Economic and Environmental Impacts of Closing the Minneapolis Upper Harbor

Jerry Fruin, Applied Economics

Monday, February 23

A number of proposals have contemplated closing the Minneapolis Upper Harbor and converting the Mississippi River Corridor area above the St. Anthony Dams to housing, light industry, and recreational uses. Those plans would eliminate, or severely reduce, the barge movement of commodities to and from the Upper Harbor.

Several of these studies have assumed that elimination of the barge movements would eliminate movement of these commodities through the Upper Harbor area of Minneapolis. However, there would continue to be a need to move materials such as sand and gravel from Gray Cloud Island to Minneapolis; cement, steel products, and other construction materials into Minneapolis; and, scrap iron and waste metals from Minneapolis. In addition, truck movements of grain and fertilizer from/to northwest of Minneapolis would have to be rerouted to downstream harbors. The displacements of these movements, from barge to truck, would cause increased monetary and public externality costs that were not previously quantified.

This study was designed to determine the costs of the economic and environmental consequences of truck traffic that would result if barge traffic above the St. Anthony Dams was stopped and the existing freight was forced to switch to another mode. The impacts estimated include transportation costs, differences in fuel consumption, changes in air emissions, highway congestion impacts, highway accident impacts, and changes in highway maintenance requirements. Coefficients from the FHWA Highway Cost Allocation Study were used to monetarize the estimated public costs such air emissions and highway maintenance expenses.

Results from the “most probable” scenario indicate an addition of 66,000 truckloads traveling 1.2 million miles in the metro area each year. Annual increases in transport costs to shippers or customers exceed $4 million, while public cost increases exceed $1 million.

Usage Patterns of Diesel and Fuel Oil in Minnesota: Considerations for Using Biodiesel to Reduce Emissions

Douglas G. Tiffany, Applied Economics

Tuesday, February 24

This project represents a first effort to determine seasonal and locational usage patterns of various types of machines utilizing diesel and fuel oil in Minnesota.

This study was conducted to facilitate policy analysis in advance of development of policies designed to increase the use of biodiesel for targetted uses. Identification of diesel usage patterns may serve policymakers seeking to reduce the emissions patterns most affecting individuals or large groups of people, especially those residing in the Twin Cities Metro Area.

An Excel workbook was constructed in order to allocate usage patterns according to highway, off-road, school transport, public transport, agricultural, home heating, and industrial and other categories. In addition to the type of machine using diesel, the month and county of use were also determined. Because diesel engines are capable of utilizing various blends of biodiesel, this spreadsheet will offer policymakers the opportunity to determine costs of implementing various policies. Suppliers and distributors of fuel products will gain information on emerging seasonal needs of biodiesel.

Earth Pressure Behind a Retaining Wall

Joseph Labuz, Civil Engineering

Tuesday, February 24

Mn/DOT's response to regulations suggesting that retaining walls be designed for at-rest rather than active conditions was to measure the earth pressure behind a wall. Factored loads and resulting moments would increase significantly with the addition of specifications that require at-rest pressures. Mn/DOT walls have performed well and they traditionally have been designed for active loading.

Earth pressure cells, tiltmeters, strain gages, inclinometer casings, extensometers, and survey reflectors were installed in fall 2002 during construction of a reinforced concrete cantilever retaining wall located along I-494. A data acquisition system with remote access monitored some 60 sensors on an almost continuous basis.

Analyses of the data indicated the development of active earth pressure. Movement of the 26-ft (7.9-m) high wall at the end of backfilling consisted of translation away from the backfill (+12 mm), rigid body rotation into the backfill (-4 mm at the top of the stem), and deflection of the structure away from the backfill (+4 mm at the top of the stem). Back-calculation of loading on the wall from deflection readings also indicated the development of active earth pressure.

The presentation will also explore the relationship between wall translation, lateral loading, and the effectiveness of the shear key.