Cold recycling technologies such as Full-Depth Reclamation (FDR) are sustainable and cost-effective techniques for pavement rehabilitation. Previous research has found current mechanistic-empirical (M-E) default values to be non representative and overly conservative, leading to an underestimation of the true performance capabilities of FDR materials. To address this gap, this research analyzes the performance of 11 FDR sites constructed throughout Colorado and compares their long-term performance with M-E predictions.
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.
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.
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.
States' Departments of Transportation (DOT) are trying to utilize the best practices of managing low-volume roads (LVRs) due to limited resources and declined transportation funding. Diverse maintenance practices and fluctuating budget allocations are noticed on LVRs which significantly impact the overall pavement performance. In this study, the optimal scheduling of maintenance strategies and effectiveness of different maintenance policies are investigated.
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.
CDOT has prioritized the research of select methods to evaluate the performance of the I-25 Gap work zone and future CDOT construction projects. Work zone performance measures provide comparative metrics that quantify the level of impact a work zone has on travelers, residents, businesses and workers. CDOT has identified the need to research and apply performance measures to the I-25 Gap construction project; establishing a foundation to improve the decisions that are made during planning, design and construction for the remainder of the I-25 Gap project and for future CDOT highway construction projects.
The replacement of the CDOT Region 1 Twin Bridge over Smith Road and Union Pacific Rail Road (UPRR) on I-70 provided an excellent opportunity for the performance evaluation of GRS (geosynthetically reinforced soils) abutment. The performance of the GRS abutment was measured using SAA (shape accel array) for lateral deformation and vertical settlement measurement, Geokon 4810 for horizontal earth pressure, 4800 for vertical earth pressure, 4420 for separation measurement between abutment and top of sheet pile wall, 4150 for strain of anchor rod, and optic fiber for geosynthetic strain measurement.
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.
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.
This report presents a comprehensive evaluation on the effect of drilling fluid infiltration in claystone bedrock on the axial capacity of drilled caissons. The methodology of this research combines experimental testing and numerical simulations. The results obtained in the experimental phase are used to inform the numerical study.
Transportation impacts to historic streetcar lines in Denver and other communities in Colorado are often unforeseen given that many tracks lay underneath paved streets and are not well documented. This results in frequent unanticipated discoveries during construction of publicly assisted transportation improvement projects in Colorado. A historic context was developed to provide a consistent methodology for the evaluation of historic streetcar lines. A corresponding GIS component was developed to provide reliable and consistent mapping of the former streetcar line in Colorado along with pertinent information relative to each streetcar line, including ownership, technical information, dates of operation, and current condition, if known.
This report provides a synthesis on the use and design of snow sheds to protect transportation corridors against avalanches. This report summarizes the various snow shed designs and standards, regulation environment, construction and operational costs, risk, benefits, loading considerations, operational and design considerations, and alternate methods employed when snow sheds are no longer needed, or when alternative long-term mitigation measures are employed.
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.
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.
Deployment of 2+1 Road with Barrier in Colorado certainly has potential to improve safety where it replaces conventional 2-lane highways, primarily by preventing head on and sideswipe crashes. The Swedish design is most widely implemented and has a record of success, so Colorado drivers expect the "slow" lane to be the ending lane, and somewhat gentler tapers than Sweden employs.
