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2017WinterShotcreteEMag

2016 Outstanding Repair & Rehabilitation Project Shotcrete Segment of the O’Hare and Midway Reconstruction Project By Cathy Burkert This project was part of a 5-year, $39 million contract to repair both Midway and Chicago O’Hare International Airports and its surrounding property. American Concrete Restorations (ACR) was hired to perform over $2 million of concrete repairs. The first task for this contract was to repair all concrete at O’Hare located at the lower level on the “Arrivals” ramp. This ramp spans approximately 3000 ft (900 m) and is the pickup location for passengers arriving at Chicago O’Hare International Airport from the domestic airlines. The repairs consisted of a majority of the overhead areas located throughout the concrete slab and beam structures at Domestic Terminals 1, 2, and 3. CHALLENGES Prior to the start of the project, the specification called for formed concrete repair. The General Contractor submitted the use of shotcrete due to the many site and condition challenges on the project. O’Hare Airport is always hectic, with flights arriving 24/7. To work around some of the busiest times for terminal congestion, the contractor was directed to work at night. Working night shifts always has major risks and challenges. However, the night shift work for this project was further complicated by a 6-hour shift working time. This 6-hour limit included daily mobilizing of equipment from off site, setup, and cleanup. Because the airport and the arrivals ramp were required to be kept operational during the repairs, these shifts were often interrupted due to delayed flights. The contractor’s shifts were often postponed for several hours after the scheduled start, thus shortening its shift by that much more. Weather was usually the cause of these delays and sometimes it wasn’t a weather issue in Chicago, but rather in departure cities for arriving flights. Another factor leading to delay was the nightly security checks. Every night, the contractor’s equipment needed to be cleared by security, including a thorough search by police dogs. An additional challenge was managing the congestion of the pedestrian and motor traffic. The contractor was only given 100 ft (30 m) of one lane or roadway at a time. O’Hare’s arrivals ramp has five lanes, all separated by pedestrian medians, including two taxi lanes (Lanes 1 and 2), two bus/limo lanes (Lanes 3 and 4), and a regular commuter pickup/rental car lane (Lane 5). The contractor was given the first 100 ft (30 m) of Lane 1 for a period of time until completed and the second 100 ft (30 m) of Lane 1 upon completion of the first 100 ft (30 m) and so forth. No more than 100 ft (30 m) of one lane could be closed off at the same time. Not only was the contractor given restricted access, some of the repairs were in areas with difficult access, such as repairs over the taxi vestibules. Most of the areas were also congested with lighting, police cameras, and other conduits throughout, not to mention the actual vestibules the passengers exited from the airport terminals. Most of the “obstructions” used sheet plastic for protection from dust, debris, and overspray. The pedestrian vestibule exits were closed and pedestrians detoured to other vestibules. Each 100 ft (30 m) work area was surrounded by orange barriers and caution tape to help keep the exiting passengers from entering the work zone. Because some pedestrians were focused more on their phones than the world around them, the contractor set up safety officers around the work zone to help direct the pedestrian traffic. Motor traffic was another challenge, specifically the taxi cabs. The taxi drivers seem to be oblivious to construction zones and, as you can imagine, are not the most relaxed drivers. To ensure the safety of the workers and surrounding area, arrow boards and traffic control were set up in close coordination with the airport operations manager. It was imperative to maintain excellent communication with the operations manager, as the contractor was only allowed access to the site after the operations manager approved it each night. The contractor’s access was strictly controlled by operations, and sometimes resulted in mobilization delays from the staging yard that was totally out of the contractor’s control. While logistics was a very large challenge on this project, performing the actual work came with its challenges as well. As previously mentioned, each shift included daily mobilization from the staging yard, cleanup, and demobilizing. The work zone had to be completely opened to the public and spotless come sunrise. Dust was certainly an issue during 38 Shotcrete | Winter 2017 www.shotcrete.org


2017WinterShotcreteEMag
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