The loadability of ice depends on its thickness.

The ice cracks under the weight of a person and falls through.
It can support a person weighing up to 85 kg.
It can support a horse without any cargo.
It can support a horse and a ton of cargo on a sled.
It can support empty railcars.
It can support a cargo of 23 tons (artillery, tanks, tram, and trolleybus).
It can support two loaded railcars.
It can support steam locomotives of the Ch and Tk series.
It can support a train consisting of 15 loaded railcars and an O series steam locomotive