Swareflex wildlife warning reflectors were installed on a four-mile section of road near Denver. Two half-mile test sections were alternately covered and uncovered for a three-month period to see if any significant change in deer-vehicle accidents could be detected. No accidents occurred in the test sections during the evaluation period. The cover/uncover evaluation method proved too costly for the limited budget of this study. Photometric measurements of the reflectors have been made using vehicle headlights as the light source. The use of wildlife warning reflectors should be discontinued until more evidence is available on their effectiveness--especially on mule deer. A regional pooled-fund study should be started to investigate the effect of the reflectors on mule deer. This needs to be a large-scale effort to obtain results in a short period of time and to ensure validity.
Due to concerns that the hydrologic regime of the wetland complex in and around Summit Lake Park has been significantly altered by development of State Highway 5 (SH 5), a field study of the hydrology, soils, and vegetation above and below the roadway was initiated in 2018. The objectives of this study are to investigate the natural hydrologic processes and vegetation up-gradient from SH 5, and how they may be impacted in down-gradient areas. A review and synthesis of the road design elements that mitigate the effects of freeze-thaw and permafrost degradation, as well as minimize hydrologic disruption to adjacent wetlands is also included.
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.
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.
The Western Slope Wildlife Prioritization Study (WSWPS) emerged from a commitment to increased collaboration between CDOT and Colorado Parks and Wildlife (CPW) to address wildlife conflicts on roads. The study's objective involved identifying wildlife highway conflict areas where targeted mitigation could have the greatest impact on reducing WVCs. To meet this objective, the mule deer and elk to make cross-highway movements, particularly during migration or within winter range. This report includes a decision-support framework and tools to guide mitigation implementation in the highest advance the outcomes of this research.
This research report used a pilot project to examine the Migratory Bird Treaty Act (MBTA) and how Colorado Department of Transportation (CDOT) transportation improvement projects may result in noise and vibration levels that could affect migratory birds. The pilot project examined the vibration and noise levels that occurred as a result of standard maintenance activities.
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.
This research report documents the findings of an investigation into automated temporary traffic control device (TTCD) deployment and retrieval technologies. The researchers found that some automated TTCD deployment and retrieval products may reduce one or more types of worker risk while increasing other types of risk. A fully automated product has the potential for the greatest risk reduction overall, but also has a much higher cost than less complex systems.
The Colorado-specific safety knowledge base, developed and effectively applied in the design process at CDOT, is not yet used to inform the planning process. This report transfers the use of these Colorado-specific, predictive and diagnostic tools to the transportation planning process. It develops a proposed methodology for the Explicit Consideration of Safety in the Transportation Planning Process by focusing on science-based and data-driven project selection, which considers susceptibility to cost-effective correction, rather than simply observed frequency and severity of crashes. This methodology will aid in ranking and prioritizing safety aspects of projects in concert with other attributes, such as mobility, air quality, noise, etc. It effectively translates state-of-the-art safety analysis techniques into an applied, practical methodology that transportation planners and practicing engineers can use.
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.
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.
This project focused on the chloride-induced corrosion of reinforcing steel in structural concrete. The primary goal of this project is to analyze the surface chloride concentration level of the concrete bridge decks throughout Colorado. The study indicates three factors that can affect chloride concentration levels in bridge decks: age of the concrete, traffic, and weather. Samples were collected from decks and curbs of bridges in different climate regions with various concrete ages and traffic levels. Water-soluble chloride concentrations were tested for all samples. Chloride concentration profiles for all the locations were listed and plotted. The deepest concrete powder was collected at a depth of 2 inches. The rebar level of the bridge was usually at or below this depth. The chloride concentrations of most bridge decks were below the critical values at the rebar level. The chloride concentrations of bridge decks are usually greater than that of bridge curbs. However, these bridge curbs showed deeper chloride penetration than the bridge decks. Younger bridges had much lower chloride concentrations, which is expected. Heavier traffic resulted in higher chloride concentrations. The bridges built in colder regions had a higher chloride concentration up to 2" depth (the rebar level). Climate may be the most significant influential factor among age, traffic, and climate when considering chloride concentration of bridge decks in Colorado. Corrosion protection should focus on the bridges decks who locate in the cold climate zone and with high traffic volume.
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.
