Dive summary:

• It appears, based on a study from Sweden, that bridge maintenance engineers are in the same boat as drivers in the north when it comes to worrying about the corrosive effects of salt used in roads in winter.
• Researchers looked at 10-year and 25-to-35-year time frames for two types of concrete and found that chloride ions progress through them to reach steel reinforcing inside.
• The work was done with computer models that assumed heavy traffic moving at speed over salted structures. The researchers said they think it will help both with maintenance and with bridge design to find less salt-permeable materials.

From the article:

Swedish scientists have studied models to help road and bridge maintenance engineers work out how much damage salting the roads in winter might cause to steel-reinforced concrete structures. ...