Decks and context
As cities rebuild and repopulate, and as communities born of the new-urbanist movement grow, their parking structures are also resurgent in numbers and in creativity of concept and execution. Enabled as much by teamwork as by technical approach, many new projects offer useful guidance in the dos and don'ts of city parking. Recent examples include four quite different but equally suitable solutions: A cylindrical deck across from the morphing Renaissance Center in Detroit; a Chinatown mixed-use garage near a Central Artery off-ramp in Boston; a straight-ahead fringe facility for the University of Wisconsin, Madison; and an infill lot worthy of historic Winter Park, Fla. All of these projects have won awards lately for their noteworthy designs, but they've also pushed the outside of the scheduling and coordination envelope. Urban sites are uninhibited and demanding; to live with their quirks, building teams usually think about tight schedules, frequent-dispatch deliveries and remote staging for precast and other critical items, says E.G. Clawson, industrial group vice president with construction firm Walbridge Aldinger, Detroit.
"You might need to find an empty parking lot or warehouse where you're keeping long-lead equipment, like generators," Clawson explains. "It's critical to be able to offload to right where you need it, rather than to a storage space or on site. And you have to deal with multiple agencies and get special permits for cranes, city water use and traffic interruptions."
After the dust and the mayhem subside, however, the new neighbor sits ready to accept vehicular customers. Gates up.
The slender but engaging masses of a new lot for BlueCross BlueShield of Michigan, for example, can house 480 cars on nine stories, fed by a double-helix ramp system. Like many parking structures, its bones are of precast concrete; what sets it apart is its curve and color.
According to Ken Neumann, principal with Southfield, Mich.-based architect Neumann Smith & Associates, the design responded to neighboring buildings and the curved ramp within. To one side of the "postage stamp sized" site is a 1960s vintage glass and concrete box, and to the other, an auction house built in 1920s-era industrial lofts. Across the street rise the cylindrical towers of Renaissance Center, General Motors' new headquarters.
"Parking garages are often throw-away designs, but we said, 'No, it's still a building and contributes to the city and should be treated as seriously as a county courthouse,'" Neumann recalls. The design solution included a bow to the adjacent designs: the rounded façades of Renaissance Center, the brick hues and punched-out windows of the old loft and a sleek glazed stairwell shaft akin to the modern office structure. While a brick finish was initially preferred, the project team turned to a more economical colored precast for the curved façade.
With only two interior columns, the structure is mainly supported by perimeter wall panels, says David J. Vander Wall, principal of Walker Parking Consultants, Kalamazoo, Mich. "We used a 10-ft. panel that is curved in front and rectangular behind, so [precast] production costs were not particularly high," he notes. A strap beam carries the building's off-center load from the foundations to the columns, a distance of more than 50 feet. Another key issue was drilling caissons without undermining the adjacent properties, says Vander Wall. The result is straightforward, car-friendly and expressive.
A precast structure of a decidedly different flavor was developed for another context-dependent design in Winter Park, Fla., where a turn-of-the-century commercial row saw its first significant new neighbor in more than 25 years. The historicist solution, part of the mixed-use SunTrust Plaza, uses precast wall panels that mimic the balconies, decorative grilles, metal handrails and window boxes found on the original landscaped facades.
The village-scale parking concept, with ground-level retail and a second-floor courtyard, had to pass muster in a thorough design review involving owner Rollins College, the town planning commission, the mayor and the city council, says James J. Leonard, associate vice president of A/E firm RTKL Associates Inc., Baltimore. To achieve the most important goal-architectural compatibility-at a reasonable cost, the team partnered early on with the precast contractor Finfrock Industries of Apopka, Fla.
"The precaster helped outline a perforated load-bearing exterior wall system that allowed the structure to be classified as an open-air garage, eliminating the need for mechanical ventilation and allowing us to manipulate the dimensions of the openings," says Leonard. "So we were able to articulate traditional window openings, making [the garage] look like a series of buildings marching down the street."
The structural design employs 12-ft.-wide pretopped "double-tees," setting an efficient 12-ft. module for precast columns and walls and reducing the number of connection details and components, says Richard W. Kinnell, vice president of Southfield, Mich.-based Rich & Associates, parking consultant for the project. Parking stalls are typically about 9 feet wide, meaning the design would suit a 36-ft. column grid with three double-tees, rather than using four 9-ft. tees.
"The cost of precast is very much tied to the number of pieces that a supplier needs to bring to the site. By going to the double-tees, it's more cost-effective for the precaster," says Kinnell, noting that the 12-ft. double-tees have been increasingly specified throughout the United States over the last several years. He adds that the pretopped tees offer a driving surface that many feel is as good as those made from finishes applied on site.
Enhanced durability can be another benefit of precast structures, adds Vander Wall: Most of the reinforcing steel is 24 inches to 30 inches below the driving surface, helping to inhibit corrosion from salt water, enemy number one of parking decks. While the rebar in cast-in-place and post-tensioned concrete is generally closer to the surface, some post-tensioned designs feature an effective plastic-coated, high-strength steel strand.
To resolve issues of context and engineering, precast concrete was also employed as the structural basis for a new 800-car multistory deck at the edge of the University of Wisconsin, Madison campus, says John G. Burgan, project manager and structural engineer in the Milwaukee office of A/E firm HNTB Corp. "Based on our past state projects and our life-cycle cost analysis, we selected precast as a system of choice for the deck and exterior," he explains, "and an architectural design that reflects the image of adjacent buildings."
Unlike many commercial parking developments, long-term performance was a driver for the state-owned facility. Mechanical and electrical systems are robust and generously sized, structural connections are of stainless steel and a liquid-applied traffic coating was specified for the decks. Even lighting fixtures were upgraded to minimize glare and light pollution in the residential neighborhood and to supplement natural light from extensive glazing in stair and elevator shafts. As a convenience, a piped-in water supply was included to allow school maintenance crews to wash down the decks.
The campus and residential context drove the image of the building, on the other hand. Straddling the university's sports complex and engineering school on north, the facility "coordinates architecturally with adjacent buildings, but it's not meant to be an exact match," says Burgan. "It's a marriage in terms of forms and materials because it also has to blend in with the campus, which has no overriding style."
While many urban parking garages seem to intermediate or blend in between adjacent properties, numerous building teams have developed designs that simply stand out, perhaps with a subtle nod to their context. In Minneapolis, for example, decorative aluminum screens on the new Convention Center Parking Garage by architect Milo Thompson appropriate the filigree of an adjacent Gothic church, and limestone-hued piers echo a nearby art deco landmark. In Chicago, on the other hand, The John Buck Co.'s new North Bridge project by local architect Solomon Cordwell Buenz features an engaging metal screen that advertises the slope and structure of its deck, setting the façade apart from its new neighbors.
A small mixed-use renovation project in Boston's Chinatown area-at the foot of a Central Artery off-ramp-offers yet another approach. Designed by architect Brian Healy for owner/developer Intercontinental Real Estate Corp., both of Boston, the five-story concrete and steel structure was reclad with galvanized standing-seam metal sheets and a rain screen of imported precast panels attached directly over original asbestos panels.
The curved façade of the Lincoln Street Garage, which matches the arc of the Central Artery elevated highway, is unlike its more modest neighbors, says Healy. "This one is indiscreet, funky and raw, and we've allowed it to remain that way by leaving its evolution on display," he explains. "Every particular use of this building is articulated, allowing it to be sort of edgy." Its uses are indeed numerous, with a grocery and a bakery on the first floor, three floors of parking above and 23,000 square feet of office space housing an Internet start-up at the top.
Along with energy and accessibility upgrades that bring the facility up to code, the new design features respond to the unique Boston location. For one, the parapet was extended to match the height of adjacent turn-of-the-century warehouses in the city's "leather district." Along with the new profile, says Healy, a new overhang faces the ceremonial gateway to Chinatown, a polite bow to its cultural setting.
"The building adjusts itself to the particulars of the site," says Healy, perhaps offering a mantra to help make all urban parking solutions more successful.
Neumann adds a note of caution for building teams. "It's easy to get jaded as an architect and say, 'Oh, it's not an important building type,' but they're even more interesting because there's not a lot of ingredients, fancy finishes and flourish," he explains. "A parking garage first has to have some integrity to its use, and then make a contribution to the urban landscape."