Posts tagged with "Bridges":

Hyperbolic Paraboloids Can Save Animals

How do you solve the problem of wildlife crossing a major highway? Build a bridge! On Sunday, the NY Times reported that Michael Van Valkenburgh and Associates (MVVA) was named winner of an innovative competition to build a wildlife crossing over a Colorado highway. Together with construction company HNTB, the team's design calls for a lightweight precast span that will improve animal and driver safety as well as help reduce habitat fragmentation. Finalists for the ARC Competition were announced last year including proposals from Balmori Associates, Olin Studio, Janet Rosenberg & Associates, and Zwarts & Jansma Architects. (View a gallery of the finalists' proposals below.) The competition carried a $40,000 award. MVVA's proposal is called hypar-nature after its structural system comprised of hyperbolic paraboloid vaults that support a vegetated wildlife crossing wide enough to create areas of distinct habitat for a variety of animals including forests, shrubs, and meadows. An expansive fence along the highway would shepherd animals to the bridge. Designed to be a prototype for a network of future crossings, the design features modular precast pieces that can easily be set into place over the roadway. While Colorado has not dedicated funds to the project or determined what site to pursue, officials hope to study the finalists' proposals.

Calatrava's Arch Towers Over Dallas

Construction continues at Santiago Calatrava's bold Margaret Hunt Hill Bridge in Dallas after it's signature arch was topped off in June.  The cable-stayed bridge is one of three planned as part of the Trinity River Corridor Project, which aims to redevelop the Trinity River and its floodplains, improving traffic flow, increasing parkland, and providing flood protection for the region. Standing 400 feet tall, the Italian-made, steel catenary arch will support six lanes of traffic connecting Singleton Boulevard with with downtown Dallas.  When complete in 2011, the 1,200-foot span's cables will create a fluid, sculptural pattern as they descend to the center of the roadway. A time-lapse camera has been set up offering up-to-date construction photos of the bridge.

Not a Bridge too Fair

Ever since the tragic collapse of the I-35 bridge in Minneapolis in 2007, politicians and public authorities nationwide have been scrambling to get theirs up to code. New bridges, or at least proposals for them, abound, some nice, some not so much. Fortunately, the Port Authority appears committed to a high-design bridge. The authority released a request for information [PDF] this week, a precursor to an RFQ. The Observer picked up on the PA's interest in building the thing with a public-private partnership, an approach with a mix of benefits—no upfront costs—and risks—less control or long-term revenue. But what is promising, nonetheless, is the PA's commitment to constructing what could be called a statement bridge. It's a pretty strong commitment, especially for an agency with an uneven track record—consider the World Trade Center, JFK, and the loathsome bus terminal. The design requirements, along with these handy renderings, are put thusly in the RFI:
The appearance of the structure is of great importance to the Authority, and the illustrative design has been subject to considerable attention as regards visually significant elements such as pier shape and cable layout. However, the “illustrative design” has been presented at public meetings with the proviso that it may be subject to amendment. The Authority is developing aesthetic requirements to clearly define unacceptable solutions (e.g. “smokestack” pylon design) and help Proposers determine the range of design solutions that may be acceptable. Aesthetic guidelines will cover overall form and function and matters such as edge detailing and finishes that are not yet reflected in the Authority’s “illustrative design. The Authority expects to assign some weight to a DBFM [design, build, finance and maintain] Company’s “visual management plan” which would provide detailed commitments on how aesthetic quality would be taken into account in the detailed design.
While we're still trying to figure out what a "smokestack pylon" is, that there are unacceptable designs is at the very least a promising sign, as there will be no race to the bottom, an especially risky proposition with public projects. The prioritization of pedestrian and bicycle access as well as room for a future transit component running down the middle is a nice touch. Granted, such design guidelines are probably a necessity given that the PA will be giving up some control over the project as a result of its undertaking a public-private partnership. Still, given that this may be the new normal, at least for the time being, as the PA continues to commit more money and time at Ground Zero, it's good to see the agency taking a smart, aesthetically driven approach, one that will hopefully persist on sister projects.