(AP) — At least two major U.S. freight railroads are trying to install cameras in their locomotives to make sure crews are following rules and avoiding cellphone use.

Union Pacific filed a court action this week asking a federal judge to declare that it has the authority to install the cameras under the railroad’s labor agreements. Kansas City Southern railroad won a similar lawsuit last month over the objections of labor unions.

Installing these inward-facing cameras to monitor crews was recommended by the National Transportation Safety Board after the 2008 collision of a Metrolink commuter train and a Union Pacific train in southern California that killed 25 and injured more than 100.

Metrolink did install cameras after that crash, which was blamed on a distracted engineer sending text messages.