Grade separation pedestrian systems (GSPS), including skywalk systems and underground pedestrian
systems (UPS), have been an emerging phenomenon in the city centres of megacities since early last century.
Despite the examples of many successful GSPS in operation around the world, the application and performance of
GSPS are not yet well understood by local authorities. This review discusses the functionality of GSPS through an
examination of the performance of GSPS in terms of opening hours, facilities for vulnerable populations, signage
systems, spatial structure, arrangement of entrances/exits, transportation, safety issues, comfort and amenities.
Issues that have emerged from previous discussions in relation to their negative impacts on street life, social
inequality of their usage and the privatisation of public spaces of GSPS are also discussed. The review concludes
that GSPS have a diversity of functionality in varied urban settings. It also reveals shortcomings in the performance
of GSPS. The literature review suggests research aspects that need to be updated, including the lack of
empirically based studies, particularly studies from the perspective of the pedestrians using the systems, and a
lack of investigation of the functionality of GSPS in cities other than North American cities, in particular, cities
with UPS in developing countries.

• Assessing grade separation pedestrian systems: Planning, design and operation