-section of the roadway as a method to inform drivers they need to reduce their speeds. These changes could be something as simple as introducing curb and gutter or using pavement markings to give the illusion of lane narrowing. Other strategies to slow drivers may include channelization, raised medians, allowing on-street parking, the introduction of curvilinear alignments and the extension of the urban environment further into the transition area (for example, by the use of landscaping and lighting). With these design countermeasures, it is important that they are introduced in such a way that they do not become or create a safety hazard. The use of distinctive road design features such as those noted above help to identify a change in the environment and can influence the driver's speed approaching, and in, the transition zone. Reference should be made to the discussion on self-organizing roads under Strategy E1 for further information regarding the use of physical and visual measures to achieve appropriate speed behavior. As well as their use as an effective method of intersection control, roundabouts are often used to reinforce a change in environment (e.g., rural to urban) in conjunction with a change in speed. The roundabout also provides an opportunity to provide a "Gateway"--a device to mark such a transition from a higher speed facility to an environment requiring a lower speed and greater driver attentiveness, particularly if the driver had been driving on the "faster" facility for a relatively long time. The use of roundabouts is discussed further under Strategy E3, including the importance of providing ample warning to enable the driver to effect a safe speed transition on the approach to the roundabout (for example by the introduction of a raised median "splitter" island, or the introduction of a curvilinear alignment). One non-geometric method used in the United Kingdom, and found to be effective in reducing collisions associated with speed adaption, is to apply yellow transverse bar markings on high speed approaches to roundabouts. The transverse markings are typically placed at decreasing intervals on the roundabout approach to affect the driver's visual field and encourage the driver to slow down. Details of the United Kingdom markings and their spacing are provided in Chapter 5 of the United Kingdom's Traffic Signs Manual. Earlier research on trial markings at 42 roundabouts in the United Kingdom showed a 57% decrease in speed related crashes over a period of 4 years (Helliar-Symons, 1981). Although traffic calming measures are more typically associated with an urban type setting, there may be opportunities to use such techniques in a rural environment to encourage a reduction in speed. These techniques may include lane narrowing (physical or visual), installation of median islands and other forms of channelization, and changes to the roadway surface. These techniques can be used in combination to reinforce the message to the driver that there is a change in the environment requiring a speed adjustment. In the United Kingdom, "Gateways" exist in a wide variety of forms to influence the driver's behavior on the approach to an area requiring a lower speed and greater attentiveness. The primary feature is a conspicuous vertical element at the side of the road (for example, enhanced signing, often with yellow backing boards; countdown signs on the approach to the gateway; vegetation; walls and fences; etc.). Other elements typically incorporated include lane narrowing (visual or physical), colored road surfacing, and special pavement markings (for example, speed "roundels" and "dragon teeth" lane edge markings). Using these measures in combination, and in conjunction with good sight lines, generally improves the Gateway conspicuity and its effect on reducing speeds. However, care should be taken to avoid introducing additional hazards (such as non-yielding signs and other roadside features), and consideration should also be given to possible visual V-71

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SECTION V--DESCRIPTION OF STRATEGIES intrusion. Research in the United Kingdom (Wheeler et. al., 1994, Wheeler and Taylor, 1999) indicates typical average speed reductions of 1 to 2 mph from simple signing and marking; 5 to 7 mph from more comprehensive signing/marking with high visual impact; and about 10 mph with physical measures. In another rural application (Steinbrecher, 1992), the district of Neuss, Germany implemented a combination of traffic calming measures on the approaches to 13 rural towns which included reducing the lane widths to about 5.5 m; adding strips of pavement stones to optically narrow the road further; installing refuge islands; and raising the road in asphalt. The road raising was achieved by constructing 3 m long ramps with slopes of about 35:1, which could be negotiated comfortably at speeds of 30 mph. Steinbrecher noted that the road raising aspect in combination with the refuge islands seemed to achieve the greatest effect of speed reduction. Results indicated speeds dropped in all 13 towns with before treatment speeds averaging between approximately 45 to 53 mph, and those after treatment averaging about 37 to 45 mph. The average speed reduction was just over 5 mph (varying between about 1 and 9 mph). The overall impact on average crash rate was a reduction from 1.1 per year to 0.6 per year. Further information on traffic calming measures and their effectiveness is provided under Strategy E9 in this guide. Construction zones are known to present increased challenges to drivers, as they typically form choke points requiring drivers to transition from a higher speed relatively unrestricted environment to a lower speed congested environment. This transition takes place on the approach to the work zone, and this area represents a particularly serious collision risk as some drivers do not respond well to the speed and lane changes that are required on the work zone approach, and often make unexpected or dangerous maneuvers. The key is to provide ample advance warning to enable drivers to reduce their speed on the approach to the work zone so that they can safely enter the zone and make any necessary lane changes or merges in a safe and efficient manner (it is also important that measures are implemented to guide drivers through the work zone itself). Reference should be made to the Manual of Uniform Traffic Control Devices and to NCHRP Report 350 for further information regarding the standardization of work zone areas in terms of traffic control and work zone safety devices. Volume 17 of the NCHRP Report 500 series, on reducing work zone fatalities, should also be referenced. If a roadway has a speed transition into an area with a large number of pedestrians, possible design countermeasures include speed tables, pedestrian bulb outs, and raised crosswalks. These items are discussed in more detail in Strategy E3, Appendix 1, and Exhibit V-17. EXHIBIT V-17 Strategy Attributes for Effecting Safe Speed Transitions through Design Elements and on Approaches to Lower Speed Areas (T) Attribute Description Technical Attributes Target This strategy targets drivers who fail to sufficiently slow down approaching and in reduced speed zones. The strategy specifically is designed to provide drivers with information on the presence of a reduced speed zone ahead and aims to deter drivers from speeding in these zones. V-72

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SECTION V--DESCRIPTION OF STRATEGIES EXHIBIT V-17 (Continued) Strategy Attributes for Effecting Safe Speed Transitions through Design Elements and on Approaches to Lower Speed Areas (T) Attribute Description Expected Effectiveness There are many studies that indicate the effectiveness of enforcement, rumble strips, signing, and design features to reduce travel speeds and improve safety. While there are not many studies that indicate the effectiveness of these techniques specifically for lowering speeds on transitions to reduced speed zones, there are many studies that indicate their effectiveness on high-speed roads. NHTSA conducted a survey to determine what countermeasures were effective in reducing speeding and unsafe driving. The survey results indicate that road design changes and speed bumps are considered to be effective in reducing speeding by 78 percent of respondents. Using transverse rumble strips on approaches to unsignalized intersections was reviewed as strategy 17.1 E6 in NCHRP Report 500, Volume 5. In this particular application, it was reported that there was no consensus on their effectiveness, but up to a 50% reduction in specific crash types (i.e., running the Stop sign) were reported. Other states have experimented on using movable rumble strips on approaches to work zones, but the response has generally not been favorable because of the difficulties of keeping the movable rumble strips in place. Studies on the effectiveness of rumble strips in the United Kingdom indicated average reductions in 85th percentile speeds of about 2 to 6 mph (Webster and Layfield, 1993, Barker, 1997). Injury collision reductions were reported, but found to be not statistically significant. There is little information relating the actual effectiveness of "reduced speed zone ahead" signs, but dynamic displays that show actual travel speeds have been studied and found to be effective. More information on this use of active speed warning signs is provided in Strategy D2. The use of design elements (perceptual or physical) to alter driver behavior has been reviewed in Strategies D4 and E1, and E3 of this guide. Final Report 2002-18, Methods to Reduce Traffic Speed in High Pedestrian Area, by the Minnesota DOT provides literature on devices that can be used in conjunction with safe speed transitions in pedestrian areas (Kamyab et al., 2002). Countermeasures included in this report include traffic calming, educational campaigns, law enforcement presence, rumble strips, lighting, pedestrian refuge islands, sidewalks, and signage. Refer to this document for further details. Keys to Success A key to success with this strategy is the identification of locations where drivers are failing to slow down on the approach to areas with posted reduced speed limits and are continuing to speed in the reduced speed zones. Typical ways to identify these locations are talking to law enforcement agencies, listening to concerned citizens, and reviewing crash histories. After a location has been identified as potentially having a speeding problem, then actual vehicle speeds need to be recorded to verify that drivers are indeed speeding. Each countermeasure may be more effective in certain situations than in others. Identification and prioritization of the appropriate countermeasure technique will rely on characteristics such as traffic volume, frequency and severity of crashes, average travel speeds, and alignment. Further, use of multiple countermeasures implemented at a single location may produce the best results in controlling speed. For example, reduced speed ahead signs could be used solely, but they could also be used in conjunction with rumble strips, flashing beacons, and increased enforcement at areas where speeding-related crashes pose a serious problem. V-73

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SECTION V--DESCRIPTION OF STRATEGIES EXHIBIT V-17 (Continued) Strategy Attributes for Effecting Safe Speed Transitions through Design Elements and on Approaches to Lower Speed Areas (T) Attribute Description Potential Difficulties One of the major difficulties with this strategy is the cost associated with controlling travel speeds. Of the countermeasures suggested, rumble strips and signs will have a relatively low implementation cost for each site. However, other strategies, such as increased enforcement, automated speed detectors, and road design changes, may have a high initial or recurring cost. Public acceptance of enforcement countermeasures, either traditional or automated, may not exist initially, but could grow through education and demonstration that the enforcement is preventing crashes. Appropriate Measures Measures of implementation include the number of locations and type of and Data countermeasures applied to speed transitions. Likewise, the type of reduced speed zone should be recorded (e.g., school zone, rural-to-urban transition, pedestrian activity, etc.). A key impact measure is whether vehicle speeds decrease. The frequency and/or rate of collisions and severity of crashes that occur at approaches or within reduced speed zones on high-speed facilities are additional areas to measure. Comparing before and after crash data will help determine the effect on safety. Other measures include gaining public feedback, to see if there is any negative or positive opinion concerning these countermeasures. Associated Needs Associated needs might include public information or educational campaigns, explaining why various changes in speed transition areas have been made. Organizational and Institutional Attributes Organizational, Highway agencies should adopt or review policy concerning criteria and guidelines Institutional and for the use of speed reduction countermeasures specific to speed transition areas. Policy Issues Policies should identify attributes, such as the road type and placement, to ensure that countermeasures are used consistently and in the proper situations. Issues Affecting Implementation time varies depending on the type of countermeasure used. Some Implementation Time strategies that may be quickly implemented include increased enforcement, signage, or application of rumble strips. These types of countermeasures would typically take no more than 1 year to put into place. Strategies that require considerable policy decisions or design time usually take longer to implement. Costs Involved Costs vary depending on the countermeasures used for this strategy. Rumble strips and increased signage are a few of the lowest cost strategies for speed transition zones. Implementing variable message boards and/or automated speed enforcement devices is more expensive as the costs of acquisition, installation, and routine maintenance are higher. Redesigning the roadway to help encourage slower speeds would be a high-cost alternative. Training and Other Highway agency personnel may need training to help them identify the proper Personnel Needs circumstances for when to deploy each countermeasure technique and the effectiveness of these techniques when administered as part of normal operations. In order to provide the resources necessary for the traditional enforcement countermeasures, the responsible law enforcement agency may need to pay for overtime or redirect enforcement from other locations. Legislative Needs None identified. V-74

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SECTION V--DESCRIPTION OF STRATEGIES EXHIBIT V-17 (Continued) Strategy Attributes for Effecting Safe Speed Transitions through Design Elements and on Approaches to Lower Speed Areas (T) Attribute Description Other Key Attributes Compatibility of This strategy is one aspect addressing the overall design of a roadway, and it is Different Strategies compatible with the other strategies discussed in this guide. Other Key Attributes to None identified. a Particular Strategy Strategy E3--Provide Appropriate Intersection Design for Speed of Roadway (T) Intersection design plays a large role in the safety of roads. According to A Policy on Geometric Design of Highways and Streets, "The efficiency, safety, speed, cost of operation, and capacity of the highway system depend on the design of its intersections" (AASHTO, 2004). The main objective of intersection design is to, "reduce the severity of potential conflicts between motor vehicles, buses, trucks, bicycles, pedestrians, and facilities, while facilitating the convenience, ease, and comfort of people traversing the intersections" (AASHTO, 2004). To provide safe intersections to road users, there are five elements that should be considered in the design (AASHTO, 2004): 1. Human factors 2. Traffic considerations 3. Physical elements 4. Economic factors 5. Functional intersection area This strategy aims primarily at addressing traffic considerations and physical elements that apply to intersection design. Some of the important factors to consider for intersection design are the grade, angle, horizontal and vertical alignment, median type, turn lanes, corner radii, and traffic control devices at the intersection. See Appendix 1 for additional information on these design elements. Roundabouts provide an important alternative to signalized and all-way stop-controlled intersections. Modern roundabouts differ from traditional traffic circles in that they operate in such a manner that traffic entering the roundabout must yield the right-of-way to traffic already in it. Roundabouts are a good option for low-speed roads, as they can serve moderate traffic volumes with less delay than signalized or all-way stop-controlled intersections because traffic can normally traverse the roundabout without stopping. It has been found that single-lane roundabouts operate more safely, and though not necessarily with fewer crashes, but with lower injury rates than two-way stop-controlled intersections. For further details regarding roundabouts, reference should be made to NCHRP Report 500, Volume 5. V-75

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SECTION V--DESCRIPTION OF STRATEGIES Comprehensive details regarding the improvement of safety at both unsignalized and signalized intersections are provided in NCHRP Report 500, Volume 5 and Volume 12, respectively. Of particular relevance, the unsignalized intersection report (Volume 5) provides guidance on the choice of appropriate intersection control (Strategies 17.1.F1 through F3) and also on the use of geometric design improvements to reduce collision frequency and severity (Strategies 17.1.B1 through B18). The signalized guide (Volume 12) provides similar guidance (Strategies 17.2.B1 through B5). Because detailed discussion is contained in these other guides, the discussion in this guide will present an overview of speeding-related fatalities, and the other guides should be referenced for additional information. Also see Exhibit V-18 for further discussion of design issues. EXHIBIT V-18 Strategy Attributes for Providing Appropriate Intersection Design for Speed of Roadway (T) Attribute Description Technical Attributes Target The target for this strategy is the appropriate and consistent design of intersections. This strategy relates to existing and future/planned intersections in rural, urban, and suburban areas. Expected Effectiveness While there are many different design features and related studies for intersection design, there are studies that identify the effectiveness of these individual elements. These are discussed in detail in Volume 5 (Non-signalized Intersections) and Volume 12 (Signalized Intersections) in this NCHRP Report 500 series. Keys to Success A key to success for this strategy is to coordinate efforts of highway agencies and local agencies, as well as enforcement agencies. Their involvement is important in identifying design issues at intersections to help address current safety concerns and prevent the creation of new ones. The use of additional warning devices can help improve driver awareness of intersections. Examples include advisory signs ("yield," "watch for cross traffic," "reduce speeds"); flashing beacons; and rumble strips. Potential Difficulties Options for redesigning many intersections will be limited by difficult geometry, roadside development, high volumes, or other conditions. The high cost of reconstructing an intersection (such as to convert to a roundabout) may prohibit short-term implementation of such an improvement. Appropriate Measures Process measures should include the number and locations of intersections where and Data designs are reviewed, as well as intersections for which new design features are implemented. Impact measures include the frequency or rate of collisions and their severity. Observing crash data before and after intersection design improvements will help determine the effectiveness of the improvements. Associated Needs Coordination with the public to gain input and inform drivers of proposed changes is important. Providing drivers with information on future construction at intersections is important to ensure their safety and provide them with alternative routes if needed. It is also important to gain input from the public on intersections where they feel changes may be warranted. Information such as educational materials on intersection safety and how the elements of road design apply to safety should also be made available to the public. V-76

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SECTION V--DESCRIPTION OF STRATEGIES EXHIBIT V-18 (Continued) Strategy Attributes for Providing Appropriate Intersection Design for Speed of Roadway (T) Attribute Description Organizational and Institutional Attributes Organizational, Agency policy should address processes for changing an intersection design or Institutional and elements of the intersection, including review of crash information to determine the Policy Issues most appropriate improvements. Issues Affecting Implementation time varies depending on the change made to an intersection Implementation Time design. Design and construction of a turn lane, for example, can be completed in less than 1 year if complicating right-of-way issues are not encountered. Conversion to a roundabout would likely take several years. Costs Involved As mentioned previously, it can be expensive to implement some of these key design elements. The costs are highest where major construction is required such as realignment of an intersection. Adding turn lanes, medians, or other precautionary safety measures is less costly compared to fully reconstructing an existing intersection. Likewise, maintenance costs will vary depending on the type of intersection. Operation and maintenance costs for roundabouts are somewhat higher than for unsignalized intersections, but less than those for signalized intersections. Training and Other Intersection design improvements should be covered in normal agency training Personnel Needs courses, with an emphasis on the appropriateness of designs for different roadway types. Legislative Needs None identified. Other Key Attributes Compatibility of This strategy is compatible with the others discussed in this guide. Different Strategies Other Key Attributes to None identified. a Particular Strategy Strategy E4--Provide Adequate Change + Clearance Intervals at Signalized Intersections (P) Change + clearance intervals are the portion of a signal between the end of a green phase and the beginning of the next green phase for a conflicting movement. (Note: The "change + clearance" interval will simply be referred to as clearance interval for the remainder of this discussion.) Clearance intervals should be designed to account for expected approach speeds in order to reduce the potential for red-light-running collisions. Clearance intervals that are too short can result in drivers not being able to stop in time for the red signal, and intervals that are too long can breed disrespect for the signal in drivers familiar with the intersection. Either situation can result in red-light running, which increases the risk for angle collisions, the severity of which is compounded by speeding. Clearance intervals provide safe transitions in right-of-way (ROW) assignment between conflicting streams of traffic. Clearance intervals can include both yellow and all-red timing between conflicting green phases. NCHRP Report 500, Volume 12: "A Guide for Reducing Collisions at Signalized Intersections" covers material on V-77

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SECTION V--DESCRIPTION OF STRATEGIES optimal clearance intervals in Strategy 17.2 A2; therefore, an overview of the information is presented in this guide, and Volume 12 should be referenced for additional information. There is no specific standard for determining clearance intervals at an intersection. Clearance intervals are dependent on many factors, including operating speeds, intersection width, vehicle lengths, and driver characteristics such as reaction time and braking. ITE has developed an equation for determining the length of the change + clearance interval but some agencies may use a uniform clearance interval. See Appendix 2 of NCHRP Report 500, Volume 12: "A Guide for Reducing Collisions at Signalized Intersections" for more information on establishing clearance intervals. (http://safety.transportation.org/). There are different issues with poor clearance intervals at high speed intersections. Clearance intervals that are too short in length result in drivers stopping abruptly, which may lead to rear-end collisions. Furthermore, a too short clearance interval could result in an angle collision involving vehicles traveling through the intersection after the end of a phase and vehicles entering the intersection on the subsequent phase. One study showed that the effect of clearance intervals shorter than those calculated using ITE guidelines had higher crash rates for rear-end and right-angle crashes (Zador et al., 1985). Clearance intervals that are too long may result in a growing problem of red-light violations as studies have suggested. For more information on yellow and all-red intervals refer to Volume 12 of this series, as well as Making Intersections Safer: A Toolbox of Engineering Countermeasures to Reduce Red-Light Running. (McGee, 2003). This can be accessed online at: http://www.ite.org/library/ redlight/MakingInt_Safer.pdf Strategy E5--Operate Traffic Signals Appropriately for Intersections and Corridors (Signal Progression) (T) Traffic signals are timed and phased with the objective of providing efficient movement of traffic. The coordination of traffic signals, or signal progression, has been found to have many safety benefits. Signals that are properly coordinated produce platoons of vehicles that travel the road without having to stop at multiple signals. This results in less stopping and can be expected to reduce rear-end collisions at intersections. Signal progression also improves turning movements at intersections. Signal progression creates platoons of vehicles, which creates more gaps in traffic and allows vehicles to make left turns and right turns onto the major street more easily. This is an important benefit for high speed roadways where larger gaps are needed for a vehicle to safely enter and accelerate, or cross the traffic stream. In addition, judging gaps at high speeds may be more difficult, especially for older and inexperienced drivers. The topic of signal coordination is discussed in detail as part of Strategy 17.2 A4 in "A Guide for Reducing Collisions at Signalized Intersections" (NCHRP Report 500, Volume 12), and therefore the information is not repeated in this guide. The reader should refer to Volume 12 for additional details on this strategy. Strategy E6--Provide Adequate Sight Distance for Expected Speeds (P) Sight distance is a fundamental element in geometric design and reflects the driver's ability to see the road ahead and other road users so that the facility can be used in a safe and V-78

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SECTION V--DESCRIPTION OF STRATEGIES efficient manner. The amount of sight distance provided to the driver is a function of the three- dimensional features of the highway--the cross-section (roadside), vertical alignment (grades and vertical curves), and horizontal alignment. The total sight distance requirement essentially comprises the distance traveled during two key events, often referred to as the perception- reaction time and the maneuver time. The former refers to the time needed for a driver to recognize an object or condition requiring a response and deciding what action is required (e.g., initiating contact with the brake), and the latter refers to the time from the initiation of the vehicle response to the completion of the driving maneuver (e.g., from the time the driver applies the brake to the time when the vehicle comes to a complete stop). These time periods, and hence distances, will vary depending on vehicle speeds and the types of maneuvers being undertaken, for example, stopping, turning, or passing. Roads designed with insufficient sight distance for the expected speed can not always provide drivers with adequate time to identify a hazardous situation, decide on a course of action, and then complete their maneuver. Sight distance at curves (horizontal and vertical), intersections, passing zones and areas where drivers have to negotiate through a complex or unexpected situation (i.e., lane drop, toll plaza, etc.) should account for the speeds expected in those locations. Providing adequate sight distance can reduce rear-end crashes involving vehicles stopping suddenly when the driver views something unexpected, angle crashes related to drivers accepting gaps that are too small for their turning maneuver, and head-on, passing-related crashes. Clearing sight lines, removing roadside objects that block views, and possibly flattening curves are potential solutions for improving sight distance. More information regarding sight distance is provided in Strategy 15.2 A3 of Volume 7 on horizontal curves, Objective 17.1 C of Volume 5 on unsignalized intersections, and in Strategy 17.2 C1 of Volume 12 on signalized intersections, as well as in Exhibit V-19 of this guide. EXHIBIT V-19 Strategy Attributes for Providing Adequate Sight Distance for Expected Speeds (P) Attribute Description Technical Attributes Target This strategy targets roads with sight distance issues. A primary target for stopping, intersection, and passing sight distance issues is rural 2-lane highways, including intersections along these roadways. Passing sight distance is not applicable for expressway and freeway facilities; further, these facilities were typically designed to higher standards and likely meet stopping sight distance requirements. However, intersection sight distance is important for at-grade expressway intersections, and decision sight distance is very relevant to expressways and freeways at critical locations (i.e., lane drops, interchanges, toll plazas). Expected Effectiveness As described in NCHRP Report 500, Volume 5 on unsignalized intersections (Objective 17.1 C), after a literature review by a group of safety experts, it was decided that if available sight distance in any quadrant of an unsignalized intersection is less than or equal to the design sight distance for a speed of 20 km/h (12 mi/h) less than the actual 85th percentile speed of the approach, the frequency of related crashes at the intersection would be increased by 5 percent (Harwood et al., 2000). Therefore, improving sight distance at an intersection may be 0 to 20 percent effective in reducing related crashes (angle- and turning-related crashes) depending on the number of quadrants with a sight distance restriction and the severity of the sight distance restriction. V-79

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SECTION V--DESCRIPTION OF STRATEGIES EXHIBIT V-19 (Continued) Strategy Attributes for Providing Adequate Sight Distance for Expected Speeds (P) Attribute Description Strategy 15.2 A3 of NCHRP Report 500, Volume 7 (horizontal curves) reports that the safety effectiveness of improving the sight distance at a horizontal curve when the actual sight distance is slightly less than the required has not been adequately quantified. However, NCHRP Report 400 indicates that there is a safety benefit to improving sight distance when there is a sizeable sight distance restriction (Fambro et al., 1997). FHWA's Signalized Intersections: Informational Guide (2004) provides estimates of expected reductions in the number of crashes per intersection per year when sight distance is increased. For example, for an ADT between 5,000 and 10,000 vehicles per day, an increase in sight distance between 50 and 99 feet could be expected to result in 1.30 fewer crashes at that intersection each year. For additional ADT and increased sight distance ranges, refer to the FHWA guide at http://www.tfhrc.gov/safety/pubs/04091/. A more recent FHWA report cites sight distance improvements as being one of the most cost-effective treatments (FHWA, 1996); see "Safety Benefits Associated with Sight Distance Improvements: Selected Findings" below. Fatal collisions were reduced by 56 percent and nonfatal injury collisions were reduced by 37 percent at intersections having sight distance improvements. Safety Benefits Associated with Sight Distance Improvements: Selected Findings Treatment Implication Sight distance improvements 56% estimated reduction in fatal collisions. 37% estimated reduction in injury collisions. Keys to Success Evaluation of available sight distance should take into account both posted speed limits as well as actual travel speeds, in order to ensure that enough sight distance is provided for the speeds expected. Preferably, inadequate sight distance would be addressed by increasing the sight distance by either removing the sight obstructions or redesigning the roadway. If the sight distance cannot be increased, at a minimum, the location should be reviewed to determine if advance warning signs are appropriate. Potential Difficulties Effective solutions to sight distance limitations may include roadway realignment projects. The high cost of such projects may render them unfeasible for implementation. Highway agencies may need to carefully explore other lower-cost options to determine feasible treatments for specific locations. Some coordination with the public or residents near a roadway may be necessary in order to make clear why trees or other landscaping items are being removed. Appropriate Measures Key process measures include the number of miles of roadway or intersection and Data locations where sight distance was increased and the amount of increase in sight distance achieved. The crash frequency and severity, by crash type, are key measures of safety effectiveness. Separate analysis of crashes targeted by specific sight distance improvements is desirable for before and after the application. Associated Needs None identified. V-80

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SECTION V--DESCRIPTION OF STRATEGIES EXHIBIT V-19 (Continued) Strategy Attributes for Providing Adequate Sight Distance for Expected Speeds (P) Attribute Description Organizational and Institutional Attributes Organizational, Agency policy should include guidance on low-cost, short-term treatments for Institutional and improving sight distance adequate for expected speeds. Policy Issues Issues Affecting Implementation time varies depending on the specific sight distance issue. Projects Implementation Time involving the removal of roadside objects that are located on the highway right-of- way can often be implemented quickly, usually in a matter of days or a few months. Locations where roadside obstructions are on private property will require more time, especially if laws do not allow highway agencies to remove items on private property. Regardless of the authority of the highway agency, the property owner(s) must be contacted, informed of the problem, and come to an agreement to remove the object. Treatments for locations where sight distance issues exist due to the road alignment have a longer implementation time. This might include reconstructing the realignment which can take well over 1 year. Costs Involved Costs vary depending on the location and type of sight distance issue and chosen solution. Costs should be low in cases where objects need to be removed in the right-of-way. Locations where alignment reconstruction is needed will require higher cost improvements, especially if additional right-of-way is required. Potential funding sources include state and local highway agencies and, to the extent required by law, individual property owners. Training and Other Training concerning sight distance issues for passing, stopping, decision, and Personnel Needs intersections should be included in highway agency training concerning geometric design, highway safety, and maintenance. Legislative Needs The only potential legislative need identified is the legal authority of highway agencies to control sight obstructions on private property. In some jurisdictions, highway agencies may need the legislature to strengthen laws on this issue. Other Key Attributes Compatibility of This strategy is compatible with the others discussed in the guide. Different Strategies Other Key Attributes to None identified. a Particular Strategy Strategy E7--Implement Protected-Only Signal Phasing for Left Turns at High-Speed Signalized Intersections (High Speed Only) (T) Protected-only left turn signals have a phase designated specifically for left-turning movements (known to be one of the highest risk movements at intersections), which is indicated with a green arrow. Protected-only phases are applicable on high speed roadways and/or in high traffic volume situations, where there may be a lack of adequate gaps to V-81

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SECTION V--DESCRIPTION OF STRATEGIES complete turning movements. In addition to vehicle speeds and volumes, there are several factors that may warrant the use of protected-only "left turn" phases, such as delay, visibility, distance of the intersection, and safety at the intersection (e.g., crash history). Benefits of protected-only left turns include increasing left-turn capacity and mitigating intersection delays for vehicles turning left (Brehmer et al., 2003). The use of protected left turn phases also improves safety by removing conflicts during a left turn movement. This characteristic can be especially important on high speed roadways where the prevailing speed can contribute to the crash severity and may play a role in the difficulty a driver has with identifying and selecting a safe gap. Even though protected/permissive left-turn phases are warranted under certain conditions, this strategy focuses on protected-only left turn phases due to the increased safety benefits that can occur at high speeds. To help in the selection of the appropriate left turn phasing (permitted, protected-only, and protected/permitted), several website sources that provide additional information on left turn signal phasing include: http://www.webs1.uidaho.edu/niattproject/ http://www.dot.state.mn.us/metro/trafficeng/dsg_crse/chap21.html#_Toc429824696 Additionally, refer to NCHRP Synthesis 225, "Left-Turn Treatments at Intersections," for additional guidance on the type of left-turn phase to use (Pline, 1996). Because protected-only left turn phasing was already reviewed as part of Strategy 17.2 A1 in "A Guide for Reducing Collisions at Signalized Intersections" (NCHRP Report 500, Volume 12), that guide should be referenced for an in-depth discussion of left turn phasing. Strategy E8--Install Lighting at High-Speed Intersections (High Speed Only) (T) High speed roads with unlit or poorly lit intersections, as commonly found in rural highways, can pose a hazard to drivers. Lighting is desirable at intersections of high speed roadways to provide drivers with adequate vision of other vehicles and obstacles which may pose safety issues, such as sight distance limitations, at intersection approaches. Intersection lighting has not been proven to prevent speeding nor is it intended to be a speed reduction strategy, but providing adequate lighting at high speed intersections is a proactive approach to avoiding collisions where speeding may play a role, particularly during nighttime and adverse weather conditions. Studies have found that the installation of lighting at intersections is effective in reducing nighttime collisions. This strategy aims at preventing collisions along high speed roads, particularly at rural intersections by providing lighting. Lack of adequate lighting at high speed intersections can increase exposure to high severity collisions. Because intersection lighting is discussed in detail in Strategy 17.1 E2 in NCHRP Report 500, Volume 5, "A Guide for Addressing Unsignalized Intersection Collisions," Volume 5 should be referenced for an in-depth discussion of lighting intersections. V-82

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SECTION V--DESCRIPTION OF STRATEGIES Strategy E9--Reduce Speeds and/or Volumes on Both Neighborhood and Downtown Streets with the Use of Traffic Calming and Other Related Countermeasures (Low Speed Only) (T) When implemented appropriately, traffic calming can alleviate speeding problems on neighborhood roads and downtown arterials, as well as on an area-wide scale. Divertive measures can control vehicular volumes on neighborhood roads by restricting access, and forcing vehicles to use the arterial roadways. There are many different traffic calming techniques that can be used to control vehicle speeds and are appropriate for low speed roadways. Descriptions of these strategies are described in more depth in NCHRP Report 500 Volume 10: "A Guide for Reducing Collisions Involving Pedestrians." Traffic calming may be applied at intersections, mid-block, or even along entire segments of a corridor. When the purpose of a traffic calming measure is to control speeds, the specific traffic control device implemented may need to be repeated along the corridor. Otherwise, the drop in vehicle speeds is likely to be isolated to the vicinity of the device. Speeding traffic through residential neighborhoods is often a concern with the residents living in the area, especially when the traffic is (or at least is perceived to be) cut-through traffic. Drivers may choose to cut through a neighborhood to avoid busy sections of urban arterials, possibly even to avoid a single intersection, or to avoid residential collectors with existing traffic calming. When drivers leave higher speed arterials for the low speed residential streets, they may be unwilling to slow down and drive at the posted speed limit in the residential area. A combination of speed and volume control measures can help mitigate neighborhood speeds through either physical traffic calming elements, or by divertive/restrictive measures, which force vehicles to use the arterial roadways. Jurisdictions across the country have implemented traffic calming measures to discourage drivers from using neighborhood shortcuts, and some have even prohibited vehicles from turning into residential areas by partially closing intersections or prohibiting access during peak periods. The goal of these approaches has been to make the shortcut a less attractive option or not an option at all. In doing so, it is important to improve the attractiveness (i.e., improving the operations) of the arterial streets or urban road system intended to provide mobility. This may be accomplished through a variety of measures, including adding through lanes, removing unnecessary signals, improving signal timing, and coordinating signal systems. These changes may involve improving a small area, or even a single intersection. However, changes may need to be implemented across a large portion of a system if there is significant congestion. For example, at a signalized intersection where vehicles are often delayed for more than one cycle length, consideration could be given to increasing capacity through the intersection by providing an auxiliary lane in advance of the intersection, and continuing it for sufficient distance downstream of the intersection to allow vehicles to adjust their speeds and safely merge back to the original lane configuration. Such a treatment should be implemented only where it will be clearly understood, and not where it may cause confusion to drivers which may introduce additional safety concerns. Area-wide traffic calming programs implement these measures on a larger scale. Such a program could include conversion of one-way streets to two-way, or two-way streets to one- way; narrowing lanes; and installation of vertical and horizontal speed control measures on collectors and/or local streets throughout the area. Such programs have been tried in several European countries and in Japan, with some success in reducing vehicle speeds. V-83

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SECTION V--DESCRIPTION OF STRATEGIES For further guidance, the Institute of Transportation Engineers provides a report entitled, "A Toolbox for Alleviating Traffic Congestion and Enhancing Mobility," which includes a section on potential solutions for application to urban arterials. Details of these solutions, including descriptions, implementation issues, benefits and costs, example applications, and references, are included in the document (Meyer, 1997). The various traffic calming measures used to control speeds and volumes are described in Appendix 3, including those that mitigate speeds by altering vertical and horizontal paths of vehicles, as well as those that control volumes, especially along residential collectors, by diverting or restricting traffic. Some strategies are discussed in Exhibit V-20 of this guide. EXHIBIT V-20 Strategy Attributes for Reducing Speeds and/or Volumes on Both Neighborhood and Downtown Streets with the Use of Traffic Calming and Other Related Countermeasures (T) Attribute Description Technical Attributes Target This strategy targets the use of traffic calming measures to mitigate speeding along low-speed roads, including low-speed neighborhood and downtown arterial streets. The strategy also seeks to divert cut-through traffic from local collector roads back onto arterial streets, primarily by the improvement of operations on the arterial streets. Expected Effectiveness The effectiveness for each of the different traffic calming devices is discussed in further detail in NCHRP 500, Volume 10, "A Guide for Reducing Collisions Involving Pedestrians." Keys to Success It is important that traffic calming devices be applied along the appropriate streets for which they are intended, primarily low-volume residential, and low-speed collector and arterial streets. It must be noted that it may be necessary to repeat a measure along the corridor to effectively reduce speeds along the entire corridor. To discourage diverting traffic to another street that may not be able to handle additional traffic, traffic calming measures can be applied area-wide. Additionally, a real key to the success of these measures is residential input and consensus. Traffic calming devices can be designed to incorporate the needs of cyclists by including bicycle lanes in the design. Problems for visually impaired pedestrians can be avoided by using standard traffic calming designs that incorporate textured surfaces. Traffic calming strategies should be designed to accommodate emergency response vehicles. Average fire truck emergency response time is predicted to increase by 2 seconds in calmed areas; this impact is considered too small to quantify. Potential Difficulties In general it must be kept in mind that though traffic calming can be an effective strategy for reducing speeds, it may not be the most appropriate solution for all situations. Certain traffic calming applications are best suited to arterial roadways, some to local, and some to both. Some drivers who are unfamiliar with traffic calming devices may be confused, and drivers who currently exceed the speed limit can be expected to be frustrated by traffic calming measures. These are both considered short-term effects that should wane with time. V-84

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SECTION V--DESCRIPTION OF STRATEGIES EXHIBIT V-20 (Continued) Strategy Attributes for Reducing Speeds and/or Volumes on Both Neighborhood and Downtown Streets with the Use of Traffic Calming and Other Related Countermeasures (T) Attribute Description Roundabouts, traffic circles, and curb extensions typically involve landscaping. This will require additional watering and maintenance. It is not recommended to use brick pavers or grass, in lieu of proper landscapingparticularly on roundabouts and traffic circles, as this does not enable the approaching driver to have proper visibility of the traffic calming device. As with any traffic control measure, there has been litigation related to various traffic calming devices. Having clear policies, guidelines, and practices for selection and use of various traffic calming measures can help reduce litigation problems. Appropriate Measures The primary measure of effectiveness is the reduction of motor vehicle speeds and and Data the reduction of speeding-related crashes. This includes localized uses of the strategy, in small-scale applications such as residential neighborhoods, as well as on a larger scale, as in area-wide traffic calming measures. Motor vehicle speeds alone are also a useful measure. The impact on motorist delay is an operational measure of interest. Associated Needs When traffic calming measures are being considered in a neighborhood, the residents of the neighborhood must be involved in the decision-making process. This may require a program providing public information and education about the various devices, as well as their importance to neighborhood safety and livability. Affected residents should have the opportunity to provide input on the change, or reduction in access, to ensure that the tradeoffs will be acceptable. Organizational and Institutional Attributes Organizational, In addition to neighborhood residents, other parties that may be affected include Institutional, and businesses, schools, the local fire and police departments, and others. These Policy Issues parties should be included in the decision-making process. Some agencies may have design policies or standards that do not include traffic calming techniques or that would inhibit their use. It may be necessary to create new policies to address inclusion of these stakeholders. Issues Affecting It can take up to 1 year or more to implement some of these traffic calming Implementation Time measures. This time reflects what is required for conducting the necessary engineering studies, as well as for deliberations and discussions with all affected parties. Design and construction of such measures can take place within a short period of time, as long as no additional right-of-way is needed. Speed humps or tables may be installed rather quickly, if or when consensus among residents exists. Traffic engineers often conduct engineering studies to determine whether one or more of these measures are warranted at a specific location. The process includes working with affected parties, including residents, businesses, schools, the local police and fire departments, and others to address their concerns. This public involvement process may take a significant amount of time, especially if the proposed traffic calming measures prove to be controversial. The types of traffic calming, and the locations within a neighborhood, may need to be modified. The availability of funds to cover the costs of installation depends upon local and state funding cycles. Depending upon local climatic conditions, installation may be feasible year-round, or only during the warmer months. V-85

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SECTION V--DESCRIPTION OF STRATEGIES EXHIBIT V-20 (Continued) Strategy Attributes for Reducing Speeds and/or Volumes on Both Neighborhood and Downtown Streets with the Use of Traffic Calming and Other Related Countermeasures (T) Attribute Description Cost Involved The costs for installing traffic calming devices will vary, depending upon the type of improvement and the local conditions, particularly if additional right-of-way is needed. For further details, see Appendix 4. Training and Other Agency personnel should be adequately trained in the proper selection, design, and Personnel Needs implementation of such traffic calming devices. Training in consensus building and public involvement will also be helpful. Legislative Needs None identified. Other Key Attributes Compatibility of This strategy is compatible with the others discussed in this guide. Different Strategies Other Key Attributes to None identified. a Particular Strategy V-86