Frankly, there are very few public officials who have the guts to tell the truth about this subject. It is a TCM, because constraining available roadway obviously discourages people from driving. In contrast, HOV lanes are not TCMs unless they are created from existing lanes. In other words, they are for all practical purposes synonymous with highway expansion. You are putting the cart before the horse.
Air quality is mandated by law.
Transportation plans must conform to air quality requirements, not vice versa. You quote the federal Clean Air Act as including highways among indirect sources, and hence coming under the purview of indirect source controls. Please elaborate on this. Guidance is needed here. The AB471 discussion is irrelevant, if it isn't funded yet, particularly since its overwhelming emphasis is on highway expansion .