My friends and I feel that G40 would be well served by a land base (that can be purchased and tactically bombed) to match the role of Air bases with air units, and Shipyards with naval units. I think the obvious candidate here is rail!
But rather than create a complex rules dynamic with special territory restrictions, I think it should be a base like the ones for air and ships. Provides a simple movement bonus to units that start their non combat movement phase on a territory with a railroad. Infantry, Artillery, anti aircraft artillery guns, move +1 out of a territory that has “Rail” for its land units, tied it’s operational ability.
This seemed a very simple way to get rail into the game, but also to provide some limit on its combat effectiveness by restricting the advantage to the non combat phase.
Basically the purchase cost and abilities would match the cost of air bases and shipyards, but this Rail system would be for ground units.
The total number of units that can move out of rail territory could be limited to 3 if desired and tied to the operational status of the railway. For example, at full operation, the rail can move at a total of 3 ground units +1 space on non com. If it is Tac bombed -1, it may only move 2 ground. If Tac bombed -2 it can move 1 ground. Tac bombed -3 and it is inoperative and cannot move any ground unless repaired.
Movement could also be restricted if desired, only along territories which have railroad bases connected (so you must both begin your non combat moment and end it at a territory with a rail hub.) Basically rail to rail for movement purposes. Or we could run it just like the other tactical movement bases. Long as you start your non com in the territory you get the +1. Questions might be whether to allow tanks or mechs to move along the rail hubs.
The rail base marker could be the same size as shipyards and airbases, with a similar design aesethetic, but including a simple railway or engine graphic to easily distinguish it from the other two.
So here you have the normal production facility units, which are tied to strat bombers. And the 3 tactical facilities, one for land, air, and sea, tied to tactical bombers. Starting rail would be limited to just a few locations at the beginning. The transcontinental railroads in North America and Europe. The Trans Siberian across Asia.
Prime candidate territories for a starting Rail base might be places like…
Moscow, Novosibirsk, Yenisey and Buryatia.
Poland, Germany, Western Germany, France.
Ontario, Eastern United States, Central United States, Western United States etc