Extension of the safety zone at Monterey Regional Airport entailed the lengthening of a higher plateau. In the interests of stability, TenCate Miragrid® geogrids were chosen for a robust wall embankment, bearing in mind the proximity of the San Andreas Fault.
The runway safety area or runway end safety area (RESA) is the zone surrounding each end of a runway which serves as a safety net in the event that an aircraft overruns on take-off, overshoots, or veers off the side of the runway. According to past regulations, an RSA should extend 60 metres beyond the end of the runway. The International Civil Aviation Organisation (ICAO) has now increased this figure to 90 metres. In the US, the recommended distances are 150 metres wide and 300 metres beyond the runway. The standard measurements have been increased over time to accommodate bigger and faster aircraft and further raise the level of safety.
The regional airport of Monterey (California, US) has two parallel runways, respectively 7,404 and 3,503 feet long (picture: SharpShots Aerial Photography)
The RSA on 10R-28L, the primary runway of Airport MRY, failed to meet the standards prescribed by the American aviation authorities. The primary runway was constructed many years ago by levelling the top of a hill. Lengthening the runway involved extending an earthen embankment out over a low-lying flood plain area. The proximity of the San Andreas Fault played a role when it came to the slope stability analysis. After taking various aspects into consideration, it was decided to reinforce the underlying soil with a geogrid: TenCate Miragrid®.
The over 30-metre-high grade separation for the runway extension consists of in total seven terraces and segmental retaining walls based on TenCate Miragrid®.
Following comprehensive studies, plans for the extension were approved in November 2013. Work began on the east side of runway 10R-28L in February 2014 and was completed in April 2015. Part of the work involved the construction of terraced retaining walls to support the plateau for the installation of a so-called engineered material arresting system (EMAS) bed. EMA systems facilitate controlled and timely deceleration of an aeroplane.
Installation of TenCate Miragrid®
Construction of the outside curve involved the overlapping of three layers of geogrid. According to current installation regulations, the overlap must be 15 cm thick. By following the TenCate Technical Note: Miragrid Overlaps on Curves and Corners, the building contractor Graniterock had no need to use fill material, thus saving significant time.
Picture by SharpShots Aerial Photography
The over 30-metre-high grade separation for the runway extension consists of seven mechanically stabilised earth terraces and segmental retaining walls. In total 42,000 m2 of TenCate Miragrid® was used for this construction. This video shows the extension.