Public transport facilities are not something most Indian cities are proud of. In many cities, it is a no-win situation, with passengers encountering poor quality of service and the transport corporation running on losses. Now, engineers from the Department of Civil Engineering, Indian Institute of Science, Bangalore, have proposed a new take on changing this situation in the Bangalore metropolitan area. In a recent study, the researchers have devised a ‘hub and spoke’ model for bus routes in the city.
This model, the researchers claim, outperforms the existing system on indicators of operational efficiency. If implemented, it would mean a reduction of fleet size by 19.17%, save about 67103 litres of diesel per day and reduce the required workforce by 5575 staff. This could translate to a whopping 200 crores of saving for the transport corporation per year! It would also contribute to a significant reduction in carbon dioxide emissions, making it a step towards sustainability as well.
The existing routes serviced by the Bangalore Metropolitan Transport Corporation (BMTC) follow a simple point-to-point (P2P) network pattern, where every node (bus stops, in this case) is connected to every other node. If one wants to get from point A to point B in the city, he/she simply takes a bus from point A that is travelling towards the destination. In contrast, a ‘hub and spoke’ model identifies a limited number of central ‘hubs’ at the busier or more important routes. Each of the non-hub nodes is connected to one of these central hubs by feeder routes- which act as ‘spokes’.
“The inspiration for this work was that the BMTC has recently set up as many as 10 Traffic Transit Management Centres (TTMC) all around Bangalore city integrating the functions of a bus depot/bus terminal along with a plethora of added facilities for passengers like park and ride, commercial establishments, etc. This has opened up a unique opportunity for centralised operations and we wanted to demonstrate that a huge improvement in efficiency is possible if these centres were properly utilised”, says Prof. Ashish Verma, who led the study. Accordingly, in the proposed hub and spoke network for the city, the hubs are chosen to be in places where TTMCs already exist.
In the proposed hub and spoke model, the route from point A to point B now becomes point A –> Hub 1 –> Hub 2 –> point B, Hubs 1 and 2 being the respective central hubs to which points A and B are allotted. From an individual passenger’s point of view, taking such a circuitous route seems quite counterintuitive, not to mention the one or more transfers in between. Yet, looking at the bigger picture, the model promises distinct advantages.
The current point-to-point route based system in a large city leads to a vast number of long transit routes which overlap on certain corridors leading to bus bunching (unnecessary pile up of buses in the same route) and road congestion in these parts. Compared to this, in a hub and spoke network, the number of routes and operation costs go down due to hub based centralised operations. These translate to advantages to individual passengers in the form of lower fares and waiting times, prevention of bus bunching and improved quality of service.
A paradigm usually used in airline and communication networks thus far, Prof. Verma and his team have now adapted this hub and spoke pattern to suit the specific requirements of a bus transit network. The design of this model involves consulting traffic data and deciding the hub locations, allocating each bus stop (nodes) to one of the hubs, finding optimal routes between the hubs and between a node and a hub, and determining the required frequency of buses on each route.
“We gathered transit data from a comprehensive transport study of the whole of Bangalore city done recently and treated designing the model as an optimisation problem”, explains Prof. Verma. To solve these computationally intensive problems, the engineers made use of a ‘genetic algorithm’ – called so since it mimics the process of genetic evolution. Here, an initial set of solutions is improved upon in each successive ‘generation’, until the desired solutions are reached.
The hub and spoke network design for the Bangalore as suggested by the researchers consists of 12 hubs, 132 optimal inter-hub routes, 2904 nodes and 212 feeder routes. The higher number of bus transfers made necessary by this model are expected to be taken care of by the smooth transfer facilities available at TTMCs, making travel times, transfer times and bus waiting times reasonable for the passengers.
The results of the study have been submitted to BMTC and are under consideration. The hub and spoke model sure looks like the right step for Bangalore towards an efficient and sustainable transit network.