Calhoun Avenue is a historic road in Alaska’s capital city that connects downtown Juneau to the state’s Governor’s Mansion and continues to recreational parks and residential neighborhoods. proHNS planned this road reconstruction project into two phases, spread out over two years, with the goal of minimizing impacts to adjacent residences and commuters through this main thoroughfare. Due to the historic nature and age of the surrounding infrastructure, pre-and-post surveys were done on adjacent buildings and retaining walls along with the required monitoring of construction activities. The overall goals of the project included improving ADA accessibility and pedestrian safety, providing bicycle facilities, improving driver safety, and replacing deteriorated infrastructure. proHNS designed both Phase I & II of this project and provided contract administration and inspection services throughout its construction.
Phase I of this project occurred between Gold Creek Bridge and West 7th Street. proHNS, in partnership with the City and Borough of Juneau (CBJ), led an extensive public involvement process to ensure all users’ needs were incorporated as best as possible with the modern design. Major items of work included the replacement of the water, sewer, and storm drain system, rehab and/or replacement of existing retaining walls and new road base, new pavement, and concrete sidewalks.
Initial investigations of the site led proHNS to believe there was a shallow bedrock profile that prevented the installation of a new water line to current standards. proHNS partnered with an industry specialist to perform a ground penetrating radar survey to locate the bedrock depth and designed an insulated, shallow buried water line to account for it. Due to the nature of the roadway’s limited corridor width, sidewalks were designed with a thickened edge curb absent of a gutter pan. Instead, the design provided for special storm drain inlets to strike a balance and maximize both sidewalk and lane width. Further solutions provided to encourage multi-use transit include:
- Widening curb returns at intersections to provide a better line of sight
- Incorporating colored concrete sidewalks to improve crossing location awareness
- Designating bicycle signing and stripping to encourage safe shared use of the corridor
The following year, Phase II of the reconstruction of Calhoun Avenue began from W. 7th St. (the site of the Governor’s Mansion) to Main St. Major design and construction items on this phase of the project included:
- Replacement of underground water main lines and services
- Rehabilitation of storm and sewer structures
- Sealing and repairs to existing retaining walls, including a full replacement of the failed wall
- Replacement of concrete curb & gutter sidewalks
- Asphalt pavement roadway resurfacing
- Replacement of existing street and pedestrian lights
Unique aspects of this project included rehabilitating approximately 200 feet of the existing sidewalk that was structurally connected to an existing retaining wall and pedestrian handrail. Rehabilitation was done by milling the top two inches of the existing sidewalk slab and placing a special concrete mortar designed for cold weather applications. This section of roadway also spans an existing concrete viaduct that needed spalling concrete repairs and new bridge joints. Upon removing the asphalt roadway surfacing it was discovered that additional repairs to the deck were required. proHNS responded quickly to develop repair designs and was able to avoid construction delays.
