Search results | Colorado State Publications Digital Repository

Title: Visual impact assessment mitigation strategies research
Date: 2018

Title: Investigation of seismic performance and design of typical curved and skewed bridges in Colorado
Abstract: This report summarizes the analytical studies on the seismic performance of typical Colorado concrete bridges, particularly those with curved and skewed configurations. A set of bridge models with different geometric configurations derived from. a prototype bridge selected in Denver area were studied. Some discussions about the connection modeling are carried out in terms of the interior bent support. For the displacement-based and force-based designs, due to the lack of design details that without detailed analyses of all possible detailing options. Therefore, some general observations of these two design concepts are ummarized in the end of the report. In the appendices, the design examples of 2-span and 3-span bridges are listed to help the engineers to conduct bridge seismic analysis in Colorado.
Date: 2018

Title: Evaluation and performance of HDPE pipes under CDOT highways, T-REX, and other locations
Abstract: HDPE pipes used in CDOT drainage systems are expected to have a 50-year design life. During the T-Rex project in 2003 a number of HDPE pipes were installed with shallow cover. Later, the majority of these pipes had to be removed and replaced after they were damaged by construction equipment driving over installed pipes, and excavations occurring near installed pipes. In this study, performance of HDPE pipes under CDOT highways was evaluated by: an extensive literature review; field studies utilizing manual inspection, CCTV video inspection, and laser-ring profiling technology; and, by observing a CDOT HDPE pipe installation project.
Date: 2018

Title: Development of cost-effective ultra-high performance concrete (UHPC) for Colorado's sustainable infrastructure
Abstract: This report presents the development of ultra-high performance concrete (UHPC) using locally available materials that reduce construction costs compared with commercial products. With the aim of achieving a specified compressive strength of 20 ksi, a UHPC mixture is formulated. The implications of various constituent types are examined with an emphasis on silica compounds (silica fume, silica powder, silica sand, finer silica sand, pyrogenic silica, and precipitated silica), including steel and polypropylene fibers. Bond tests are conducted to evaluate the development length of the UHPC. Cost analysis shows that the prototype UHPC is up to 74% less expensive than commercial products.
Date: 2018

Title: Post-fire ground treatments
Abstract: The objective of this project was to assess the efficacy of post-fire ground treatment in mitigating erosion and runoff on soil slopes subjected to wildfires. This objective was achieved through physical slope-model experiments and discrete element method (DEM) modeling. Model simulations indicated that an increase in the root network inhibited particles dislodgement and decreased downslope movement of particles.
Date: 2018

Title: A multi-perspective study on safety performance at the Colorado DOT
Abstract: This is the second of a two-part research effort to determine how to improve the effectiveness of CDOT safety efforts. This effort focuses on the safety culture within CDOT and the effectiveness of the CDOT safety programs on improving safety culture. The study used a survey approach based on interviews with senior safety officials to determine the scope of the survey questions. Based on the survey results, it is recommended that CDOT continue to engage in culture enhancement activities. Of particular importance is the continued discussion of the Excellence in Safety program and the undertaking of a follow-up effort to understand why specific regions have a higher level of implementation and change than others. Additionally, the effort needs to focus on understanding the differences in perception between supervisory and field crew personnel.
Date: 2018

Title: Dynamic modulus of cold-in-place recycling (CIR) material
Abstract: This study investigates the dynamic modulus of Cold-in-Place Recycling (CIR) pavement material and its performance using pavement performance data, field testing, laboratory testing, and Pavement Mechanistic-Empirical Design Guide (PMED) software analysis. Colorado Department of Transportation (CDOT) has 37 projects with over 8 million square yards using CIR materials. Sites from ten projects were selected to monitor the performances, and collect samples for laboratory testing. Field sampling, R-value testing of base/subgrade, and resilient modulus of base/subgrade were conducted. Dynamic moduli testing on the CIR cores were conducted by the CDOT. Considering the field performances of tested CIR pavements, this research recommends CDOT use the data derived from this study to support and implement the continued deployment of this recycling technology.
Date: 2018

Title: Hybrid A-frame micropile-geosynthetic reinforced wall with impact barrier : design development and construction approach
Abstract: This report presents the results of a comprehensive evaluation of a hybrid A-frame micropiles-geosynthetic reinforced soil wall design to support roadways with TL-4 impact road barriers on mountainous roads and its accompanying engineering options in dealing with the foundation stability problems in road widening and construction projects.
Date: 2018

Title: Comprehensive evaluation of pavement maintenance activities applied to Colorado low-volume paved roads. Phase II
Abstract: The Colorado Department of Transportation (CDOT) has been trying to identify the most effective methods for managing low-volume roads (LVRs). These roads are facing multiple challenges including: reductions in maintenance budgets, impact of industrial activities, and potentially not receiving the most cost effective treatments. Considerable savings can be secured by implementing an effective and informed management system for all LVRs engineering issues, including: planning, design, and maintenance.
Date: 2018

Title: Evaluation of tack coat bond strength tests
Abstract: Poor bonding between asphalt pavement overlays and the substrate pavement layer can greatly influence the long term performance of hot mix asphalt (HMA) in the form of premature cracking and fatigue. The primary method to achieve bonding between layers is by hot mix asphalt (HMA) in the form of premature cracking and fatigue. The primary method to achieve bonding between layers is by using an asphalt emulsion tack coat. Additionally, field staff is charged with determining whether an existing pavement, especially a milled surface, is clean enough prior to tack coat placement, to ensure an adequate bond.
Date: 2018

Title: Innovative and economical steel bridge design alternatives for Colorado
Abstract: The majority of Simple Made Continuous bridges currently in use are constructed with concrete diaphragms. This report presents the results of numerical analysis and laboratory testing of an alternative simple-made-continuous connection scheme that uses steel diaphragms in lieu of concrete diaphragms. A bridge using steel diaphragms was constructed by the Colorado Department of Transportation in 2005 serves as a basis for the research presented herein. Preliminary analysis discovered potential design flaws in the current bridge connection. This bridge should be inspected and retrofitted based on the results of the physical test. Steel diaphragms are a promising alternative for future SMC bridges and the design guidance provided in this report can be used to create better bridge designs.
Date: 2018

Title: Developing bridge-scour equations for Colorado mountain streams
Abstract: CDOT currently uses FHWA's HEC-18 methods to estimate bridge-pier scour values. The FHWA equations was based largely on streams with uniform sediments, subcritical-flow conditions, and flatter gradients. In western states where many bridges cross steep mountain channels, bridge-scour equations are applied beyond the range of conditions for which they were derived. In this research study, a new bridge pier-scour equation has been developed suitable for streams flowing through mountainous regions of Colorado.
Date: 2018

Title: Joint removal implications, thermal analysis and life-cycle cost
Abstract: This study analyzes the effects of temperature change and thermal gradients on deck joint movement and provide recommendations regarding deck joint elimination. The data indicates that temperature shifts and thermal gradients through the depth of the girders along the joint are impacting the bridge's movements and causing changes in stress. A strong parallel is shown between the temperature changes and the study joint's movement and changes in stresses in the girders. Despite being clogged, the joints showed some movements, which corresponded to specific level of stresses in the adjacent girders, which was higher in the steel girders than the concrete girders.
Date: 2018

Title: Best practices to support and improve pavement management systems for low-volume paved roads. Phase I
Abstract: The Colorado Department of Transportation (CDOT) has been trying to identify the most effective methods for managing low-volume roads (LVRs). These roads are facing multiple challenges including: reductions in maintenance budgets, impact of industrial activities, and potentially not receiving the most cost effective treatments. Considerable savings can be secured by implementing an effective and informed management system for all LVRs engineering issues, including: planning, design, and maintenance.
Date: 2018

Title: Emergency escape ramps (EER) improvements
Abstract: The objective of this research is to develop a set of design and operational recommendations to reduce the number of rollover, jackknife, and rollback end positions for trucks entering the emergency ramp. The products of this research is a series of recommendations focusing on: a) maintenance/material replacement, b) signage and pavement marking, c) shoulder strengthening/widening, d) new construction, e) lighting, and f) drivers' outreach.
Date: 2018

Title: State Highway 9 wildlife crossings monitoring, year 2 progress report : December 2015 through April 2017
Abstract: This research evaluates the effectiveness of the SH 9 Colorado River South Wildlife & Safety Improvement Project, including two wildlife overpasses, and five wildlife underpasses connected with 10.4 miles of wildlife exclusion fencing in Grand County, CO. The project was designed to improve driver safety while allowing for wildlife movement across the road. This study uses motion-activated cameras and WVC crash and carcass data to determine how successful the mitigation measures are. In addition to the crossing structures, deer guards, escape ramps, pedestrian walk-through gates and the fence end are being monitored.
Date: 2018

Title: Rock cut perimeter blasting best management practices. Phase 1
Abstract: An examination of CDOT design procedures, blasting methods, blast calculations, and aesthetic considerations to specify best management practices for highway rock cut operations for the Colorado Department of Transportation (CDOT) that could be followed when a Contractor or Permittee is proposing to blast. A method was developed to assign quantitative values for aesthetics, called the Percent Aesthetic Enhancement (PAE). By following the PAE practices, the CDOT Engineer-In-Charge can ensure that the Contractor accomplishes the work in a safe manner while preserving scenic, aesthetic, and environmental resources.
Date: 2018