Design for the second phase of Halperin Park on Interstate 35E in Dallas is underway, following the initial opening of the first 2.8 acres last month. The $300 million boundary project that reconnects neighborhoods divided by the freeway’s original construction included widening the freeway and “capping” the bridge above it. The second phase, led by SWA for landscaping and HKS for architectural elements, will expand Halperin Park to more than five acres.
The highway’s headland project is one of many across the country that aims to reconnect communities divided by the interstate’s construction in the 1950s. Project officials highlight the broad contribution of Oak Cliff communities in shaping the vision of the park at the top.
“With [the Texas Dept. of Transportation] put a platform for the deck based on a previous design, a lot of what we did was take the hopes and dreams of the community and coordinate with TxDOT,” says Russell Crader, director of the global culture practice and director of HKS. “We were fine-tuning weights, materials; it was a puzzle.” Community input influenced every element “down to a tree,” he adds.
In a joint press release, the design firms note, “In 2017, when TxDOT began a complete reconstruction of I-35E, community leaders identified an opportunity to reverse that legacy by building a park on top of the highway, creating new public land where none existed, and connecting the cut-off neighborhood.
“Halperin Park was designed to feel grounded in Oak Cliff’s unique landscape, history and daily life. Sculpted landforms echo the escarpments and topography of the area, while a variety of programmed spaces support recreation, performance, learning and retreat.”
Highlights include a 12th Street Promenade that runs north-south through the deck, forming the main spine for pedestrians and lined with trees, seating and cultural elements; a “big lawn”, a wooden band performance space; scheduled water features; perennial gardens; a wooden pavilion and shaded plaza that hosts vendors and performances; a series of steps that form an outdoor enclosure with capacity for 300 people; a children’s park with wooden structures, stone benches and a future grove; and a terrace that will be expanded in Phase 2.
The release continues: “Sculpted landforms rise from the deck to form an abstract escarpment that references the chalk, shale, and limestone strata underlying the Oak Cliff neighborhood. Formed of fiberglass-reinforced concrete panels, the escarpment provides visual identity while shielding the sights and sounds of interstate traffic below.”
Looking for quick answers on construction and engineering topics?
Try Ask ENR, our new intelligent AI search tool.
Ask ENR →
When TxDOT began its I-35E expansion, the release notes, the Southern Gateway Public Green Foundation formed an Equitable Development Plan Task Force, led by Dr. Lorin Carter of C-Suite Equity Consulting. The task force engaged more than 500 residents, businesses and organizations to shape the park’s Community First Plan, which addresses six focus areas: history and culture, economic development, health and wellness, education, housing stability and neighborhood safety.
The design of Halperin Park was heavily informed by community stakeholders.
Photo courtesy of SWA/Bill Tatham
“We spent a year on this plan,” says April Allen, the foundation’s president and CEO. While there was an initial conceptual design, “our board wanted to start fresh, with the ideas of the community at the center of the work. We started a new RFP process to identify and select a design team … made up of people who understood our communities.”
The foundation formed a public-private partnership to raise the funds, which include philanthropic donations, bonds and a $25 million IIJA grant. The TxDOT-led catchment project on the freeway was approximately $47 million.
A preliminary analysis by the University of North Texas at Dallas estimates that Phase I alone could attract more than two million visitors annually and generate more than $1 billion in economic impact in its first five years, including increased property tax revenue and retail activity, the statement said.
“Community involvement was the first step,” says Todd Strawn, director of SWA. Despite the pandemic, the commitment continued. “We were gathering as much information as we could,” he recalls, with 15 design sketches as a result. “We knew it would be in phases. The key elements of the program: water, playground, green space, housing, multipurpose [facilities] — would be in Phase 1. Phase 2 will add more playgrounds and meeting spaces.”
Lawn and Loads
WSP analyzed the cap and the various loads involved with the park, including the 250,000-pound roof and various structures, says Mofid Nakhaei, principal structural engineer. “We couldn’t analyze it like a typical bridge. We worked with the designers to revise some of the loads to fit the existing bridge superstructure.” For example, the team used geofoam for soundproofing and because of its lighter weight compared to conventional materials, at 2.5 pounds per cubic foot, Nakhaei says.
McCarthy and EJ Smith’s joint venture on its roughly $58 million contract installed 450,000 cubic feet of geofoam in five months, says senior project manager Thomas Shepheard. “We waterproofed the deck of the bridge and created a bathtub 4.5 feet deep from the adjacent roads and put in the utilities.”
Building a structure on the edge of the new bridge with the interstate about 65 feet below, “we had to figure out how to build right up to the edge without compromising safety,” adds Shepheard. TxDOT allowed the crew to do 30 nights of up to two lane closures for night work. “We worked with a business partner, BakerTriangle Prefab, who pre-fabricated the wall panels,” says Shepheard. The 13 cold-formed metal panels range from 20 feet to 32 feet high x 8 feet to 10 feet wide.
KSC Inc., served as the fabricator of metal panel accessories for three-pane architectural facades, and Equity Glass and Glazing worked with Baker to install windows horizontally in a shop environment, he adds. Crews also installed fiberglass-reinforced cornices for the zoo’s elevated landing structure.
With elevation changes of about 8 feet, the park is essentially a two-story space, Allen says, with the promenade as the spine in the middle. Crader adds that the multi-purpose building, the double-curved band entrance door and the playground equipment together constitute “one of the most important uses of solid wood in Dallas.”
The multipurpose building consisted primarily of south Alabama yellow pine, manufactured in Tennessee, Shepheard says. Crews installed a dozen Douglas fir columns in the front, with roof panels up to 3,000 pounds and joists up to 2,000 pounds. The cross laminated timber ceiling consists of 3 layers, each 4.5 inches thick.
Wood and Trees
The band canopy consists of seven arches of German larch. “We hired StructureCraft – they designed, procured and installed them on a turnkey job,” says Shepheard. “There are three double-curved glulaminate components for each arch. It takes on a chair shape.”
The clear lights of the arches range from 45 feet to 55 feet, with heights of 20 feet at the rear and over 27 feet at the front, joined by round metal beads. Manufactured and pre-assembled in Germany, the arches arrived by boat and were lifted by a crane weighing more than 200 tonnes.
According to the team, the park’s planting design emphasizes hardy species capable of withstanding North Texas’ seasonal temperature changes and periodic drought. More than 100 trees representing approximately ten species are beginning to establish a canopy throughout the site. Evergreen plantings provide year-round structure, while more than a dozen perennials and flowering shrubs introduce seasonal color. Six-species native grasses add texture and movement while supporting habitat and ecological health.
The design of the second phase to add another 2.4 acres of parkland could take about two years and may include a dog park, a second pavilion and a bridge linking to the Dallas Zoo. Because of the extended canopy over the freeway, “fire safety will be an important design element,” says Nakhaei, noting possible fans, lighting and electrical systems.
Both WSP and McCarthy were involved in a similar earlier cap-and-park project in Dallas—Klyde Warren Park. “It helped [McCarthy] understand how to build [cap parks],” says Shepheard.Like Halpern, Klyde Warren Park will also be expanded by about two acres, with construction expected by the end of the year.
With other freeway expansions, such as an $888 million, 2.3-mile I-30 Canyon project between the I-35E and I-45 interchanges in downtown Dallas, even more projects like Halperin Park are planned for the region, Nakhaei says. “In the next five to 10 years, we’re probably going to see a lot more indoor parks.”
