A valve assembly is provided, wherein the valve assembly includes: a valve member; a base including a base portion, at least two columns and at least two through holes, the base portion including a first side and a second side opposite to each other, the first side being configured to be abutted on a mounting surface, the at least two columns being protrusive from the second side and configured to support the valve member, the at least two through holes being disposed through the first side and the second side respectively and configured for installation of at least two positioning members which are configured to be disposed through the at least two through holes and secured to the mounting surface; and at least two fasteners being disposed through the valve member and connected to the at least two columns respectively.

Personal transportation system includes plurality of personal transportation vehicles (PTVs) driven on a track network with series of track sections. PTV main section has lateral width adapted to contain single occupant. PTV driving mechanism propels PTV and includes track engaging element protruding downwards from main section and having narrow lateral width such that main section is prone to fall over when PTV is at rest. The space between lateral width of main section and track engaging element can be occupied by public infrastructure. Each track section includes a ground portion, minimally adapted to accommodate track engaging element lateral width, and an empty space above ground portion, free of non-transient obstacles and minimally adapted to accommodate main section lateral width. A guidance mechanism guides PTV along track network and prevents PTV deviating from track sections. A stabilization mechanism stabilizes PTV along track network and prevents PTV from falling over when turning/merging/diverging.

Personal transportation system includes plurality of personal transportation vehicles (PTVs) driven on a track network with series of track sections. PTV main section has lateral width adapted to contain single occupant. PTV driving mechanism propels PTV and includes track engaging element protruding downwards from main section and having narrow lateral width such that main section is prone to fall over when PTV is at rest. The space between lateral width of main section and track engaging element can be occupied by public infrastructure. Each track section includes a ground portion, minimally adapted to accommodate track engaging element lateral width, and an empty space above ground portion, free of non-transient obstacles and minimally adapted to accommodate main section lateral width. A guidance mechanism guides PTV along track network and prevents PTV deviating from track sections. A stabilization mechanism stabilizes PTV along track network and prevents PTV from falling over when turning/merging/diverging.