Making headway on ‘bus bunching’

New research from transport engineers at the University of Melbourne is shedding light on the causes, consequences and control strategies surrounding one of public transport’s most intractable and annoying features: bus bunching.

Bus bunching refers to a situation where two or more modes of transport on the same route end up closely following each other, rather than maintaining a regular and evenly spaced schedule. It is a pervasive issue affecting urban public transport globally, leading to delays, inefficiencies and passenger dissatisfaction.

And in the context of global attempts to address the climate crisis it is timely and relevant.

According to PhD researcher Mustafa Rezazada, to curb emissions people are being encouraged to use public transport wherever possible, but the reliability and efficiency of PT is a make-or-break factor affecting commuters’ willingness to regularly opt for bus, tram or train.

“We’ve all been in situations where we wait ages for a bus to arrive, only to have three arrive at once, the first one packed with passengers, the third half empty says PhD researcher Mustafa Rezazada, who authored a paper on the topic recently published in the journal Transport Reviews. The paper was co-authored with colleagues Dr Neema Nassir and Professor Egemen Tanin from the University of Melbourne and distinguished Professor Avishai (Avi) Ceder from the Technion-Israel Institute of Technology in Haifa.

“Bus-bunching is not only frustrating, it can have a significant impact on people’s ability to be on time for work, school or other appointments, their comfort and overall willingness to use public transport,” he says.

“Imagine traveling from point A to B, like from Melbourne CBD to the University of Melbourne, in either five or ten minutes. However, upon arriving at your destination stop, you find yourself waiting just a few meters away from the stop for an additional five minutes for the bus ahead to depart. This kind of experience can be exceptionally unpleasant, especially if it causes you to be late for a crucial meeting or important work appointment. This is a clear example of how bus bunching can disrupt our daily activities and travel experiences.

“Our research offers practical solutions and insights that can significantly improve the reliability and efficiency of public transport systems. With the increasing focus on sustainable urban mobility, addressing bus bunching is crucial for encouraging more people to use public transport.”

The team has created a framework to evaluate and categorise control methods to address bus bunching. This framework considers the interests of both passengers and operators (most existing solutions prioritise operators), providing a structured approach for decision-makers.

Managing the problem is multi-faceted and the researchers explored potential trade-offs while advocating for solutions that enhance both user experience and operational efficiency.

The study introduces a user-centric perspective by considering passenger behaviours, preferences and incentives. The authors note that even slight adjustments, like changing the location of payment devices to speed up boarding, offering incentives, and providing real-time information about the next arrival and onboard crowding can influence user willingness to wait, help distribute loads evenly, and ultimately lead to more consistent headways and fewer instances of bunching. Additionally, hybrid methods, such as combining occupancy-based priority mechanisms at signalised intersections with adaptive holding or stop skipping, show potential.

Recognising the role of emerging technologies like real-time data collection and machine learning, the research suggests aligning control strategies with these advancements to proactively prevent bus bunching.

The team is now looking into tram bunching and working closely with PTV/Yarra Trams to develop a model that accurately simulates real-world bus and tram operations and bunching, Research findings will be coming soon.