An Adventurous Design Expands Austin's City Limits

Landmark Building Plans Move Through Austin's new City Hall

Creating a signature architectural work that will serve as a gateway to a rapidly redeveloping downtown was a primary goal when designers and city planners set out to map Austin's new City Hall. The new structure will not only house government offices for the city whose unofficial moniker is "The Live Music Capital of the World," it will also boast a permanent stage offering yet another venue for Austin's local music and performing arts scenes.

By Rob Patterson

To create Austin's new $49 million City Hall, a wealth of lofty conceptual notions and goals had to be blended with aesthetic aspirations and practical considerations.

It's no surprise then that the term "learning curve" pops up in the lexicon of many of the projects' principal players.

The four-story, 100,000-sq.-ft. concrete structure faced with Lueders limestone and a copper skin is intended to "create an icon for the city," said Nathan Schneider, the redevelopment projects coordinator who is overseeing the job for the city.

The striking design by acclaimed New Mexico-based architect Antoine Predock will not only house city offices and meeting spaces, it will boast a four-story atrium with five pedestrian bridges, a tree-shaded plaza with a performing-arts amphitheater, multiple balconies and trellises and a ground-floor outdoor cafe beneath a cantilevered corner of the building's second floor.

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For a downtown that's lacking in visionary modern architecture, the city government committed itself to creating a signature building certain to become a local landmark that will draw worldwide attention.

The project also aims to earn silver LEED certification and feature up-to-the-minute Internet and telecommunications technology. Its blend of form and functionality reflects Predock's accent on what he called "the Austin-ness of the project."

Two major cues informed the design. First was the informality and interactivity that Predock sees as prime aspects of the Austin community and personality, prompting a spatial approach that he likes to think of as "participatory" by making the seat of city government open and multifunctional.

"That means a lot of interactive spaces," the architect said. "You can break out of a City Council meeting and go have a huddle. You can have entertainment. The lobby is a theatrical space."

The structure will draw visitors in through the ground-level plaza on the south end and the north entrance, which will be flanked by retail spaces.

The other cue is taken from the site overlooking Town Lake within the backdrop of the Balcones Escarpment on the western edge of the city. The oblique angles and craggy outcroppings of the building's four stories bear the imprint of the limestone stratum of the nearby hills, underscored by the masonry. The goal of Predock, partners Cotera + Reed of Austin and the city was to create an architectural work that will serve as a gateway for a rapidly redeveloping downtown.

For Colorado-based Hensel Phelps, the general contractor on the project, the result is a design that is "intricate and difficult, with no 90-degree angles and a lot of trigger work," said project manager Brad Winans of Hensel Phelps' Austin-based southwest district.

Other obstacles include the constrictions of the central city site (with a nearby residential construction project under way), several unique materials and the restrictions of green building.

Nonetheless, the project is proceeding on time and within budget to a November ribbon cutting. Hensel Phelps came aboard for phase three of the overall project in April 2002 after a first phase of excavation and a second to put in a three-level underground parking garage up to the basement floor of the building.

The first two phases were performed by Martin K. Eby Construction of Austin.

The previous phases also included the construction of a pedestrian tunnel around the edge of the site linking the two neighboring buildings occupied by Computer Services Corp. The city's land-lease agreement with CSC was part of the City Hall funding mechanism, and it also included specifications for compatibility with CSC's recently erected structures.

Predock planned an enclosure of two towers linked by the atrium and fronted with a sweeping plaza on the southern end of the site just across from the South First Street bridge that crosses Town Lake. Native Texas limestone covers the first two stories while copper panels line levels three and four.

Expanses of glass open the interior to daylight, and the angularity of the design extends to its low-angled, copper-paneled, standing-seam roof. A trellis shading the concrete steps of the amphitheater will be topped with photovoltaic panels as part of the LEED rating plan.

A permanent concrete stage in the plaza will offer Austin's lively local music and performing arts scenes-a source of great civic pride-yet another venue.

"I tell people that this is a prototype building," Schneider said. "We have a lot of standard materials and systems in the building, but the utilization of these systems and materials in anything but standard. The coming together of the various components has been an incredible daily challenge."

Coordination within the engineering efforts enabled Hensel Phelps to begin building a structure with complex loading factors atop the previously built base of the parking garage. The differing angles and projections on each level created "cantilevers that land on cantilevers that land on transfer girders," said Phillip Reed, associate architect for the project and a partner with Cotera + Reed.

The division of the project into phases turned out to be fortuitous, Reed said. He added that the under-structure supported a lot of transfers from the building onto the garage.

Predock said the differing angles of each level give every floor its own personality so "you know where you are." He added that the imaginative design was derived from internal necessity.

The materials used contribute to the City Hall's LEED rating points tally, though the approach meant dealing with construction materials that are not the most readily available items, said Dwight Runkels, area superintendent for Hensel Phelps.

The reinforcing steel is 99 percent recycled, the concrete masonry units 80 percent and the sheetrock 45 percent. Separate dumpsters on the site for different kinds of waste and debris continued the recycling effort.

Randomly cut stone made the limestone masonry work something of a jigsaw puzzle, but it was the copper paneling that proved to be the daunting aspect of the structure's facing.

The original plan called for a Zaner copper paneling system. "But when it came down to the bid packaging, it was way out of the money," Schneider said. D.R. Kidd instead provided custom-made 12-in.-wide copper-folded panels that sheathe the exterior of levels three and four and cover the roof.

Due to the chemical reactivity of the copper, gloved workers had to install the panels to prevent denting or staining them.

"There is a level of care involved with the installation that has been a learning experience for all involved," Schneider said. By completion time, the panels' patina is expected to achieve a consistent coloration.

The lush Austin landscape and the parkland surrounding most of Town Lake provide a theme that is carried onto the plaza. As part of the landscaping package, 13 mature trees ranging from 6 in. in diameter to a 16-in. live oak will be planted in the plaza.

"Antoine's design caused us to figure out how to do a lot of things that you traditionally try to not do, such as putting large trees and landscaping over a parking garage with 7 ft. of soil that has to be supported and drained," Reed said. The solution involves a waterproofing membrane atop the garage roof with a root barrier and a perforated pipe drainage system. The greenery will continue with large planters on upper-level balconies.

The building's main entryway is accented by a water-course feature representing the river and numerous creeks that run through the city. A runnel hugging the side of the building extends out into the plaza and ends in a pool. Water also flows over the top of the runnel and cascades down a 40-ft.-high rock wall to the bottom of the garage.

The cut in the plaza naturally lights an adjoining stairway into the parking levels and provides what Reed called a "memory tool" to help visitors easily recall the location of their vehicles.

To the west of the south entrance is the City Council meeting chambers. Large windows set in angled walls admit daylight while deflecting harsh sunlight and are easily curtained to darken the room for audio-visual presentations. The building will host two fully equipped television studios to broadcast meetings, and a conduit system throughout allows for information technology and telecom cables.

The City Hall will also serve as a hub for the Greater Austin Area Telecommunication Network, a fiber-optic system serving local and state government and the University of Texas.

A highly distinctive element is a cantilevered balcony on the north side extending from the second floor to a sharp point over Second Street. Dubbed "the stinger," its bracing below will be boxed within a copper-panel marquee while an arrowhead-shaped roof shields it from above.

Less-radical balconies also grace the other levels and sides of the structure, allowing easy outdoor access.

For Predock, the stress is on interactivity, multiple utility, a welcoming mix of public space and offices and a touch of theatricality. The "sociability" of the ground level, as Predock referred to it, is intended to create a common living room for the city at large.

As with most adventurous designs, its execution sometimes limits the imaginative touches. "What you are seeing is as close as we could get to Predock's great design," Reed said.

Schneider said he tells people on the job that "you will never work on another building like this." The end result is a notable work of first-rate architecture in a redeveloped downtown district that, only a decade ago, was marked by empty warehouses and vacant lots. "Austin is getting the icon it wanted."
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Project Team:
Owner: City of Austin
General Contractors: Hensel Phelps Construction Co., Greely, Colo.
Area Superintendents: Dwight Runkels, Shane Stone, Hensel Phelps
Project Manager: Brad Winans, Hensel Phelps.
Architect: Antoine Predock, Albuquerque, N.M.
Associate Architect: Cotera + Reed, Austin
Structural Engineer: Datum Engineering Inc., Austin
Mechanical, Electrical & Plumbing Engineer: ACR Engineering Inc., Austin
LEED Consultant: Galen Schraeder, Austin
Concrete Supplier: Rainbow Materials Inc., Austin
Masonry Supplier: Custom Masonry Corp., San Antonio
Copper Supplier: D.R. Kidd Company Inc., Round Rock
Electrical Supplier: Schmidt Electric LP, Austin
Mechanical Supplier: AIRCO Mechanical Ltd., Austin
Glazing Supplier:Win-Con Enterprises Inc., New Braunfels