Bridges are sensitive components of the traffic infrastructure, and their lifetimes are limited. The accident at Genoa has made it clearer than ever before that they require closer attention. Weigh In Motion systems by Kistler offer an efficient way of monitoring bridge use and imposing restrictions when necessary – as illustrated by an application that is now operational in western Mexico.
A serious accident occurred on the El Carrizo highway bridge in January 2018: a tanker full of diesel fuel crashed and caught fire. Fortunately, nobody was injured – but the road had to be closed for weeks to investigate possible damage to the bridge. With a central tower that is 226 meters tall, El Carrizo is currently the second highest bridge in North America. It is a link in the spectacular route that was opened in fall 2013 through the Sierra Madre Occidental, part of the North American Cordillera.
The route from Mazatlán to Durango is important in terms of tourism as well as commercial transport, and the new road from the coast to the interior of Mexico has slashed the journey time from six or more hours to only three. But after the bridge was closed, trucks had to take a long detour through the mountains: this extended the driving time to eight hours until the route was fully re-opened to traffic at the end of August 2018. To prevent serious accidents in the future, two checkpoints with Weigh In Motion (WIM) technology have now been installed by SEMIC, who developed a customized hardware-software solution. Vehicles that exceed the permitted total weight are automatically preselected so they can be turned back at the toll plazas that were already in place. Kistler supplied the local contractors responsible for this project with the necessary technology: the Type 9835A WIM system, with four Lineas Type 9195GC41 WIM sensors and the WIM data logger (5204AC04).