Search results
(161 - 180 of 227)
Pages
- Title
- Sensitivity of dynamic modulus and flow number of CDOT HMA mixes in the pavement mechanistic-empirical design (PMED)
- Abstract
- Colorado Department of Transportation (CDOT) has dynamic modulus (E*), and flow number (N) database of different mixes from different regions of Colorado. The sensitivities of these mixes considering factors such as mix types, aggregates source, volumetric properties, contractors, preparation times, binders, etc. on E*, and N, and on the pavement performances are investigated in this study.
- Date
- 2020
- Title
- Bridge deck repair investigation and quantity estimation
- Abstract
- This report presents a case study on the evaluation of bridge decks using various non-destructive test methods. The primary interest lies in quantifying delaminated areas in deck concrete covered with asphalt overlays. Analytical and computational models are formulated to decompose the intensity of GPR scales into two categories: i) initiation and progression of corrosion and ii) delamination of deck concrete, which show good agreement with repaired areas. Parametric investigations emphasize the significance of rebar spacing and concrete cover in determining the extent of deck delamination.
- Date
- 2020
- 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
- Comparison of Colorado component hot mix asphalt materials with some European specifications
- Abstract
- The purpose of the report is to identify differences in Colorado's aggregates and asphalt cements as measured and compared to some of the European tests and specifications. Performance-related tests for asphalt cements developed by SHRP will be the ultimate method to identify performance and should be well received in Europe. Based upon the standard empirical tests on asphalt cements from four refineries commonly used in Colorado, the asphalt cements are comparable to those used in France. The 17 most frequently used aggregate sources in Colorado were tested for the study. The angularity of fine aggregates is measured with the NAA test procedure. The quality of the P200 is measured with respect to angularity, durability, and stiffening.
- Date
- 1992
- Title
- Development of environmental product declarations (EPDs) for sustainable pavement procurement
- Abstract
- This project aims to assist CDOT with the initial implementation of Section 118 of Colorado HB 21-1303, "The Buy Clean Colorado Act". The bill requires contractors to submit Environmental Product Declarations (EPDs) for asphalt and asphalt mixtures, cement and concrete mixtures, and steel installed on CDOT projects. Ultimately, the bill instructs CDOT to establish greenhouse gas (GHG) emission limits for these materials, and contractors on CDOT construction projects will need to comply with the limits established by CDOT. The objectives of this study were to assess the current state-of-the-practice of EPDs in construction material manufacturing; to educate stakeholders regarding life cycle assessment (LCA) and EPDs; and to help develop protocols uniquely suited to Colorado that CDOT and material producers can use to integrate EPDs into the framework of Buy Clean Colorado.
- Date
- 2023
- Title
- Transportation of hazardous materials through Eisenhower-Edwin C Johnson Memorial Tunnel study, executive summary
- Abstract
- Senate Bill (SB) 19-032 required CDOT to conduct a study assessing the feasibility of allowing the transportation of hazardous materials through EJMT and to prepare a study report that includes the findings and recommendations as to whether and under what conditions the transportation of hazmat through the tunnel could be allowed.
- Date
- 2020
- Title
- Influence of the Mount Evans highway (SH 5) on alpine wetland hydrologic processes, permafrost, and vegetation, Colorado Rocky Mountains
- Abstract
- Mount Evans Highway (SH 5) has been severely damaged by permafrost degradation and freeze-thaw processes. We assessed the effects of the current roadway configuration on the permafrost, hydrologic processes, vegetation, and soils of the Summit Lake Park wetland complex. We also reviewed and synthesized available literature to develop design recommendations for mitigating permafrost degradation, thaw-induced subsidence and frost damage, and hydrologic alterations to alpine wetlands. The existing roadway has profoundly altered permafrost conditions, hydrological processes, and wetland plant communities.
- Date
- 2021
- Title
- Construction and design soil property correlation
- Abstract
- Proper structural design of pavement systems requires knowing the resilient modulus of the soil as this parameter is a proven predictor of the stress-dependent elastic modulus of soil materials under traffic loading. In addition, the R-value test is conducted using a device called a stabilometer, where the material's resistance to deformation is expressed as a function of the ratio of the transmitted lateral pressure to that of the applied vertical pressure. Both tests are expensive and time consuming; however, establishing accurate and reliable correlations between the test results and the soil's physical properties, in lieu of laboratory testing, can save a considerable amount of time and money in the analysis and quality control process. For these reasons, correlations are typically used for estimating the resilient modulus and R-value for soils. The variability of a given soil type in different regions and states requires developing modified and specific correlations for each state based on statistical analysis of the statewide soil data collected. The main goal of this research study was to develop correlations among R-value, Resilient modulus, and soil's basic properties for available AASHTO soil types in databases in Colorado.
- Date
- 2020
- Title
- Assessing Gazex avalanche control effectiveness with terrestrial laser scanning
- Abstract
- This 2-year project used a ground-based laser scanner to map avalanche path snow depths to support an effectiveness assessment of recently-installed Gazex avalanche control systems in the Loveland Pass (Seven Sisters) and Berthoud Pass (Stanley) highway corridors. Scans were collected during snow-free conditions for a baseline, and then prior to and post-storm event and post control operations, as weather and logistics allowed. Snow depth and snow depth change maps were derived from the laser scans, informing an assessment of specific controlled avalanche events and the general performance of the Gazex exploders in the individual starting zones.
- Date
- 2019
- Title
- In-situ monitoring of infiltration-induced instability of I-70 embankment west of the Eisenhower-Johnson Memorial tunnels, phase II
- Abstract
- Infiltration-induced landslides are common hazards to roads in Colorado. A new methodology that uses recent advances in unsaturated soil mechanics and hydrology was developed and tested. The approach consists of using soil suction and moisture content field information in the prediction of the likelihood of landslide movement. The testing ground was an active landslide on I-70 west of the Eisenhower/Johnson Memorial Tunnels. Results indicate that the unique hydrology of the site is a key component in its stability and considering the whole water basin and not just the failure area is important.
- Date
- 2017
- Title
- Comparison of results obtained from the French rutting tester with pavements of known field performance
- Abstract
- The French rutting tester has been used successfully in France to eliminate the occurrence of rutting. The Colorado Department of Transportation (CDOT) and the Turner-Fairbank Highway Research Center (TFHRC) were selected to demonstrate this equipment. Thirty-three sites across Colorado with good and poor performance and a variety of temperature and traffic conditions were selected. Test results indicated that the French rutting tester, using the French specifications, was overly severe for many of the temperature and environmental conditions encountered in Colorado. However, by adjusting the testing temperature to match the highest temperature at a site location, the French rutting tester did an excellent job of predicting pavement performance. The results from the French rutting tester also had good correlation with actual rutting depths when temperature and traffic levels were considered.
- Date
- 1992
- Title
- Analyze and validate bearing pressure requirements for truncated base mechanically-stabilized earth/geosynthetically-reinforced soil (GRS) walls
- Abstract
- Truncated base mechanically stabilized earth walls are the MSE walls with narrow base excavation length and steep excavation slope designed to save construction cost while pushing the technological envelope of geosynthetic reinforcement development. A wall with truncated geometry of a narrow base length and steep excavation slope can significantly increase its base bearing pressure.
- Date
- 2020
- Title
- Effect of magnesium chloride on asphalt pavements
- Date
- 1999
- Title
- Statewide transit plan
- Abstract
- Public transit is an integral part of Colorado's multimodal transportation system providing mobility to thousands of residents and visitors throughout the state. Not only does transit connect residents, employees, and visitors to major activity centers for jobs, schools, shopping, medical care, and recreation, but it also promotes greater personal independence. Provision of transit services contribute greatly to the economic, social, and environmental health of the state and provide many benefits to individuals and communities in both rural and urban areas from fostering economic development along routes and at station locations to creating mobility options for all.
- Date
- 2020
- 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
- Evaluating effectiveness of crash type SPFs in safety management : comparing the effectiveness of network screening and diagnostic methods using aggregate SPFs and test of proportion with crash type SPFs
- Abstract
- Since 2000 CDOT has made effective use of Safety Performance Functions (SPF), Level of Service of Safety (LOSS) concept and diagnostic norms to prioritize, plan and scope safety improvements on all projects. A recent trend in road safety research, however, is to develop SPFs for each crash type. This approach is significantly more costly and labor intensive than the one used by CDOT, the benefits of this approach, however, were not well understood. It was not known if having crash type-specific SPFs will improve effectiveness of safety management, or if it will simply make the process more labor-intensive and less accessible to practicing engineers and planners. The intent of this project is to compare the effectiveness of network screening and diagnostic methods using aggregate SPFs and Test of Proportions with crash type SPFs.
- Date
- 2020
- 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
- State Highway 9 wildlife crossings monitoring, year 3 progress report : December 2015 through April 2018
- 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
- 2019