November 22, 2021
Three of seven of the Epstein-renovated pedestrian tunnels at O'Hare International Airport are now open.
When traveling through O'Hare, the general public may not realize that getting to their destination within Terminals 1, 2 or 3 via the Elevated Parking Structure, Surface Lot C, the Hilton Hotel and even the CTA Blue Line requires you to walk through one of seven pedestrian tunnels. These access points are located underneath the Terminal lower level Roadways and were constructed in 1977 of cast-in-place reinforced concrete varying in lengths. The interior of the tunnels was originally lined with terrazzo finishes, tile walls and drop ceilings. In between the drop ceilings and the tunnel top are infrastructure utilities, and in between the tunnel top and lower level roadway subgrade, are general site utilities for storm, sanitary, water and electrical.
Over the last decade, the existing tunnels have experienced significant leaks during heavy rain. This has resulted in repeated maintenance, drying and cleaning of the interiors spaces and, on occasion, the temporary closing of a tunnel by the Chicago Department of Aviation (CDA). The toll of the leakage over time has also caused damage to the interior finishes. Past attempted localized repairs have not been fully effective; therefore, the CDA made the decision to implement a permanent solution.
Initially, Epstein's civil engineers were tasked with evaluating the existing conditions of the seven tunnels to determine the source of water infiltration and provide recommendations to remediate the infiltration. The scope of work consisted of:
- 3D laser scanning surveys of the interiors of each tunnel
- Creating a 3D BIM model in Autodesk Revit of each of the tunnels
- Analyzing the existing groundwater conditions in the adjacent areas of each of the tunnels
- Investigating the potential source of water infiltration
- Developing remediation options with preferred solutions
- Creating a sample test area for the polyurethane injection
- Providing construction documents for the selected remediation options
- Providing Construction Phase Services
The proposed design improvements consisted of:
- Lining of existing storm sewers systems affecting the tunnels
- Replacing failed or collapsed storm sewers systems affecting the tunnels
- Replacing deteriorated sidewalk surfaces or sealing joints in precast sidewalk surfaces in the Terminal areas above the tunnels
- Removing tunnel architectural wall and ceiling finishes
- Conducting structural inspection of the walls, and floors
- Injecting polyurethane to provide soil densification outside of the tunnel walls
- Repairing concrete walls and ceilings
In addition, Epstein's interior architects and engineers were selected by the CDA to design a complete interior renovation of the tunnels in conjunction with the Water Infiltration Remediation project that was already in progress by Epstein's civil engineers.
The project construction was phased, resulting in a situation where the water infiltration remediation and the interior renovation projects were highly integrated, said Laura Rebbe, AIA, LEED AP BD+C, Epstein's vice president and senior project manager. Because of this, both projects were permitted and released for bid as one single project.
For the architectural design of the tunnels, Epstein's interior architects conducted several charrette sessions with the CDA to finalize the concept. The inspiration was Chicago, a city that is vibrant, continuously changing, modern, but with a rich history, and a leader of the sustainable movement in the U.S. Additionally, the theme of each tunnel follows the same color scheme of the terminals they serve, through the use of gradient wallcoverings in blue, orange or green.
The design intent focused on several approaches.
Epstein's design team eliminated the inherent symmetry of the tunnels by creating an asymmetrical design. We accomplished this by extending equally-spaced, curved metal wall and ceiling panels past the center of the tunnel. The opposite side of the tunnels features phenolic panels with a wood finish. The lighting scheme supports the asymmetric design by introducing pendant fixtures in between the metal panels and a linear fixture on the opposite side.
The finishes were selected for their durability, clean-ability, and availability in the event that replacement is required. All of the metal and phenolic panels are removable, for easy access to utilities and spaces behind the finishes. The finishes also hide a lined concrete trench along the tunnel walls, designed to carry trace amounts of moisture down to the lowest point, where it can be evaporated by a heat trace system.
Epstein's design team broke up the linearity of the fairly long tunnels by introducing large LED screen areas. Each features a different floor finish pattern as well as a different lighting scheme, and creates a pause in the architecture, breaking up the long tunnels. The LED screens feature scenes of Chicago, important travel information and, if needed, can broadcast emergency notices.
In addition to Epstein's design services, the interior renovation scope also includes:
- Developing energy efficient and effective lighting concepts and systems
- Modifying and upgrading the mechanical system serving the project area
- Replacing all tunnel expansion joints
- Replacing existing architectural finishes and architectural renovation of all pedestrian tunnels
Currently, these tunnels are the primary connection arteries for passengers and public arriving by the CTA Blue Line or parking in the garage, as well as guests of the O'Hare Hilton. The original tunnel space was an uninviting welcome to O'Hare, Laura said. This project will put an end to the CDA’s constant maintenance of these areas, with regard to water infiltration. Of equal importance, this project will provide the airport with a beautiful, welcoming first impression for the traveling public!
This project demonstrates Epstein's unique services and capabilities by highlighting our engineering acumen, through solving a vexing water infiltration issue, as well as our design talent, in which we took a dark and utilitarian piece of infrastructure and re-imagined it as a vibrant public access space.
The remaining four tunnels are scheduled to be open in the spring of 2022.