Missouri Department of Transportation

This article investigates alternatives for soil compaction testing to potentially replace the standard nuclear density gauge by examining alternate testing devices and methods. Gauge reproducibility and repeatability is used to compare various devices including the Light Weight Deflectometer and the Dynamic Cone Penetrometer. The objective of this study is to find the appropriate means for measuring repeatability and reproducibility in the field for the testing devices. This article considers both measurement system analysis in the form of gauge repeatability and reproducibility and statistical data assessments including: (1) coefficient of variation; (2) statistical error compared to the mean; (3) one-way ANOVA; and (4) hypothesis test for paired samples.

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.

Lack of sufficient funding for infrastructure management is an issue in many State Departments of Transportation in the USA.This leads to deteriorating infrastructure that calls for proper management of resources.Pavement Management System (PMS) has demonstrated to be an essential tool for proper management of infrastructure and proper utilization of available funds.Numerous software have been developed for this purpose.The University of Tennessee at Chattanooga conducted a study that utilized HDM-4 software to determine the optimal utilization of available funds for Hamilton County in Tennessee using PMS.The software was used to assess the existing pavement conditions and predict future conditions of one state route and one interstate.Two pavement treatment options were assessed and results indicated that although micro-surfacing seemed to cost less, it does not necessarily improve all the distresses, while an overlay improves the roadway section significantly.In this study, HDM-4 software was used not only to provide the cost-effective maintenance treatment needed for a particular section or funding optimization, but also to estimate fuel consumption for the vehicle fleet, and to calculate the road agency and road user costs.From this study, fuel consumption was found to be higher at peak hours due to reduced traffic speeds.The road user cost was higher on the state route than the interstate due to traffic signals and stop and go motion.The road agency cost for the state route is calculated to be about four times higher than the agency cost for the interstate.

To replace an aging deck truss bridge over the Lake of the Ozarks, the Missouri Department of Transportation chose an alternative technical concept submitted by the contractor that shaved three months from the schedule.

The double crossover diamond (DCD) (also known as the diverging diamond interchange) was first introduced conceptually to engineers and planners in the United States less than a decade ago. The concept has been spreading rapidly since that time; as of July 2013, DCDs had been constructed in 19 locations in eight states and had been studied in countless other projects nationwide. Nearby frontage roads pose operational challenges for all interchanges, and DCD geometry intensifies this problem. Reverse curvature for crossover points reduces the storage length between ramps and nearby frontage roads in DCDs. The crossover roundabout concept was conceived as a potential solution to this challenge. Instead of a signalized crossover point (as in a DCD), a five-legged roundabout was proposed for the intersecting arterial, frontage road, and ramps. A crossover roundabout would function essentially like any other roundabout except that it would adjoin an arterial roadway with travel directions flipped on one side. The operational and safety benefits of typical roundabouts are expected to apply to crossover roundabouts; no new driver behaviors must be learned. Variations of crossover roundabout interchanges are possible: one crossover roundabout could adjoin half of a DCD, or two crossover roundabouts could form a complete interchange. Interchanges with two crossover roundabouts would look like typical double-roundabout diamond interchanges with the arterial road directions flipped between the roundabouts. Crossover roundabouts are not required to contain frontage roads to function. Microsimulation and cost estimations have shown the concept to have merit; crossover roundabouts can combine the best attributes of DCDs and roundabouts.

Summary Restored and constructed habitats can play important conservation roles. Predators help shape communities in these habitats through complex interactions with prey, other predators and biotic and abiotic characteristics of the environment. However, introduced predators can have dramatic effects that may be difficult to predict. Using regression models, we compared influences of introduced invasive western mosquitofish Gambusia affinis to those of two naturally colonizing predators (crayfish and dragonflies), and vegetation, on three anuran species in experimentally constructed wetlands. Using analyses of covariance, we also examined influences of mosquitofish and vegetation on aquatic invertebrate communities. We found that mosquitofish reduced abundances of grey treefrogs Hyla versicolor and H. chrysoscelis and boreal chorus frog Pseudacris maculata, but had no significant influence on green frog Lithobates clamitans. Mosquitofish also reduced invertebrate abundance, but their effect on richness was less clear. Vegetation cover did not significantly increase most anuran or invertebrate abundances. However, vegetation increased invertebrate richness. After fish removal, invertebrate abundance increased. Fish removal may have facilitated chorus frog re‐colonization into wetlands with low abundance of invertebrate predators. Our results indicate that mosquitofish are detrimental to wetland communities, and we recommend that managers avoid stocking mosquitofish. We also encourage temporary or drainable wetlands to prevent mosquitofish persistence if colonization occurs. Implementing these recommendations will improve the conservation potential of restored wetlands.

Most amphibians require suitable wetlands for breeding, oviposition, and juvenile development. Newly metamorphosed juveniles disperse into terrestrial habitat where they spend the majority of their adult lives in undisturbed forest or grassland adjacent to the wetland. Development of new infrastructure can result in wetland draining and habitat fragmentation thereby disrupting necessary life history functions. To ensure the long-term survival of amphibians, it is imperative that developers take into account their conservation needs during project planning and construction of replacement wetlands. In order to assist planners and managers in this effort, we present an index that quantifies the biotic integrity of amphibian populations within constructed wetlands throughout northern Missouri. The index is modeled after Ohio's Amphibian Quality Assessment Index (AQAI) and it incorporates ecological and abundance information for each species inhabiting a wetland. Although refinements will continue, current results indicate this tool can help assess the biological integrity of constructed and natural wetlands. The index can be modified to accommodate regional differences in species' ecology.

Deterioration of concrete due to corrosion of embedded steel reinforcing bars and prestressing strands represents a significant challenge for inspection and maintenance engineers. Delaminations develop in the concrete manifest as spalling, which further exposes the steel to the corrosive environment and accelerates the deterioration process. The typical method for detecting these delaminations is hammer sounding, which requires hands-on access to the material under inspection. Specialized equipment and lane closures are frequently necessary to achieve the required access. Application of infrared imaging to detect the subsurface features in concrete can image such defects from a distance, such that direct access to the surface of the concrete is not required. However, the method relies on environmental conditions to create thermal gradients in the concrete so that these subsurface features can be detected. A study examined the optimum environmental conditions for detection of subsurface features in concrete. The goal was to provide guidance on the practical application of infrared imaging for inspection of concrete bridge components. The effects of solar loading from direct sunlight and wind speed have been examined to determine their impact on the detectability of subsurface features in concrete. The optimum time of day for detection of subsurface defects and the effect of their depth is discussed. Characteristics of optimum inspection conditions for using infrared cameras in the field are described.

The paper describes an innovative precast pavement system located on I-57 near Sikeston, MO. Overview of precast pavement technology and associated merits are presented in addition to instrumentation and monitoring plans and preliminary results from the investigation. Early age response and stress transfer measurements are reported. Plans for monitoring in-service performance data are also discussed. Analysis of preliminary results from the investigation, [Dailey 2006, Davis 2006], follow, and include: (a) the early age behavior of the panels during and immediately after fabrication (effects due to hydration and differential thermal stresses during curing), (b) material characteristics such as unrestrained creep and shrinkage, chloride permeability, and freeze thaw resistance, (c) transfer of transverse pre-tensioning, (d) frictional stress losses during post-tensioning operations, and (e) plans for the future monitoring of long-term inservice performance of central anchor panels, base panels, and joint panels.