Building a Prototype LPG Public Utility Vehicle for Philippine Public Transport

The “jeepney” is a major mode of public transportation in the Philippines which are essentially re-purposed U.S. military jeeps leftover from WWII. It has since evolved from 6 to 18–22 passenger vehicles, a large number of which are plying Metro Manila routes. Currently, most jeepneys are fabricated in backyard shops using imported second-hand diesel powertrain components fitted on locally made chassis and body. Since the basic design is unchanged except for its length, the jeepney provides an uncomfortable ride, with high levels of diesel emissions, and insufficient safety features. To address these issues, the Philippine government in 2017 launched the Public Utility Vehicle Modernization Program (PUVMP) to provide a safer, more efficient, and environmentally sustainable transportation system in the country. A major feature of the PUVMP is the replacement of jeepneys with PUVs (minibuses) of similar capacity based on Euro 4-compliant diesel OEM vehicle platforms. This feature assured compliance with engineering and local vehicle standards and mass production by established light truck and bus builders. In line with efforts to use other clean/alternative fuels for this transport mode, a project to build a prototype LPG-powered PUV was undertaken. The project sought to determine the technical feasibility of locally building this vehicle given existing Philippine supply chain conditions which cater only to diesel vehicles for public transport. This paper narrates the experience from building the prototype, design features, difficulties encountered, successes, and lessons learned. The foremost difficulty encountered is the unavailability of a gasoline or LPG OEM vehicle platform for this application. A gasoline engine with an LPG conversion system fitted to a diesel rolling chassis was instead implemented to form the powertrain. Full system integration could not be achieved due to the lack of engine ECU documentation. Electronic fare collection, CCTV, dashcam, public address system, internal/external signages, and a wheelchair lift were installed for passenger convenience, safety, and access for PWDs. Because of restricted under chassis space, the wheelchair lift was mounted at the rear instead of the ideal curb side of the vehicle. The air conditioning ventilation system was designed using CFD to minimize cross flow of breath particles among adjacent passengers to mitigate Covid-19 transmission. The main feature of the ventilation design is the installation of cabin air exhaust ducting with appropriate grilles and exhaust fans below the side-facing bench-type passenger seats. This resulted in a vertical bulk flow with minimum eddies of airconditioned air from ceiling ducting grilles to the underside of the passenger seats. The prototype LPG PUV was tested on a university passenger route for final LPG tuning for acceptable performance. If government policy on clean alternative fuels wants to immediately mainstream LPG PUVs in the Philippines, OEM vehicle platform supply issues need to be resolved first or consider completely built units for the initial roll out.