The most obvious thing everyone is missing is the type of truck used to transport these units.  Are they extra heavy duty or are they just flat bed trucks.  Modular homes which are empty weigh much less  than the ones which are packed with road building equipment and supplies.  What ever they are doing, one thing is for sure they are building something.  The next major shipment along the route will tell the real story. A convoy a mile long would indicate major construction activities, like a road, that's when things get real interesting.