Award of Merit: Transportation Category
Strengthening Rehabilitation of Periferico Freeway
Mexico City, Mexico
Submitted by BASF Corporation
Tlalnepantla de Baz, Mexico
The Periferico Freeway is a vital transportation artery in Mexico City, Mexico. The highway is an outer beltway that was constructed in the 1920s. In the early 2000s, with the traffic demand on the beltway far exceeding the capacity, Mayor Andrés Manuel López Obrador proposed a highly publicized solution to the traffic problem. The southern portion of the highway would receive a “second floor,” making it a two-story highway. Construction of the “second floor” was completed in 2006. Some segments of the freeway even required a third level.
The freeway structure consists of two columns, each supporting a cantilevered support beam. Trapezoidal box girders with overhanging top flanges form the roadway that rests on these support beams.
Based on an assessment of the structure for live loads, some transverse beams were determined to be inadequate for torsion. In addition, the freeway structure, including the 2006 expansion, required upgrades. Some early parts of construction (which began in 2002) were also designed to older codes that considered lighter truck traffic than current codes require. To accommodate higher loads than originally designed, it was necessary to reinforce certain elements of the elevated freeway for torsional loads. This strengthening effort had to be performed without disrupting traffic on the Periferico. An externally bonded carbon-fiber composite system was selected as the optimal solution to this strengthening problem. The design was quite challenging given limited experience with torsional strengthening of concrete with externally applied systems.
Ultimately, carbon fiber-reinforced polymer (CFRP) provided a relatively simple and fast solution for shear and torsional strengthening of the transverse beams in the structure. This was accomplished without significant disruption to the traffic flow on the highway.