25 April 2008
With around 85 million passengers a year passing through Hartsfield-Jackson Atlanta International Airport, Atlanta, US, it is the world’s busiest airport. In 2000, it started a 10-year, US$ 5.4 billion expansion programme to cope with the 120 million passengers predicted to be using it by 2010.
The programme included a new, US$ 1.2 billion, fifth runway, which opened on time and under budget this May. It is 2.75 km long with a full-length parallel taxiway and dual north-south taxiways. Crossing ten traffic lanes of Interstate 285, two-thirds is on the west side and the remainder on the east. Linking the two sections is a US$ 159.5 million bridge. This allows planes to take off/land on top of I 285. The runway bridge is 365 by 148 m, and the taxiway bridge is 137 by 137 m.
Sub-contractor Pioneer Concrete Pumping used Putzmeister truck-mounted BSF 63Z and BSF 52Z concrete pumps - 63 and 52 m of reach respectively - during construction of the bridge. Slabs skewed at 45° were pumped with concrete at the rate of about two 1860 m2 slabs a week. Over 52100 m3 of concrete was needed to complete the two bridges, which feature 764 T-shaped pre-cast beams with a total length of 27450 m. The 2.06 m tall beams vary in length from 28.6 to 40.5 m. The combined bridge decks cover 67380 m2 and contain 28300 m3 of concrete. The bridge structure consists of 40000 m2 of cast-in-place and pre-cast walls. The runway’s interior substructure features 1 m high concrete walls, which vary in height from 10.6 to 18.3 m.