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Current Issue | Previous Issues | Subscribe November 2003 - Vol. 1 No. 5

Policy & Planning

Civil engineering researcher publishes book: Financing Transportation Networks

Will toll roads ever be the norm and "free" roads a distant memory? This is the question assistant professor David Levinson of the Department of Civil Engineering asks in the introduction of his new book, Financing Transportation Networks.

Hybrid vehicles, alternative fuels, congestion, pollution, intelligent transportation systems, and the shift from construction to maintenance all call for a reconsideration of the existing highway revenue mechanisms, in particular, the gas tax. Levinson explores the fundamental theoretical basis of highway finance, focusing on the use of tolls, and supports that theory with empirical evidence. He examines highway finance from the perspective of individual jurisdictions and travelers, and considers their interactions, rather than specifying a single optimal solution.

Topics covered in the book include the historical rise and fall of turnpikes, the deployment of electronic toll collection, and why some states impose tolls while others rely more heavily on gas and other taxes. Levinson also develops frameworks for evaluating the effects of financing decisions and offers possible deployment scenarios that could lead to widespread adoption of road pricing.

Congestion pricing has long been a goal of transportation economists, who believe it will result in a more efficient use of resources. Levinson argues that if the governance were to become more decentralized and collection costs continue to drop, tolls could return to prominence as the preferred means of financing roads for both local and intercity travel. An approach that creates the "local winners" necessary to implement road pricing is required before it can be expected to become widespread, he cautions.

Levinson is involved in several research projects at the Intelligent Transportation Systems Institute within CTS. These include examining strategies for freeway ramp meter regulation, determining driver acceptance of ramp delays, forecasting travel behavior, and estimating the value of traveler information for motorists.

The book is based in part on Levinson's doctoral dissertation, "On Whom the Toll Falls," completed in 1998. To order a copy of the book, which is part of the Transport Economics, Management and Policy Series from Edward Elgar Publishing Limited, please e-mail info@e-elgar.co.uk, or visit Elgar's Web site at www.e-elgar.co.uk.

U researchers calculate how much freeway expansion is needed to address congestion woes

No matter how you look at it, moving Minnesota is getting tougher. More people, a lot more cars, and even more vehicle-miles traveled mean increasing delays on more of the metro freeway system. In a recently published report, University researchers have calculated that the freeway system will require at least a 70 percent expansion (or, an estimated 1,146 lane-miles) by 2020 to provide uncongested "free-flow" travel at a minimum level of service where movement is restricted and greater care is needed to drive safely.

While clogging transportation arteries around Minnesota may come as no surprise, figuring out just how bad it is and what to do about it is making the news. University civil engineering professor Gary A. Davis and graduate student Kate Sanderson presented their latest findings from research examining area congestion in a CTS research seminar on October 8 entitled "Building Our Way Out of Congestion?" In addition to a University classroom packed with fellow academics, transportation professionals, and policymakers, WCCO-TV news and the Star Tribune also covered the hour-long seminar based on research sponsored by the Minnesota Department of Transportation.

"A substantial fraction of the public thinks we ought to build more roads,"Davis observed, referencing several sources that suggest adding more capacity to area road networks is the best way to deal with traffic congestion. "Our question is, 'What would it take to build our way out of congestion?'"

To answer the question, Davis and Sanderson developed an algorithm to determine a minimal set of highway-capacity expansions necessary to accommodate future travel demand and guarantee mobility. Their model for accommodating future growth is based on projected travel demands for the year 2020 and does not factor in changes in travel behavior away from the use of single-occupant vehicles during peak times. Davis classified the modeling task as a "network design problem" and said that the problem of implementing formulations and solution algorithms for large-scale networks has challenged researchers for three decades.

The researchers focused their initial efforts on testing transportation networks in Sioux Falls, South Dakota, and in Waseca, Minnesota, before taking a crack at the much larger Twin Cities network. Despite using a supercomputer, computational difficulties with the large amount of data from the Twin Cities network eventually forced the team to develop an alternate approach, which involved incorporating their sequential linear expansion (SLIE) algorithm into the method of successive averages. In the end, Davis and Sanderson solved the large-scale problem on a personal computer. What’s more, their results using the alternative procedure were consistent with standard methods when applied to smaller-scale scenarios such as Sioux Falls and Waseca.

In concrete terms, the numbers add up to several more lanes in each direction at critical points on the metro freeway system—and that's just to meet minimally acceptable levels of service. Davis and Sanderson defined levels of service in terms of traffic speed and density, with free-flowing traffic being the ideal. They also presented several examples of where more lanes would be needed by 2020. For instance, where I-35E and I-94 meet in St. Paul near the state capitol—and near Mn/DOT's main offices, an additional eight eastbound lanes and six westbound would be needed. On I-94 northwest of the beltway, seven additional lanes in each direction would be needed.

During their presentation and the question-and-answer session that followed, both Davis and Sanderson stressed that their solution algorithm is simply a quantitative exercise and they declined to make policy recommendations for fixing traffic congestion. However, the pair suggested that future research could test the effect different transit ridership scenarios might have on the level of roadway capacity expansion needed. In addition, future research also might incorporate the solution algorithm into a standard travel-demand model.

Davis and Sanderson's report of their Mn/DOT-sponsored research, Building Our Way Out of Congestion? Highway Capacity for the Twin Cities, may be found online at: www.lrrb.gen.mn.us/pdf/200201.pdf.

Intelligent Transportation Systems

High-tech assistance for snowplow drivers

The difficult and sometimes dangerous task of clearing snow from roadways could become easier, thanks to a driver-assistive system developed by researchers at the ITS Institute. The system is described in a new Mn/DOT-published report, Driver Assistive Systems for Snowplows, by ITS Institute director Max Donath and Intelligent Vehicles Program director Craig Shankwitz.

Designed for plow operators working in near-zero conditions of blowing snow and winter darkness, the experimental system provides enhanced information about the world outside the cab.

The system's centerpiece is a custom designed head up display (HUD), similar to those used in military fighter aircraft. The HUD augments the driver's field of view by displaying lane lines, roadside features such as signs, and the locations of other vehicles on the road. Onboard computers combine information from multiple radar sensors and digital maps to produce the HUD display.

Behind the scenes, the system relies on an extremely accurate geospatial database of the plow route. A pair of high-accuracy Global Positioning System (GPS) receivers track the plow's location to within inches and compare this position with the database to generate a digital representation of objects which may be obscured by snow.

The researchers focus on providing effective, non-distracting assistance to drivers performing complex tasks is characteristic of several current ITS Institute research projects. Research is currently underway on developing similar technologies for bus drivers operating in narrow bus-only road shoulders, as well as other specialty vehicles such as highway patrol cars and ambulances that have to operate at high speeds in all weather conditions.

The report (Mn/DOT 2003-13) is available from the Minnesota Department of Transportation's Research Services Section Web site at www.research.dot.state.mn.us/detail.asp?productID=1849.

Abstracts sought for 2004 National Rural ITS Conference

Abstracts for presentations are due December 1 for the 2004 National Rural ITS Conference. ITS Minnesota is hosting the conference next August 22–24 in Duluth.

The goal of the conference is to equip professionals from all modes of non-urban transportation with tools and information to aid in the common goal of saving time, lives, and money, and to improve the quality of life with an economically feasible approach.

To learn more about the conference or to submit an abstract, please visit www.itsmn.org/ruralits2004/index.html, call Shirley Mueffelman at 612-624-4754, or e-mail smueffel@cce.umn.edu.

Transportation Infrastructure

Research on Mechanistic Properties of Asphalt Mixtures

University of Minnesota researchers have released a report on dynamic and resilient modulus testing of four standard Mn/DOT asphalt mixtures. Engineers hope that research of this kind will make complex modulus a standard design parameter in the mechanistic pavement design process, and lead to the ability to predict rutting and fatigue cracking in paved surfaces.

Dynamic and Resilient Modulus of Mn/DOT Asphalt Mixtures, by Mihai Marasteanu, Timothy Clyne, Xinjun Li, and Eugene Skok of the Department of Civil Engineering, covers tests carried out on pavement samples from the Mn/ROAD testing facility.

Their work was prompted by recommendations in the 2002 Guide for the Design of New and Rehabilitated Pavement Structures, currently under development by the National Cooperative Highway Research Program, that dynamic modulus serve as a design parameter and a simple performance test. The team used procedures specified in the 2002 Design Guide to test samples of four typical Minnesota pavement mixes at a variety of temperatures and frequencies.

The researchers' main objective generate master curves of modulus vs. frequency from the test data. They then compared the experimental master curves to modulus values obtained from two predictive equations proposed by 2002 Design Guide.

In two of the four cases, the researchers were able to obtain experimental modulus curves that corresponded well to the predicted values. However, their results indicated that sample preparation procedures have a significant impact on the results, so adherence to the Design Guide specifications is essential. In the other two cases, experimental results did not conform well to the predicted values, indicating a need for additional research.

The report (Mn/DOT 2003-09) is available from the Minnesota Department of Transportation's Research Services Section Web site at www.research.dot.state.mn.us or from the Minnesota Local Road Research Board (LRRB) Web site at www.lrrb.gen.mn.us/PDF/200309.pdf.

Transit & Alternative Modes

BRT Lane Assist Technology Systems final report released

Intelligent Transportation Systems Institute researchers have completed a final report on Lane Assist Technology Systems for Bus Rapid Transit (BRT). Published by the Federal Transit Administration (FTA-MN-26-7003), the report is now available for download in Acrobat/PDF format on the ITS Institute Web site at www.its.umn.edu/research/brt/index.html.

Volume I of the report evaluates lane-assist technologies in Europe and the United States, including the results of the earlier Lane Assist Requirements Survey. Volume II presents a pilot study of bus driver stress while using lane assist technology.

According to the FTA, "BRT combines the quality of rail transit and the flexibility of buses. It can operate on exclusive transitways, HOV lanes, expressways, or ordinary streets. One of the more likely candidate IVI applications to be initially implemented on BRT systems will be lane assist technology. The premise behind lane assist technology is to increase the safety of BRT vehicles as they operate in the more unique environments, such as narrow lanes. Lane assist technology will allow BRT vehicles to operate at the desired higher operating speeds while maintaining the safety of the passengers, BRT vehicle and the motoring public."

Issues associated with lane assist and precision docking systems are addressed in this report. Report specifics include: (1) the results of a study to determine US requirements for lane assist and precision docking systems, (2) a review of available lane assist and precision docking system technologies, (3) a comparison of lane assist and precision docking technologies based on system functionality, and (4) an assessment of these technologies with respect to national requirements. The report includes a comprehensive review of human factors issues associated with narrow lane usage, including a pilot study to assess driver response to a lane assist system.

TCRP research publications available online

The federal Transit Cooperative Research Program, 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. TRCP publications may be viewed at www4.trb.org/trb/crp.nsf.

Here are recent TCRP publications, with associated reference information and summary from the TRB Web site:

• Strategies for Improved Traveler Information (TCRP Research Report 92)
  
• Economic Benefits of Coordinating Human Service Transportation and Transit Services (TCRP Research Report 91)
  
• Bus Rapid Transit, Volume 1: Case Studies in Bus Rapid Transit (TCRP Research Report 90)
  
• Public Transportation Security Volume 4, Intrusion Detection for Public Transportation Facilities Handbook (TCRP Research Report 86)
  
• Yield to Bus--State of the Practice(TCRP Synthesis Report 49)
  
• Real-Time Bus Arrival Information Systems(TCRP Synthesis 48)
  
• Impact of the Americans with Disabilities Act on Transit Operations (TCRP Legal Research Digest 19)

Journal of Public Transportation

The Journal of Public Transportation, Volume 6, No. 3, 2003, published by the National Center for Transit Research at the University of South Florida, includes these articles, available at www.nctr.usf.edu:

• Bus Priority at Traffic Signals Evaluating Strategy Options
• Contract Areas and Service Quality Issues in Public Transit Provision: Some Thoughts on the European and Australian Context
• Pupil Fatalities on Public Transit Buses: A Comparison with School Buses
• Valuing Rider Quality in Swedish Special Transport Services New Findings
• Journeys to Crime: Assessing the Effects of a Light Rail Line on Crime in the Neighborhoods

Safety

"Amber Alert" program prompts research on Changeable Message Signs

Changeable message signs (CMSs--also known as variable message signs and dynamic message signs--were originally intended to warn motorists about traffic tie-ups and weather conditions. Today CMSs are being considered by the Minnesota Department of Transportation for the presentation of safety, law-enforcement, and travel-quality messages. And as part of a nationwide program, CMSs are now also used in the Amber Alert System to flash emergency alerts to motorists when a child is abducted.

All of these possible traffic-related and non-traffic-related uses of CMSs have raised a number of questions about their effectiveness and the safety impacts they may have on traffic. Human factors research associates Kathleen Harder and John Bloomfield, of the University's College of Architecture and Landscape Architecture, are attempting to answer several key questions Mn/DOT has raised regarding these issues.

Questions addressed in Harder and Bloomfield's work include:

• Should messages be presented on CMSs only when they are necessary, or should there always be some message on them?
• Do the messages presented on CMSs cause slowdowns?
• Do the messages on CMSs actually work?
• What is the impact of CMS messages on traffic flow?

Using a STISIM™ low-cost driving simulator with an automotive-style seat and three 17-inch CRT displays, Kathleen Harder and John Bloomfield of the University of Minnesota recently conducted two back-to-back experiments in which they examined how drivers responded to traffic-related and non-traffic-related messages. In one experiment, the team investigated the effectiveness of site-specific, time-critical messages; in the second, they focused on Amber Alert messages.

The research participants, 120 licensed drivers, "drove" along simulated highways while various CMS messages were presented. In both experiments, participants were asked to respond either by reacting to the CMS message or by reporting the message. Researchers recorded the accuracy of the participants' responses.

In the first experiment, more than half of the 120 participants followed the CMS instructions, which directed them to take an alternate exit due to a crash. But of those who did not follow the CMS instructions, nearly 40 percent ignored the CMS message either because they did not think it applied to them or because they did not understand it. Nearly a quarter of the participants who did not take the exit claimed they did not see the message.

While the results indicate that gender did not affect how a participant responded, the research team determined that age did have a statistically significant effect: the older the driver, the more likely he or she was to follow the directions presented on the CMS. But Harder and Bloomfield believe it is possible that prior exposure to other CMS messages affected the response to the exit message. In the experiment, participants who were not exposed to non-time-critical, non-site-specific CMS messages were more likely to take the alternate exit.

In the second experiment, the participants were assigned to one of four categories on the basis of their Amber recall scores: Poor, for participants who remembered nothing or responded with incorrect information; Fair, for those who remembered "Amber Alert" and some vehicle information; Good, for participants who remembered "Amber Alert," some vehicle information, and part of the license plate number; and Excellent, for those participants who recalled "Amber Alert," vehicle information, and five or six alphanumerics on the license plate. In the end, only 10 of 120 of the participants were in the Excellent category; 62 participants were in the Good category, 38 were in the Fair category, and 10 participants were in the Poor category.

Other findings revealed that neither the age of the participants nor prior exposure to non-time-critical, non-site-specific CMS messages affected the Amber recall scores. In contrast, gender did significantly affect the Amber recall scores--there were many more females than males in the Excellent category. Additionally, the results show that age has a significant effect on slowdowns associated with Amber Alerts. Older drivers (ages 55 to 65) were eight times more likely than younger drivers (ages 18 to 24) to slow down when presented with an Amber Alert message.

Based on these and other, findings, Harder and Bloomfield came up with a series of recommendations they believe will help increase the effectiveness of CMS messages, including Amber Alerts. First, the team suggests that the Minnesota Department of Public Safety increase its efforts to make the public more aware of the Amber Alert system. The researchers also recommend changing the Amber Alert messages themselves. Since the experiments show that it is particularly difficult for drivers to remember the license plate number flashed on a CMS, the Amber Alert messages should, instead, tell drivers to tune into an appropriate radio station, whose call sign will be easier to remember. Then, when drivers tune into that station, the full Amber Alert message, including the license plate number, should be repeated frequently. According to Harder and Bloomfield, this will greatly increase the likelihood that if a driver encounters the vehicle mentioned on the Amber Alert he or she will be able to recognize it. This also will likely result in fewer slowdowns than occurred in the experiment.

Their other recommendations include changing the crash-related CMS messages to say "ROAD CLOSED," which should greatly increase the number of drivers who take the exit, or "LANE CLOSED," so that the information is conveyed more clearly to drivers, allowing them to make an informed choice about whether or not to stay on the freeway. Harder will present these research results at an ITS Institute Advanced Transportation Technologies Seminar on December 2.

Upcoming Events

Visit the CTS web site www.cts.umn.edu for more comprehensive event information.

November 7
New Transportation Systems Based on Cybernetic Vehicles, ITS Institute Seminar, U of M East Bank. View more information.

November 10
Rethinking Transportation Finance Roundtable: How Should Transportation Be Funded in the Future? Minnesota History Center, St. Paul. View more information.

November 12
Mechanistic-Empirical 2002 Guide for Design of Minnesota Low-Volume Roads: The Future of Pavement Design is Here! (almost), CTS Research Seminar. U of M East Bank campus. View more information.

November 18
Adaptive Modulation for Bandwidth and Power Efficient Transmission Over Wireless Links, Advanced Transportation Technologies Seminar Series. View more information.

December 2
The Effectiveness and Safety of Traffic and Non-Traffic Related Messages Presented on Changeable Message Signs, Advanced Transportation Technologies Seminar Series. View more information.

December 5
CTS Annual Freight and Logistics Symposium, Four Points Sheraton Hotel, Minneapolis. Contact Shirley Mueffelman, 612-624-4754, smueffel@cce.umn.edu.

February 18, 2004
CTS Winter Luncheon, Minneapolis.

February 19, 2004
Minnesota Pavement Conference, Earle Brown Center, St. Paul. Contact Teresa Washington, 612-624-3745, twashing@cce.umn.edu.

March 3, 2004
Transportation Career Expo, Coffman Union, Minneapolis. Contact Mindy Carlson, 612-625-1813, carlson@cts.umn.edu.

May 4-5, 2004
15th Annual CTS Transportation Research Conference, RiverCentre, St. Paul. To learn more and submit abstracts online, please visit www.cts.umn.edu/events/rescon. You may also call Shirley Mueffelman at 612-624-4754 for more information.