Colorado Department Of Transportation Research Articles

GRS bridge abutments—an effective means to alleviate bridge approach settlement

Field tests of segmental block-faced geosynthetic-reinforced soil (GRS) bridge abutments and piers have demonstrated excellent performance characteristics and very high load carrying capacity. One important feature of GRS abutment is that it can potentially eliminate the use of piling when situated over a weak foundation. This will not only reduce the costs but also reduce “bridge bumps” often experienced at the ends of a bridge resting on a pile-supported abutment. This study was undertaken to investigate the potential of GRS bridge abutments to alleviate bridge approach settlements. The study was conducted by the finite element method of analysis using the computer program DACSAR. The program was first calibrated by comparing its results with the measured data of the Founders/Meadows bridge abutment recently constructed by the Colorado Department of Transportation. A parametric study was then conducted to examine the effects of different foundation soils, ranging from loose sand to stiff clay, on the performance of a GRS abutment. Special attention was placed on the maximum vertical and horizontal movements of the abutment as well as the approach settlement characteristics. The study indicated that the finite element computer code DACSAR is a reliable analytical tool for analyzing the performance of GRS bridge abutments and that the GRS abutment is an effective means to reduce differential settlements between the abutment and the approach embankment.

Habitat Approach to Streamlining Section 7: Colorado Department of Transportation’s Shortgrass Prairie Initiative

Starting in January 2000, FHWA, the Colorado Department of Transportation (CDOT), the U.S. Fish and Wildlife Service, and partners at public and private resource organizations came together to design an impact assessment and advance a mitigation and conservation banking process to aid in the recovery of declining species on Colorado’s Eastern Plains. The Shortgrass Prairie Initiative provides programmatic clearance for CDOT activities on the existing road network in the eastern third of Colorado for the next 20 years—through 2022; addresses 3 listed and more than 20 declining species with the greatest likelihood of being listed as threatened or endangered; and covers 90,000 acres of right-of-way in four of CDOT’s six regions. The agencies involved sought to invest resources, which would otherwise be spent on a project-by-project clearance process, in more comprehensive and proactive species conservation that would help alleviate the need for further listings and improve predictability in the project development process. Methodologically, the project focused on impacts to habitats rather than species individuals and estimated potential impacts using best available data, supplemented by expert opinion. The resulting project offers programmatic clearance with 1:1 (that is, 1 acre of impact to 1 acre of conservation/mitigation) habitat conservation, regulatory streamlining, cost savings in several categories, and more effective habitat and species preservation. The uniqueness of this project stems from its primary focus on species currently unlisted as federally threatened or endangered, coverage of major as well as minor projects, and the scale at which conservation is being pursued, including planned preservation of approximately 15,000 to 20,000 acres from 2002 onward.

Survey and Evaluation of Damaged Concrete Bridges

It is well known that the U.S. bridge inventory stands in need of repair. For a rational allocation of U.S. investment resources to bridge maintenance, life cycle cost and probabilistic methods must be used. This requires a quantitative estimate of the remaining strength over the intended lifespan for a given bridge. Although nondestructive evaluation methods are becoming established for bridge inspection purposes, specific recommendations for the application of these methods for individual bridges do not exist. This study focuses on reported damage and damage modeling for concrete bridges, with particular attention to Colorado bridges. A survey on degradation mechanisms is briefly presented. Bridge damage is reviewed for a variety of concrete bridges based on information in the literature and from field studies performed by the Colorado Department of Transportation. A catalog of damages and examples that illustrate the variety and severity of damage in these bridges are presented. For the bridges conside...

A DENDROGEOMORPHOLOGICAL ANALYSIS OF SNOW AVALANCHES IN THE COLORADO FRONT RANGE, USA

Despite the growing risk of avalanche-related death and property damage associated with the burgeoning tourist industry in the Colorado Front Range, no dendro-geomorphological studies have been conducted to assess avalanche history in this region. In this study, dendrogeomorphological techniques are used to develop avalanche event chronologies and to reconstruct past slide magnitude at two sites located near Loveland Pass. At Mount Bethel, historical data compiled by the Colorado Department of Transportation (CDOT) and the Westwide Data Network for the period between 1974 and 1996 corroborate four of eight dendrochronologically dated event years. At Grizzly Peak, four of five dendrochronologically determined event years occurring between 1981 and 1996 are supported by historical data kept by CDOT, the Westwide Data Network and the Arapaho Basin Ski Patrol. Avalanche path reconstruction and the examination of vegetative indicator species reveal periodic fluctuations in slide magnitude at both sites, suggesting that larger avalanches have run outside the present tracks multiple times. The chronicling and assessment of each path's slide history informs of past occurrences and alerts us to future risks. [Key words: avalanche, dendrogeomorphology, Colorado Front Range.]

Recommendations for Developing Customer Focus in Statewide Transportation Planning Process

The Intermodal Surface Transportation Efficiency Act of 1991 ushered in a new era in transportation planning, transforming the missions of transportation departments into more diverse agendas that include information management and long-range planning. Today's transportation officials face a complex task. Success in transportation planning is measured not just in terms of connectivity and operational efficiency, but in the ability to respond to a host of complicated concerns; the ability to achieve a variety of operational, managerial, and financial objectives; and in proficiency in involving the public in the entire transportation planning process. The Colorado Department of Transportation, in cooperation with the Graduate School of Business Administration at the University of Colorado at Denver, conducted a three-phase investigation on the development of customer focus in the statewide transportation planning process. From this systematic methodology, the research team established a series of recommenda...

Recommendations for Developing Customer Focus in Statewide Transportation Planning Process

The Intermodal Surface Transportation Efficiency Act of 1991 ushered in a new era in transportation planning, transforming the missions of transportation departments into more diverse agendas that include information management and long-range planning. Today's transportation officials face a complex task. Success in transportation planning is measured not just in terms of connectivity and operational efficiency, but in the ability to respond to a host of complicated concerns; the ability to achieve a variety of operational, managerial, and financial objectives; and in proficiency in involving the public in the entire transportation planning process. The Colorado Department of Transportation, in cooperation with the Graduate School of Business Administration at the University of Colorado at Denver, conducted a three-phase investigation on the development of customer focus in the statewide transportation planning process. From this systematic methodology, the research team established a series of recommendations for developing a customer focus in the statewide transportation planning process. These recommendations were developed in several areas including broadening the mission and process; strengthening public involvement in project orientation; improving organization flexibility; and implementing marketing orientation, market research process, and techniques and approaches for dealing with high priority public involvement issues.