River Crossing rule rationale?

[Blackcloud6]

Within the time span of most scenarios (4-6 hours) it is mostly assault boats and pontoon crossings for vehicles (ferries), especially when we look at early WW II scenarios.  With such scenarios spanning a timeframe from 1936 through 1951 the ruleset needs to accommodate a huge change in tactical capabilities.

One could put in Bailey Bridges for US and UK forces and they could be constructed in some of the longer scenarios.