(ABC 6 News) – One day after the Baltimore Key Bridge collapse, construction workers are still missing and are now presumed dead. As Baltimore crews shift to a recovery phase, the Iowa Department of Transportation shares how it makes sure bridges are safe no matter what comes their way.

“The older bridges aren’t always designed for the type of impacts that we could have now, so that’s why we built dolphins. Newer bridges are designed to take the impact themselves, without having to build a dolphin in front of them,” said Scott. Neubauer, the bridge maintenance and inspection engineer at the Iowa Department of Transportation.

IDOT is required to inspect bridges every two years regardless of their condition. Inspectors have the authority to shut down passage if they see something that looks concerning.