The Calgary International Airport is an important economic engine for the City of Calgary, region, and Province of Alberta, generating more than $6 billion in economic activity. For over twenty years, the Airport has experienced steady growth, and with demand exceeding the Airport’s runway capacity, the Calgary Airport Authority embarked on developing a new parallel runway and retained Associated Engineering to lead the Prime Consultant team, including CH2M HILL, for this $620 million project.
With an expected increase in travellers to and from the airport terminal, the City of Calgary wished to construct new roads to improve access to the terminal and support the road network to the east. With work on the new runway closing major roads near the airport, the City saw the opportunity to construct a tunnel to extend one of the roads, Airport Trail, under the new runway. With Associated Engineering already on the team working on the design of the runway, the City of Calgary retained this consultant team to complete design of the $295 million Airport Trail Tunnel.
Each project was a major design and construction effort. Delivering both projects together increased the level of complexity. Our team prepared more than 45 discussion papers to identify design criteria, options, constructability issues, and risks, allowing the Calgary Airport Authority and the City of Calgary to efficiently make decisions.
To suit Calgary’s climate, we developed a custom concrete pavement mix for the runway. The concrete mix produces a durable pavement with reduced permeability, which is less prone to segregation or degradation from freeze-thaw.
The new parallel runway is designed for the largest Code F aircraft (Airbus A380 and Boeing B747-8) with the most advanced, Category IIIa runway lighting system. It allows uninterrupted aircraft operations at runway visual range down to 175 metres with no decision height. The design included more than 5,000 runway and taxiway lights with over 700 kilometres of airfield power cables and 40 kilometres of fibre optic cables originating in the Field Electric Center. Dave Anderson, Aviation Specialist, tells us, “During construction, we identified that LED runway edge and runway centerline airfield lighting equipment had become available and recommended substituting energy-efficient, high intensity LED lights for the specified runway lighting, marking the first use of inset and elevated edge LED lights for a Category IIIa runway in Canada and the United States.”
Calgary Runway features first use of energy- efficient LED lights in Canada
Determining structural design loads for the tunnel and underpass structures was a challenge since this information is not part of Canadian codes and standards and few structures are exposed to such high loads. The team evaluated aircraft weights and wheel base loads in various configurations to determine the design load. Using complex finite element analysis models, the reinforced concrete structures, consisting of over 85,000 cubic metres of concrete and 16,000 tonnes of reinforcing steel, were designed to support the worst case static and dynamic loading scenarios from the aircraft.
Associated Engineering designed the major stormwater lift station and storage tank under the eastbound approach roadway, which were both part of a multi-faceted stormwater management system for the tunnel.
The tunnel’s electrical and control systems were very complex and required innovative approaches. The power supply was provided from two different ENMAX substations. If one went down, the other could carry the load for the tunnel and switch over within two seconds. Uninterrupted power supply was provided to cover the two second switchover period, so power is never lost in the tunnel for critical elements. In total, illumination is provided by over 1100 lights and aid drivers during daytime by helping adjust their eyes to the different lighting conditions within the tunnel.
Fast-track tunnel design and contract packaging allowed construction to begin in select areas of the project, while tunnel design was ongoing. Careful sequencing and scheduling of the contract packages was required to complete segments of the tunnel at critical deadlines, which allowed runway and taxiway construction to proceed on top of the tunnel. An innovative formwork system was used for the tunnel to achieve the aggressive fast track schedule.
The Airport Trail Tunnel and the Calgary International Airport’s parallel runway opened in Spring 2014, marking the completion of these projects on time and on budget. With the ability to land new, larger aircraft, the new runway boosts local, provincial, and the Canadian economy, bringing local and international travellers, encouraging surrounding development, and creating jobs.