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Current Issue | Previous Issues | Subscribe February 2004 - Vol. 2 No. 2

Policy & Planning

Understanding highway network growth

The development of a metropolitan highway network poses difficult questions for planners. By studying the history of the Twin Cities’ freeway network, civil engineering researchers at the University of Minnesota are building a more complete understanding of transportation network growth, and laying the foundation for more informed planning decisions.

To manage highway network growth effectively, planners must respond to changing patterns of population growth and employment, while at the same time trying to influence how these patterns will evolve in the future. Every decision to add capacity, build new roads, or maintain the status quo is constrained by choices made in the past; likewise, planners are aware that their decisions today may cast a long shadow over future plans.

Assistant professor David Levinson and graduate students Ramachandra Karamalaputi and Wei Chen model the Twin Cities’ freeways as a network made up of discrete links, or highway segments. Using two decades of data on physical attributes of the network, construction, and traffic levels, the researchers develop detailed models of link expansion and network growth. A non-linear cost model of highway construction in the Twin Cities also emerges.

The researchers also consider the development of the freeway network at the area level, using detailed GIS data from 1958 to 1990 and logit modeling to predict network growth in the Twin Cities. Correlating network growth with specific conditions of land use, population distribution, and industrial development provides insights into the effects of surrounding land use on highway construction and improvement.

Among the broad issues explored in this research are phenomena of induced supply (high demand triggering expansion of network capacity) and induced or latent demand (construction of new links or increases in capacity leading to higher use levels).

The researchers hope that a better understanding of long-term network dynamics will enable planners to make better decisions about how to invest scarce resources, and help policymakers understand the implications of public policy decisions. If They Come, Will You Build It? (Mn/DOT 2003-37) is available in PDF format at www.lrrb.gen.mn.us/pdf/200337.pdf.

Transportation planning options for urban redevelopment

Due to various periods of urban development and change, the St. Paul Central Corridor is currently a hodge-podge district without an integrative vision. Researchers from the University of Minnesota developed a study in order to devise design approaches that would create a district that integrates light industrial job creation and retention along the Pierce Butler route in St. Paul.

The St. Paul Central Corridor Study: Pierce Butler Industrial Redevelopment Parkway, written by lead researchers Lance Neckar, James Pettinari, and Mary Vogel of the Landscape Architecture Department, outlines the proposed planning and design approaches. One of the main focuses of the district is the creation of a permanent, value-added public open space armature, which is designed to perform multiple functions and be adaptable to changes in employment strategies over time. The method for creating the armature that the researchers propose is to redevelop contaminated brownfields while establishing a permanent public recreational greenway.

Another objective of the proposed district would be to reroute trucks to nearby streets in order to improve the surrounding neighborhood livability. Doing so would reduce safety concerns, noise, and air pollution in the residential areas within close proximity.

Overall, the researchers suggest that the redevelopment district could achieve several significant goals, including neighborhood stabilization, job creation and diversification, reduced truck traffic in neighborhoods, pedestrian environment enhancement, transit-oriented infill along critical bus routes and the rail corridor, and integrated truck and rail connections. The research team will work in conjunction with public policymakers and planners to guide future development of the corridor so that ideally, the vision described in the research report can become a reality.

The St. Paul Central Corridor Study: Pierce Butler Industrial Redevelopment Parkway (CTS 03-08) is available in PDF format at www.cts.umn.edu/pdf/CTS-03-08.pdf.

Intelligent Transportation Systems

UMD's transportation program holds second annual research event

The Northland Advanced Transportation Systems Research Laboratories (NATSRL) held its second annual Research Day November 13 at Mn/DOT District 1 Headquarters in Duluth. A large crowd of faculty, students, transportation engineers, and others attended the day-long event. NATSRL, located at the University of Minnesota Duluth, is a program of UMD and the Intelligent Transportation Systems (ITS) Institute at CTS.

Research posters were a new feature this year. Twelve project teams presented detailed updates on their research efforts. Many of the students who are involved in the program presented the updates and answered questions on their specific roles in the projects, along with the status of their findings.

Dr. Martha Wilson of Mechanical and Industrial Engineering described her snowplow operations modeling project. Please see our previous article in the February 2003 CTS Research E-News for more details about her project.

Dr. Taek Kwon of Electrical and Computer Engineering gave a synopsis of his work on archiving and accessing large volumes of data from Mn/DOT’s roadway sensors.

Brian Brashaw, a timber and forestry specialist from UMD’s Natural Resources Research Institute (NRRI), showed a video on the implementation of his research in non-intrusive means of performing inspections on timber bridges, which is being used across rural areas in both Minnesota and Wisconsin.

Drs. Mohammed Hasan and Fernando Rios-Gutierrez from the Electrical and Computer Engineering Department discussed their analysis of a sensor in surveying and detecting pavement conditions when ice/snow is present.

Dr. Ryan Rosandich from the Mechanical and Industrial Engineering Department gave a brief report on his initial work in developing a model to evaluate and quantify the risk in transportation construction project schedules.

David Hopstock, working with Larry Zanko from NRRI, gave an overview of the possibilities of using taconite as a source of road aggregate material for use in deicing and pothole patching applications.

Adding to the success of the event, Roberta Dwyer, Mn/DOT District 1 Engineering project manager, presented an update on Mn/DOT’s research agenda, tying the efforts in progress under NATSRL to current needs and applications within Minnesota’s state transportation program.

More information on the Northland Advanced Transportation Systems Research Laboratories can be found on the NATSRL Web site at www.d.umn.edu/natsrl/.

Transportation Infrastructure

Composite materials show promise for steel bridge repair

Composite materials have been used extensively in aerospace, automotive, and mechanical applications where light weight and high strength are required. One high-tech composite, carbon-fiber reinforced polymer (CFRP), is showing potential for repairing fatigued steel bridge girders with less disruption and expense than traditional rehabilitation methods.

Researchers Carol Shield, Jerome Hajjar, and Katsuyoshi Nozaka from the Department of Civil Engineering recently tested commercially available unidirectional CFRP strips by bonding them to steel girders with epoxy adhesives, then measuring strength and stiffness of the resulting structure. Static and cyclic fatigue loading tests, as well as computational analysis, were used to determine the effectiveness of CFRP installation in a typical bridge rehabilitation scenario.

Bonding CFRP strips to girders would be used to prevent the propagation of cracks that could lead to girder failure. Because of its light weight, the composite material is relatively easy to handle compared to steel girders; therefore, the researchers say, repairs could often be undertaken without closing the bridge to traffic.

Test results indicate that the use of CFRP strips resulted in significant strain reduction except in the case of small cracks, where benefits proved difficult to identify. The mechanical characteristics of the adhesive used to secure the reinforcing strips proved to be highly important to the performance of the repaired girders.

Because new composite materials and adhesives are constantly being developed, the researchers conclude that further testing of materials and adhesives is necessary to fully understand the behavior of composites in bridge rehabilitation. In particular, additional multi-layer CFRP strips should be tested, and further testing should be carried out to evaluate the effects of environmental factors such as high humidity and temperature cycling.

Repair of Fatigued Steel Bridge Girders with Carbon Fiber Strips (Mn/DOT 2004-02) is available in PDF format at www.lrrb.gen.mn.us/pdf/200402.pdf.

Transit & Alternative Modes

U receives federal funds for bike research

Chosen in a national competition, the project is funded by the National Cooperative Highway Research Program (NCHRP). Principal investigators are Kevin Krizek and Gary Barnes of the University's Humphrey Institute of Public Affairs, and David Levinson of Civil Engineering. There are also major subcontracts with Planners’ Collaborative (Cambridge, Mass.) and the University of North Carolina (UNC). The research builds upon an earlier Mn/DOT-funded project that helped develop the expertise and ideas that allowed the University to win this contract award.

Barnes says that motivation for the project came from the belief among some bicycle advocates and others that bicycle facilities can be marginalized in the general transportation planning process because of a lack of quantitative evaluation. Although highway and transit investments are evaluated and justified using standard methodologies to estimate benefits and costs, no equivalent tools exist for bicycle-related investments.

The focus of this research is to develop guidelines to measure the benefits and costs of bicycling facilities in order to achieve four principal objectives:

• To compare investments in bicycling with other modes
• To evaluate whether a particular facility is justified
• To choose the appropriate facility
• To better integrate bicycling into the general transportation planning process

The final project objective is to develop the tools for measuring costs and benefits into a guidebook that can be used by planners and others to evaluate and justify bicycle investments using the same kind of “hard” quantitative analysis that is used for auto and transit investments. The guidebook will be published by NCHRP in paper form, and a computerized version will be available on the Internet. The project is scheduled for completion in August of 2005.

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 from the TRB Web site:

• TCRP Annual Report of Progress - 2003 (1.52 MB PDF)
• Transit Capacity and Quality of Service Manual, 2nd Edition (TCRP Research Report 100)
• Traveler Response to Transportation System Changes (TCRP Research Report 95)
• Use of Rear-Facing Position for Common Wheelchairs on Transit Buses (TCRP Synthesis 50)
• Traveler Response to Transportation System Changes: An Interim Introduction to the Handbook (TCRP Research Results Digest 61)

Upcoming Events

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

February 18, 2004
CTS Winter Luncheon, "A National Perspective on Current Highway Safety Issues," Radisson Metrodome Hotel, Minnneapolis. Contact Shirley Mueffelman, 612-624-4754, smueffel@cce.umn.edu. View details.

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

March 3, 2004
Transportation Career Expo, Coffman Union, Minneapolis. Contact Mindy Carlson, 612-625-1813, carlson@cts.umn.edu. View more information, including attendee registration and exhibitor registration.

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