Reliability: Providing a Highway System with Reliable Travel Times
Overall research program goal: To provide highway users with reliable travel times by preventing and reducing the impact of nonrecurring incidents.
Challenge of Providing Reliable Highway Travel Times
As indicated in Chapter 4, vehicle-miles traveled (VMT) on the nation’s roadways increased 76 percent between 1980 and 1999, a period during which the total lane-miles of roads increased by only 3 percent. Along with rising VMT, there are some indications that congestion is getting worse. In its study of 68 urban areas, the Texas Transportation Institute (TTI) found that on average, the percentage of daily traffic in congested periods increased from 32 percent (about 5 hours per day) in 1982 to 45 percent (about 7 hours per day) in 1999 (Schrank and Lomax 2001). FHWA reports that average daily delay (based on the difference between estimated actual travel speed and free-flow travel speed) increased 8.5 percent between 1993 and 1997, from 8.268 to 8.973 hours per 1,000 VMT (FHWA and FTA 2000).1 Average daily vehicles per lane on urban Interstates rose 43 percent between 1985 and 1999, from 10.331 million to 14.757 million (FHWA 1999; FHWA 2001a). In addition, highway trips are longer and involve more interstate travel; there are fewer alternative routes for many of these trips; and more bottleneck situations have developed in many regions, causing significant user delay. In 1999, 4.5 billion hours and 6.8 billion gallons of fuel were wasted in just 68 urban areas as a result of highway delay. The cost of this congestion was estimated at $78 billion (Schrank and Lomax 2001). Moreover, VMT increases are expected to continue with very little additional capacity for the foreseeable future. As a
consequence, the importance of managing existing capacity for optimal performance is rapidly increasing.
Optimal performance for many users (travelers and freight haulers) is a totally free-flowing system. However, it is unlikely that congestion can be entirely eliminated, or even significantly reduced. In fact, recent FHWA surveys show that drivers have accepted a certain amount of recurrent travel delay and have made lifestyle adjustments to accommodate the reality of congestion (FHWA 2001b). Moreover, shippers and carriers of goods account for expected congestion in their scheduling and logistics algorithms. The real problem for users is unexpected delay, the time they do not plan to spend on the highway—in short, the unreliability of the system (Loudon and Layden 2000; Golob and Regan 2001). The closer to capacity a system operates, the more severely it will react to disruptions, and therefore the greater will be the impact of its unreliability on users. For freight carriers, unreliability is a two-edged sword: as a result of the emergence of just-in-time delivery, carriers are penalized for being too early as well as too late. Reliability of the highway system is important for transit vehicles as well, so they can adhere to the schedules their riders expect. And when emergency evacuation is required, reliability is required to move people to safety predictably and consistently on very short notice.
There are many sources of unreliability in highway travel time. Perhaps most obvious are nonrecurring incidents such as crashes, broken-down vehicles, road debris, and spills. In addition, the need to renew significant portions of the highway system means an increasing number of work zones, with corresponding impacts on reliability. Special events such as parades, sporting events, and large conventions can significantly increase travel times as well if drivers are not aware of them in advance and are not given the opportunity to adjust their travel time or route. Precipitation, sun glare, and the occasional lost tourist can also have dramatic effects on the flow of traffic. Efforts to improve system reliability may address all these issues and more.
Improving travel time reliability is primarily a matter of system operations, but the discipline of highway operations is still an emerging field.2 While
The development of the field of transportation operations is a top priority for many in the transportation community. Since 1999, a National Dialogue on Transportation Operations, sponsored by the ITS Joint Program Office at FHWA with the involvement of AASHTO, the American Public Transportation Association, and the Institute of Transportation Engineers, has engaged transportation professionals in wide-ranging discussions about the future of the field. Information on this initiative is available at www.ite.org.
operational improvements are continually being made, the urgency of practical, day-to-day problems forces most agencies to respond reactively to operational demands as they arise. Many new technologies are available to aid managers and users of the highway system, including simulation and prediction models, better signal systems, traffic control technologies, driver information systems, and other technologies developed through research on intelligent transportation systems (ITS), but these tools need further development and integration into effective strategies aimed at more clearly defined performance expectations.
In addition, roadway operations in their broadest sense involve a wide variety of people and institutions. Beyond users of the highway itself—private individuals, commercial users, transit (buses), pedestrians, and cyclists—others are affected by highway operations, such as adjacent businesses and communities and local and regional economies. Various types of incidents and special events involve a host of other interested parties. For example, police, fire, and rescue personnel may be involved in responding to crashes; hazardous materials (hazmat) specialists have responsibility for responding to hazardous spills; and managers of sports stadiums and convention centers and organizers of major civic events are important stakeholders in the highway operations surrounding their events. Successfully integrating the involvement of all these customers and stakeholders—with their widely varied objectives, incentives, and cultures—is one of the greatest challenges facing those who would manage highway operations for improved system reliability. Box 6-1 describes an example of how the state of Rhode Island addressed special events in the city of Providence, while Box 6-2 illustrates a statewide approach to incident management and response in the state of Maryland.
In this context, the committee proposes for F-SHRP a program of research focused on improving travel time reliability by addressing the impacts of particular types of nonrecurring incidents and special events. A portion of this problem is already covered under the highway renewal program (see Chapter 4), which addresses user delay from work zones. Under the present program, integrated approaches to other types of incidents will be developed. Examples include vehicle breakdowns and spills, which cause physical impedance to traffic both when they occur and while they are being addressed on site by various authorities; special events, which are becoming increasingly common, especially in already congested metropolitan areas where stadiums and convention centers are being built to boost the local economy; and other conditions that can affect travel time reliability, such as weather, wind, and sun glare.
Incident Management Plan, Providence, Rhode Island
Providence, Rhode Island, was not accustomed to the multihour peak traffic periods common to many metropolitan areas, so the state highway agency—and not a few highway users—were surprised when traffic came to a standstill one day in February 1999 as a result of a flower show in the city’s convention center. Upon further investigation, it became clear that the reason for the unexpected tie-up was that the many authorities and stakeholders associated with the event—the Rhode Island DOT (RIDOT), the police department, the convention center authority, the transit agency, private parking operators, and a private developer that had a lane closed for construction of a nearby building— had not communicated with each other, but had performed actions or given clearance for actions that compounded the effects of the flower show on traffic conditions. No plan was in place for dealing with such events, and several even larger special events were scheduled for the ensuing months.
Given the potential impact on city streets and Interstate 95, which passes through Providence, RIDOT set about developing a traffic management plan. This effort involved coordination of more than 30 stakeholders, integration of several innovative technologies and techniques (including variable message signs, highway advisory radio, use of radio and television to inform travelers, traffic signal systems, surveillance cameras, surveillance personnel stationed in vehicles, and a traffic operations center), and more traditional techniques (such as signs, pavement markings, and cones). The information needed to carry out the plan was documented in a “playbook” that was given to each stakeholder so everyone would have the same information. The plan went into effect for the next special event, which went off very smoothly; even the newspapers commented on how good the traffic flow and parking were.
Source: Shaw et al. (2000).
Statewide Incident Management Plan, Maryland
As part of its statewide operations program, CHART, the Maryland State Highway Administration (SHA) has developed a nationally recognized incident management program. In cooperation with the Maryland State Police and the Maryland Transportation Authority, SHA ensures an immediate response to traffic incidents to protect the safety of travelers and emergency personnel and to allow normal traffic flow to resume as quickly as possible. The incident management program involves a number of tools: emergency traffic patrols provide emergency motorist assistance and relocate disabled vehicles out of travel lanes; emergency response units establish traffic control at crash locations; and freeway incident traffic management trailers quickly set up preplanned detour routes when incidents require full roadway closure. Maryland uses a “clear the road” policy that calls for rapidly removing vehicles from travel lanes instead of waiting for a private tow service or time-consuming off-loading of disabled trucks that are blocking traffic. An Information Exchange Network Clearinghouse, provided by the I-95 Corridor Coalition, shares incident and traveler information with member agencies along the corridor. Other tools to facilitate incident management include portable arrow boards, portable variable message signs, and portable traveler advisory radio transmitters for traffic management; front-end loaders, tow rigs, and push bumpers to move vehicles; and training exercises to maintain a high competency level for teams working under hazardous conditions.
Source: Most of this paragraph is taken directly from the Maryland State Highway Administration website at www.sha.state.md.us.
Improving travel time reliability involves more than addressing nonrecurring incidents and special events; however, it is crucial to the effectiveness of the research program that there be an application-specific focus. The emphasis of the proposed research on incidents and special events is not meant to imply that other aspects of the problem are unimportant, but to concentrate intellectual, financial, and implementation resources on specific problems with measurable outcomes. As an indication of the magnitude of the impact of nonrecurring incidents, the above-referenced TTI study (Schrank and
Lomax 2001) suggests that in 1999, such incidents were responsible for approximately 54 percent of highway delay—2.4 billion person-hours at a cost of $42 billion—in the 68 urban areas studied. An effective incident management and response program can be an excellent investment: Chicago’s program has an estimated benefit/cost ratio of 17 (Cambridge Systematics, Inc. 1990). Nonrecurring incidents also increase the likelihood of secondary crashes, thereby reducing highway safety.
Significant improvements in travel time reliability can thus be achieved through a focus on nonrecurring incidents and special events. To this end, the proposed F-SHRP research will address customer performance requirements, institutional issues, data and information needs, and selected technologies associated with this aspect of the travel time reliability problem. Lessons learned from a focus on this aspect of the problem will certainly apply to other challenges faced by highway system managers.
Providing Solutions for the Reliability Challenge Through a Future Strategic Highway Research Program
How improved travel time reliability for highway users meets the first criterion set forth in Chapter 1 for selecting the strategic focus areas for F-SHRP was described in the preceding section: it is an issue that bears on national transportation goals and is of continuing concern to highway agencies. The other two F-SHRP criteria—appropriateness for a SHRP-style program and the effectiveness or expected impact of the research—and how the proposed program of research meets these criteria are addressed in this section.
Appropriateness for a SHRP-Style Research Program
A SHRP-style research program is appropriate for addressing the impact of nonrecurring incidents and special events on travel time reliability for several reasons. First, to achieve a significant improvement in system reliability will require a predictable concentration of resources on a clear goal over a period of several years. It will also require an integrated, systems approach involving numerous stakeholders, issues, and potential tools. Important work addressing the problem of nonrecurring incidents is being conducted in existing research programs, and a number of jurisdictions have developed incident management programs. However, a concentrated effort aimed specifically at improving travel time reliability—with emphasis on defining customer performance requirements and responding to those requirements through the
advancement and interplay of technology, data, and institutions—conducted in coordination with existing activities, can accelerate progress toward specific operational goals. Indeed, the institutional aspect of this issue is so critical and so neglected in terms of solid research foundation that work on this aspect alone may make the most significant contribution to a significant improvement in highway system operations. A focused independent program such as F-SHRP, because of its relative freedom from the institutional constraints of existing programs, is best equipped to sponsor research in this sensitive area and to integrate the aspects of customer needs, data, and technology into a single, outcome-oriented program. Finally, while the benefits of improved highway travel time reliability will accrue to many individuals and groups, some of the necessary investments in research and development are unlikely to be made by the private sector (since individual firms would not be able to capture the returns on these investments); this is therefore an appropriate area for public-sector involvement.
Effectiveness or Expected Impact of the Research
Given recent technological advances, integration of the salient technologies— together with research in customer requirements, data needs, and institutional issues—can be expected to yield substantial improvements in highway operations that will significantly increase system reliability. The potential impact of such improvements is large. One measure of the potential impact is the user savings from reduced highway delay. As noted earlier, TTI’s study of 68 urban areas revealed that highway delay cost users in these areas approximately $78 billion in 1999, about 54 percent of which could be attributed to nonrecurring incidents such as construction work, disabled vehicles, and crashes. If implementation of the results of the research described in this chapter and Chapter 4 reduced such incident-related delay in these urban areas by just 5 percent, the result would be annual savings of about $2.1 billion.
It is reasonable to expect the proposed research to yield results in 5 to 7 years. Barriers to implementation will be largely institutional and financial, which is why these areas will be the particular emphasis of research and stakeholder involvement. The implementing community is a diverse group, and focused effort will be required to assist them in the implementation effort. Finally, some of the proposed research—especially in the institutional area—will require expertise and research methodologies not commonly brought to bear in highway research; new sources of research capacity (primarily in the social
sciences) will therefore need to be sought and introduced into the highway operations arena.
Proposed F-SHRP Research
Major Research Objectives
The proposed research program has two major objectives:
To characterize the chosen incident types in terms of likelihood of occurrence, impacts on users, and customer expectations for management and response; and
To develop integrated strategies or approaches that effectively apply the many tools and technologies available for managing and responding to the chosen incident types.
What meeting these objectives entails and how the objectives are addressed by the proposed focused research program are described in more detail in this section.
Characterizing Incident Types
A number of different types of nonrecurring incidents and special events affect highway operations and consequently travel time reliability. Several of these are briefly described here as examples. One of the first tasks of the research program will be to choose which of these incident types can be addressed most effectively.
Crashes Crashes generally require a quick response, especially for the care of injured parties. The use of sensing and communications technology can help authorities identify incidents and respond both more quickly and with the most appropriate equipment and medical help. Very serious crashes may require the presence of fire trucks, ambulances, and helicopters, all of which take up significant space on the roadway. The police must gather certain data at the crash scene, which can be facilitated by advanced data-gathering technologies. All of these activities cause disruption to the flow of traffic and increase the likelihood of secondary crashes. The involvement of multiple institutions (police, fire, medical, state highway forces) introduces complex issues of coordination and authority, which can also add to the time the
roadway is blocked. In addition, motorists not involved in a crash often contribute to disruptions in traffic flow in both directions by slowing down to view the scene.
The unplanned nature of crashes (as well as other types of incidents) poses challenges for the task of communicating with users about impacts on traffic flow and travel time and about alternate routes. A number of technologies are available to address this challenge, but effective communication about incidents is still in its infancy. Technologies are also under development that would allow highway system managers to adjust signal timing (where applicable) to reduce the impact of incidents on traffic flow.
Disabled Vehicles Vehicles can break down for a number of reasons, including mechanical failure, a flat tire, or lack of fuel. The response to such events is much less urgent than in the case of crashes with injuries. However, the presence of a stationary vehicle in the roadway is disruptive to traffic flow and can potentially cause a crash. Minor crashes are similar situations, but usually with the added factor of two or more drivers standing in the road exchanging insurance information or waiting for police to arrive. The main objective in all these cases is to clear the vehicle (or vehicles) from the roadway as quickly as possible in order to reduce the safety hazard and the traffic disruption. Many states have experimented with ways of achieving this objective. Examples are the use of “courtesy patrols”—DOT vehicles that travel over major commuting routes to help motorists with broken-down vehicles by changing a tire, providing fuel, or towing a vehicle out of the travel lane—and the posting of signs asking motorists to pull off the road in the case of a fender bender instead of leaving their vehicles in the travel lanes.
Hazardous Materials Spills Any material spill on a highway will disrupt traffic flow and pose a potential safety problem, but in the case of hazardous materials, additional human and environmental safety considerations frequently cause a roadway to be completely closed even if the actual physical impediment is small. Procedures for cleaning up such spills can be quite time-consuming as well. As in the case of crashes, the use of technology to quickly learn of a spill event, respond, identify the nature of the hazardous material, and contain or remove it can significantly reduce the impact on traffic flow and safety.
Road Construction and Maintenance Construction work zones constitute another type of incident, although usually one that is planned well in advance—a fact
that provides the opportunity to communicate with users about potential traffic impacts and to address alternative routes, times, and modes of travel. Work zones also introduce specific types of safety concerns, both for workers who are in close proximity to moving vehicles and for drivers who may have difficulty negotiating new traffic patterns established during construction activities. As noted, the impacts of work zones on highway users will be dealt with in some detail under the proposed highway renewal research (see Chapter 4).
In contrast to highway renewal work, maintenance activities are frequently smaller-scale activities that may take less time or may progress along the highway, creating a moving bottleneck. Moreover, such activities often are not planned well in advance, since they can include filling a pothole, removing an animal struck by a vehicle, or repairing a sign or signal. At the same time, these activities may not involve coordination with other institutions and so may be amenable to a broader range of strategies for which DOT staffs can be well prepared.
Special Events The special events referred to here generally consist of planned activities of sufficient size or duration that they may have significant impacts on traffic flow and access. Such events can include parades (which often involve closing long stretches of road, with consequent impacts on cross streets as well), conventions, sports events, and civic events. Some special events (including those that are annual or seasonal) may occur on a regular schedule and at a fixed location (for example, a stadium or convention center). In these situations, it may make sense to install specialized traffic control technologies in the vicinity of the events and develop a management plan for repeated use. Other events are irregular or unique and may involve special considerations. Their sponsors may not be accustomed to thinking about traffic impacts and may have no experience with planning the transportation logistics related to their events (including bus access, parking, roadway capacity, and the time it takes for a large volume of vehicles to negotiate even a simple traffic pattern). Much of the activity may take place on private property but may have significant spillover effects on public roadways. Engaging the many types of sponsors of such events in transportation management and operations poses significant institutional challenges.
Characterizing the Selected Types It will be necessary to develop a full characterization or understanding of each type of incident or special event chosen
for the research. This characterization should include, for example, the following points:
Frequency of incident occurrence and likelihood of occurrence under particular circumstances (such as inclement weather) or in particular locations (such as near shopping malls or on long stretches of rural highway).
Impact of incident type on different classes of users (commuters, vacationers, truckers, transit users, shippers).
Customer requirements that may drive incident management and response, such as how far in advance commuters must be informed of a special event or what type of detour information is useful to a commercial vehicle operator when a crash occurs. (For example, truckers need information well in advance of their destination so they can decide what to do; commuters are not usually that far from their destination, so the timing of their information needs may be different.)
Performance requirements for different authorities responding to an incident (police, DOT personnel, hazmat experts, fire and ambulance personnel) and for various sponsors of and participants in special events.
To the extent that some of these characterization efforts have already been addressed by other programs, the F-SHRP research will synthesize and build on those efforts. For example, in a study sponsored by the Trucking Research Institute in 1990, it was estimated that disabled vehicles accounted for 80 percent of recorded incidents and approximately 20 percent of incident-related vehicle-hours of delay, while crashes accounted for 10 percent of recorded incidents but nearly 60 percent of incident-related delay.3 Updated information of this sort could help determine the specific focus of the research program.
Developing Integrated Approaches
For effective management of and response to incidents and special events, it is necessary to have strategies or approaches that integrate institutional issues, data and communication issues, and associated tools and technologies. These three topics represent distinct research areas, as described below. Yet following a systems approach, which is an important part of F-SHRP’s
philosophy (see Chapter 1), requires that these three areas be addressed in an integrated manner. For example, data and communication issues are clearly affected by both institutional culture and technology. Technologies must fit with institutions, and institutions often must change in response to technologies to better carry out their mission. The F-SHRP research will address these topics in an integrated way and produce results—analyses, information, technologies, best practices—that can likewise be implemented in an integrated manner, with appropriate guidelines for application to specific operational environments.
Institutional Issues Incident management and special events can involve a wide range of stakeholders with diverse goals, incentives, and cultures. One of the biggest challenges to consistently achieving effective incident management is coordinating and integrating the responses of the groups involved, each with responsibility to serve the public, but with sometimes divergent priorities and performance objectives. Highway personnel are sensitive to their public responsibility of keeping the roads operating smoothly, knowing that disruptions in traffic flow have very real safety and economic implications. Fire and rescue personnel are concerned with the safety and medical care of those immediately involved in an incident, as well as with the safety of their own people who are exposing themselves to traffic, fire, and other dangers. Hazmat specialists are concerned with environmental safety as well as immediate human safety. Police, in addition to victim, public, and personal safety, are responsible for specific law enforcement actions and record keeping (such as citations and accident reports). All of these people expose themselves to personal danger in the name of public service. Each group has its own norms, guidelines, sense of authority, and internal culture (based largely on the development of trust among team members). The involvement of multiple groups can threaten the sense of security and authority of each, leading to situations that may, ironically, cause such groups to unconsciously de-emphasize the public good each has set out to serve. Even within highway agencies, institutional challenges exist with respect to improving system operations. Performance measures, incentives, training, and resources can all constrain an agency’s ability to meet customer expectations more consistently.
Addressing such issues is not as straightforward as research and development in technological areas. However, it is possible and critically important to engage in systematic and objective research in this area to find or develop ways to overcome the institutional obstacles involved. The committee believes a
portion of F-SHRP resources should be focused on this topic. Research methods may include a variety of approaches appropriate to social science studies, such as surveys, interviews, case studies, and quasi-experimental designs. It may even be possible to perform demonstrations of best practices in this area. The challenge is twofold: (a) bringing the diverse groups involved together to design and carry out the research program and (b) conducting a research program that differs significantly from traditional highway research in engineering and planning disciplines. The F-SHRP program is ideally suited to address these challenges by bridging institutional, cultural, and disciplinary boundaries.
Data and Communication Issues In the context of travel time reliability, information is important to both users and managers of the system. Managers must have accurate, timely, and consistent data on system operation. To this end, they need data collection tools that are easy and inexpensive to install, require little maintenance, and record data reliably and accurately. Once the data have been acquired, they must quickly be analyzed and transformed into useful information about system operation, in this case travel time reliability. This information must then be made meaningful for various classes of highway users and communicated to them in a timely manner. Accurate and timely information about system operation can at least forewarn users about unusual travel delays when they occur, and in combination with information about alternative routes and modes, system operation information allows users to make choices that best meet their own requirements and priorities. Even better, the right information about system operation, combined with predictive simulation models and various traffic control tools, can allow planners and operators of the highway system to respond to events to mitigate their impact on reliability, or even anticipate events to reduce the severity of potential impacts.
Every step of this process is fraught with both challenges and opportunities. Technologies exist, at various levels of sophistication, for implementing each step. The institutional, technological, and economic issues discussed elsewhere are among the challenges, but questions about the human factors aspect of data and communication also require focused research. It is necessary to know what reliability means to different users, how physical measures of events occurring on the system relate to these customer performance requirements, what kind of information users need to make appropriate decisions about travel, and when and in what format they need this information. The success achieved in providing answers to these questions may well determine whether the new nation-
wide 511 number allocated by the Federal Communications Commission for traffic information will survive beyond its 5-year trial period. Research in this area may also address privacy issues arising from the collection and communication of certain types of data (concerning, for example, vehicle location).
Tools and Technologies A wide variety of tools, technologies, and techniques exist to aid highway agencies in operating their systems. These include detection or sensing technologies, traffic simulation models, prediction tools, travel information technologies, responsive and adaptive traffic control technologies, analysis and design methodologies, management techniques that improve highway flow and contribute to crash reduction, the deployment of ITS infrastructure that enables real-time management of highways, and the availability of information that allows customers to use the transportation system more efficiently.
While much more research and development needs to be done in all these areas and others, there are at least two implementation challenges with regard to existing technologies. First, it is not always clear how these technologies can best be used, and in what combinations, to achieve particular performance requirements in specific operational settings. Second, the implementation of many new technologies is extremely resource-intensive. The initial cost of equipment and installation is the first barrier, but regular maintenance then requires money and trained personnel, both of which are scarce in most jurisdictions. The F-SHRP research will help address the first challenge by assessing the effectiveness of existing technologies for improving travel time reliability in the management of incidents and special events. This assessment, in combination with lessons learned in the institutional research, will help address the second barrier by providing guidelines for the development of technologies that are more compatible with institutional realities, possibly by encompassing the technology development itself in some cases, and by helping institutions better implement tools designed to address customer needs for improved system reliability.
Proposed Research Tasks
One of the objectives of the interim work for this focus area (see Chapter 8) is to choose the set of incidents on which the research will focus. Examples of nonrecurring incidents have been described earlier in this chapter. The choice of specific incident types should be based on the greatest potential benefit to users. This determination may include estimation of the relative
impact of each type of incident on overall travel time reliability (or its contribution to delay) and the potential for alleviating this impact through the application of research and technology.
The research proper will involve the development of effective approaches to increasing travel time reliability through management of and response to incidents and special events and will integrate institutional efforts, data, and technology. To this end, the research will focus on the following tasks:
Identify customer needs and expectations regarding travel time reliability. Customer needs and expectations for different market segments (passenger versus freight movement, work commute versus recreational, special needs of particular groups) will be identified and quantified.
Develop corresponding performance measures and indicators for reliability. Consensus-based performance measures and indicators will be developed for appropriate levels of system application and operational intensity to help agencies determine cost-effective approaches to meeting customer needs.
Perform research on institutional issues. This task will include identifying diverse institutional goals, incentives, and requirements; describing institutional cultures; identifying best practices (e.g., of institutional coordination, communication, and resolution of authority); demonstrating and testing new methods; and developing guidelines for implementing best practices and for identifying and meeting education and training needs.
Perform research on information needs. This research will involve identifying information needs for different customer segments under various travel conditions (such as commute, recreation, work zone, disaster, special event, and freight delivery) and under various geographic, weather, and travel density conditions, as well as for functional specifications of various roadway classes. It will also include developing indicators or indices that adequately communicate system performance to customers and operators in useful ways, studying human factors aspects of effectively communicating the information within the constraints of various media (telephone, broadcast, personal digital assistant, Internet, variable message signs), and determining how best to provide information about intermodal connections and alternatives.
Synthesize and assess existing and emerging technologies. Syntheses of the status of salient technologies will be produced; their impact on reliability through application to incident and special event management will be assessed; and human and financial resource needs for implementation will be identified. Technologies addressed may include the following:
Models for predicting travel time under different scenarios;
Techniques for predicting location, frequency, duration, and type of incident as the basis for improving incident detection and response protocols, including prepositioning of service patrols, equipment, and personnel and targeting of traveler information;
Use of on-site technologies (such as the Global Positioning System and video imaging from surveillance cameras) to substantially reduce the documentation requirements of serious crashes;
Technologies for collection, storage, analysis, and communication of data;
Simulation technologies for modeling impacts of incidents and special events;
Micro traffic simulation models for more user-friendly applications;
Low-cost/low-maintenance traffic-adaptive signal technology, especially for use in areas where special events occur regularly (such as near stadiums and convention centers); and
Sensing and detection technologies, especially those that are low-cost/ low-maintenance.
Perform research to improve or develop selected technologies. Assessment of existing technologies may indicate that significant improvement can be gained from additional development of selected technologies or that specific technologies yet to be developed could improve the reliability of the highway system. Research and development may be conducted in these areas.
Develop guidelines. The effectiveness of various treatments and approaches for achieving performance will be evaluated, and guidelines and warrants for using these approaches will be developed.
Relationship to Other Work
Other Research and Technology Efforts
Much related work in this area deals with incident management: describing the state of the art, promoting incident management techniques, and developing incident management programs in particular jurisdictions. Various state DOTs have developed incident management and response programs and protocols; this work has included successful efforts to address institutional issues. FHWA has sponsored work in traffic simulation models, traffic adaptive control systems, dynamic traffic assignment models, and the development of other technologies through the ITS program. The agency has
conducted customer surveys and undertaken some initial work on defining reliability and other performance measures for highway users (for example, performance measures for freight movement across international borders) and has recently increased efforts to involve the public safety community in incident response. Under NCHRP, research has been done on performance measures, traffic control devices, and other aspects of traffic operations. The private sector also develops various traffic control and other technologies. The F-SHRP research program will be formulated and conducted in cooperation with these and other efforts.
Other Strategic Focus Areas in F-SHRP
This research is closely related to other F-SHRP focus areas. As noted, research on performing rapid, long-lived, minimally disruptive highway renewal will include a significant emphasis on work zone operations to determine how to decrease the impact of work zones on highway users. Improvements in safety resulting from a better understanding of crash factors and effective countermeasures will reduce the impact of crashes on the travel time reliability of the highway system. Better management of all kinds of incidents will, in turn, improve safety by reducing the risk of secondary crashes.
Administrative and Implementation Considerations
The importance of involving all relevant stakeholders in the conduct of this research and the implementation of its results was noted earlier. These stakeholders include state, federal, and local government agencies; fire, rescue, police, hazmat, and towing personnel; industries involved in developing the relevant technologies; and property owners and organizations involved in special events. In addition, the institutional research is likely to yield information that could significantly affect the education and training of transportation and other professionals. Universities and training professionals will also need to be engaged in this aspect of the program.
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