Transport Planning & Operations

The research program in transportation planning and operations is broadly focused in four areas:

• Travel behaviour research for developing countries
• Public transport – network and operational planning
• Access, mobility and exclusion
• New technologies and data in transport

Examples of recent work in these areas:

Using stated preference analysis and market segmentation to plan better public transport in Johannesburg

Advanced revealed and stated preference surveys using computer-aided interviews were used to derive models of modal captivity and choice for commuters in Johannesburg. The models showed that about half of commuters are effectively captive to public transport, while about 16% are so-called "lifestyle" car captives - people whose lifestyle choices and preferences mean that they will never consider taking public transport for daily travel. Amongst the remainder, so-called choice passengers, most people value cheap fares and short walks and waits for public transport much more highly than fast buses. This has implications for how and where we deploy bus rapid transit (BRT) in our cities.

Useful references: "Segmenting the Market for New modes Using Stated and Revealed Preferences", Transportation Research Record, 2018.

Using GPS tracking data to assess the social equity of toll versus fuel levy funding mechanisms for freeway upgrades

A sample of 720 drivers in Gauteng were tracked over multiple days to understand and measure driving patterns, including the frequency and distances of freeway use. By examining how these patterns differ across different income segments, researchers were able to calculate what the impact would be of changing the Gauteng e-toll scheme into a dedicated fuel levy scheme. The results showed that, because low-income people tend to use freeways less and drive less fuel-efficient cars than higher-income drivers, they would be more adversely affected by a dedicated fuel levy than by a freeway toll.

New metrics for measuring the accessibility benefit of transport

In collaboration with the HSRC, CTD researchers developed a new method for measuring and mapping spatial accessibility that is particularly relevant to low-income public transport users. Called access envelopes, the technique takes the availability and routing of public transport services, the location of job opportunities, the wage earnable at these jobs, and the cost and time needed to travel to these jobs into account. The final indicator reflects the net wage a worker can expect to access from a particular location, taking all these factors into account. The method has been applied in Tshwane and Johannesburg to evaluate the social impact of various public transport strategies.

Useful references: 

• “Access envelopes: A new accessibility mapping technique for transport and settlement planning”. Town and Regional Planning, 2014.
•  “Assessing the potential of bus rapid transit-led network restructuring for enhancing affordable access to employment – The case of Johannesburg’s Corridors of Freedom”. Research in Transportation Economics, 2015.
• “Time-series analysis of accessibility in the city of Johannesburg”, Southern African Transport Conference, 2017.
• “Accessibility in a Post-Apartheid City: Comparison of Two Approaches for Accessibility Computations”, Networks and Spatial Economics, 2017.

Accessibility as a participatory planning tool

CTD researchers have been collaborating with MIT to test a web-based, interactive approach to engage citizens in local planning of their transport solutions. The approach, named CoAXs (Collaborative Accessibility-Based Stakeholder Engagement for Public Transportation Planning) was tested during four workshops that were held in Pretoria during 2018. The results indicated that while it holds promise, further tailoring of the interface is needed to improve its responsiveness to the concerns of local communities. CoAXs is simultaneously being tested in other cities, including Bogota (Columbia) and Concepcion (Chile).