The Design Build (DB) team of United Infrastructure Group (UIG), Johnston Design Group (JDG) and Infrastructure Consulting & Engineering (ICE) worked together for Hughes Development Group, Inc., and the City of Mauldin to deliver a new pedestrian bridge over I-385. The bridge connects the BridgeWay Station development with Mauldin City Trail and the well-known Swamp Rabbit Trail system in Greenville County, SC. This Progressive Design Build project required close coordination with multiple stakeholders including Hughes Development, Inc. (Client – Developer), City of Mauldin (Client – Municipality), Laurens Electric (Utility), Greenville County (Strom / Water Quality Permits) and SCDOT (Interstate Owner – Design Review and Approval). UIG successfully worked with all parties to deliver a signature pedestrian bridge facility with unique architectural and aesthetic features, while meeting the structural design requirements of SCDOT and staying within an established guaranteed maximum price.
The project consisted of building a pedestrian bridge over I-385 and paved trail approaches on each side of the bridge. The DB team managed the project from conceptual design through substantial completion, incorporating design elements requested by the stakeholders into the final design. Every stakeholder’s vision for the project was integrated into the cohesive and unique final concept. The bridge’s location in close proximity to an existing sound wall, box culvert, and Bridges Road interchange required the DB team to work closely with SCDOT to secure proper permits for the project. SCDOT also granted the DB team a design variance for median width that allowed incorporation of the signature architectural center pier arch.
The structure is a four span, 360’ long, 15’ wide pedestrian bridge with spans consisting of box beams and cored slabs. The two end bents (bents 1 &5) are integral abutments founded on 14×73 steel piles. The shoulder bents (bents 2 & 4) are founded on pile footings with aesthetically treated concrete columns and caps. The columns extend 14’ above the bridge deck and feature cast in place reveals and cornices, with decorative column caps for additional architectural interest. The superstructure of the bridge is cored slab beams on spans 1 & 4 and box beam girders on spans 2 & 3, with a structural cast in place deck. Cored slabs and box beams were used because of the architectural aesthetic provided by the clean, flat outside profile of the beam. The eastern end bent (bent 5) required a Forix retaining wall developed by Earth Wall Products to accommodate bridge placement near an existing storm drainage feature, existing sanitary sewer line, and potential wetlands. The Forix wall reaches heights of over 31’ to provide the required traffic clearance on I-385 and to support larger pedestrian plaza leading to the BridgeWay Station development. UIG designed and installed a custom fabricated metal pedestrian fence across the portion of the bridge over I-385 (spans 2 & 3). The custom architectural fence provides safety and creates an open-air feeling for pedestrians. UIG also implemented hand-formed cast-in-place architectural concrete rail on spans 1 & 4 of the bridge, and around the plaza. The design of the rail is inspired by architectural bridge rails found on iconic bridges around South Carolina. The project also included a short extension of the future Swamp Rabbit Trail, connecting the bridge to the existing portion of trail and allowing access to BridgeWay Station from Swamp Rabbit Trail and the City of Mauldin.
The highlight of the structure Is the architectural median arch inspired by the famous Arc de Triomphe in Paris, France. This center arch, designed by JDG and ICE, stands 60’ tall above I-385. The 48-foot-wide arch is three feet thick and features a center arched passageway that is 14 feet wide. The median arch bent is founded on 24 14X73 steel piles that required removal and replacement of the existing concrete median barrier and shoulders of I-385. UIG elected to design the median arch as a hybrid concrete structure that uses 76 architectural precast panels in conjunction with reinforced cast-in-place concrete column infill for additional structural support. The precast panels served as formwork for the reinforced concrete infill and provide the very high level of aesthetic and architectural quality desired by the client. The use of precast concrete provides very consistent texture and color for the entire arch structure and minimizes the number of joints and patches. The arch median pier and spans 2 & 3 include a lighting system that illuminates and accents the structure at night.
The Design Build team overcame difficult challenges and devised innovative solutions to deliver the project. The most successful aspect of this project is the completion of the center arch. UIG leveraged knowledge from across the company, and relationships with subcontractors, to complete the unique precast arch work safely and efficiently. The limited workspace in the median of I-385 required the team to develop innovative shoring, rigging, access, and rescue plans to perform the work in a safe and timely manner. The UIG team worked through the challenges to provide the highest-quality work without claims or litigation, and within the client’s defined budget. The project was completed within the timeframe provided by the client.
This project was very different from a typical highway grade separation because of the exceptionally unique architectural elements that are consistent with the ambitious development it serves. An exceptionally high standard of quality level of detail was necessary to achieve the final finishes that would result in overall success. UIG met these challenges with determination, hard work, innovation, attention to detail, innovation, and a culture of safety. The use of architectural precast panels as the formwork for cast-in-place bridge substructure is a first in South Carolina and possibly a first in the nation. The use of box beams over an interstate, Forix retaining wall, an inverted-T cap, and custom pedestrian fence panels are first-time uses in South Carolina. UIG worked with the architect to find materials that would fit their vision but stay within the guaranteed maximum budget for this project, while minimizing the need to compromise. UIG held weekly meetings with the client (developer and the city of Mauldin), architect, and designer to discuss schedule and issues arising during construction. These weekly meetings were central to the effective communication and coordination that prevented claims and facilitated completion of the project on time and within budget.
“This pedestrian bridge is a major accomplishment for the City of Mauldin, and I believe it will become a focal point for our community,” said Seth Duncan, city administrator. (“Help Name Mauldin’s New Pedestrian Bridge.” WSPA 7NEWS, 8 Aug. 2023, www.wspa.com/news/local-news/help-name-mauldins-new-pedestrian-bridge/.)
“The few that I’ve seen that entertain the word gateway appeals to me because that bridge represents the connectivity for the Swamp Rabbit segments that we have in plans here for the City of Mauldin, but it now gives the entire golden strip a way to get across a major interstate, 385,” said Mayor Merritt. Winter, Dana. (“Upstate Mayor Surprised with Response to Name Bridge.” Https://Www.foxcarolina.com, 30 Aug. 2023, www.foxcarolina.com/2023/08/30/upstate-mayor-surprised-with-response-name-bridge/.)
