mega roller moduals usual width of a mega roller is 6 railways thick 
front to back
spider leg modual to effectively place studs and allow suspend the
foundry cantilevering it over where the placing cement blocks are suppose to go moments after being finished 
then the docking to the main tower
rear rail yard that supplies logistical back bone wraps around the tower in casing the lower sixth in a web of struts
if its a super roller or a perpose built digger it can have huge scooped arms iether side of it bulldoying the old world to feed the furnace and keep the factories supplied with iron