Is the work of a civil engineer in drawing and supervising construction plans considered usury, taking into account that some of these projects result from usurious loans?

It is permissible for you to work in mapping and supervising it, provided that you do not map out forbidden places such as usurious banks and liquor halls, as that would constitute aiding in sin. However, mapping out a permissible building, even if its owner will borrow with usury, is not problematic, because you are not aiding him in usury; rather, you are performing a permissible act. The Prophet, peace and blessings be upon him, and his companions, engaged in buying and selling with the Jews despite their involvement in usury. Similarly, selling building materials is permissible for someone who builds a permissible building with them, even if the owner deals with usury.