As for roads, I'm yet to see the place in the constitution where the federal government is granted the power to build roads.
Article I Section 8:
"The Congress shall have Power ... To establish Post Offices and post Roads"
This clearly grants the federal government the authority to engage in infrastructure projects in the fields of communication and transportation. The TVA needs a broad interpretation of the necessary and proper clause for its electricity infrastructure to be deemed constitutional. Building the interstate highway system doesn't.