Speaker:

David Levinson, Richard P. Braun/CTS Chair in Transportation Engineering and Associate Professor, Department of Civil Engineering.

Description:
This presentation examines the changes that occurred in the rail network and density of population in London during the nineteenth and twentieth centuries. It aims to disentangle the ”chicken and egg” problem of which came first—network or land development—through a set of statistical analyses clearly distinguishing events by order.

Using panel data representing the 33 boroughs of London over each decade from 1871 to 2001, the research finds that there is a positive feedback effect between population density and network density. Additional rail stations (either underground or
surface) are positive factors leading to subsequent increases in population in the suburbs of London, while additional population density is a factor in subsequently deploying more rail. These effects differ in central London, where the additional accessibility produced by rail led to commercial development and concomitant depopulation. There are also few differences in the effects associated with surface rail stations and Underground stations, as the Underground was able to get into central London in a way that surface rail could not.

Lessons for the development of modern cities and deployment of new infrastructure systems will be drawn.

Speaker:

Arturo Schultz, Associate Professor in the Department of Civil Engineering

Description:

Establishing patterns of susceptibility to fatigue and fracture in the Mn/DOT bridge inventory can help estimate future spending and rehabilitation needs. Details in steel bridges that are sensitive to fatigue and fracture can be enumerated and rated by their overall frequency and consequence of fracture.

The research conducted includes a review of case studies and predictive formulas for fatigue and fracture, as well as a timeline of changes to applicable bridge code provisions. Historic cases of cracking from fatigue and fracture were gathered, and the frequency of occurrence was defined by means of a national survey of departments of transportation. The result is a classification system expressed as a comprehensive table correlating geometric constraints to rank numbers for eighteen common steel bridge details that are possible locations for fatigue or fracture cracking. A computer program was developed that can be used to calculate a composite rank number from the classification system for each bridge based upon distribution and rank of the individual details present in the bridge.

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Speaker:

Keith K. Knapp, Research Manager, Center for Excellence in Rural Safety, Humphrey Institute of Public Affairs

Webinar information

Description:

The conversion of four-lane undivided roadways to three lanes (one lane in each direction with a two-way left-turn lane) is not a routine consideration. The successful implementation of this type of conversion requires additional attention to certain details and close consideration of a large number of factors.

This presentation focuses on the factors/process that could be followed to evaluate the feasibility of four-lane to three-lane conversions. The factors recommended for consideration in past research will be identified, and the details of those analyzed for a case study location will be provided. The characteristics of particular interest along a case study segment will be described. These characteristics included the segment's desired and actual roadway function and vehicle speed, intersection operations and design, business access, truck traffic, pedestrians, right-of-way availability, and a nearby parallel railroad track.

There will also be a discussion of the advantages and disadvantages of the four-lane to three-lane conversion in comparison to other proposed cross-section alternatives. The observations and lessons learned during the impact evaluation of this case study segment will be noted.