Alternative Mobility Funding Systems and Impact Fees; Authorizes local governments to adopt alternative mobility plan & fee system; provides requirements for application of adopted alternative system; prohibits alternative system from imposing responsibility for funding existing transportation deficiency upon new development; prohibits local governments that do not issue building permits from charging for transportation impacts associated with development; requires local governments that issue building permits to collect for extrajurisdictional impacts; prohibits local governments from assessing multiple charges for same transportation impact; revises requirements for calculation of impact fees by local governments & special districts.