Also using the cards for building depots, forts and redoubts would be logical, keep the element builds as a back up but increase the cards for building these.
Change the "Defensive works" to something else, people use it for loyalty, I propose just one "Public Works" card to replace it and "Development".
The Virginia Board of Public Works was a governmental agency which oversaw and helped finance the development of Virginia's transportation-related internal improvements during the 19th century. In that era, it was customary to invest public funds in private companies, which were the forerunners of the public service and utility companies of modern times. The state often invested in up to 40% of the stock to build turnpikes, toll bridges, canals, and water and rail transportation enterprises.
In 1861, with the onset of the American Civil War, Virginia's investments in "Public Works" was interrupted. The State had purchased a total of $48,000,000 worth of stock in turnpike, toll bridge, canal, and water and rail transportation enterprises.
https://en.wikipedia.org/wiki/Virginia_Board_of_Public_Works