In very cold weather, what issue could a train operator expect when making up trains in a yard?

In very cold weather, train operators can indeed experience issues with the doors of train cars. When temperatures drop significantly, mechanical components become more rigid and can freeze. This can lead to doors not opening or closing properly, or becoming stuck—all of which can hinder the process of making up trains efficiently in a yard. Additionally, the lubrication in door mechanisms can become less effective in extreme cold, increasing the chances of malfunctioning.

While other factors, such as frozen tracks, engine issues, and brake malfunctions, can also occur due to cold weather, the problem with doors is particularly prominent during the assembly of trains. Door malfunctions can lead to delays in loading and unloading cargo or in the overall readiness of a train, making it a critical concern for train operators operating in frigid conditions.