Anyone who has ever ridden a city bus knows that it can be a bumpy ride. Now, a team of UTS researchers from the has measured just how bumpy it is, potentially paving the way for more comfortable public transport.
The research team, led by UTS Professor of Risk Management and Injury Prevention David Eager, investigated the various types of movement passengers encounter during bus rides on routes across the Sydney CBD.
The study, titled “City bus seat vibration analysis using 6-axis accelerometer and gyroscope sensors,” was recently published in leading science journal, Nature.
The researchers used specialised devices to measure acceleration in different directions, including forward-backward, side-to-side, and up-and-down motions.
“We wanted to measure these vibrations because they have the potential to affect passenger comfort and even contribute to long-term health issues,” said Professor Eager.
The study measured the vibrations and sudden movements frequently experienced by bus passengers during starts, stops, and turns, especially in urban traffic conditions.
These movements can be more noticeable and potentially uncomfortable compared to other forms of transport like trains or long-distance coaches.
The researchers discovered that average seat acceleration during bus operation was about 0.12 times the force of gravity, with peaks reaching up to 0.44 times gravity.
This level of vibration can lead to discomfort for passengers, particularly those with pre-existing health conditions such as muscle weakness or spinal issues.
Dr Anna Lidfors Lindqvist, a lecturer at the School of Mechanical and Mechatronic Engineering at UTS and co-author of the study, said that one of the key metrics measured was ‘jerk'.
“Jerk is what you feel when the bus brakes or accelerates. It's the rate of change in acceleration, and if it's done very quickly, you may feel it like a jolt where your body is pushed forward or backward in your seat.
“If you have been on a city bus, you have likely experienced this due to sudden changes in traffic or when a bus stops or starts to pick up passengers.
“Research suggests that jerk might be a better indicator of passenger discomfort than just measuring acceleration alone,” said Dr. Lidfors Lindqvist.
Previous research at UTS on lift comfort shows that rapid changes in acceleration cause passenger discomfort.
The implications of this research also extend beyond individual comfort.
“We know from studies by other researchers that prolonged exposure to whole-body vibrations can cause fatigue and pose health risks such as musculoskeletal disorders or injuries involving the lower spine, neck and shoulders.” said Professor Eager.
To improve the riding experience and safety, the research team has identified several potential enhancements, including better suspension systems, redesigned seats to absorb vibrations more effectively, and driver monitoring systems to encourage smoother driving practices.
These changes could not only make rides more comfortable but also improve fuel efficiency and reduce wear on vehicles.
Professor Eager said that while the findings may not surprise regular bus users, the study provides valuable data that can serve as a baseline for future improvements in bus design and operation.
“Now that we have quantified these vibrations, we can measure the effectiveness of any changes made to improve ride comfort.”
Changes could involve optimising design trade-offs or driver operations using AI tools for predictive modelling.
The team's work opens up possibilities for collaboration between engineers, health professionals, and city planners to create public transportation systems that are not only energy efficient but also prioritise passenger well-being.
“As cities worldwide promote increased use of public transport to combat traffic congestion and meet climate goals, it's essential that passenger comfort and safety are prioritised to encourage more people to choose buses over private vehicles,” said Professor Eager.
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