Optimizing the value of soil compaction testing quality assurance and control using stochastic life cycle cost, comparative and statistical analysis

The nuclear density gauge has been the standard soil compaction acceptance method for the Missouri Department of Transportation (MoDOT) for several decades. However, the cost of licensing, security, transport protocol and training imposed by the federal government have caused MoDot to question whether it remains a cost effective testing technology.. Nuclear density testing\u27s rapidity and accuracy has been crucial in enabling MoDOT inspectors to keep contractor grading processes on schedule. But, in the last two years MoDOT\u27s Quality Management program has shifted the bulk of testing requirements to the contractor, reducing the need for MoDOT inspection on grading projects. As a result, MoDOT is investigating compaction testing alternatives to the nuclear density gauge which can provide the necessary results at a lower life cycle cost. The investigation comprised a comprehensive review of previous research into compaction testing alternative as well as key findings and gaps in research. This led to the purchase of XX pieces of alternative test equipment which were employed simultaneously alongside the nuclear density gauge on four large structural fill projects. The field testing yielded a set of comparable test results taken at the same time, in roughly the same location, and under the same environmental conditions, and arguably making this research the most comprehensive study of compaction testing technology on record. The dissertation discusses MoDOT\u27s Quality Management program\u27s development and links to its origin in Design-Build project best practices, which provided the motivation to seek alternatives to the nuclear density gauge. Life Cycle Cost Analysis and Cost Index theory was utilized in comparing the compaction testing alternatives and presenting present cost per compaction test for the Department. For MoDOT project sites, linear and multiple regression analyses were developed to determine if correlations existed between soil density and associated modulus or Clegg Impact Values. Lastly, an assessment of the repeatability and reproducibility of the light weight deflectometer and the dynamic cone penetrometer on a project site was completed with three distinct statistical analytical methods. The data presented herein can be integral elements in MoDOT\u27s decision to eliminate or keep the nuclear density gauge

Soil Nailing: The MoDOT Experience

Soil nailing is a construction technique that is used to strengthen existing ground by installing grouted steel bars into the ground at closely spaced intervals. This increases the shear strength of the in-situ soil so that successive excavation lifts from top down can be made. The Missouri Department of Transportation (MoDOT) has overseen the construction of two temporary soil nail walls in the St. Louis metro area and one permanent wall in the Kansas City metro area. All three projects involved roadway widening under existing overpasses, which required the removal of the soil berm and construction of a soil nail wall next to the existing abutment. The ground conditions, construction methods and soil testing procedures for the projects varied widely from one another. These projects provided experience and valuable lessons in the design and construction of soil nail walls not only to MoDOT personnel, but also to the wall constructors and design firms involved in the projects

Contractor-Furnished Compaction Testing: Searching for Correlations Between Potential Alternatives to the Nuclear Density Gauge in Missouri Highway Projects

The Missouri Department of Transportation’s (MoDOT) past and present Quality Control and Quality Assurance programs for construction are examined. MoDOT’s present Quality Management program along with a small number of grading projects has lowered the number of Quality Assurance (QA) soil compaction tests completed in the past two years. The Department would like to rid itself of using the Nuclear Density Gauges because of burdensome Federal regulations, required training, security and licensing fees. Linear and multiple regression analysis was performed to see if a correlation between nuclear density gauge dry densities values and Light Weight Deflectometer modulus values/ Clegg Hammer Clegg Impact Values exist. These relationships or lack thereof will determine the technology used by construction contractors to perform compaction quality control testing if MoDOT moves away from using nuclear density gauges for soil density verification

Managing geotechnical risk on US design-build transport projects

Awarding design-build (DB) contracts before a complete subsurface investigation is completed, makes mitigating the risk of differing site conditions difficult, if not impossible. The purpose of the study was to identify effective practices for managing geotechnical risk in DB projects, and it reports the results of a survey that included responses from 42 of 50 US state departments of transportation and a content analysis of DB requests for proposals from 26 states to gauge the client’s perspective, as well as 11 structured interviews with DB contractors to obtain the perspective from the other side of the DB contract. A suite of DB geotechnical risk manage tools is presented based on the results of the analysis. Effective practices were found in three areas: enhancing communications on geotechnical issues before final proposals are submitted; the use of project-specific differing site conditions clauses; and expediting geotechnical design reviews after award. The major finding is that contract verbiage alone is not sufficient to transfer the risk of changed site conditions. The agency must actively communicate all the geotechnical information on hand at the time of the DB procurement and develop a contract strategy that reduces/retires the risk of geotechnical uncertainty as expeditiously as possible after award

Managing geotechnical risk on US design-build transport projects

Awarding design-build (DB) contracts before a complete subsurface investigation is completed, makes mitigating the risk of differing site conditions difficult, if not impossible. The purpose of the study was to identify effective practices for managing geotechnical risk in DB projects, and it reports the results of a survey that included responses from 42 of 50 US state departments of transportation and a content analysis of DB requests for proposals from 26 states to gauge the client’s perspective, as well as 11 structured interviews with DB contractors to obtain the perspective from the other side of the DB contract.  A suite of DB geotechnical risk manage tools is presented based on the results of the analysis. Effective practices were found in three areas: enhancing communications on geotechnical issues before final proposals are submitted; the use of project-specific differing site conditions clauses; and expediting geotechnical design reviews after award. The major finding is that contract verbiage alone is not sufficient to transfer the risk of changed site conditions. The agency must actively communicate all the geotechnical information on hand at the time of the DB procurement and develop a contract strategy that reduces/retires the risk of geotechnical uncertainty as expeditiously as possible after award

Incremental cycle bases for cycle-based pose graph optimization

Pose graph optimization is a special case of the simultaneous localization and mapping problem where the only variables to be estimated are pose variables and the only measurements are inter-pose constraints. The vast majority of PGO techniques are vertex based (variables are robot poses), but recent work has parameterized the pose graph optimization problem in a relative fashion (variables are the transformations between poses) that utilizes a minimum cycle basis to maximize the sparsity of the problem. We explore the construction of a cycle basis in an incremental manner while maximizing the sparsity. We validate an algorithm that constructs a sparse cycle basis incrementally and compare its performance with a minimum cycle basis. Additionally, we present an algorithm to approximate the minimum cycle basis of two graphs that are sparsely connected as is common in multi-agent scenarios. Lastly, the relative parameterization of pose graph optimization has been limited to using rigid body transforms on SE(2) or SE(3) as the constraints between poses. We introduce a methodology to allow for the use of lower-degree-of-freedom measurements in the relative pose graph optimization problem. We provide extensive validation of our algorithms on standard benchmarks, simulated datasets, and custom hardware

Arts and Culture Policy and Creative Placemaking in Detroit

This report focused on arts and culture policy and creative placemaking. It was an investigation of community-based arts and culture in Detroit and its economic benefits, with recommendations to foster creative placemaking. The research included: (1) compiling an inventory of neighborhood arts and culture in Detroit, (2) creating a map to identify existing clusters, (3) conducting case studies, and (4) interviewing subject-matter experts such as artists, arts entrepreneurs, business owners, the former Director of the Detroit Planning Commission, a former state Representative, and an Associate Program Officer of Community Development at the Kresge Foundation

Examining the Association Between Rurality and Positive Childhood Experiences Among a National Sample

Purpose The present study examines the association between rurality and positive childhood experiences (PCEs) among children and adolescents across all 50 states and the District of Columbia. Recent work has quantified the prevalence of PCEs at the national level, but these studies have been based on public use data files, which lack rurality information for 19 states. Methods Data for this cross-sectional analysis were drawn from 2016 to 2018 National Survey of Children\u27s Health (NSCH), using the full data set with restricted geographic data (n = 63,000). Descriptive statistics and bivariate analyses were used to calculate proportions and unadjusted associations. Multivariable regression models were used to examine the association between residence and the PCEs that were significant in the bivariate analyses. Findings Rural children were more likely than urban children to be reported as having PCEs: volunteering in their community (aOR 1.29; 95% CI 1.18-1.42), having a guiding mentor (aOR 1.75; 95% CI 1.45-2.10), residing in a safe neighborhood (aOR 1.97; 95% CI 1.54-2.53), and residing in a supportive neighborhood (aOR 1.10; 95% CI 1.01-1.20) than urban children. Conclusions The assessment of rural-urban differences in PCEs using the full NSCH is a unique opportunity to quantify exposure to PCEs. Given the higher baseline rate of PCEs in rural than urban children, programs to increase opportunities for PCEs in urban communities are warranted. Future research should delve further into whether these PCEs translate to better mental health outcomes in rural children