Paving Stone a Keystone to Altoona's Revitalization

42,000 sf (4,200 m2) of concrete pavers with the keystone logo enhance Altoona's living room.

Call it what you will—the core, downtown, central business district, city center—in every case it's really a city's living room. It's the place where life and commerce interact, a keystone location that supports and perpetuates citizens' notion of community. Successfully designed living rooms have flooring, furniture, plants, lighting and music that make you feel comfortable and Altoona's does that to you.

Altoona's living room accommodates about 52,000 residents. The 11th Avenue Streetscape sets the stage for a variety of downtown civic events for them: the Fourth of July, Christmas tree lighting, Halloween, concerts, farmers markets, and the 500-rider Tour-de-Toona bicycle race. The city's stage flooring consists of interlocking concrete pavement for the plaza, sidewalk and streets. Its herringbone pattern enabled the designers, Icon Architecture of Boston, Massachusetts and Pellegrini Engineers in Altoona to integrate it into a repeated pattern of keystones, the omnipresent state logo for Pennsylvania and its historic railroad company. In addition, an existing mural depicting an earlier image of the city provides a stage backdrop for the public square known as the 14th Street Plaza. Further reminiscences are found in an antique railroad car that serves as a city and local attractions information center.

The streetscape was a collaborative effort initiated by a steering committee of downtown business owners and other stakeholders whose design was ultimately presented to and approved by the city council. The design came from landscape architect John Ryther now with Icon Parks Design. In the late 1980's, he designed the downtown revitalization scheme for French Square Park enveloped by the commercial core of Winthrop, Massachusetts (see photo). The success of that 16,000 sf (1,600 m2) project was pitched with Mr. Ryther's railroad logo design to Altoona's steering committee.

U. S. federal ISTEA (Intermodal Surface Transportation Efficiency Act) funds provided 80 percent of the project with the remainder from the Pennsylvania Department of Transportation and city resources. The $4.2 million purchased 42,000 sf (4,200 m2) of interlocking pavement, trees, lighting, furniture, street signs and banners. Mr. Ryther's project extends the railroad theme in the pavement to the plaza and furniture. The rollerblade area in the plaza doubles as an amphitheater for outdoor concerts and the plaza reminds visitors of railroad architecture.

Pavement Rehabilitation with Concrete Pavers
According to Dave Diedrich, Altoona's Director of Public Works, pavers were selected because "they enabled the keystone designs with a durable surface for traffic." About 4 inches (100 mm) of existing asphalt was removed from the streets. There was still some asphalt remaining after years of overlays. The concrete base under the asphalt remained in place and undisturbed. An inch (25 mm) of sand was placed on the asphalt and covered with 3 1/8 in. (80 mm) thick concrete pavers.

For the sidewalks, a 6 to 8 in. (150 to 200 mm) thick compacted stone base (PennDot 2A modified crushed stone) supports an inch of sand and 2 3/8 in. (60 mm) thick pavers. Geotextile was used under the base for the sidewalks. The project was completed in 1997.

The layout of the repetitive keystone pattern was carefully detailed in the drawings, almost paver for paver. This enabled the contractor to do the first one and repeat the pattern around the city square. By joining the pattern, it generates another entirely new pattern, and an entirely new living room for Altoona.

This article originally appeared in the May 2002 issue of Interlocking Concrete Pavement Magazine. (See PDF or paper issue for any illustrations or photos to which this article refers.)