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November 2009 – Vol. 7, No. 10

Policy & Planning

Policy and technology of automated traffic enforcement

Automated enforcement of red-light running and speeding remains both a controversial public policy issue and an area of rapid technological development. A new report by University of Minnesota researchers John Adams and Barbara VanDrasek, sponsored by the University Metropolitan Consortium, reviews current legal and technological issues in the United States and around the world, focusing on implications for Minnesota.

The installation of cameras at intersections to record the license plates of red-light violators has prompted heated debate about the limits of government surveillance of citizens. The report reviews the history of automated enforcement in Minneapolis, where red-light cameras were installed at numerous intersections during 2005 and 2006; the program was halted after the state supreme court ruled that the city lacked legal authority to implement automated enforcement of traffic laws.

Speed limit enforcement is covered in a series of case studies highlighting successful speed enforcement programs.

The report also discusses issues related to automated enforcement in a variety of jurisdictions across the United States where differing political cultures have led to approval or rejection of automated enforcement programs. Local attitudes and values, the authors note, play an important role in the implementation of automated enforcement systems.

Debates over automated enforcement are also discussed, including the issue of promoting safety vs. raising revenue, the reliability of enforcement technologies, and appropriate procedures for using automated enforcement. Legal issues related to automated traffic enforcement are summarized in a series of appendices to the report.

Automated Enforcement of Red-Light Running & Speeding Laws in Minnesota: Bridging Technology and Public Policy (CTS 09-26) is available from the CTS Web site.

Intelligent Transportation Systems

Second-generation geospatial database to enable ITS applications

The University of Minnesota’s Intelligent Vehicles (IV) Laboratory, part of the Intelligent Transportation Systems Institute, has developed a new version of its geospatial database software. The newly optimized database brings the benefits of real-time access to extremely accurate and dense geospatial data to a wider variety of ITS applications. The new system was developed by IV Lab researchers Bryan Newstrom and Curtis Olson, who documented the process in a recently published report; lab director Craig Shankwitz served as principal investigator on the project.

The database was initially designed and optimized for in-vehicle applications, and is a cornerstone of the driver-assistive systems developed by IV Lab researchers and deployed on a variety of vehicles including transit buses, snowplows, and emergency vehicles. These systems integrate locational data from the database with advanced obstacle-detection sensors and driver-interface technologies, enabling drivers to operate safely in extremely low visibility conditions.

In addition to vehicle systems, the database has proved useful in a variety of other applications, including the ITS Institute’s Intersection Decision Support system, where it improves the ability of a radar system to determine whether an approaching vehicle represents a hazard to stopped vehicles waiting to enter an unsignalized intersection. The database is also being used in driving simulators to provide realistic driving environments.

To meet the needs of this and other new applications, IV Lab researchers took a global approach to the database redesign and developed a new front end component capable of serving a broad application base. The data model of the new database better matches the physical characteristics of road environments and conforms to open Geographic Information Systems (GIS) standards. To support real-time simulation and visualization, the researchers created a process to merge and transform 2D and 3D GIS datasets into a 3D simulator database; in the process, they also identified areas for improvement in the mapping process and in the algorithms for data merging.

Multiuse, High Accuracy, High Density Geospatial Database (CTS 09-05) is available from the ITS Institute Web site.

Transportation and the Environment

Researchers seek efficient methods to find noxious weeds

Locating certain invasive weed species in roadway rights-of-way in order to eradicate them can be accomplished using relatively simple presence/absence survey techniques, according to a recent study by University of Minnesota researchers. Caleb Arika and John Nieber of the bioproducts and biosystems engineering department, Donald Wyse of the agronomy and plant genetics department, and Roger Moon of entomology collaborated on the study, which was supported by the Minnesota Department of Transportation.

By law, the task of controlling noxious weeds along highway rights-of-way falls to state departments of transportation and local government agencies. The study sought to identify the most efficient and cost-effective sampling methodology for surveyors, taking into account travel times to reach sampling sites as well as associated sampling tasks. Using efficient sampling and eradication methods can reduce the costs of weed control along highways, a significant expense for the agencies reponsible.

According to the researchers’ final report, the presence/absence survey methods evaluated in this study are not suitable for estimating weed infestation densities due to the high estimation variances it produces. However, if a sufficiently large number of sampling sites are used, the technique can be a cost-effective option for detecting rare invasive species in rights-of-way.

Implementation of Methodology for Weed Management Practices – Phase II (Mn/DOT 2009-28) is available from the CTS Web site.

Transit, Bicyling, and Walking

Transitway impacts highlighted in research briefs

University of Minnesota researchers have completed a pair of studies examining the economic and behavioral impacts of the Hiawatha light-rail transitway in Minneapolis. Research briefs highlighting findings from the study are now available, and will soon be followed by full research reports. The research, part of the CTS Transitway Impacts Research Program (TIRP), was conducted by Edward Goetz and Jeff Mattson of the Center for Urban and Regional Affairs and by Jason Cao of the Hubert Humphrey Institute of Public Affairs.

The Hiawatha Light-Rail Transit Line, completed in 2004, connects downtown Minneapolis and its southern suburbs. Since its opening, the service has proven extremely popular with commuters; the most recent regional transportation plan identifies several potential transit corridors in the Twin Cities metropolitan area, and planning for an additional east-west line linking Minneapolis and downtown St. Paul is now underway. In this context, thorough analysis of the effects of the Hiawatha Line is seen as essential to future transit planning.

Cao’s component of the study focused on the demographic and behavioral differences between transitway riders and other transit riders in the Twin Cities area. Among the issues explored were: differences between “choice” riders (those who choose to use transit rather than driving their own cars) and “captive” riders who have no other mode option; ways of accessing the transitway (including park-and-ride lots and pedestrian access); and the residential locations of transitway riders.

Goetz and Mattson, by contrast, examined the economic impacts of the transitway. The researchers found that the transitway has increased the values of both single-family and multi-family residential properties in surrounding areas, and estimate that the total residential property value increase has been in excess of $47 million. In addition, the transitway has spurred new housing construction in the nearby area relative to a control area.

Support for the research was provided by CTS, the Metropolitan Council, the University Metropolitan Consortium, Mn/DOT, and the counties of Anoka, Hennepin, Ramsey, and Washington through the Transitway Impacts Research Program; other TIRP partners include the cities of Minneapolis and St. Paul, the Itasca Project, and Dakota County.

Demographic and Behavioral Differences between Hiawatha Light-Rail and Other Transit Riders [164 KB PDF] and The Hiawatha Line: Impacts on Land Use and Residential Housing Value [186 KB PDF] are available from the CTS Web site.

Transportation Infrastructure

Recycled materials: How do they measure up?

The high cost associated with using virgin aggregate materials for roadway construction can be significantly reduced by using recycled materials in the base and subbase layers. State and federal agencies are now encouraging the use of these materials, but a thorough understanding of their hydraulic and mechanical properties is necessary if they are to be used successfully. Satish Gupta, Dong Hee Kang, and Andry Ranaivoson of the University of Minnesota’s Department of Soil, Water, and Climate studied several materials to determine their suitability for road construction. Their research was funded by the Minnesota Local Road Research Board.

Materials tested in the project included reclaimed asphalt pavement, fly ash, reclaimed concrete material, and foundry sand. The recycled materials were mixed with virgin aggregates in various proportions to produce 17 different test mixes, which were compared with a sample of 100 percent virgin aggregate.

The materials were subjected to a variety of laboratory tests to determine water retention or pore size distribution curves, saturated and unsaturated hydraulic conductivities, resilient modulus (MR) at optimal water content and water content corresponding to 300 kPa suction, shear strength at optimal water content and water content corresponding to 300 kPa suction, and leaching characteristics under both saturated and unsaturated conditions.

Based on the results of their tests, the researchers concluded that fly ash, recycled asphalt, and recycled concrete mixtures could serve as acceptable substitutes for virgin aggregates in road construction; foundry sand, the fourth substance tested, may not be suitable for subgrade use due to its less than optimal hydraulic properties. However, the researchers note that additional testing of the materials will be necessary before the findings can be implemented.

Hydraulic and Mechanical Properties of Recycled Materials (Mn/DOT 2009-32) is available on the CTS Web site.

Upcoming Events

November 23
Martin Olav Sabo Lecture Series - Performance Driven: A New Vision for U.S. Transportation Policy, Cowles Auditorium, 8:30 a.m. - 1:30 p.m.

December 3
CTS Seminar Series: Novel Battery-Less Wireless Sensor for Traffic Flow Measurement, 3:30 p.m. – 4:30 p.m., 1130 Mechanical Engineering

December 4
2009 Freight and Logistics Symposium, Ramada Plaza Hotel, Minneapolis

February 11, 2010
14th Annual Minnesota Pavement Conference, Continuing Education and Conference Center, Saint Paul