A Runway Model [defined]
Cleveland Hopkins International Airport (CLE) is the largest commercial airport in northeast Ohio, serving almost 12 million passengers annually. Since becoming operational in 1925, the airport has developed a rich historical timeline that includes several “firsts.” In 2006, CLE became the first airport in Ohio to construct a Centralized De-Icing Facility (CDF). To keep the project on schedule, the construction of the facility required swift and organized surveyors, state-of-the-art robotic total stations, GPS equipment and data collectors, and the ability to stay one step ahead of the contractors. With its vast experience, civil engineering and surveying firm KS Associates answered the call.
Complex ConstructionIn cold climates like that familiar to Cleveland, aircraft de-icing is necessary for safe flight operations. De-icing is required whenever there is snow, sleet, freezing precipitation or the potential for frost to form on aircraft surfaces. At CLE, airport personnel spray glycol on aircraft during de-icing operations. While glycol is a common de-icing agent that helps to prepare aircraft for safe flights, in large amounts, the solution washes into storm drains. And with the increasing number of aircrafts at CLE--as many as 30 departures during peak times--the airport needs to limit this discharge to neighboring streams while complying with Ohio Environmental Protection Agency (OEPA) mandates.
CLE contracted R.W. Armstrong of Cleveland to design a sophisticated collection system that virtually eliminates glycol discharges from entering the surrounding storm water system. The primary goal of the project was to manage de-icing fluid while handling the aircraft as efficiently as possible. To promote quick departures after de-icing, an enormous concrete pad was to be installed near the middle of the airfield. This location helped to reduce taxi time, regardless of the departure runway used.
The construction of the large-scale de-icing pad was awarded to Independence Excavating, a Cleveland-based contractor specializing in challenging industrial projects. Based on KS Associates’ technical capabilities, experience with airport projects and its involvement early in the design phase of the project, Independence Excavating selected KS Associates to provide staking and as-built surveying services for the installation of the pad.
Opened in the fall of 2006, just in time for winter de-icing needs, the finished facility can handle the de-icing of eight commercial aircraft at once. According to Mark A. Yeager, PS, director of KS Associates’ Survey Group, “the size of the project, the complexity of the design and the speed at which the de-icing pad needed to be installed posed several challenges, making this an interesting project for our surveying team.”
Accuracy is ParamountThe backbone of the de-icing facility is an enormous concrete pad that supports moving aircraft and those waiting for take off; below it lies the glycol recovery system. Installation of the pad required a surface grade of no greater than 1.5 percent to be maintained.
Using the AutoCAD-generated DTM and design drawings, KS Associates set out to calculate staking points and establish grades for more than 50 acres of paving. With Trimble (Sunnyvale, Calif.) TSCe survey controllers, KS surveyors continuously double-checked staking points and data to avoid errors, knowing that the grades were critical to construction. With Trimble 5600 Robotic Total Stations, Trimble S6 Robotic Total Stations and Trimble 5800 GPS receiver systems, they also staked utilities, pavement markings and lighting, and performed as-built surveys of the constructed project elements, logging more than 4,500 hours just for the completion of the project’s construction staking. Two-person survey crews worked independently of each other. The inventory of advanced technology helped to reduce labor hours, requiring only two to three survey crews instead of the four to six required by more conventional equipment.
More than 20,000 points over the 170-acre project site were calculated, checked, set and rechecked to provide accurate stakes indicating cut-and-fill rates. The Trimble TSCe survey controllers gave the surveyors the technology they needed to perform the staking quickly and served as a tool for quality control since they were able to check points in the field, keeping the project moving. KS crews compared staked coordinate and elevation values against the calculated points, and because the elevations were critical to ensure proper drainage, they were also double-checked by comparing the staked values against the surface generated by the DTM.
According to Yeager, “One of the particularly impressive components of this project was the amount of checking and rechecking performed by the surveyors to be certain everything was staked correctly and to keep the project on schedule.”
Intense CoordinationOn a project of such large scale and with such low tolerances, challenges were inevitable. KS Associates did not have the luxury of calculating all points for the entire project in advance of staking. The construction schedule required the installation of the pad to occur in sections, or lanes, which had to be calculated, staked and checked according to an extremely rigid schedule. While surveyors were calculating one section, crews were staking the next, then going back to perform as-built surveys in the installed sections. Concurrent activities of calculating, staking and rechecking required intense coordination among in-house CAD technicians, onsite surveyors and contractors.
In addition, each section of the installed de-icing pad had multiple layers of paving, adding to the complexity of the coordination efforts.
“The coordination was extremely important,” says Mark McNulty, KS Associates survey technician. “As the survey technician, I worked very closely with the design engineer, multiple contractors, the excavating company and the onsite field crew to keep the project moving along and staying on course. The accuracy requirements were so tight that everything had to be just right.”
Little Room for ErrorWorking on airport grounds does not offer the benefit of open ground. Aircraft at CLE maintained regular schedules, and surveyors were challenged to work around moving aircraft as well as numerous pieces of construction equipment and up to 100 construction workers onsite at any given time. Additionally, taxiway closures left small windows of time in which surveying activities could continue, sometimes at night or in challenging weather conditions. Hard work, diligence and organization kept the project on schedule.
To meet the intense schedule, KS Associates crews had to stay one step ahead of the construction contractor. Without the staking and measurements from KS survey crews, Independence Excavating could not proceed with the pad installation. During the peak of construction, from March to September 2006, surveyors logged 975 hours of overtime to meet the schedule.
The CLE de-icing pad project began in September 2005 and the facility was operational just one year later. Applying advanced technology, assigning skilled professional surveyors and understanding airport operations all contributed to the project’s success.
According to Rick Costello, KS survey party chief, “One of the most satisfying components of this project was knowing our team worked hard to safely deliver a project that not only improved airport operations, but also had a positive impact on the local environment.”
Sidebar: A Rich History of "Firsts"
- Cleveland Hopkins International Airport (CLE) is the first municipally owned commercial airport in the United States.
- In 1930, CLE became the first U.S. airport to operate a radio-equipped control tower and the first airport in the world to have an air traffic control tower. During that same year, the airport unveiled the nation’s first Airfield Lighting System, featuring a three million candle powered beacon to identify the airfield for aviators and a 1½ billion candle powered floodlight to illuminate the field.
- In the 1950s the airport installed the first electric flight information board.
- In 1968, CLE became the first airport in the United States to have direct rail transportation access from the terminal to downtown.
- In 2006, CLE became one of only two airports in the country to install a centralized de-icing system.