Is this a bug/mistake?

[Huib Versloot]

There should be no difference anymore between heavy and medium bridges since Bridging engineers can only construct medium bridges (program limits). Most tanks in the game have since been modified to be able to cross medium bridges (some may have been forgotten, like the Churchill Crocodile for example).
From a design point of view this was the best option. It is near impossible to find out how much weight each bridge could carry in an historical scenario anyway.

Huib