Weidlinger received the award for merging proven post-tensioning and concrete segmental technologies to produce an extremely cost efficient and streamlined light-rail viaduct in Monterrey, Mexico.

New York, NY – Weidlinger Associates received an Engineering Excellence Diamond Award from the American Council of Engineering Companies (ACEC) New York for the design of a viaduct for Line 2 of the STC Metrorrey light-rail system in Monterrey, Nuevo Leon, Mexico. The award will be presented at the organization's annual gala in New York on March 27, 2010. Weidlinger will also be honored next month for the same project as an ACEC National Finalist.

Occupying the median of a busy and narrow six-lane roadway, the streamlined viaduct is a persuasive argument for using both light rail and concrete segmental technology to reduce reliance on cars in congested cities. Metrorrey ridership more than doubled from 180,000 to 395,000 passengers for only a 25% increase in line length. Weidlinger’s client was Constructora Garza Ponce, Monterrey, Mexico, a member of Siemens-Bombardier-Grupo Garza Ponce. Monterrey is Mexico’s third largest city with about 3.7 million inhabitants.

Segmental concrete structures are economical because of their repetitiveness, but Weidlinger’s team merged proven post-tensioning and concrete segmental technologies to produce even more cost efficiencies. By fully prestressing the superstructure, reinforcement was reduced by half. Further reductions in steel reinforcement and application to heavy rail are future possibilities.

The new viaduct is neighborhood friendly and aesthetically pleasing. It has no visible shear keys, rust-producing exposed steel, or heavy noise walls. Two rail tracks fit side by side within the open cross-section, reducing vehicle noise, visibility, and derailment danger. Torsional stability is enhanced by the wide bottom, and derailment potential is reduced by the trains’ deeper confinement. In comparison, Metrorrey’s Line 1 concrete segmental viaduct, completed in 1991, lacked aesthetic appeal and its construction was intrusive, among other deficiencies.

To enlist crucial neighborhood support for Line 2, Metrorrey engineers initially asked for a full-span precast concrete girder concept with a cross-section similar to the one used for the Santiago Metro in Chile, South America’s most modern and extensive light-rail system. Weidlinger’s team persuaded Metrorrey that concrete segmental technology had advanced significantly and it would provide a speedier and more economical a solution. Designers retained the shape of Metrorrey’s preferred cross-section but modified it to a more stable “Omega,” simplifying its dimensions to facilitate casting and erection.

The viaduct was designed and constructed in only 28 months. Spans were erected segment by segment with overhead gantries. No lane-blocking heavy girders, cranes, or underslung trusses were required. Manhours were saved by the reduction in reinforcement and the streamlined design that eliminated cast-in-place joints and traffic-blocking footings.

Weidlinger received design assistance from Garcia Bridge Engineers on the structure and Corven Engineering on the substructure (both of Tallahassee, Florida). TGC Geotecnia, Mexico City, Mexico, was the geotechnical engineer.