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.
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 purpose of this Manual is to provide guidance on preparing and processing documents that comply with NEPA and other applicable state and federal environmental laws affecting transportation projects in Colorado. This Manual provides references and links to related federal and state laws, executive orders, regulations, and policies. It also provides "best practice" examples for various compliance processes where appropriate. It is intended that CDOT staff, local agency representatives, and consultants use this Manual to implement NEPA in an effective manner, producing more consistent, improved environmental documents that decision-makers may use to make well-informed transportation decisions.
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.
