Bridge Answer Man column: The complexity of utility design and coordination
The Grand Avenue bridge utility project for the pedestrian bridge is the most complex utility project in CDOT Region 3 to date.
We sat down with Dwight Burgess, project utility consultant with HDR Inc. and former CDOT utility manager, to understand how the utility vault works and what role it plays in the overall design and location within the project. Though the construction for the new bridge may seem to upstage the utility project, don’t let this fool you. Designing and planning for this major utility installation took years of coordinating with multiple agencies.
“It may seem simple,” Burgess said as he pulled out a three-dimensional graphic of the south vault, “but we needed to create this 3-D mock up so we can see and understand how all these utilities will terminate into one location.”
The mock-up was designed and created by Jennifer Forbes, senior engineer at Amec Foster Wheeler and one of the pedestrian bridge designers. What makes this project complex is fitting the amount of utilities needed in a small, confined area while keeping them functional and hidden from view.
Forbes explained that typically, the more space to work with is better for utilities, but not for a location directly in public view. The goal was to essentially hide the utilities while still being able to access and maintain them.
Another piece of the challenge was to produce an end product that met all the needs of the partners involved. This included CDOT and CDOT’s utility team, the city of Glenwood Springs, the Downtown Development Authority and all the utility companies. Forbes said she even met with the local historical society to ensure the outer design matched the city’s historical aesthetics.
“We went through months of trying different space iterations before we finalized the design,” Forbes said. “It’s a challenge to make utilities pretty.” CDOT works with utilities on many projects and must go through a utility clearance process before plans are approved. There is typically a regional utility manager who approves utility plans, mitigation and costs.
Installation to date:
The two concrete utility vault structures were poured on site, while the additional vaults were precast concrete, or brought to the site already constructed. And while the north vault utilities are a linear connection to existing tie-ins in various locations near Sixth Street, the south vault utilities run in a sharp bend downward to connect to their tie-in locations. The installation should be complete by the end of this year.
The utilities belong to CDOT, Glenwood Springs and three private sector utility companies: Century Link, Black Hills Energy and Comcast. The utility companies contributed $1.5 million to the cost of running the utilities through the pedestrian bridge. Additionally, Glenwood Springs paid for an upgrade to the water line in the area to accommodate future growth. Garfield County is also a significant contributor to the overall cost of the pedestrian bridge construction.
Onlookers can view the exposed water, gas, electric and fiber optic lines right now on Seventh Street.
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