Browsing by Author "Swenson, Joel"

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    Moisture Effects on PVD and DCP Measurements
    (2006-06-01) Swenson, Joel; Guzina, Bojan; Labuz, Joseph F; Drescher, Andrew

    This study deals with the experimental investigation of the effects of moisture and density on the elastic moduli and strength of four subgrade soils generally representing the range of road conditions in Minnesota. The testing approach involved i) reduced-scale simulation of field compaction, ii) field-type testing on prismatic soil volumes, and iii) element testing on cylindrical soil specimens. The field-type testing included: i) the GeoGauge, ii) the PRIMA 100 device, iii) the modified light weight deflectometer (LWD) device, iv) the portable vibratory deflectometer (PVD) and v) the Dynamic Cone Penetrometer (DCP). To compare the Young's modulus values stemming from the field-type and laboratory experiments, cylindrical specimens were extracted from the prismatic soil volumes and tested for the resilient modulus (Mr), small-strain Young's modulus using bender elements.

    The results reveal that both moisture and density have a measurable effect on the elastic modulus and strength of all four soils. On the element testing side, the small strain estimates from the bender element tests were in good agreement with the resilient modulus values. In the context of field testing, there was significant scatter of the estimated Young's moduli depending upon the particular testing device.

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    Urban Design, Transportation, Environment and Urban Growth: Transit-Supportive Urban Design Impacts on Suburban Land Use and Transportation Planning.
    (2003-03-01) Swenson, Joel; Dock, Frederick
    This report summarizes the development and utilization of enhancements to the regional transportation model to measure the individual and accumulative impacts of transit-supportive urban design strategies. The report has three main sections: 1) urban design analysis of four transit-supportive development proposals; 2) development of model enhancements in the form of a subarea model; and 3) use of the subarea model to analyze a subregional transit-supportive growth scenario. The urban design analysis demonstrated that transit-supportive development principles are adaptable to suburban settings and that use of the principles does improve land use mixes and walkability. It also confirmed that guidelines for transit-supportive development can be used to create a network of suburban sites that meets city and regional goals. The subarea transportation model proved sufficiently sensitive to detect changes in tripmaking patterns at the site and subregional scales. Two types of tripmaking contributed to these changes: short-distance trips between transit-supportive developments and walk or bicycle trips within developments. Results from the subregional analyses most clearly demonstrated the benefits of transit-supportive development strategies. At the subregional scale, the model tracked travel interactions between transit supportive development sites, which revealed the accumulative benefits. If the entire region were modeled accordingly, it is expected that benefit indicators would show even greater improvements.