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Current Issue | Previous Issues | Subscribe November 2006 - Vol. 4 No. 10

Policy & Planning

Second Access to Destinations conference announced; call for papers issued

Researchers from all disciplines with an interest in transportation, land use, and public policy are invited to the University of Minnesota August 23 and 24, 2007, for the second Access to Destinations Conference. A call for papers has been issued by the conference organizers, with the goal of attracting submissions from a variety of disciplines as well as interdisciplinary projects.

In November 2004, the Center for Transportation Studies at the University of Minnesota hosted "Access to Destinations," a conference featuring more than 25 invited papers and 75 attendees. This international conference resulted in a set of proceedings and a book containing select papers. More information is available on the Access to Destinations Web site.

Building on the success of the 2004 conference, the Center for Transportation Studies at the University of Minnesota is sponsoring a follow-up two-day conference with a similar theme: "Access to Destinations."

Issues that this conference seeks to address include:

• The relationship between transportation services, the location of activities, and the ability of individuals to access destinations including work, education, medical care, shopping, and recreation.
• The factors influencing the location decisions made by households and organizations and the investment and service provision decisions made by public agencies and private firms.
• The effectiveness of policies, including land development strategies, zoning, and neighborhood designs, in affecting accessibility.

This two-day conference is scheduled for August 23 and 24, 2007, on the University of Minnesota campus. It will feature a half-day of presentations and discussions open to the public, followed by a day-and-a-half of presentations and discussions with approximately 75 invited-only participants and researchers. The meeting will be launched by commissioned papers from select international researchers addressing various issues related to accessibility, land use, and transportation. These leading researchers will also serve as rapporteurs to vet papers received from this call.

Additional manuscripts are being solicited through this call for abstracts to be presented during the invited-only sessions.

Submission guidelines

Researchers with an interest in accessibility are invited to submit abstracts for consideration. Accessibility is traditionally defined as the ease with which destinations (customers, suppliers, activities) can be reached, but this can be operationalized in many ways: for different travelers, to different destinations, using different means of travel, and incorporating different measures of travel quality.

Papers breaking new ground or illustrating the state of the art in applications and empirical research, or theoretical or methodological aspects of accessibility research, are particularly welcome. The organizers strongly encourage multidisciplinary approaches.

Abstracts (approximately 1,000 words) are due February 7, 2007 to David Levinson: dlevinson@umn.edu.

Authors of selected abstracts will be invited to submit a full paper of approximately 5,000–7,500 words. The paper will be due in electronic format by June 1, 2007, and will be distributed to other conference presenters as well as to participants.

The 2004 Access to Destinations Conference resulted in a peer-reviewed book published by Elsevier showcasing several works from the meeting. We again anticipate publication of selected articles from this conference in a bound volume or journal special issue.

Limited funds are available to reimburse expenses of some presenters; please submit this request with your abstract.

Business as usual? Research looks at options for the future of transportation networks

"You can’t always get what you want—but if you try sometimes, you get what you need." The Rolling Stones may not have had transportation planning in mind when they penned their hit single, but the sentiment might strike a chord with planners puzzling over how best to preserve the public investment in transportation infrastructure and meet the needs of the future. To help answer that question, University of Minnesota civil engineering professor David Levinson has worked with the Minnesota Department of Transportation (Mn/DOT) on systematic analysis of alternative scenarios for the future of the Minneapolis-St. Paul metropolitan highway network.

Continuing previous research on the development of Minnesota highway networks, Levinson worked with graduate students Feng Xie and Norah Montes de Oca to model likely patterns of new construction and link expansion under a variety of investment and decision-making strategies. Their findings are presented in a new research report titled Beyond Business as Usual: Ensuring the Network We Want Is the Network We Get.

In previous research funded by Mn/DOT, Levinson led a team that reviewed historical data and developed empirical models to describe observed network growth, incorporating a variety of factors including travel demand, demographic characteristics, and budget constraints. The new research aims to answer three major questions about the future implications of historical and proposed strategies:

1. Will a “business as usual” approach (in which planning and investment are guided by observed historical trends) produce networks that meet future needs?
2. Will the adoption of new decision-making strategies produce better networks?
3. How can observed patterns of network expansion be harnessed to achieve planning goals?

At the heart of this research is the second generation System of Network Growth (SONG 2) model, developed by the research team. The structure of the model reflects decision-making processes mapped out through interviews with employees of Mn/DOT, county and state government, and the Twin Cities regional planning organization.

Like other transportation planning models, SONG 2 starts with data on initial network conditions, population demographics, land use characteristics, and model parameters. The model includes a travel demand component that generates patterns of travel and measures of system effectiveness; these data serve as inputs to the model’s investment component, which uses budget parameters and decision rules to prioritize the construction and expansion of network links.

An important feature of SONG 2, say the researchers, is that changes in the transportation network—the results of investment decisions—are reincorporated into the model. As the shape and capacity of the network evolves, these changes in turn affect the future options available as the model seeks to optimize network performance using available resources.

Levinson’s research team used SONG 2 to evaluate a range of scenarios for future network management. The “business as usual” approach, in which decision-making was governed by current trends and processes, served as a baseline condition. Other scenarios tested the effects of region-wide adoption of different sets of decision rules governing investment, and increasing or decreasing budget allocations.

In the final analysis, greater investment in the transportation system proved to have the most profound impacts on performance, while different decision-making strategies produced marginal changes in comparison. However, developing the model revealed important findings about how transportation planning works in the complicated context of regional growth and governance.

Beyond Business as Usual: Ensuring the Network We Want Is the Network We Get (Mn/DOT 2006-36) is available from the CTS Web site.

Hybrids: hype or hope?

Record oil prices over the past few years have prompted a renewed interest in alternatives for cheaper energy. According to University applied economics professor Alfred Marcus, hybrid vehicles offer an opportunity to greatly reduce oil consumption, but the technology alone will not provide a suitable solution.

"Technological innovations are critical for solving our energy problems," Marcus explained, "but they are just a means to an end. What we're really trying to do is solve energy problems. We have to use in this society less carbon-based energy for a variety of very important reasons."

Marcus, describing his hybrids research at a September meeting of the CTS Transportation and the Economy Research Council, identified the main reasons for addressing our growing energy problems. These include concerns for the environment, the economy, and national security. His presentation, titled "Hybrids: Hype or Hope?" was part of the CTS Research Seminar Series for students, faculty, and practitioners about transportation research at the University of Minnesota.

In Marcus's view, national energy policy and consumer behavior figure more into the solution than any specific technology. In particular, gains made as the result of technological innovation have been foiled by increased consumption. The real challenge, he said, is to lower consumption without lowering the utility derived from transportation.

"Hybrids give us the illusion that we have attacked and achieved something with regard to this issue with less reliance on carbon-based energy," he said.

Applying the "snapback" theory of consumer psychology, though, Marcus likened hybrid vehicles to low-calorie foods, to which dieters often respond by eating more because the calories don't add up so fast. Similarly, the improved energy efficiency and lower operating costs derived from hybrid technology have prompted consumers to drive more miles and drive more large vehicles, thus diluting the benefits of these improvements. The same snapback dynamic appears to be at issue, too, when drivers exploit new technologies by taking more risks like choosing not to wear safety belts or speeding on rural roads, Marcus added.

Marcus described the two basic types of hybrids. One is a "mild" hybrid for which the primary engine is gasoline and an electric motor is used for hills, acceleration, and high-demand situations. A "full hybrid," technology that is owned exclusively by Toyota, uses an electric engine for low speeds and gas for highway driving and acceleration. The greater efficiency of hybrids is due to three major features: regenerative braking, which captures, stores, and converts energy from deceleration that is wasted in conventional vehicles; automatic start and shutoff, which prevents idling waste; and the use of lighter materials.

Still, Marcus pointed out that hybrids, although 45 percent efficient compared with conventional vehicles at 25 percent, account for a lot of wasted energy. In addition, whether they are really worth the investment yet depends on the specific situation of each buyer. Marcus illustrated through a variety of feature and price comparisons that payback is modest when comparing models in different classes. For instance, if gas costs $5 per gallon, switching from a Toyota Corolla to a Prius would take nine years to recover the extra initial cost. However, switching from a Camry to a Prius would yield almost immediate savings.

"I personally really like the technology and I don't currently drive one," Marcus said. "But when I purchase my next car, I would buy the hybrid."

But the most important factor for reducing consumption of carbon-based energy, Marcus stressed, is changing the mindset of consumers to favor smaller vehicles. To accomplish that, he said, supportive public policies are necessary. While higher gas taxes and changes to the Clean Air Act mandating higher fuel efficiency standards may be untenable, Marcus proposed what he felt are more viable options, including a new government agency, grants and subsidies, and investments.

Safety & Security

Robotics center receives federal grant for transportation security research

The University's Center for Distributed Robotics, led by CTS Faculty Scholar Nikolaos Papanikolopoulos, was awarded $1.95 million in the 2007 Defense Appropriations Bill. The funding was secured by Congressman Martin Sabo to advance the center's robot technology and its transportation security applications.

The robotics center is closely coordinated with SECTTRA—Security in Transportation Technology Research and Applications—a joint program of the Department of Computer Science and Engineering (CSE) and CTS established earlier this year. Papanikolopoulos, a CSE professor, is SECTTRA's director. SECTTRA's mission is to earn recognition for the University of Minnesota as a world leader in the development and application of technologies for transportation security.

"This support will take our transportation security research leadership to a new level of national importance," says Robert Johns, CTS director.

The robotics center is developing transportation security technology that can be used in many ways. For example, it responded to the U.S. military's need for a small, throwable robot for urban warfare situations. The remote-controlled, four-inch "scout robot" is especially useful as U.S. forces secure buildings, caves, tunnels, and underground bunkers in urban combat situations, particularly in Iraq.

This robot is significantly less expensive than similar technology in use, and could also be used by search/rescue teams, firefighters, and SWAT teams.

Advancements in the robot technology will also be used by the University to enhance transportation security technologies for monitoring transit stations, airports, and other critical infrastructure.

The scout robot is featured in the University's Driven to Discover^SM promotional campaign, a two-year initiative designed to communicate how University researchers have changed life for the better for people all over the world—and continue to do so every day. The campaign includes print, radio, and TV ads; signs and posters; and other materials.

As part of the campaign, a video featuring Papanikolopoulos was aired during halftime of a recent Minnesota Gophers football game. More information about transportation security research is on the SECTTRA Web site.

Intelligent Transportation Systems

Toward scalable and privacy-aware location-based services in transportation

If you have ever wondered how far it was to the nearest gas station, struggled to remember which neighborhood grocery store was open late, or wandered through an unfamiliar area in search of that new restaurant, then you have an interest in location-based information. For centuries, signs have been the primary means of communicating this kind of information; today, however, explosive growth in personal electronic devices, wireless electronic communications, and geographic information systems (GIS) is driving the rapid development of new kinds of location-based services.

Providing location-based services to meet this growing worldwide demand, while ensuring that users’ identities and personal information are protected from prying eyes, is the goal of research by Mohamed Mokbel of the Department of Computer Science and Engineering. Mokbel presented his ongoing work in an Advanced Transportation Technologies Seminar sponsored by the ITS Institute October 24, 2006.

As the required technologies continue to mature, Mokbel foresees the potential for location-based services to penetrate every aspect of life. However, he says, two important challenges must be overcome in order for this potential to be realized.

The first challenge is in the area of privacy. Recent news reports of Global Positioning System (GPS) receivers being surreptitiously used to spy on victims point out the potential for location-aware technologies to enable privacy violations. True location-based services, incorporating users’ personal information to drive information retrieval, present even greater potential for abuse. At present, location-based services adhere to a model in which users give up privacy in order to gain access to information; for example, a user may agree to let the service provider know her exact physical location in order to receive information about nearby travel routes.

In order for users of location-based systems to receive accurate information while at the same time preserving their anonymity and masking their exact coordinates, a new technology must be added to the mix. Mokbel described the operation of CASPER, a “location anonymizer” developed during his research, which acts as a trusted third party between the end user and the location-aware information provider. CASPER enables users to define privacy profiles that control how much information service providers receive about them.

CASPER “blurs” users’ private information in two ways. First, users can stipulate that their information must be hidden within a group of other users, with the size of the group controlled by the user; for example, users may specify that their transmitted location must include at least ten other users. Second, users can define a spatial boundary on their exact position, such as a radius of half a mile. By using these two methods together, it is possible for users to develop a variety of profiles suitable for different situations.

Mokbel described how location anonymizers such as CASPER would be embedded within location-based database servers, enabling such systems to process queries based on blurred spatial regions rather than exact positional information. He went on to describe an algorithmic approach to such a query, along with mathematical proofs of its correctness. He then demonstrated a prototype system in operation using geospatial data on the Minneapolis area.

The second major issue holding back the development of location-based services—scalability—was the subject of the remainder of Mokbel’s presentation. He argued that the traditional “snapshot” approach to database queries, in which a new query is issued every time data must be updated, is inadequate to the demands of location-based systems that require continuous updates. Instead, he proposed an incremental query model in which results are continuously updated with new data. In order to support this model, he explained, database architecture for location-based systems must move from a layered approach (with location-based systems built on top of GIS on top of data storage) to an integrated approach in which location-based query processing is a part of the database itself.

Another important aspect of Mokbel’s proposed architecture is shared execution. Instead of each query being handled by an individual “thread” of program execution, shared execution enables a single thread to handle multiple continuous queries, thus reducing computational overhead.

These principles are implemented in Mokbel’s location-based data server, dubbed PLACE for Pervasive Location-Aware Computing Environments. Working together, PLACE and CASPER form a backbone for future location-based services that are both highly scalable and capable of ensuring the privacy and anonymity of users.

Mokbel closed his presentation with an invitation for researchers to attend an international workshop on privacy-aware location-based services, to be held in conjunction with the Eighth International Conference on Mobile Data Management in Mannheim, Germany, May 7–11, 2007.

Transportation Infrastructure

Michael Darter is new PRI director

The Pavement Research Institute (PRI), a joint program of the Department of Civil Engineering (CE) and CTS, has a new director.

Michael I. Darter, Ph.D., P.E., is Emeritus Professor of Civil and Environmental Engineering at the University of Illinois and principal engineer with Applied Research Associates (ARA), Inc. Darter has been involved in pavement engineering throughout his entire 40-year career and is an internationally recognized authority in highway and airport infrastructure.

“Through his extensive work in research, teaching, and consulting, Professor Darter has contributed significant new knowledge and many widely used engineering tools,” says Robert Johns, CTS director.

Darter will have a 25 percent appointment while continuing his work with ARA, says John Gulliver, CE department head.

Darter succeeds Erland Lukanen, who accepted a position in Mn/DOT’s Office of Materials.

For more about the PRI, please visit www.pri.umn.edu.

New bridge prefabrication techniques benefit from study

In the tug-of-war between "do it fast" and "make it last," Minnesota engineers are looking with interest at a new design for prefabricated concrete bridges. Developed by the Minnesota Department of Transportation (Mn/DOT) based on techniques popularized in Europe, the design is the subject of research by University of Minnesota civil engineering professors Catherine French and Carol Shield and graduate student Charles Bell II.

Construction or replacement of a concrete bridge generally entails significant traffic disruption. Designs that use precast components offer the potential for time savings, as the time-consuming tasks of building formwork, placing steel reinforcements, and curing poured concrete are eliminated. But durability problems have long been the bane of prefabricated bridges. The repair and maintenance costs associated with issues such as longitudinal reflective cracking have largely offset the perceived benefits of rapid construction.

A new research report by French, Shield, and Bell, highlighting numerous engineering issues relevant to precast concrete bridge construction and the describing the researchers’ ongoing study of a new precast bridge in Minnesota, has been published by Mn/DOT.

In search of a combination of fast construction and structural durability, the Federal Highway Administration (FHWA) and the American Association of State Highway and Transportation Officials (AASHTO) initiated a research tour of Europe and Japan for American engineers to review state-of-the-art techniques for rapid construction. Following the tour, Mn/DOT began to develop its new prefabricated design based on a system used in France.

The "Poutre-Dalle" system, as it is known in France, is based on inverted-T precast concrete members placed adjacent to one another and topped with cast-in-place (CIP) concrete. The shape of the precast members simplifies the CIP installation by serving simultaneously as formwork and as a working surface for the placement of reinforcing bars.

Mn/DOT modified the original French design to increase its overall durability and performance and to make it easier to construct. The potential for reflective cracking was one of the Minnesota engineers’ chief concerns; this was addressed by adding reinforcements and modifying the design of the precast sections. Adequate continuity of the superstructure system was also ensured through conventional deck reinforcements and concrete between adjacent precast sections.

To study the new design in action, the university researchers designed a system of instrumentation that has been installed in a new bridge constructed in Center City, Minnesota. The bridge will be closely monitored over a two-year study period, with testing to include measurements with weighted test trucks.

The researchers are hopeful that a full analysis of field data will enable them to recommend future directions for the development of the new prefabricated design. For Minnesota travelers, the payoff will come in the form of new bridges that are quick to build and as durable as their traditional counterparts.

Application of Precast Decks and Other Elements to Bridge Structures (Mn/DOT 2006-37) is available from the CTS Web site.

Transit & Alternative Modes

TCRP research publications available online

The federal Transit Cooperative Research Program (TCRP), administered by the Transportation Research Board, provides practical transit research to address technical and operational issues. TCRP emphasizes putting research results into the hands of organizations and individuals that can use them to solve problems. TCRP publications may be viewed at www4.trb.org/trb/onlinepubs.nsf/web/crp.

Recent TCRP publications include:

• Guidebook for Evaluating, Selecting, and Implementing Suburban Transit Services (TCRP Report 116)
• HOV Facilities -- Traveler Response to Transportation System Changes (TCRP Report 95, Chapter 2)
• Commuting in America III (Joint NCHRP and TCRP project)
• Design of Track Transitions (TCRP Research Results Digest 79)
• Managing Capital Costs of Major Federally Funded Public Transportation Projects (TCRP Research Results Digest 78)
• The Case for Searches on Public Transportation (TCRP Legal Research Digest 22)

Upcoming Events

Here are selected events related to transportation research. Visit the CTS Web site, www.cts.umn.edu/events, for more comprehensive event information. You may also subscribe to e-mail event announcements using our subscription form.

November 29, 2006
"At 50: Economic Issues Facing an Aging Interstate System," Minneapolis, Minnesota. Contact Stephanie Malinoff, 612-624-8398, malinoff@umn.edu.

December 1, 2006
Freight and Logistics Symposium, Minneapolis, Minnesota. Contact Electra Sylva, 612-624-3708, conferences5@cce.umn.edu. [More]

December 5, 2006
Advanced Transportation Technologies Fall Seminar: VII Communications, Minneapolis, Minnesota. Contact Stephanie Malinoff, 612-624-8398, malinoff@umn.edu. [More]

February 8, 2007
CTS Winter Luncheon with Bruce Simons-Morton, Minneapolis, Minnesota. Contact Electra Sylva, 612-624-3708, conferences5@cce.umn.edu.

March 1, 2007
Transportation Career Expo, Minneapolis. Contact Mindy Carlson, 612-625-1813, carlson@cts.umn.edu.

May 1-2, 2007
18th Annual CTS Transportation Research Conference, RiverCentre, St. Paul. Contact Electra Sylva, 612-624-3708, conferences5@cce.umn.edu.