National Academies Press: OpenBook

Roadway Safety Tools for Local Agencies (2003)

Chapter: 4 OTHER SAFETY TOOLS

« Previous: 3 PROACTIVE SAFETY TOOLS
Page 15
Suggested Citation:"4 OTHER SAFETY TOOLS." National Academies of Sciences, Engineering, and Medicine. 2003. Roadway Safety Tools for Local Agencies. Washington, DC: The National Academies Press. doi: 10.17226/21959.
×
Page 15
Page 16
Suggested Citation:"4 OTHER SAFETY TOOLS." National Academies of Sciences, Engineering, and Medicine. 2003. Roadway Safety Tools for Local Agencies. Washington, DC: The National Academies Press. doi: 10.17226/21959.
×
Page 16
Page 17
Suggested Citation:"4 OTHER SAFETY TOOLS." National Academies of Sciences, Engineering, and Medicine. 2003. Roadway Safety Tools for Local Agencies. Washington, DC: The National Academies Press. doi: 10.17226/21959.
×
Page 17
Page 18
Suggested Citation:"4 OTHER SAFETY TOOLS." National Academies of Sciences, Engineering, and Medicine. 2003. Roadway Safety Tools for Local Agencies. Washington, DC: The National Academies Press. doi: 10.17226/21959.
×
Page 18
Page 19
Suggested Citation:"4 OTHER SAFETY TOOLS." National Academies of Sciences, Engineering, and Medicine. 2003. Roadway Safety Tools for Local Agencies. Washington, DC: The National Academies Press. doi: 10.17226/21959.
×
Page 19
Page 20
Suggested Citation:"4 OTHER SAFETY TOOLS." National Academies of Sciences, Engineering, and Medicine. 2003. Roadway Safety Tools for Local Agencies. Washington, DC: The National Academies Press. doi: 10.17226/21959.
×
Page 20
Page 21
Suggested Citation:"4 OTHER SAFETY TOOLS." National Academies of Sciences, Engineering, and Medicine. 2003. Roadway Safety Tools for Local Agencies. Washington, DC: The National Academies Press. doi: 10.17226/21959.
×
Page 21
Page 22
Suggested Citation:"4 OTHER SAFETY TOOLS." National Academies of Sciences, Engineering, and Medicine. 2003. Roadway Safety Tools for Local Agencies. Washington, DC: The National Academies Press. doi: 10.17226/21959.
×
Page 22

Below is the uncorrected machine-read text of this chapter, intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text of each book. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

15 SAFETY STUDY DATA—EFFECTIVE SAFETY TOOLS There is often a need to supplement crash data with other factual traffic and user information. Outlined here are these types of safety data and the value added to the analysis to improve safety. A more detailed discussion of these data types and methods can be found in the references, particularly the ITE Manual of Transportation Engineering Studies (45) and the Fundamentals of Traffic Engineering (47), which provide details and sample data collection forms. In addition, these references provide other types of study concepts and useful survey forms, experimental design concepts, survey design concepts, statistical analysis tools, and ways to present the results of these studies, both in written and presentation for- mats. Special concern for the safety of personnel during data collection for all studies should be considered. The wearing of safety vests, parking of work vehicles to minimize the im- pact on traffic, and use of traffic control devices and enforce- ment personnel are important considerations. Specific data collection concepts helpful in evaluating safety issues are associated with traffic volumes, speeds, travel time and delay, intersections and driveways, inventories, traffic access and impacts, traffic conflicts, pedestrians, and com- pliance with traffic control devices (9,45,47). The utility of these study data and the value of these different types of safety data are presented in the following section. • Traffic volume studies—This is a basic and widely used type of data, which has many different forms and col- lection techniques. In reactive analysis, the use of these data helps to identify crash differences owing to the influence of different traffic volumes. In the case of the RSAR, volume data are useful in aiding the classifica- tion of the local facilities. In most cases, the volume data that are collected will need to be viewed as a repre- sentative sample. • Speed studies—There are a number of different types of speed data. For local safety, the issues generally pertain to spot speed, travel speed, and posted speed. Spot speed data reflect the instantaneous speed at a given point. Analyzing a sample set of data provides average values. These data also provide information concerning the variation of speeds. The range of speeds can be used to identify safety issues and to aid in evaluating safety decisions. For a neighborhood where complaints of higher than desired speeds are reported or where there may be a large number of crashes, spot speed studies are often used. If a safety improvement was made, then the effectiveness of the change in reducing the speed is evalu- CHAPTER FOUR OTHER SAFETY TOOLS ated by using a before-and-after spot speed study, for example, in identifying the effectiveness of a speed hump in reducing traffic speeds. The use of instantaneous speeds, coupled with information on the classification and/or location of the facility, is also helpful in estab- lishing the posted speed limit. Generally, there is a need to lower or raise vehicle speeds by the posting of limits. The ideal result is all vehicles traveling at or near the same speed, to provide the safest environment. Locally, there is often a need to evaluate locations where there is a concern for providing vehicle speed guidance, such as posting an advisory curve speed. A device referred to as a ball bank indicator is an inexpensive tool for this purpose. • Travel time and delay studies—These studies provide measures of a facility’s ability to accommodate traffic flow. The longer the travel time and the more the delay, the greater the potential for safety problems to occur because of driver frustration. For a specific facility, iden- tifying the sources and amounts of delay is useful in providing potential corrective countermeasures. • Intersection and driveways studies—A number of special studies associated with these locations are typically col- lected during safety investigations. The key to enhanc- ing safety is how to apply the data correctly to identify specific safety issues at the locations. One primary use is to determine the adequacy of intersection sight dis- tance for a vehicle or a pedestrian to make a crossing or turning movement. In applying these study results, it is essential to ensure that adequate sight triangles at the corners of the intersection are maintained. As a vehicle approaches an intersection, a clear sight triangle is needed for all different types of vehicles using the intersection. This generally requires 3 to 8 vertical ft for clear lines of sight, for both passenger cars and truck drivers. The size of the sight triangle is a function of the vehicular approach speeds. AASHTO provides recommendations for sight distances at intersections, which consider the type of traffic control at the intersection (20). If the measured sight distances are not available, then remov- ing the sight obstruction should be considered; if that is not possible, then the intersection approach speeds should be reduced or the type of intersection traffic control changed to reflect the available sight distances. It is equally important that the intersection itself be visible and clearly identified. It is also important to recognize that when vehicles are delayed for a long period of time because of inadequate gaps that prevent a safe turn or cross, driver frustration often results. This situation may lead to crashes, near misses, and a potential to ignore

16 changing traffic control, resulting in behavior such as red light running. • Inventories—Basic record keeping, an inventory of exist- ing conditions, improvement activities, and crashes, is essential to improving local safety. Such efforts comple- ment the functional classification of the local network. Knowing the types, locations, and conditions of differ- ent traffic control devices; knowing the condition of the road surface (both roughness and skid resistance); and providing a historical log of actions taken will enable local agency officials to make better informed safety decisions and help maintain a safer roadway network. • Traffic access studies—A proactive tool for safety is the traffic access study. As new development is proposed, the consideration of access, both ingress and egress to the new development, is the best time to ensure safety for the new intersections and driveways that may be created. It is also an optimum time to evaluate internal safety considerations for larger developments in which both pedestrian travel and internal vehicle travel become a greater concern. Landscaping needs to be evaluated with a concern for sight distances. Is there adequate off-street storage provided for the activity? Delivery vehicles need to be evaluated for maneuvers required to load and unload. Turning radius requirements must be evaluated. AASHTO’s A Policy on Geometric Design of Highways and Streets (20) provides information on vehicle turning radius. It is equally important to con- sider the effect of the access for smaller developments. Vehicle maneuvers and adequate storage for dwelling vehicles are sometimes overlooked. Safety problems may result from vehicles stacked into and on the through roadway, or there may be unsafe multiple access points if parking is developed in which vehicles are required to back out into the street. The access study should also address the issue of possible future expansion of the pro- posed development or how a change in the allowable use of the facility may affect the safety of the proposed development. Once these factors have been considered and a plan approved, it is important to ensure that the plan has been implemented as approved. • Impact studies—This is also a proactive type of study that focuses on new development. Generally, an impact study determines the amount of traffic that will result from the new development. This situation becomes im- portant from a safety perspective in considering whether or not additional or improved traffic control may be re- quired. Traffic generated by the new development de- creases with increasing distance from the development, although the impact may be significant for many miles, and traffic may affect safety well beyond the site. The ability of the network to accommodate the development and future growth, plus the existing level of operational service, are used in assessing the impact. Understand- ing the effect of traffic helps with decisions to initially size facilities and also to fully evaluate the impact of the changes in land use. Assessment of movement, access, and safety impact of the new development on the net- work should consider the functional classification of adjacent facilities. Figure 1 illustrates the need to sepa- rate movement and access, where and whenever possible, to achieve an overall safe and efficient system. • Traffic conflicts—Conflicts are often viewed as near misses. Conflict studies assess actions that are taken to avoid a collision and are used in safety analysis to evalu- ate the types of safety problems at a particular location. This type of study may be initiated in response to citizen complaints. Conflict studies are an easy and efficient means to check a location’s safety issues when there is limited or no crash data. Another form of conflict analy- sis is to explore all of the potential legal maneuvers of all road users at the location. Sketching the movements and locating the points where the various path lines cross can be done. Classifying potential conflicts as merge, diverge, or crossing helps to evaluate the issues associ- ated with geometric design alternatives. This approach is useful in understanding maneuver situations for new road and street developments, as well as the impact of the location on various activities, such as mailbox place- ment and associated road safety issues. Evaluating the actual maneuvers at similar locations also provides behavioral data that will help to elevate safety (52). • Pedestrian studies—Pedestrian studies focus on actual behavior and are used to guide safety decisions associ- ated with the need for increased clearance time for signalized intersections where large numbers of pedestrians are crossing. Other applications are for safety considerations of special pedestrian groups such as the young, the elderly, or pedestrians with disabilities. Providing special crossings for pedestrians is often accomplished by considering the gaps that exist in the traffic stream that is being crossed and the number of opportunities available to make a safe crossing. These studies determine the number of gaps of adequate time for the type of pedestrian making the crossing. Observ- ing the actual behavior of pedestrians making crossings also provides useful information for safety analysis. Established behavioral knowledge, such as noting that pedestrians almost always take the shortest path, should not be overlooked in guiding safety decisions. When possible, it is advisable to use known facts as an effec- tive safety tool. Aspects of the Americans with Disabili- ties Act (ADA) should be considered and compliance with ADA requirements met (32,34,53). • Compliance with traffic control devices—These studies concentrate on issues of behavior for different user groups as they relate to the safety of the traffic control device. There are a number of different types of com- pliance studies. Bicycle compliance as a special study may investigate the use of and need for more exclusive

17 FIGURE 1 Schematic relationship between access and movement function of streets. [Source: Fundamentals of Traffic Engineering, 15th ed. (47).] bicycle lanes. The need for special enforcement to help improve the safety at selected locations is often supported with a compliance study. With the recent focus on red light-running, similar studies at stop control locations may reveal problems related to excessive waiting times. These types of studies are often considered in a before- and-after analysis. • Photographs and videotaping—Both aerial and at-grade photographs are useful safety tools. Aerial photographs provide data on the location of obstructions and are often used to check sight distances at corners. Photographs aid in the consideration of the effects of vegetation growth and landscape planting. Documenting and pre- senting situations where sight restrictions exist can be made easier with the use of digital technology. Video logs of the roadway provide a reference base for judging safety improvements and documenting the changes made. LOCAL PARTNERS—EFFECTIVE SAFETY TOOLS Traditional partners in enhancing safety are engineering, edu- cation, enforcement, and emergency response services. Com- munication among partners is a tool that may produce value far beyond any site-specific improvement made in response to reactive crash analysis. Crash reactive analysis tools apply to site-specific evaluations only after the location has been identified as a high crash location. Collaboration is the key. In most cases, there are several local jurisdictions with some responsibility for a given road- way. The interactions of partners advancing the safety of the local transportation network by working together on both gen- eral and specific issues are valuable safety tools that should not be overlooked. Establishing effective communications with local decision makers, the media, the general public, law enforcement, and other agency personnel is important. Locally, schools are often a focus of safety. It is important that the decisions on schools be undertaken in a cooperative partnership. Understanding the movement of all users into and out of a school is necessary to achieving safety (16,32,54,55). Separation of the various activities of passen- ger loading and unloading activities will often provide for increased safety. There is also an increased need to consider the ADA, which provides an increased focus on other special user needs. The needs of older drivers and pedestrians are also enhanced by forming partnerships. There are several excellent references which will help to enhance the needed safety considerations for these groups (33,34).

18 Facts, tips, and briefing sheets designed to help local agencies have been developed on a number of safety topics. Examples are provided in Appendixes F and G. These tools can help to educate groups toward understanding the positive benefits of many safety activities and are useful in respond- ing to concerns from citizens or politicians. One such brief- ing is adapted and highlighted here to demonstrate the value of such tools. The FHWA, ITE, and the Advocates for High- way Safety have worked independently and cooperatively to develop many of these briefs. The content is adapted from a portion of Appendix G of this synthesis. BASIC COUNTERMEASURES TO MAKE INTERSECTIONS SAFER Collisions occur at intersections because motor vehicles are in conflict with one another when crossing or turning in traffic. Improving the engineering of intersections is the first step toward reducing accidents, because vehicle conflicts—com- bined with flawed highway or street design and poor signage— often result in collisions of vehicles with roadside objects, pedestrians, and other vehicles. Types of Collisions at Intersections There are four major types of vehicle crashes at intersections. 1. Crossing collisions occur when one vehicle strikes the side of another. These are the most severe types of crashes and can result from vehicles attempting to drive straight through or turning within an intersection. 2. Rear-end collisions are common at intersections. They can be the result of poor street design or inadequate traffic engineering measures, but usually are the result of dangerous driver behavior, such as speeding, following too closely, and braking too late. 3. Vehicles changing lanes improperly or crossing a road’s centerline are less common at intersections than are crossing and rear-end collisions. 4. Pedestrian and bicycle collisions occur most frequently in urban areas, particularly with older and younger age groups. In 2000, 34% of pedestrian deaths among people aged 65 and older, and 10% of pedestrian deaths among children age four and younger, occurred at intersections. Only 2% of motor vehicle-related deaths involved bicyclists, but 33% of these deaths occurred at inter- sections (56). Multiple Causes of Intersection Crashes There are four primary causes of intersection crashes. 1. Poor physical design of both the intersections and their approach roadways can be factors. A major aspect of safety design is restricted sight distances, where drivers do not have enough time to stop or avoid hitting a pe- destrian or another vehicle. 2. Traffic engineering may be inadequate. In some cases, traffic control devices, such as signs, are improperly used, placed in the wrong locations, are too small to be seen, or have suffered damage or deterioration. In other instances, the growing number of automobiles on the road has outpaced what used to be acceptable traffic engineering measures. 3. Driver licensing and education often fails to train drivers to safely negotiate intersections. Some drivers do not know the basic traffic laws, fail to understand the meanings of certain signs and pavement markings, or do not respect the rights and safety needs of pedestrians (57). 4. Drivers disregard traffic control at intersections. Even knowledgeable drivers sometimes disregard the clear messages of traffic control devices—including stop signs, signals, and pavement markings—and repeatedly violate traffic laws. Combined with speeding, the dis- regard for traffic control at intersections is a major source of serious crashes. Driver distractions, such as cell phone use and inattention, as well as drug and alcohol use, are additional human factors that cause accidents with death and injuries. Countermeasures to Improve Intersection Safety Safety problems must be identified by an engineering review. The most important point to remember when improving safety at intersections is that countermeasures that improve vehicle traffic flow or reduce vehicle crashes should not compromise pedestrian safety. There are three strategic decisions to consider when improving intersection safety design and operation. 1. Eliminate vehicle and pedestrian conflicts when possible. 2. When not possible, reduce unavoidable vehicle and pedestrian conflicts to lower the chances for collisions. 3. Design intersections so that when collisions do occur they are not as severe. Studies have shown that providing turn lanes for left-turning vehicles can reduce accidents by 32%. Signalization counter- measures include using 12-in. signal heads; providing separate signals over each lane; installing higher intensity signals; and changing the length of signal cycles, including the yellow change interval and the red clearance interval. Traffic engineering strategies to improve the movement of vehicles and pedestrians are crucial to improving intersec- tion safety. They consist of a wide range of devices and opera- tional changes such as the following:

19 • Addition of turn lanes at intersections—Turn lanes are used to separate turning traff ic from through traffic. As mentioned, studies have shown that pro- viding turn lanes for left-turning vehicles can reduce accidents by approximately 32%. Personal injury accidents involving left-turning vehicles can be decreased by as much as 50%. Separating right- turning vehicles from other vehicles can significantly affect operations at an intersection. The addition of a separate right-turn lane at an intersection with a signal can reduce the delay experienced by drivers on an approach. At intersections without a signal, right-turn lanes can safely remove turning vehicles that are slow- ing down in through traffic lanes. Turn lanes at major driveways can also improve safety, especially on high- volume or high-speed roadways. • Signals—A number of actions can be taken includ- ing increasing the size of signal heads from 8 to 12 in. to increase their visibility; providing separate signals over each lane; installing higher intensity signal lenses; and changing the length of signal cycles, including the yellow clearance interval and the all- red phases. • Nontraditional intersection design—There could be exploration of nontraditional intersection designs such as roundabouts or traffic circles. • Pavement condition—The pavement quality could be upgraded to better drain the road and help resist skidding. • Improving drivers’ sight distance—Actions can include restricting parking near intersections and moving stop lines back from intersections. • Upgrading and supplementing signs—Enforcing laws that prohibit dangerous intersection driving is a neces- sity to even well-designed and regulated intersections. Enforcement must be consistent because motorists who tend to violate traffic control are aware that the chances of receiving a citation are low. Sustained enforcement efforts have been proven to lower both intersection viola- tions and crash rates, sometimes to a dramatic extent. Many smaller local agencies do not have the resources to maintain a full-time engineering function, and without that function, the use of tools like reactive analysis may not be considered. For these smaller local jurisdictions, enhancing safety by working with the partners is a valuable approach. The facts, tips, and briefing sheets are useful tools for under- standing and communicating safety issues. These tools will also be valuable in strengthening the partnerships. One component of a successful partnership is cooperation. Understanding the issues of safety from different points of view is essential, although difficult to achieve. Any steps that elevate the consideration of safety will be beneficial. PROFESSIONAL ORGANIZATIONS—EFFECTIVE SAFETY TOOLS Public and professional organizations also provide excellent sources for monitoring new safety developments. Such groups are identified in Appendixes D, L, and M. Appendix M provides the LTAP addresses and other contact information associated with LTAP centers. These centers can be excel- lent sources of information to assist local agencies in their safety program efforts. Appendix D contains a listing of free and low-cost publications, many sponsored by professional organizations, which can assist local agencies in staying current with the latest developments in safety tools. COMPUTER-BASED SOFTWARE—AN EFFECTIVE SAFETY TOOL Appendix E provides information on computer-based safety software that is available in both the public and private sector. Descriptions of these software programs provide the reader with a quick overview of each program and cites the advan- tages and requirements for using each program. These tools range from easy to use to complex. WORLD WIDE WEB—AN EFFECTIVE SAFETY TOOL Appendix C provides several computer websites that can pro- vide local agencies with the most current information on safety tools, such as major reference publications, standards and guidelines, and additional safety information. Many of these websites provide links to other helpful sites. The websites listed in the appendix offer a wealth of safety tool informa- tion for local use. SAFETY REFERENCES—EFFECTIVE SAFETY TOOLS Appendix C also contains brief summaries of key safety publications, subdivided into primary and supplemental sections. Acquiring and using these references could aid any local agency’s safety program. These sources were devel- oped in part by accessing the FHWA safety website (www.fhwa.dot.gov) and that of the ITE (www.ite.org). The publications listed in Appendix C provide additional infor- mation on practical tools that can benefit a local agency’s safety program. Many of the supplemental references are available directly from the websites listed in the appendix and can be down- loaded at no cost. Although some of these sources are more than 20 years old, the concepts are still valuable. (One caution: be sure that guardrail and guardrail and bridge end treatments comply with the latest standards.) The other references

20 included in the appendix can benefit local agencies by pro- viding quick sources of information, as well as the methodol- ogy to evaluate safety issues. There are new standards for work zone traffic control and sign supports. Although the purpose of this synthesis is not to focus on work zone traffic control issues, it is imperative that local agencies understand that new safety requirements exist. Therefore, work zone issues are presented in the next section. WORK ZONE SAFETY The Millennium Edition of the Manual on Uniform Traffic Control Devices (MUTCD) (58) contains a revised section on improvements to work zone safety. Most LTAP centers can supply local agencies with work zone traffic control pub- lications, training, and the latest MUTCD updated information (36,59,60). Part 6 of the new MUTCD should be consulted to determine work zone traffic control plans, fundamental principals, and special requirements for safety. A few of the more important provisions are as follows: • Work zone requirements in the MUTCD continue to be modified. The latest revisions of the manual can be accessed at the FHWA website, or go directly to the MUTCD and click on http://mutcd.fhwa.dot.gov/. Also available at this site is access to the publication on standard highway signs, which presents information on all MUTCD approved signs, including regulatory and warning signs. Part 6 sets forth the national guidelines and standards for work zone traffic control. • Typical application diagrams are provided to aid an agency in setting up work zone traffic control. It is important for worker safety and the safety of all road users that these typical application diagrams be used with the idea that they represent a good beginning. Traffic control needs to be carefully evaluated before the work begins. • Work zone traffic control devices are now required to meet crash test standards. Approved devices continue to change as new devices are approved and tested. To determine if your local devices are still approved traffic control devices in work zones, as well as to determine new approved devices, link to http://safety.fhwa.dot.gov/ forthlevel/pro_res_road_nchrp350.htm. • Flagging in a work area requires the use of an advanced flagger warning sign. Flaggers are required to use a “STOP–SLOW” paddle when flagging. The only exception is for emergency flagging. • The LTAP center in each state or tribal area has training and pocket references on work zone traffic control that provide opportunities for local agencies to enhance safety in local work areas. ECONOMIC ANALYSIS AND PRIORITY IMPROVEMENT TOOLS A question that often surfaces when evaluating safety con- cerns the benefits of an improvement versus the costs. In addition, local agencies must determine how best to allocate their limited resources among various projects; therefore, economic analysis is necessary. There is no one specific method of undertaking an eco- nomic analysis. However, several are suggested in the Manual on Identification, Analysis and Correction of High Crash Locations (the HAL Manual) (46), including benefit–cost ratio analysis, cost-effectiveness method, net benefit method, incremental benefit–cost ratio, and dynamic programming (see Appendix C). When solving one specific safety prob- lem there are generally a number of different solutions. The cost of each solution may vary widely as may the potential safety benefits. Spending more does not necessarily result in a better and safer solution. Among the difficulties with economic analysis are the assumptions that need to be made. For example, the benefits pertaining to fewer crashes and the less severe nature of crashes need to be determined. The reductions in these two areas form the basis for determining the economic benefits. There are a number of sources available to help local agencies make these decisions. The goal of economic analysis is to evaluate the benefits for each possible countermeasure and then to determine the best solution. Useful sources include the aforementioned HAL Manual (46) and the Arizona Local Government Safety Project Analysis Model (21) (see Appendix C). They offer more details on the value of various treatments and the value associated with the reduction of certain crashes. These sources provide an estimate of the reduction in crashes and severity corre- lated to the improvement alternative. This is referred to as the accident reduction factor, or crash reduction factor. The cost of the improvement alternative includes the total cost and the potential service life of the countermeasure. The total cost includes costs of maintenance, operation of the countermeasures, and application of the appropriate rate of return for the public-sector investment. All costs are associ- ated with the same time frame for the analysis by converting the different items and using the appropriate economic factors based on the rate of return. For example, a capital recovery factor is used to convert an initial cost to an equivalent annual cost. Generally, an equivalent annual cost and benefit approach is used. The desired outcome is to maximize the benefits when compared with the costs. A benefit–cost ratio with at least a dollar return for each dollar of investment reflects a break-

21 even investment. If there is only one solution, then a benefit– cost ratio greater than or equal to one is desired. When a number of alternatives are considered, the cost of each alter- native needs to be ranked according to increasing costs, after which each alternative’s costs and benefits can be compared. When a ratio is calculated that is greater than or equal to one, then the next higher cost alternative is compared with that of the better alternative. This comparison technique is called an incremental benefit–cost analysis. The last alternative to receive a benefit–cost ratio of one or greater is the best eco- nomic alternative. There are some variations to the incremental benefit– cost ratio method, but they are all basically the same. The differences are related to the time frame of the analysis, what costs and benefits are considered, and the basis for comparison, that is, present value or annual value, and other analysis details. Other techniques are also presented in the HAL Manual (46). Furthermore, there is the need to evaluate decisions with regard to which projects need to be undertaken. Simply stated, given a set of best alternatives, how does one select those to be undertaken first? Because this evaluation deals with a mutually exclusive set of best alternatives, the decision involves how best to spend a limited amount of resources among countermeasures for different locations. The best alternatives improve different safety concerns with different levels of certainty. The evaluation of each indepen- dent best alternative provides its own set of costs and ben- efits. Economic analysis may also be a good tool to use in countering less desirable political alternatives, as well as for supporting an unpopular solution. There are a number of other factors, including environmental impacts, business effects, and jurisdictional implications; these are often not economi- cally based factors. KNOWN SAFETY IMPROVEMENTS—AN EFFECTIVE SAFETY TOOL The advantage of economic analysis is derived from the inclusion of a rationally based component into the decisions that are made. Although obvious issues are a part of any deci- sion process, the goal is to implement a countermeasure after making the best decisions possible. However, applying proven improvements as solutions to known safety problems is also a viable option. The absence of an economic analysis tool should not prevent a local agency from developing a safety improvement program. Economic analysis is only one tool; implementing a safety improvement program is the key to improving local roadway safety. EMERGING RESEARCH AND GAPS IN KNOWLEDGE This chapter has highlighted safety tools that are beneficial in evaluating safety issues. These tools are applicable to both reactive and proactive applications. To advance safety prac- tice there is a need to better understand the effectiveness of emerging safety techniques. Tools continue to change and improve. This section highlights several sources of informa- tion that provide knowledge of products reflecting the advancing state of knowledge and practice. Local agencies will find the following website of the Turner–Fairbank Highway Research Center (www.tfhrc.gov and click on the RD&T Performance Report Link) useful as they seek knowledge of the latest practice and answers to questions concerning emerging safety topics. In February 2003, this site provided a status report on topics that are of interest to local agencies, including the following: • Red light running; • Development of materials for asset management guidance; • Evaluation of low-cost safety improvements—specifi- cally, edgeline rumble strips on rural highways; and • Interactive Highway Safety Design Model software development (see Appendix E)—a continuing project that will help local rural agencies assess geometric and crash issues. The advancement of safety practice is an ongoing process. Research also continues on issues such as centerline rumble strips, traffic calming, the effects of traffic calming on safety, and older drivers and pedestrians (16,32,53,59,62,63). Also, see Appendix L for additional sources of information being developed on these diverse safety issues. It is important to remember that implementing ADA guidelines will become a greater safety concern. It is important to keep current by reviewing the latest references, accessing websites on research, and using LTAP centers as effective resources. At the local level, there is a major need to improve the collection of crash data and to adequately train those individuals who undertake this activity. The improvement of state and local cooperation and the issue of improving data collection will be addressed in an upcoming NCHRP synthesis on safety management systems that is scheduled for publication in late 2003. AASHTO is a leading force in the advancement of safety and has developed a Strategic Highway Safety Plan (64) (see Appendix K). There are 22 specific goals associated with this plan, each of which has a series of strategies designed to address these goals. Local agencies will find this plan ben- eficial in communicating the broad array of safety issues and the needed local activities to help achieve these goals. A website, http://www.transportation1.org/safetyplan/plan/

22 index.asp, provides a link to each goal, and the associated strategies and an opportunity to stay current on the develop- ments of the resource documents for implementing the strategies. The first six publication titles addressing these goals are in draft form and are cited as references in Appen- dix K, along with the AASHTO table of contents page for the strategic plan. The recognition that all crashes are local puts a local focus on this quote from AASHTO’s Strategic Highway Safety Plan. The current crash projections are unacceptable: 1 in 84 children will die violently in a highway crash during his or her lifetime; 6 in 10 will be injured, many more than once. We must not be lulled into complacency by day-to-day statistics. Existing efforts are not acceptable (64).

Next: 5 DEVELOPING A LOCAL SAFETY IMPROVEMENT PROGRAM: THE BEST SAFETY TOOL »
Roadway Safety Tools for Local Agencies Get This Book
×
MyNAP members save 10% online.
Login or Register to save!
Download Free PDF

TRB's National Cooperative Highway Research Program (NCHRP) Synthesis 321: Roadway Safety Tools for Local Agencies examines the safety tools and procedures that are practical and relatively easy to apply, and that can be implemented by agencies with limited financial support and personnel. Recognizing the wide variation in the operations and responsibilities of local agencies, the report acknowledges that the level of expertise in transportation safety analysis also varies greatly.

  1. ×

    Welcome to OpenBook!

    You're looking at OpenBook, NAP.edu's online reading room since 1999. Based on feedback from you, our users, we've made some improvements that make it easier than ever to read thousands of publications on our website.

    Do you want to take a quick tour of the OpenBook's features?

    No Thanks Take a Tour »
  2. ×

    Show this book's table of contents, where you can jump to any chapter by name.

    « Back Next »
  3. ×

    ...or use these buttons to go back to the previous chapter or skip to the next one.

    « Back Next »
  4. ×

    Jump up to the previous page or down to the next one. Also, you can type in a page number and press Enter to go directly to that page in the book.

    « Back Next »
  5. ×

    To search the entire text of this book, type in your search term here and press Enter.

    « Back Next »
  6. ×

    Share a link to this book page on your preferred social network or via email.

    « Back Next »
  7. ×

    View our suggested citation for this chapter.

    « Back Next »
  8. ×

    Ready to take your reading offline? Click here to buy this book in print or download it as a free PDF, if available.

    « Back Next »
Stay Connected!