Guide bars, or guiding bars[1] are rubber-tyred metro systems that incorporate track. They have angle irons as outside of the two roll ways.
The Busan Subway Line 4 lacks a rail track, and has I-beams installed as guide bars.
The flanges are vertical. The Sapporo Municipal Subway, that lacks a rail track as well, has no guide bars. It has a central guide rail instead. Guide bars are also used to provide guidance for guided buses.