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R&M Through the Years: C Street Extension – O’Malley Road to Dimond Boulevard

September 10, 2019

In celebration of R&M’s 50th anniversary, we are taking a look back at the projects over the last five decades that made R&M into the firm it is today. This month we take a look at a new roadway that extended a main transportation corridor through an undeveloped area of Anchorage that R&M designed in the 2000s.



C Street and O’Malley Road Roundabout

The development of the C Street corridor was included in the overall Municipality of Anchorage Master Plan and the Anchorage Metropolitan Transportation Plan to improve traffic flows within the Municipality as the city grew. Initially the project was planned as one project for the whole corridor, connecting the roadway from International Airport Road to O’Malley Road. Due to environmental concerns on sections of the planned corridor, the project was split into two phases: 1) International Airport Road to Dimond Boulevard and 2) Dimond Boulevard to O’Malley Road.

R&M became involved in the O’Malley Road to Dimond Boulevard Phase of this project in 2001 as the prime consultant responsible for roadway design. This portion involved 1.5 miles of new roadway that extended this main transportation corridor through an undeveloped area of Anchorage. It linked the roadway between O’Malley Road and Dimond Boulevard, converting a freeway intersection to an overpass interchange. Design elements included surcharge construction, muck excavation, bridge structure coordination, large diameter storm drain, major intersection realignment and a multi-plate arch drainage culvert.

Truck Apron Roundabout Accommodation

The work involved an Environmental Impact Statement reevaluation, traffic modeling, Design Study Report, right-of-way acquisition, and highway and freeway interchange design, including a modern roundabout, as well as an existing conditions survey, geotechnical explorations and design of the overpass structure.

To stay within budget and meet the construction schedule, R&M designed a fast-track peat overlay/surcharge to replace the original design for peat excavation. Detailed design of improvements to the intersection of Dimond Boulevard and C Street was required to minimize ROW acquisition and relocation of existing major utilities. R&M also followed through on environmental commitments with the design of a noise barrier to mitigate traffic noise affecting an adjacent residential area, and drainage improvements to maintain existing drainage patterns.

This project won a 2006 American Public Works Association Alaska Chapter Highway Project of the Year award.


Next month, we look at a multi-phase, multi-year runway improvement project at the Bethel Airport in which R&M was the prime consultant and engineer-of-record.

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