South Africa is experiencing a rapid rate of urbanisation, and as a result is struggling to expand infrastructure, build housing, provide health care and educate its population. Transit Orientated Development (TOD) is well known worldwide urban phenomenon linking transport infrastructure to property development in a sustainable way. It is possible that TOD principles, developed carefully within a South African context could help urbanise South Africa in a rapid, sustainable way.

Major centres in South Africa are experiencing rapid urbanisation, this is compounded by a burgeoning immigrant population from the SADC region. Johannesburg, Specifically the Gauteng city region is set to grow into a MegaCity of 30million people in the next 40 years or so (Wood, et al).

GAPP has carefully outlined a scenario of urban densification under the GSDF that aims to densify the extensive urban sprawl that exists in post Apartheid South African cities. It is carefully based on identifying sustainable city building solutions by identifying pockets of redundant land around existing and potential transport interchanges for development. This study also identifies expanded rail/transport systems as a logical extension of existing networks by consultation with transport planners.

So how to accommodate all these people in a sustainable way? It is no secret that sustainable cities (or those that are close to being so) are cities which have a great urban transit network, linked to an advanced land use policy which seeks to lessen the use of the private motor car. So how do you link land use and urban transit? Again, there is no secret here, urban transit stations (rail, BRT, etc) are well known to be great attractors of activity, especially if there are interchanges between different modes of public transport (i.e. a "modal" interchange). These places become great meeting points, retail outlets, service outlets and desirable places to live, if you can't afford a car. These hubs exist all over South Africa in a natural response to a creation of a modal interchange at any given location.

Unfortunately, these nodes have been allowed to grow without any form of guidance. Transport planners don't speak to town planners, so what results is an urban "free-for-all" that does not address land use in and around these nodes, especially with walking distance (500-800m radius) of the hub. People are crammed onto pavements, have to cross busy streets and bus ranks, do not feel safe and have to walk vast distances to their homes.

Retailers are either street traders, traders in poorly planned and built markets, or mainstream retail outlets crammed into a traditional "mall" some way from the node with high security. Notwithstanding this, they are hidden gems. If masterplanned properly, these nodes can become great places which thrive with activity. To really let these places take off you have to link them to each other via the transit network so that each node becomes a destination in its own right. If these "destinations" can offer people "work, live, play", i.e. allow people to live work and socialise without having to jump in their car. These nodes then become a "necklace of pearls"4 (Fig 1), where the "pearls" are high density nodes of mixed-use activity linked together along transit routes, be they BRT, rail or other transit network , the "the necklace".

This type of concept is further enhanced by creating a "bi-directional flow". Because each of the nodes is a destination in its own right, there is no need for the working population of a large city to surge into the CBD in the morning and then rush out in the evening, creating a wasteland after hours and letting the transit network sit and do nothing in between. Instead people ideally move in both directions, working in one node, living in another. Visiting friends and relatives, shopping, etc. This then evens out the flow in the network, allowing all day usage and therefore increasing the viability of the transit network.