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.
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.
The Colorado Department of Transportation (CDOT) and the Turner-Fairbank Highway Research Center (TFHRC) will be demonstrating some European testing equipment for hot mix asphalt. The equipment includes the French mixer, French gyratory compactor, French plate compactor, French mixer, Hamburg wheel tracking device and the Georgia loaded wheel tester. The advantages, disadvantages, costs and manufacturers are discussed. The joint research project between CDOT and TFHRC to evaluate the equipment and asphalt mixes is included.
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.
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.
The objective of the study was to validate the performance of blocked-faced Geosynthetic Reinforced Soil (GRS) wall and to validate the Colorado Department of Transportation's (CDOT) decision to waive the positive block connection for closely-spaced reinforcement. Contrary to conventional wisdom, the GRS wall measurements of this study demonstrated that facing pressure decreases as load increases. This counter-intuitive fact is due to the decrease of compaction-induced stress (CIS) with increased load. Therefore, if a GRS wall survives compaction, it survives indefinitely.
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.
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 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.
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.
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.
The U.S. Geological Survey (USGS), in cooperation with the Colorado Department of Transportation, determined the peak discharge, annual exceedance probability (flood frequency), and peak stage of two floods that took place on Big Cottonwood Creek at U.S. Highway 50 near Coaldale, Colorado on August 23, 2016, and on Fountain Creek below U.S. Highway 24 in Colorado Springs, Colorado on August 29, 2016.
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.
Historically the Colorado Department of Highways has approved roadside sign material based on data obtained using the weatherometer. While the weatherometer gives some comparative performance data related to UV stability and exposure to moisture, the true performance is best measured under actual field conditions. An outdoor exposure deck was constructed to test sign materials for their field performance and expected longevity. Sample materials were split into three pieces, one for the weatherometer testing, one for the outdoor exposure deck, and one to remain in original condition for later comparison. This report describes the construction of the deck, and the sheeting results after three years of exposure to Colorado weather.
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.
