Ahh, infrastructure. In this case the program is working as designed. Max infrastructure per province should be 200%. Each infrastructure build raises the level by 5% in 1.09. Therefore, in your Washington D.C. example 150 + (10 * 5) = 200. The build list only allows province improvements to be raised too their maximum level during serial construction runs. Now there is a bug apparently which will simply stop infrastructure serial runs at certain high percentages. This has been corrected in version 1.10 supposedly.