This paper examines the traffic and environmental impacts of various scenarios of freight vehicle restrictions in the major streets of Metro Manila. Vehicle flows and emissions are estimated for a range of alternative scenarios involving truck restraints on urban roads. Network flows are approximated through a traffic assignment model and an origin-destination matrix for Metro Manila. Vehicle emissions are then estimated using speed and emission factors. The study is aided by Geographic Information System (GIS) particularly in setting-up the transportation network and in data manipulation and visualization. The alternative scenarios are then compared and analyzed for two spatial areas; i.e. regional and area-specific areas. Results of the study show that the existing large freight vehicle restriction policy is not very effective when viewed from a regional scale, although if viewed from an area-specific scale, it can be very effective in reducing local traffic and environmental impacts.