Robot inspector helps check bridges for dangerous defects

When the I-35W bridge over the Mississippi river in Minnesota collapsed in 2007, killing 13 people, it was because of defects in steel plates that safety inspectors had missed. A new robot helper could help avoid such tragedies by making bridge checks cheaper and more accurate. Surveying a bridge used to involve drilling into the road to check the concrete and steel structures underneath. Although radar has simplified the work since the 1980s, sending out teams of people to check bridges is still expensive and can require extended road closures. The upshot is that many bridges are overdue a health check – thousands in the US alone, for instance.