Measures to prevent bridge closures due to snow accumulation

Bridge closures associated with snow accumulation have become common incidents. As the phenomenon is exacerbated in cable-stayed structures, a question that arises is whether there is a solution to this puzzle.

On February 10, 2020, the Queensferry Crossing, located in Scotland, was closed due to falling ice. The bridge is the world's longest cable-stayed structure with 3 towers, stretching for 2.7 kilometers. It was opened in summer 2017 at a high cost of about $1.76 billion. 

Before the facility's closure, at least 8 vehicles were hit by ice fragments but, fortunately, there were no victims. Martin Aitchison, a motorist whose car was damaged by falling ice, said he was frightened by the impact and could not understand what hit his vehicle. "I was going southbound when there was a huge bang and the windscreen has blown. I drove on another 200-300 yards (180-275 meters) and stopped just behind an Amey truck. The guy who was there started pointing up at the bridge," Mr. Aitchison stated.

Public opinion was judgmental as transportation challenges were caused for the 80,000 people that utilize the facility daily. 

The bridge re-opened 2 days later. Similar issues are common in most bridges located in freezing environments. 

Officials for the Port Mann Bridge, located in Vancouver, Canada have found a measure to address the issue. In particular, they wrapped metal chains around the suspension cables of the bridge which were released to mitigate the snow accumulation. The method is not automatic as the chains are released manually and its success relies on the proper operation of the system. Nevertheless, this technique would not be appropriate for the Queensferry Crossing as it would harm the facility's cables.

Scientists state that tacking the problem is extremely challenging. Certain measures have been tested but have not been efficient. "Ice is a very difficult problem to deal with. We have tried in the past many different solutions, coatings on cables, heating systems, even helicopters to come and try to blow all the snow and ice off with downwash, but it is a very difficult problem," Christos Georgakis, Professor of Structural Dynamics and Monitoring at the department of engineering, Aarhus University in Denmark, stated.

According to Prof. Georgakis, there may be a radical solution to the problem. The concept is based on protecting the vehicles from the falling ice by retaining it in the bridge's framework. Plastic or steel specialized equipment could be inserted in the bridge's cables to hold the snow until it finally melts. 

Regarding the Queensferry Crossing, officials from Transport Scotland stated that a detailed investigation of new solutions to address the issue is being carried out. Given that every region experiences different weather conditions and that the design of the bridge is unique, finding the best solution is difficult. In the following period, specialized sensors capable of measuring the ice accumulation will be installed on the facility.