McCarthy Road EIS, Anchorage, Alaska
From IHSDMDownload
User Information
Organization/Agency: ADOT&PF/CH2M HILL
Basic Project Information
Project Name/Description: McCarthy Road EIS
Nature of the Project/Study: Environmental Impact Statement
Project Location: McCarthy, Alaska
Highway Length: 60 miles
Functional Classification: Collector
Design Speed: 35, 40 and 50 mph Design Speed alternatives were evaluated
Posted Speed: 30 mph
Terrain Type: Rolling
Application of IHSDM
IHSDM Module(s) used:
• Crash Prediction
• Design Consistency
• Traffic Analysis
Purpose of using IHSDM on this project:
The purpose was two fold. First, evaluating 35, 40 and 50 mph designs allowed decision-makers to quantify the relative safety and operational performance of the various design speed alternatives and then compare them against the environmental, regulatory and cost impacts of each alternative. Second, the IHSDM software provided engineering staff a means to refine alternatives to optimize the safety and operational performance.
Stage(s) of the project development process in which IHSDM was applied (e.g., planning, preliminary design, final design, etc.):
The IHSDM software was used in the planning and preliminary design stages.
How IHSDM results were used to make design decisions:
One of the primary client goals for this project was to determine an appropriate design speed. The terrain and conditions over the 60-mile length of the route vary greatly from flat and straight stretches of road to curvilinear and steep stretches. Consequently, the original planning hypothesis was to break the route into three distinct pieces; the first and last piece would have a 35mph design speed and the middle piece would have a 50mph design speed. Subsequent analysis using IHSDM indicated that a uniform design speed of 40 mph over the entire route optimized safety and operational performance of the 35mph pieces while reducing the resource impacts of the 50 mph piece without adversely impacting the safety and operational performance.
