4
Reliability Focus Area

SHRP 2 Reliability program goal: To provide highway users with reliable travel times by preventing and reducing the impact of nonrecurring congestion.

Congestion seems to be like the weather—something we talk about but cannot do much to change. We avoid it if we can, endure it if we must. Congestion is a complex phenomenon; its interrelationships with the economy, safety, and the environment are not always straightforward. It is defined differently in urban versus nonurban areas. It may be described as “gridlock” in one city but may be bearable evidence of economic growth in another. Congestion is often a matter of perception: different travelers perceive it in diverse ways depending on its impacts, including the perceived cost or penalty for being delayed, and on the importance the traveler attributes to a particular trip. Congestion generally takes two forms: recurring, or everyday peak-hour congestion, and nonrecurring, or the seemingly unpredictable congestion that occurs at unexpected times or places. Nonrecurring congestion causes highway users to regard the highway system as “unreliable.”

The complexity of congestion calls more for a dynamic operational perspective than for the static infrastructure perspective traditional to highway engineering. Addressing the problem also requires the active participation of both public- and private-sector entities. Solutions must tap a suite of strategies, including design, construction, system operation and management, pricing, modal shifts, land use, and many other factors. New concepts and vocabulary must be employed to reflect the probabilistic and systemic nature of the phenomena associated with congestion, necessitating in turn training



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4 Reliability Focus Area SHRP 2 Reliability program goal: To provide highway users with reliable travel times by preventing and reducing the impact of nonrecurring congestion. C ongestion seems to be like the weather—something we talk about but cannot do much to change. We avoid it if we can, endure it if we must. Congestion is a complex phenomenon; its interrelationships with the econ- omy, safety, and the environment are not always straightforward. It is defined differently in urban versus nonurban areas. It may be described as “gridlock” in one city but may be bearable evidence of economic growth in another. Congestion is often a matter of perception: different travelers perceive it in diverse ways depending on its impacts, including the perceived cost or penalty for being delayed, and on the importance the traveler attributes to a particular trip. Congestion generally takes two forms: recurring, or every- day peak-hour congestion, and nonrecurring, or the seemingly unpredictable congestion that occurs at unexpected times or places. Nonrecurring conges- tion causes highway users to regard the highway system as “unreliable.” The complexity of congestion calls more for a dynamic operational per- spective than for the static infrastructure perspective traditional to highway engineering. Addressing the problem also requires the active participation of both public- and private-sector entities. Solutions must tap a suite of strat- egies, including design, construction, system operation and management, pricing, modal shifts, land use, and many other factors. New concepts and vocabulary must be employed to reflect the probabilistic and systemic nature of the phenomena associated with congestion, necessitating in turn training 60

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reliability focus area 61 and education of those responsible for planning, programming, operating, and maintaining the highway system. Political leaders need to understand how highway operations, as well as new construction and maintenance, affect congestion and consequently how suboptimal resource allocation decisions can hamper a comprehensive approach to congestion mitigation. shrp 2 reliability research SHRP 2 addresses congestion in two strategic focus areas. The Capacity focus area, discussed in the following chapter, addresses the need for new physical capacity to deal with recurring congestion and explicitly includes economic, environmental, and pricing aspects of the issue. The Reliability focus area, described here, addresses a particular operational characteristic of highway systems that is related to nonrecurring congestion: travel time reliability. From the highway user’s perspective, travel time reliability means the extent to which one can depend on completing a given trip within a consistent, pre- dictable length of time. More specifically, travel time reliability is the prob- ability or percent of time that a person or goods shipment will arrive on time (or within a time window) for a particular type of trip, departure time, origin and destination, and environmental setting. When travel times are not reli- able, travelers frequently find themselves late unless they build additional buffer time into their trips. For example, one may leave earlier to ensure arriv- ing on time for an important appointment or to catch a flight. This buffer time could have been spent on other activities and could actually be spent waiting at one’s destination if the time was not needed in the end. SHRP 2 research is aimed at improving travel time reliability by address- ing the nonrecurring portion of the congestion problem. The relatively unpredictable events that are responsible for nonrecurring congestion can be categorized as follows: • Traffic incidents: This category covers a number of different types of events. Crashes are a common example; when a crash occurs on a roadway, at least one lane of traffic is typically blocked by the vehicles involved in the crash. Often, additional lanes are blocked by police, fire, and emergency medical vehicles and equipment. Even if the crash occurs off the road or has been moved to the shoulder, through traffic must slow down for safety

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62 implementing the results of the second strategic highway research program reasons or chooses to slow down out of curiosity. Other types of incidents can also block a portion of the roadway or provide rubbernecking opportuni- ties. Such incidents may include police activity, broken-down or abandoned vehicles, debris on the roadway, and cargo spills (including spills of hazard- ous material, which require special safety and cleanup procedures). • Work zones: A heavily used and aging infrastructure requires substantial maintenance and rehabilitation, much of which must be carried out while the facility is still in use. Work zones block lanes and sometimes require reduced speeds and modified traffic patterns, all of which can add to travel time and congestion. • Weather, environmental, and emergency impacts: Rain, snow, ice, fog, and sun glare can often slow traffic even when they do not contribute to crashes or breakdowns. Even with efficient plowing, snow can reduce the number or width of lanes in locations that lack adequate space to store plowed snow. Heavy rains or poor drainage can leave portions of low-lying roads impass- able during and after a storm. Hurricanes, tornadoes, wildfires, or terror- ism threats may call for emergency evacuation or closed roads. • Special events: Football games, parades, demonstrations, marathons, motorcades of dignitaries, and many other sporting and civic events can have significant impacts on local traffic. If drivers are not forewarned about such events, they can be surprised to find their trip’s duration lengthened. SHRP 2 focuses on nonrecurrent congestion and travel time reliabil- ity for three reasons. First, approximately half of the delay experienced by highway travelers is characterized as nonrecurring or caused by nonrecur- ring events (Chin at al. 2002). Reducing the impact of incidents that cause nonrecurring congestion can have a significant effect on reducing over- all congestion and travel delay. Second, travel time is something highway users understand. They know what it means for travel times to be highly variable and what impact this variability has on their personal and profes- sional lives. Being late because a trip took longer than would reasonably have been predicted can mean missing an appointment or a plane, losing a client, or disappointing a loved one. Shippers who operate on a just-in-time basis pay a penalty for deliveries that occur outside of a narrow window, whether too late or too early. Workers know they cannot regularly be late for their jobs if they wish to remain employed. Parents picking up children

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reliability focus area 63 at day care may be charged for arriving late. The third reason for focusing on travel time reliability is that it is amenable to existing and emerging management and technological tools. In 2005, for example, traffic incident management programs reduced congestion in 437 urban areas by 130 mil- lion hours, saving $2.5 billion (TTI 2007). While the terms “recurrent” and “nonrecurrent” congestion have become somewhat conventional among highway operations profession- als, they are not truly independent phenomena. Incidents such as those cited above often take place during periods of recurrent congestion, which increases their impact. The baseline traffic volume on a road influences the severity of an incident’s impact on travel time: the closer to capacity a highway facility operates, the more sensitive it is to such perturbations as crashes, rubbernecking, and blocked lanes. Table 4-1 indicates the percent- age of lost throughput capacity on a roadway that is due to incidents that block one or more lanes or the shoulder. Design characteristics of a road system—such as traffic signal timing, the presence or absence of shoulders, and lane drops1—also influence the severity of nonrecurring incidents. Managing incidents to reduce their impact on the variability and unpre- dictability of travel times requires a multifaceted approach. SHRP 2 has iden- tified four areas in which research could make a significant contribution: • Data, metrics, analysis, and decision support: This area encompasses the following questions: How can reliability best be defined, measured, and monitored? How effectively do various strategies improve reliability? How can these strategies be used by agencies to guide actions and investments aimed at reducing nonrecurring congestion? • Institutional change, human behavior, and resource needs: In any complex system, the human participants are a critical component. This area relates to how transportation agencies can evolve to reduce nonrecurring conges- tion and mitigate its impact through highway operations. It also addresses how transportation agencies and other organizations involved in incident management and response can collaborate more effectively. In addition, it deals with training needs and driver behavior. 1 A lane drop is a reduction in the number of traffic lanes on a road, usually at an intersection, inter- change, or dividing point.

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64 implementing the results of the second strategic highway research program table 4-1 percentage of lost throughput capacity due to lane or shoulder blockage Lanes Blocked No. of Shoulder Lanes Blocked (%) 1 (%) 2 (%) 3 (%) 2 19 65 100 NA 3 17 51 83 100 4 15 42 74 87 5 13 35 60 80 6 11 29 50 74 NOTE: NA = not applicable. SOURCE: FHWA data reported in WSDOT 2007. • Incorporation of reliability into planning, programming, and design: This area involves arming transportation professionals with the technical and policy tools needed for effective management of nonrecurring congestion. The data, tools, and information about institutional and human behavior derived from research in the first two areas above will be consolidated and incorporated into the planning, programming, and design processes of transportation agencies. • Future needs and opportunities: The research in this area will focus on fos- tering innovative thinking that can form the foundation for long-term reduc- tions in nonrecurring incidents and improvements in travel time reliability. promising products, and potential users, incentives, and barriers The products of SHRP 2 Reliability research are many and diverse, as are the potential users of those products. Ideally, the products would be imple- mented in an integrated fashion. That is, transportation organizations would simultaneously apply institutional, analytical, planning, operational, design, and management strategies to leverage their synergistic relation- ships and would coordinate this implementation across user groups (see Box 4-1 for an example of such an integrated approach). For clarity of expo- sition, however, this section describes the products of SHRP 2 Reliability

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reliability focus area 65 Box 4-1 maryland charting the course The State of Maryland’s incident management program is among the most advanced in the nation. It is part of a larger organization known as the Coordinated Highways Action Response Team, or CHART, a joint effort of the Maryland State Highway Administration, the Maryland Transportation Authority, and the Maryland State Police. In addition to managing traffic incidents, CHART deals with weather- related emergencies, construction-related road closures, and other issues associ- ated with highway operations. CHART operates a Statewide Operations Center near Baltimore–Washington International Thurgood Marshall Airport. This facil- ity works in conjunction with several smaller regional traffic operations centers located throughout the state. The CHART program may have prevented as many as 766 secondary incidents in 2001 through its prompt clearing of primary incidents, according to experts at the University of Maryland. Researchers estimate that the 25.80 million vehicle hours of delay “eliminated” by the program in 2001 saved 4.35 million gallons of fuel and kept 4,027 tons of vehicular emissions out of the air. SOURCE: AASHTO 2004. research first, and then the potential users of those products and the incen- tives for and barriers to implementation. Products The products to be developed under SHRP 2 Reliability research can be grouped into the four areas described above. A list of Reliability projects and corresponding products is provided in Appendix B. Data, Metrics, Analysis, and Decision Support Research in this area will identify data types, measurement methods, and analysis tools and will develop an archive of travel time data, performance measures, and operational strategies. The archive will support transporta- tion agencies at all levels in monitoring travel times and related reliability measures, developing and using performance measures and models, and evaluating actions aimed at controlling and mitigating nonrecurring con-

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66 implementing the results of the second strategic highway research program gestion. A guidebook will help practitioners establish reliability monitoring programs. Technical relationships between mitigation measures and per- formance will be developed so that practitioners will have a basis for mak- ing informed choices. Mechanisms for incorporating reliability estimation into planning and operations models will be developed as well. Institutional Change, Human Behavior, and Resource Needs In the area of highway operations and incident management, the actors are many and diverse: managers of highway agencies and their technical staff; the political leaders who provide authorization, budgets, and oversight; driv- ers; police, fire, and emergency medical personnel; tow truck operators; maintenance and construction workers; businesses; sponsors of special events; and weather forecasters. Reducing congestion related to nonrecur- ring events will require significant modifications of the internal organiza- tional structures and business practices of transportation and public safety agencies. Impact mitigation will require new organizational systems, practi- tioner interactions, and effective communications. Research in this area will provide information to guide agency managers and practitioners in making business process and institutional changes in support of improved reliabil- ity. Managers will find guidance for effectively disseminating travel time reliability information in several alternative formats so that road users can make informed driving decisions. Box 4-2 provides an example of a format used by the Washington State Department of Transportation. Case studies from both domestic and international transportation organi- zations and from nontransportation industries, together with insights gained from research on organizational behavior, are identifying the most effec- tive practices and organizational structures for managing 24-hour facilities such as highway systems. Focusing specifically on how these approaches can improve incident management and travel time reliability, SHRP 2 research in this area will examine ways of inculcating an operations orientation in the institutional culture of transportation agencies to strengthen their capac- ity to deal with nonrecurring congestion. A focused training program is being developed to ensure that all professionals who respond to highway incidents—transportation staff, firefighters, police, emergency medical personnel, tow truck operators, material spill responders—are well versed in the state of the art of safe and efficient incident response procedures

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reliability focus area 67 Box 4-2 washington state department of transportation online travel time calculator The Washington State Department of Transportation provides an online tool trav- elers can use to calculate their commute times. The tool uses travel time data to estimate the “worst case” travel time scenario. Commuters can expect to arrive at their destination within the calculated time 95 percent of the times they make this trip at the chosen time of day; that is, they can expect to be on time for work 19 out of 20 working days a month if they allow for the calculated trip duration. Where are you SeaTac starting from? Where are you Seattle going? 8 : What time do you need to get there? 00 AM SeaTac - Seattle Your 95% Reliable Travel Time is 35 minutes. 95% of the time you would need to leave at 7:25 AM to arrive by 8:00 AM. SOURCE: WSDOT 2008. in traffic environments. Driver behavior is being addressed in two ways. One project addresses travel time information, a key need of road users, by examining the accessibility and utility of traveler information mechanisms and technologies and assessing the system performance effects of the improved traveler information they provide. The second research effort will use video and other data collected in past studies and SHRP 2’s Safety field study (see Chapter 2) to learn how drivers behave in work zones or in the vicinity of crashes, special events, or other incidents. Results from these

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68 implementing the results of the second strategic highway research program driver-behavior studies will lead to better traffic management and more effective communication with drivers. Incorporation of Reliability into Planning, Programming, and Design Planning, programming, and design processes are key tools used by trans- portation agencies to improve traffic conditions and reduce and mitigate nonrecurring congestion. Currently, no technical procedures exist with which to incorporate mobility and reliability performance measures into the transportation investment process; as a result, the effects of short- and long-term strategies addressing improved reliability on traditional capital expenditures cannot be determined. Similarly, the effects of alternative design features that can improve reliability have not been fully evaluated, and those that have been are not included in design manuals. SHRP 2 research in this area addresses the need for improved tools to iden- tify and evaluate the effectiveness of infrastructure and operational counter- measures and to quantify the impacts of nonrecurring congestion on overall highway capacity. The research will link changes in performance measures to individual reliability improvement strategies so the effectiveness of those strategies in reducing congestion can be considered fairly as a substitute for or supplement to infrastructure-based capacity enhancements in the trans- portation planning and programming process. The research will include pilot studies of the procedures in a number of agencies. In coordination with the work undertaken in the Capacity focus area of SHRP 2 (see Chapter 5), travel time reliability will be included among the factors considered in the highway planning and programming process. Reliability performance, costs, and effectiveness will be incorporated into the key steps that lead to deci- sions about how the transportation system evolves and is operated. SHRP 2 is studying highway design features—such as crash investigation sites, median crossovers, and wide pavement shoulders—to assess their costs and effectiveness in managing incidents to reduce travel time variability. Many such features are currently in use but not included in standard design guides because of perceived high costs and a lack of data on potential cost savings. Other designs used in countries outside of the United States will be evalu- ated as well. An example is active traffic management, which combines lane control, variable speed limits, hard shoulders, and accident investigation sites so that highway system managers can control traffic flow both laterally and

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reliability focus area 69 longitudinally (see Box 4-3). Results of these analyses will be used to develop nonrecurring congestion factors for the Highway Capacity Manual and the AASHTO Policy on Geometric Design of Highways and Streets—standard refer- ence materials for highway designers. Turning research results into practical guidance that meets the requirements of these design documents is essential to influencing actual highway designs. Future Needs and Opportunities The research described thus far is focused largely on making significant improvements in the short term, taking much of the current highway envi- ronment as given. However, many technological, social, and institutional Box 4-3 m42, west midlands, united kingdom On September 12, 2006, motorists on the M42 in the West Midlands, United King- dom, were the first in the country to be able to drive on the hard shoulder during busy periods as part of a scheme aimed at cutting congestion. The scheme, called active traffic management, is in effect between junctions 3A and 7 and uses elec- tronic signs to direct drivers to use the hard shoulder during times of peak conges- tion. Together with variable speed limits, which help smooth the flow of traffic, the scheme has been highly successful in reducing congestion on the M42. Safety was of critical importance during the design of the scheme. Emergency refuge areas are available at regular intervals to provide motorists with a safe place to stop in the event of a problem with their vehicle. These refuge areas are linked by telephone and closed-circuit television camera to the nearby regional control center. The Highways Agency also worked closely with emergency services to enable them to access the motorway in the event of an incident. Available to staff in the Highways Agency control room are more than 200 cameras on the 11-mile stretch, allowing them to easily spot any incident as it occurs. They can then close an individual lane or lanes by displaying a red “X” on the electronic sign above each affected lane. Taking this action protects the vehicles involved in the incident while clearing the lane to allow access by emergency vehicles. Compared with road widening, active traffic management is significantly more cost-effective but provides comparable benefits. The benefits include increased capacity, reduced travel times, greater travel time reliability, lower emissions, and lower fuel consumption.

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70 implementing the results of the second strategic highway research program developments are occurring and will continue to emerge; transportation agencies must be prepared to conduct highway operations in new envi- ronments and even to create these environments. Research in this area is focused on longer-term, more innovative thinking. One project will define user requirements, performance standards, and present and future con- cepts of operations to provide agencies with guidance on the best alter- native operations strategies for improving travel time reliability. A second project will develop a portfolio of innovative ideas, supported by accom- panying proofs of concept, aimed at improving reliability. The intent is to undertake several small experiments or pilot studies to explore innovative ideas deemed promising for future application. Potential Users, Incentives, and Barriers The ultimate beneficiaries of the products emerging from SHRP 2 Reli- ability research will be commercial highway users, bus operators, and indi- vidual motorists. Implementation of the majority of these products will lie in the hands of those agencies responsible for active and safe operation of the nation’s highways. These users of Reliability products can be divided into four broad groups according to the scope of their interest: (a) leaders of transportation agencies are concerned primarily with strategic issues related to transportation and its role in the economy and society; (b) tech- nical staff of transportation agencies are focused on delivering transpor- tation programs and services to their customers within legal, regulatory, and financial constraints; (c) nontransportation professionals with some relationship to transportation operations usually have very different scopes of responsibility, such as law enforcement, firefighting, or management of a special event venue; and (d) researchers and analysts are interested in understanding transportation operations and in developing innovative approaches to meet operational challenges. Leaders of transportation agencies represent an important user group. Support for reducing congestion by managing nonrecurring incidents must come from directors of state and local transportation agencies, who in turn must convince political leaders to provide the necessary resources. Transportation leaders are potential users of a small but critical set of prod- ucts: business process and institutional structures for travel time reliability and incident management, and performance monitoring systems. Incen-

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reliability focus area 71 tives for the implementation of SHRP 2 Reliability products by these users include providing better service to their customers, getting the most out of existing infrastructure through better management of operations, justify- ing resource requests, and basing organizational decisions and priorities on better information. On the other hand, barriers to implementation for this group can be formidable. These are busy individuals; they may find it dif- ficult to devote the time required to delve into the concepts and benefits of better incident management. There are few if any quick fixes for a complex system. Benefits will take time to accrue and may be experienced to varying degrees in different parts of the highway system. In competition for limited resources, the building of new facilities often has an edge over manage- ment of operations because construction of new highway capacity appears to provide a more direct solution to congestion. Although new construction is sometimes the right approach, agency leaders may feel pressured to focus resources on building even when operations techniques could provide a more cost-effective answer. Technical staff of transportation agencies are the largest group of potential users of Reliability products. Within this group are subgroups with particu- lar technical roles that correspond to different products. Planning staff will be able to use the planning models that incorporate travel time reliability factors developed under SHRP 2. Design staff and the consultants who work with them will use the Highway Capacity Manual and the AASHTO Policy on Geometric Design as modified by results of the SHRP 2 research. Operations and planning staff will be able to utilize the travel time monitoring systems designed under the program. The results of the driver behavior research will be useful to traffic engineers and public safety officials in improving traffic control for work zones and special events; incident managers will be able to develop better response techniques in such areas as vehicle place- ment and lighting. Incident response professionals would also benefit from joint training in safe and efficient procedures at incident scenes. Highway agency staff members are not the only transportation profes- sionals concerned with travel time reliability. Managers and operators of bus systems have a large stake in this aspect of highway performance. Bus scheduling depends on reliable expectations regarding travel time on spe- cific routes. Nonrecurring events adversely affect bus riders as much as automobile drivers; bus riders want timely and accurate information about

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72 implementing the results of the second strategic highway research program travel times in terms of bus arrivals at their origin and destination stops. Private-sector freight haulers are concerned about travel time reliability as well and are potential users of SHRP 2 Reliability analysis and planning products. Despite the technical differences among these potential users, they share similar incentives and barriers to implementation of SHRP 2 prod- ucts. Their main incentive is better quality in their respective areas of work and more efficient use of resources as a result of more solid foundations for decisions and better analysis, planning, and design tools. Field staff will experience greater safety and better coordination because of clear, consis- tent guidelines. Nevertheless, there are barriers to implementation. Trying any new technology or changing established procedures can be difficult and risky. Demonstrations and pilot tests using innovations on real projects will be necessary to convince these professionals that the innovations are more than just a good idea. Personnel constraints pose another major barrier. Most transportation agencies have been experiencing declining staff levels. Employees are often so busy that they find it extremely difficult to take time to be trained in new methods. However, a wise manager will often consider the potential benefits of innovation to be more than adequate justification for time spent in training. A more difficult challenge occurs when an inno- vation requires such a different skill set that new employees are needed. Some agencies will face such a need for new staff and be unable to obtain the authorization to make these hires. Another significant barrier is lack of data. Effective use of SHRP 2 prod- ucts, such as programming and planning models or systems for monitoring travel time reliability, will require jurisdiction-specific data so that accu- rate analyses can be performed. Although states collect a great deal of data on their highway systems, they do not all collect all the data needed for effec- tive system management because of resource constraints. Local transporta- tion agencies typically are even more resource constrained when it comes to personnel, training opportunities, and data collection. SHRP 2 research products will include advice on how to work with limited data sets. On the positive side, data are increasingly available for purchase from the private sector. Perhaps the largest potential barrier to implementation for the tech- nical staff of transportation agencies is a lack of high-level awareness of the benefits of operational management approaches to congestion mitigation—

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reliability focus area 73 a point discussed above in identifying transportation agency leaders as the first set of potential users of SHRP 2 Reliability products. Although the barriers described above are formidable for state transpor- tation agencies and even more so for local agencies, the incentives for these agencies to improve travel time reliability are significant given the impact of nonrecurring congestion in rural and urban areas both large and small. In urban areas, well over half (58 to 67 percent) of all congestion can be attributed to nonrecurring congestion; in rural areas, this figure rises to 98 percent (see Figure 4-1). Management of incidents and special events as a strategy for congestion mitigation involves an array of nontransportation professionals mentioned earlier, including police, firefighters, tow truck operators, emergency medical personnel, and special event sponsors. The effectiveness of some Reliability products will be highly influenced by the degree to which these other groups are involved in their implementation. The most salient example of this point relates to the incident response training that SHRP 2 will produce. This project is developing training for all potential incident responders—police, firefighters, emergency medical personnel, tow truck operators, and transportation agency personnel—in a consistent set of 120 100 80 Percent 60 40 20 0 Large Urban, Small Urban, Rural >1 million 0.1 million to 1.0 million figure 4-1 contribution of nonrecurring causes to congestion in urban and rural areas. Source: Adapted from Lockwood 2005.

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74 implementing the results of the second strategic highway research program procedures designed to promote safety and operational efficiency. The training is not intended to replace specialized training received by each of these groups but to supplement that training by focusing on behaviors and activities common to all responders, such as proper traffic control, use of reflective gear, and safe behavior near high-speed traffic. The need for this training is clear when one considers that in 2006, 43 percent of fatali- ties among police, firefighters, and emergency medical personnel resulted from transportation incidents (BLS 2006, Table A-6). Indeed, improved responder safety is the main incentive that incident response groups will have to participate in the training produced by SHRP 2. Public safety pro- fessionals are also interested in effective incident management to reduce the risk of secondary crashes, which account for 14 to 18 percent of all crashes and cause 18 percent of freeway deaths (studies cited by Zhou and Sisiopiku 1997). Nontransportation practitioners may become involved as well in imple- mentation of the results of the SHRP 2 research on institutional structures and future concepts of operations. In both of these areas, greater inter- action and coordination are envisioned among public and private organi- zations to improve management of incidents and special events so as to reduce nonrecurring congestion. Better interaction among responders can also improve working relationships when emergencies unrelated to traffic incidents occur. Finally, private-sector providers of traveler information should find use- ful the results of the SHRP 2 research on how drivers use traveler informa- tion. The main barrier to implementation of SHRP 2 Reliability products by nontransportation professionals will be the diverse institutional cultures involved and the difficulty of getting these disparate groups to cooperate toward a common goal. Conflicts related to operational authority can arise among police, fire, medical, and transportation organizations. Each group may also assume that there is nothing to learn from outside its own commu- nity. In some cases, there may even be laws or regulations that limit certain forms of cooperation. Mechanisms to facilitate the necessary interorgani- zational coordination and cooperation need to be developed. The SHRP 2 Reliability focus area will produce an archive of data on travel time reliability and the effectiveness of methods for improving reliability that can be tapped by researchers and analysts seeking to develop additional

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reliability focus area 75 improvements and innovations. Data on driver behavior will be of interest to both traffic operations and safety researchers. The SHRP 2 project on future concepts of operations will undoubtedly generate many innovative ideas on how to achieve future goals. Data and information tend to provide adequate incentive for researchers and analysts; they generally need little encouragement to analyze data. However, access to the data could pose a barrier. The archive of Reliability data must be retained in an easily usable format. Some data sets may include proprietary data or private information concerning individual citizens that may require special safeguards against inappropriate use. conclusion Congestion is a difficult and complex problem. A realistic and effective way to address the problem is to better manage the incidents that produce nonrecurring congestion and mitigate the associated impacts. These inci- dents, which include crashes, work zones, special events, and inclement weather, can increase congestion significantly and unexpectedly. Reducing this unpredictability is the focus of SHRP 2 research on travel time reliabil- ity. The benefits of this research, if it is effectively implemented, include an overall decrease in congestion; increased safety for motorists and incident responders; and savings of time, money, and fuel emissions. These benefits will prove of significant value to society and the nation’s economy, but only if sufficient resources for implementation are made available. references Abbreviations AASHTO American Association of State Highway and Transportation Officials BLS Bureau of Labor Statistics TTI Texas Transportation Institute WSDOT Washington State Department of Transportation AASHTO. 2004. Optimizing the System: Saving Lives Saving Time. http://downloads.trans portation.org/OptimizingTheSystem.pdf. BLS. 2006. Census of Fatal Occupational Injuries. U.S. Department of Labor, Washington, D.C.

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76 implementing the results of the second strategic highway research program Chin, S. M., O. Franzese, D. L. Greene, H. L. Hwang, and R. C. Gibson. 2002. Temporary Losses of Highway Capacity and Impacts on Performance. Report No. ORNL/TM-2002/3. Oak Ridge National Laboratory, Oak Ridge, Tenn., May. http://www-cta.ornl.gov/cta/ Publications/Reports/ORNL_TM_2002_3.pdf. Lockwood, S. 2005. The 21st Century Operations-Oriented State DOT. Prepared for NCHRP Project 20-24 (21). www.transportation.org/sites/ssom/docs/OpsOrientedDOT.doc. TTI. 2007. Urban Mobility Report 2007. College Station, Tex., Sept. WSDOT. 2007. WSDOT’s Congestion Measurement Approach: Evaluating System Performance. Aug. www.wsdot.wa.gov/NR/rdonlyres/7E5A12D8-4932-4065-8BB8-01EED96BF525/0/ Measuring_Congestion_Folio_Aug2007.pdf. WSDOT. 2008. WSDOT—95% Reliable Travel Times. www.wsdot.wa.gov/Traffic/Seattle/ TravelTimes/reliability/. Zhou, M., and V. P. Sisiopiku. 1997. Relationship Between Volume-to-Capacity Ratios and Accident Rates. In Transportation Research Record 1581, Transportation Research Board, National Research Council, Washington, D.C., pp. 47–52.