Well: https://en.m.wikipedia.org/wiki/La_Compagnie_des_glaces https://en.m.wikipedia.org/wiki/La_Compagnie_des_glaces Rail based mobile fortresses with hundred

Well: https://en.m.wikipedia.org/wiki/La_Compagnie_des_glaces https://en.m.wikipedia.org/wiki/La_Compagnie_des_glaces Rail based mobile fortresses with hundreds of powered axles are a totally normal thing in this setting. All it took was a new ice age & railway comapnies taking over what remained from human kind and banning all non-rail based vehicles. End result - no cars, tanks, airplanes, ships (well, nowhere to use those anyway), with everything on rails. :-)