Strategic Highway Research Saving Lives, Reducing Congestion, Improving Quality of Life -- Special Report 260 (2001) / Chapter Skim
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6 Reliability: Providing a Highway System with Reliable Travel Times
6 Reliability: Providing a Highway System with Reliable Travel Times
Pages 98-116
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From page 98... ...
. 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.
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From page 99... ...
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.
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From page 100... ...
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.
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From page 101... ...
, 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.
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From page 102... ...
In cooperation with the Maryland State Police and the Maryland Transportation Authority, SHA ensures an imme diate 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 re locate 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 inci dents require full roadway closure.
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From page 103... ...
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.
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From page 104... ...
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.
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From page 105... ...
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.
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From page 106... ...
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.
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From page 107... ...
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)
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From page 108... ...
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.
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From page 109... ...
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.
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From page 110... ...
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.
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From page 111... ...
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.
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From page 112... ...
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.
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From page 113... ...
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.
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From page 114... ...
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.
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From page 115... ...
2000. See It Does Work: Rhode Island's Incident Management Experience.
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From page 116... ...
2001. Highway Traffic Operations and Freeway Management: State-of-the Practice Review.
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