Success means tackling more than physical obstacles
Bridge construction requires engineering excellence that successfully connects two points. But HNTB experts have discovered it also requires teams that are savvy about the societal and psychological aspects of infrastructure projects that span not only distances, but sometimes years.
Overcoming obstaclesWhether natural or manmade, the physical obstacles bridges must overcome often are obvious — rushing water, gale-force winds, heavy traffic and difficult terrain, among others.
Experienced teams employ advanced technologies to surmount those obstacles, including software that analyzes a design’s physical tolerances, and 3-D modeling and computer animation that demonstrate how a bridge will define sense of place, enhance quality of life and contribute to economic vitality.
But today’s bridge designers and builders also must be prepared to tackle obstacles that are less obvious — the societal and psychological ones.
The fact is that engineering and construction excellence are crucial, but they simply aren’t enough anymore. Successful bridge-infrastructure teams also must be prepared to listen, write and collaborate to address environmental concerns, resistance to change and communication gaps between owners, stakeholders and the general public.
Plus, successful teams must take the long-term view, recognizing that the life cycle of a major infrastructure project is a marathon, not a sprint. The need for a Hoover Dam bypass bridge, for example, was identified in the 1950s. But it was nearly six decades before the Mike O’Callaghan-Pat Tillman Memorial Bridge opened to the public.
The Sixth Street Viaduct project in Los Angeles shows how vision and vigilance are part of the heavy lifting for a well-prepared bridge infrastructure team.
The current bridge — a backdrop in Hollywood productions such as “Grease," “Terminator 2: Judgment Day” and “Lost” — was weakened by a form of “concrete cancer.” Specifically, a chemical reaction caused by high alkali content led to cracking throughout the structure. The cracks compromised the span’s strength and elevated the risk of failure during an earthquake.
An HNTB team was selected to deliver final design and construction support services for the viaduct project because the team members recognized their task was more complex than ripping out a crumbling bridge and erecting a replacement. The winning design is the product of community discussion and deep involvement. As a result, it:
Discussion and involvement
• Pays homage to the original bridge design and continues to serve as an iconic gateway to Boyle Heights.
• Improves access for motor vehicles, cyclists and pedestrians.
• Addresses the need for urban parks and smart, sustainable development that enhances safety, stimulates investment and offers space for recreation, gathering and connecting.
• Is distinguished by efforts to secure added funding for community amenities, such as a playground and art space.
Successful bridge design and construction teams also are equipped to apply technological advances that predict the behavior of structures more efficiently and effectively. Using state-of-the-art manufacturing equipment and techniques, they can fabricate more resilient bridge components, and innovate in terms of where and how components are built, staged, combined and moved into place.
Aligning needs to surmount constraints
The Stan Musial Veterans Memorial Bridge in St. Louis is a case in point. Plans to construct the award-winning span almost were scrapped because the original cost estimate for an 8-lane, 2,000-foot bridge over the Mississippi River was unaffordable.
As lead designer, HNTB worked with the Missouri and Illinois departments of transportation to align the project needs with budgetary constraints. That resulted in a cost-effective cable-stayed design with four lanes, expandable to six in the future. Leveraging a specialized form of seismic analysis and pioneering an alternative technical concept contracting method, HNTB and the construction contractors also were able to reduce the size of the bridge’s structural components and the number of drilled shafts.
Together, those steps reduced project costs and cut months of construction time. According to the team, the key was to listen, understand issues and concerns and be equipped to adjust and innovate in a collaborative environment.
In an era in which DOTs must do more with less, bridge design and construction also is about making sure the DOT’s interests and the community’s priorities are well represented throughout any project.
Doing more with less
That’s what HNTB has done as the owner’s representative for the New NY Bridge project. One of the largest infrastructure programs in North America, the project replaces the Tappan Zee Bridge across the Hudson River between Westchester and Rockland counties.
An important part of the effort is the Community Benefits Program, which awards grants to other local transportation projects that preserve and rehabilitate local infrastructure, enhance local recreational opportunities or expand pedestrian, bicyclist and transit-user access to the new bridge.